Journals >Chinese Journal of Lasers
Contents
2006
Volume: 33 Issue suppl
126 Article(s)
Export citation format
Research Article
Spherically Symmetric Optical Resonant Cavities with Diameter in Microns by Melting a Fused Silica Fiber
[in Chinese], [in Chinese], and [in Chinese]
Ultrahigh-Q micro spherical cavities with micron dimension diameter is obtained by melting the tip of a fused silica fiber with two counter-propagating CO2 laser beams. And the two counter-propagating light beams optical system is designed and realized. To acquire the optimal condition, the full cavity-formed conditionUltrahigh-Q micro spherical cavities with micron dimension diameter is obtained by melting the tip of a fused silica fiber with two counter-propagating CO2 laser beams. And the two counter-propagating light beams optical system is designed and realized. To acquire the optimal condition, the full cavity-formed condition, the ablation process is investigated in real time by a monitor system self-designed. The geometrical figures of built cavities and the surface topography are checked and recorded by an optical microscope and an atomic force microscope (AFM). The results show that perfect silica micro spheres with diameters of 30~ 300 μm are acquired..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 101 (2006)
Reducing Lag Angle of Coherent Laser Imagine Radar Using Converging Beam Scanning
[in Chinese], [in Chinese], and [in Chinese]
In terms of the diploid relationship between scanners sway angle and light beam sway angle, the transient equation of lag angle is derived on the condition that scanning control function is simple harmonic wave. For parallel beam scanners, scanners sway angle is indirectly linear with the angle of scan field of view (FIn terms of the diploid relationship between scanners sway angle and light beam sway angle, the transient equation of lag angle is derived on the condition that scanning control function is simple harmonic wave. For parallel beam scanners, scanners sway angle is indirectly linear with the angle of scan field of view (FOV). The larger the telescope enlargement factor, the lower the scan efficiency. And the scanner lag angle is equal to the FOV lag angle. Numerical calculation indicates that when the parallel beam scans at 340 Hz of simple harmonic wave and the range of action is above 1000 m, the lag effect in spatial field is obvious and the heterodyne efficiency of image element is much below the threshold 20%. For convergent beam scanners, scanners sway angle is approximately linear with the FOV of scan system, and the proportional constant is related to the relative positions of the scanners. Scan efficiency of the system can be greatly increased by properly designing the relative positions of the scanners. Numerical calculation indicates that when the convergent beam scans at 340 Hz of simple harmonic wave and the range of act is above 3000 m, its maximum lag angle is 1/19 of that of the parallel beam scanner, so the lag effect is largely reduced..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 103 (2006)
Modification of Lidar Equation in Large Field of View
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The most important thing in the nonscanning lidar theory is the lidar equation. The classical lidar equation is suitable on the condition that the field of view is very small and the backscattering of the different part of the target is almost same, but it's unsuitable when the field of view is not very small, whenThe most important thing in the nonscanning lidar theory is the lidar equation. The classical lidar equation is suitable on the condition that the field of view is very small and the backscattering of the different part of the target is almost same, but it's unsuitable when the field of view is not very small, when the backscattering of the different part of the target is not same but follow the Lambert distribution. This paper analyses the backscattering of the target and gets a modified lidar equation suitable for the condition..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 108 (2006)
Multi-Target Tracking Algorithm Emulation Based on Coherent Ladar Range Image
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
With high angle and range resolution, the imaging laser radar is capable of producing range and intensity image of the target at the same time to form high resolved angle-angle-range-intensity images. In this paper, an ameliorated correlated algorithm is presented based on MAD and SSDA. At last, the ability to distinguWith high angle and range resolution, the imaging laser radar is capable of producing range and intensity image of the target at the same time to form high resolved angle-angle-range-intensity images. In this paper, an ameliorated correlated algorithm is presented based on MAD and SSDA. At last, the ability to distinguish similar object and to expand self-adaptively as the target become larger, tracking experiments are given under different carry noise ratio (CNR). The results show that in the present scene, the algorithm gives preferable tracking performance. No failure of tracking the target occurred and most single-frame absolute errors are sub-pixel, all of the absolute errors are below 4 pixels..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 111 (2006)
Efficient Second Harmonic Generation of Ultra Intense Femtosecond Ti:Sapphire Laser
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The methods for increasing the conversion efficiency of the type Ⅰ and type Ⅱ second harmonic generation with KDP crystal for the ultra intense femtosecond laser pulse have been discussed in detail. The results show that group-velocity mismatching is the main reason of the broadening of the second harmonic pulse and coThe methods for increasing the conversion efficiency of the type Ⅰ and type Ⅱ second harmonic generation with KDP crystal for the ultra intense femtosecond laser pulse have been discussed in detail. The results show that group-velocity mismatching is the main reason of the broadening of the second harmonic pulse and could lead to the decrement of conversion efficiency. The effects of nonlinear phase-modulation cause the distortion of the shape of the second harmonic pulse and also decrease the conversion efficiency. For the type Ⅰ second harmonic generation, the proper spatial phase-mismatching can be helpful in compensation for the decrement of the conversion efficiency caused by the self- and cross-phase-modulation. For the type Ⅱ second harmonic generation, the proper time predelay to the incident fundamental extraordinary pulse can efficiently increase the conversion efficiency, and also restrain the broadening of second harmonic pulse..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 115 (2006)
The Dual-Tripler Scheme for Increased-Bandwidth of Third Harmonic Generation in High Power Laser System
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The dual-tripler scheme of KDP crystals for third harmonic generation (THG) is studied by the equations of three interacting waves under the small signal and the high power (1.5 GW/cm2) condition. The 8 mm type II KDP tripler with an detuning angle of 0.35 mrad whereby the addition of a 6 mm type II tripler with an detThe dual-tripler scheme of KDP crystals for third harmonic generation (THG) is studied by the equations of three interacting waves under the small signal and the high power (1.5 GW/cm2) condition. The 8 mm type II KDP tripler with an detuning angle of 0.35 mrad whereby the addition of a 6 mm type II tripler with an detuning angle of -0.25 mrad can increase the bandwidth of third harmonic generation to 0.3 nm at 1.5 GW/cm2. Meanwhile, the conversion efficiency of the third harmonic generation is closely related to the distance between two triplers. If the relative phase among the three interacting waves changes π during the distance, the third harmonics from the first tripler can return to the second harmonics and the fundamental frequency and the conversion efficiency will drop by a wide margin. To ensure the optimum performance of the dual-tripler system, it is necessary to find the correct air gap during which the relative phase among the three interacting waves changes 2π..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 120 (2006)
Dynamics of All-Optical Clock Recovery Using Two-Section Distributed Feedback Bragg Lasers
[in Chinese], [in Chinese], and [in Chinese]
All-optical regeneration is the core technology in all-optical communication in the future in which the key technique is the all-optical clock recovery. Based on the carrier rate equation and the coupled wave equations the mechanism of all-optical coherent clock recovery using two-section distributed feedback Bragg (DFAll-optical regeneration is the core technology in all-optical communication in the future in which the key technique is the all-optical clock recovery. Based on the carrier rate equation and the coupled wave equations the mechanism of all-optical coherent clock recovery using two-section distributed feedback Bragg (DFB) lasers' self-pulsation is studied. Numerically simulation method is used to analyze the lockup, walk-off and phase stability in the clock-recovery process. The results indicate that the fast lockup and walk-off of the clock-recovery process are about 1 ns and on the order of subnanosecond respectively. The bit-rate detuning, bit-rate and the injection power all have influence on the phase stability. The analysis shows that the stability of self-pulsation can be enhanced by optimizing the parameters and external conditions and supply optimized designs for the research and facture of all-optical signal regeneration devices..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 124 (2006)
Application of Laser Scanning in the Underwater Optical Communication
[in Chinese], and [in Chinese]
The underwater and aerial inter-communication is realized with laser scanning technology. The construction and the principle of the two-dimensional galvanometric scanner laser scanning system are theoretically described. The methods to effectively control the laser beam with bunch expanding devices and the galvanometriThe underwater and aerial inter-communication is realized with laser scanning technology. The construction and the principle of the two-dimensional galvanometric scanner laser scanning system are theoretically described. The methods to effectively control the laser beam with bunch expanding devices and the galvanometric scanner system in the visible range and finish the scanning of the area of the goal underwater and in the air in the underwater optical communication system. And the relation among the scanning way, the scanning range and the speed of scanning is referred mainly. With the systematical simulated experiment, the realizing way and the related experimental data are obtained. Based on the light reflection principle, the mathematical relation of the mechanical angle and the optical angle is emphasized. With the experiment, the approximate calculation formulas about the rectangular scanning and the rectangular scanning area are derived. The experiment proves the feasibility of the communication method and the scanning technology, which establish the foundation for the forthcoming research and practical application..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 128 (2006)
Experimental Studies on Air-Breathing Laser Propulsion and Plasma Induced by Laser Propulsion
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A brief introduces of some experiments about using UV-preionized TEA CO2 laser pushed parabolic lightcraft is given. Using PIN to probe the intensity variations of a He-Ne laser, the information of the air disturbance due to the laser interact with the ligtcraft was obtained. The experiment showed that the focus of theA brief introduces of some experiments about using UV-preionized TEA CO2 laser pushed parabolic lightcraft is given. Using PIN to probe the intensity variations of a He-Ne laser, the information of the air disturbance due to the laser interact with the ligtcraft was obtained. The experiment showed that the focus of the parabolic lightcraft could influence the air-disturbance outside lightcraft. Two shock waves were detected for longer focus, but only one shock waves was detected for short focus, air-disturbance could be detected after 5 millisecond of laser pulse when single pulse with 32 J energy interacted with short focus lightcraft. Using monochromator detecting the spectrum of the plasma, the time evolvement process of line spectrum of the plasma has been analysised..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 131 (2006)
Emission Spectra and Gain at 1.315 μm from C2H2F3I Excited by Microwave
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
1.315 μm emission spectrum is observed by exciting C2H2F3I with microwave and main dynamic process is analyzed. Under the gas pressures of 50 Pa, 60 Pa, and 160 Pa emission spectra of 1.315 μm have been observed. This result demonstrates that C2H2F3I excited by microwave can generate iodine emission at 1.315 μm. The ga1.315 μm emission spectrum is observed by exciting C2H2F3I with microwave and main dynamic process is analyzed. Under the gas pressures of 50 Pa, 60 Pa, and 160 Pa emission spectra of 1.315 μm have been observed. This result demonstrates that C2H2F3I excited by microwave can generate iodine emission at 1.315 μm. The gain of 1.315 μm emission also has been measured by means of amplification spontaneous emission and the small signal gain coefficient of 1.02%cm-1 has been obtained by adding buffer gas of He at total pressure of 150 Pa and microwave power of 400 W..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 135 (2006)
Stimulated Brillouin Scattering in CS2 Media Under Non-Focusing Pump
[in Chinese], [in Chinese], and [in Chinese]
Using 1.053 μm, 28 ns Nd:YLF laser as pump source, adopting 3:1 inverse expander, stimulated Brillouin scattering (SBS) in CS2 liquid media under non-focusing pump is investigated experimentally. The rules of SBS energy reflectivity and pulse width versus pump energy are acquired, and compared with the results of focusUsing 1.053 μm, 28 ns Nd:YLF laser as pump source, adopting 3:1 inverse expander, stimulated Brillouin scattering (SBS) in CS2 liquid media under non-focusing pump is investigated experimentally. The rules of SBS energy reflectivity and pulse width versus pump energy are acquired, and compared with the results of focusing pump. The experimental results indicate that, SBS can be generated under non-focusing pump as also, but the threshold energy increases largely, and energy reflectivity is lower than that of focusing pump, just 17% for 155 mJ input energy. The instability of SBS energy is 10%. The rules of SBS pulse width versus pump energy are almost consistent with that under focusing pump. The pulse width of SBS is broadened with the increase of pump energy, and has a minimum ～16 ns around threshold energy..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 138 (2006)
[in Chinese]
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Amplification of high-power Stokes beam in the time serial laser beam combination by stimulated Brillouin scattering (SBS) is studied. The variation of energy extraction efficiency of Stokes beam amplification with the power density ratio of Stokes beam to pump beam is studied experimentally. The results show that enerAmplification of high-power Stokes beam in the time serial laser beam combination by stimulated Brillouin scattering (SBS) is studied. The variation of energy extraction efficiency of Stokes beam amplification with the power density ratio of Stokes beam to pump beam is studied experimentally. The results show that energy can be extracted from pump beam when power density of Stokes beam is more than that of pump beam. The more power density of Stokes beam, more energy are extracted from pump beam. There exists a maximum for the amplification of high-power Stokes beam which is restricted by the energy of pump beam, the absorption coefficient of medium and the length of medium cell, etc. The maximum of Stokes beam amplification can be increased and the higher energy extraction efficiency can be gained through optimizing the absorption coefficient of medium and the cell length..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 141 (2006)
Experimental Study on High Repetition Rate Quartz Glass Rod Stimulated Brillioum Scattering Phase-Conjugation
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
An experimental study on optical phase conjugation is developed in a double-pass high repetition rate laser diode pumped Nd:YAG amplifier. The traditional 0° HR mirror is replaced with a quartz glass rod phase conjugator. A stable phase conjugating reflection is realized at 400 Hz repetition rate with a 20 ns pulsAn experimental study on optical phase conjugation is developed in a double-pass high repetition rate laser diode pumped Nd:YAG amplifier. The traditional 0° HR mirror is replaced with a quartz glass rod phase conjugator. A stable phase conjugating reflection is realized at 400 Hz repetition rate with a 20 ns pulse width input. As a result, the beam distortion caused by the thermal effect of the gain medium is well compensated, and a better amplified output beam profile with no diffraction ring is observed. The output beam M2 is improved from 4 to 1.4. The optical breakdown or injury in quartz glass is avoided..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 144 (2006)
Experimental Study on Characteristic of Pulse Flashlamp Envelope at High Load
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The characteristic of pulse xenon flashlamp envelope, which made of cerium doped quartz glass, was studied experimentally under high input power, and the experimental results were analysed. The experimentation was performed under the condition that the input energy of flashlamp is sixty percent of the explosion energy.The characteristic of pulse xenon flashlamp envelope, which made of cerium doped quartz glass, was studied experimentally under high input power, and the experimental results were analysed. The experimentation was performed under the condition that the input energy of flashlamp is sixty percent of the explosion energy. With the number of shot increasing, map cracking occurs at the surface of the electrode, and white pattern,milky white deposition and hairline cracks emerge on the inner surface wall of the envelope. The oxygen released from the quartz glass envelope changes the color of the gas under high frequency spark discharge from indigo into green. Shock wave and thermal load are the two main effects on the envelope during the discharge. The analyse results indicate that thermal load is the major reason for hairline crack occured in the inner wall of envelope and shock wave will accelarete cracking of envelope..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 147 (2006)
Electro-Optic Q-Switched Technique for Laser Diode Side-Pumped Er:Glass Lasers
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Q-switch erbium glass lasers have important application in eye-safe laser range finder. laser diode (LD) side-pumped erbium glass laser electro-optic Q-switch experiment is reported in this paper. An Q-switched laser pulse with energy of 5.5 mJ, pulse width of 94 ns, and repetition rate of 0.5 Hz is obtained. ExperimenQ-switch erbium glass lasers have important application in eye-safe laser range finder. laser diode (LD) side-pumped erbium glass laser electro-optic Q-switch experiment is reported in this paper. An Q-switched laser pulse with energy of 5.5 mJ, pulse width of 94 ns, and repetition rate of 0.5 Hz is obtained. Experiment indicate that Q-switch delay time, pump rate and ion concentration are the major factors influencing the pulse width..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 150 (2006)
Compact Pockels Cell with 80 mm×80 mm Aperture Drived by One-Pulse Process
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Being different with the regular plasma electrode Pockels cell, the electro-optical switch is driven only through the positive and negative switching pulse voltage as the one-pulse-process (OPP) without iselated intense current plasma cells. So the reliability and the stability of optical switch are improved and its coBeing different with the regular plasma electrode Pockels cell, the electro-optical switch is driven only through the positive and negative switching pulse voltage as the one-pulse-process (OPP) without iselated intense current plasma cells. So the reliability and the stability of optical switch are improved and its cost reduced. The Pockels cell with 80 mm×80 mm aperture is designed compact and the artificial line forming technique is used in the driving source. Experimental result indictes that it has wide rang of operating pressure and negligible jitter in breakdown. The performance of the Pockels cell is excellent with static transmission of 92.9%, the static extinction of 3900, the switch efficiency of 99.7%, which are measured with pulsed laser and photodiode..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 153 (2006)
Electron Beam Properties and Lasing Experiment of FEL
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The main parts and experimental results of free electron laser (FEL) are introduced. The electron energy is about 6.5 MeV, the micropulse beam current is 4 A, the width is about 25 ps, the energy spread is 1%, the beam emittance is about 20π mm·mrad. First lasing of the far infrared FEL (FIR-FEL) at center wavelenThe main parts and experimental results of free electron laser (FEL) are introduced. The electron energy is about 6.5 MeV, the micropulse beam current is 4 A, the width is about 25 ps, the energy spread is 1%, the beam emittance is about 20π mm·mrad. First lasing of the far infrared FEL (FIR-FEL) at center wavelength of 115 μm is observed, the spectral width is 1%..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 156 (2006)
Drive Laser for the FEL Radio Fequency Photoinjector
[in Chinese], [in Chinese], and [in Chinese]
The drive laser system of the free electron laser (FEL) radio frequency (RF) photoinjector is introducted. The characteristic of the mode-locked oscillator controlling high current laser diode bar drive is presented in detail. The output power is 10.5 W, the timing jitter of the timing stabilizer is 0.56 ps. 11.9 ps GaThe drive laser system of the free electron laser (FEL) radio frequency (RF) photoinjector is introducted. The characteristic of the mode-locked oscillator controlling high current laser diode bar drive is presented in detail. The output power is 10.5 W, the timing jitter of the timing stabilizer is 0.56 ps. 11.9 ps Gaussian pulses of 266 nm wavelength are generated at a repetition rate 54.167 MHz. These “micropulses” are contained within a “macropulse” envelope as long as 6 μs. Micropulse energy of 5 μJ is abtained..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 160 (2006)
Influence of the Inherent Pre-Pulse of Blumlein Transmission Line on Soft X-Ray Laser Pumped by Capillary Discharge
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The Ne-like argon 46.9 nm laser pumped by capillary discharge was investigated experimentally. An adverse influence of the inherent pre-pulse generated by Blumlein transmission line of the capillary discharge setup on arising and stable output of soft X-ray laser was observed. The destroying effect of the inherent pre-The Ne-like argon 46.9 nm laser pumped by capillary discharge was investigated experimentally. An adverse influence of the inherent pre-pulse generated by Blumlein transmission line of the capillary discharge setup on arising and stable output of soft X-ray laser was observed. The destroying effect of the inherent pre-pulse on uniformly pre-discharging the capillary has been calculated and proved theoretically. Actually, uniformly pre-discharging gas filled in capillary before the current main-pulse is the key condition of laser arising. In order to decrease the influence of the inherent pre-pulse, a method of installing switch and capacitor for insulating the inherent pre-discharge pulse has been proposed. The experimental results show that the method can insulate the inherent pre-discharge pulse efficiently and make the discharge setup steadily operate. On the basis of this the laser spike of Ne-like argon 46.9 nm has been observed. And the stability of laser output has been realized. The range of variety of laser intensity is less than 28%..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 163 (2006)
Descriptive Method of the Optical Component's Small-Scale Amplitude Modulation
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
This article analyses the distribution of small-scale amplitude modulation and establishes its model, random amplitude modulation screen. It includes number, scale, position, and shape of small-scale amplitude modulation. Moreover, statistic analysis of the real optical component and the numerical simulation of actual This article analyses the distribution of small-scale amplitude modulation and establishes its model, random amplitude modulation screen. It includes number, scale, position, and shape of small-scale amplitude modulation. Moreover, statistic analysis of the real optical component and the numerical simulation of actual beam validate the correctness of the model..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 166 (2006)
Experimental Research on Femtosecond Optical Parametric Generation and Amplification
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Based on super-continuum white light (SWL) injection, a new method of high-energy femtosecond optical parametric amplification (OPA) is put forward which can realize the zero synchronization between 800 nm pump laser and 1053 nm signal laser, and overcome the gain narrowing effect during small signal gain amplificationBased on super-continuum white light (SWL) injection, a new method of high-energy femtosecond optical parametric amplification (OPA) is put forward which can realize the zero synchronization between 800 nm pump laser and 1053 nm signal laser, and overcome the gain narrowing effect during small signal gain amplification. In the experiment, a broadband 1053 nm laser pulse is obtained with duration of 93 fs and energy higher than 2.6 mJ just with only one stage optical parametric amplification..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 169 (2006)
Modeling of Gain Characteristics of High Average Power Nd:Glass Disk Las
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The expression for output laser intensity of solid state laser under unstable state is deduced in theory. And the gain characteristics of Nd:glass heat capacity laser is stimulated on the basis of that expression. It is shown that high pumped intensity, large emission cross-section, high aspect ratio can increase the eThe expression for output laser intensity of solid state laser under unstable state is deduced in theory. And the gain characteristics of Nd:glass heat capacity laser is stimulated on the basis of that expression. It is shown that high pumped intensity, large emission cross-section, high aspect ratio can increase the extraction efficiency. The influence of temperature on extraction efficiency can be ignored under high pumped intensity. In addition, the transmission ratio of cavity mirror has an optimum value because of the influence of temperature on the output of the pulse string..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 172 (2006)
Aberration-Free Attenuation and Compression System for High Power Large Aperture Laser Beam
[in Chinese], [in Chinese], and [in Chinese]
To diagnose the beam quality of high power and large aperture laser, a system of attenuation and compression is designed and built to realize big minification and 2D compression and diagnosis by conventional beam quality dignosis systems such as Pyrocam Ⅲ. Average power is attenuated to 104 and compression ratio reacheTo diagnose the beam quality of high power and large aperture laser, a system of attenuation and compression is designed and built to realize big minification and 2D compression and diagnosis by conventional beam quality dignosis systems such as Pyrocam Ⅲ. Average power is attenuated to 104 and compression ratio reaches 16 times of original beam aperture. The performance of the compression system irradiated by high power CO2 laser is simulated using Light Tools, and results indicate that this transformation method is simple and exact, which can realize the design targets efficiently..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 176 (2006)
Alignment of Self-Collimated Resonator and Its Two-Pass Amplification
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The beam quality of the high power master oscillator and power amplifier (MOPA) system is mainly determined by the seed of master-oscillator which needs careful optical design and precise alignment. To suppress the high amplified spontaneous emission (ASE) level in the XeCl gain medium and extract the deposited energy The beam quality of the high power master oscillator and power amplifier (MOPA) system is mainly determined by the seed of master-oscillator which needs careful optical design and precise alignment. To suppress the high amplified spontaneous emission (ASE) level in the XeCl gain medium and extract the deposited energy efficiently, a higher seed energy is needed. A master-oscillator integrated with seed generation and self-amplification which meets the MOPA system requirement is described. A grating is used to form a self-alignment resonator to obtain narrow line-width and small divergence seed using a discharge-pumped XeCl excimer laser. To get enough energy, the seed is further amplified by another two-pass amplifier in the same device. The alignment of the self-collimated grating resonator is the key issue to obtain the designed parameters like pulse energy and narrow line-width. With the help of single transverse mode He-Ne laser and a preliminary plane-parallel cavity inserted before the grating, expectedd experimental results are obtained and the measured seed laser pulse energy and intensity distribution at different position are given. After removing the plane-parallel cavity, the seed pulse energy is about 8 mJ from the grating cavity and the energy is boosted to 60mJ with additional double pass amplification and extender telescrope. And the line-width of the seed pulse is 0.6 cm-1, near the diffraction limit, and meets the demand of the following amplification..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 179 (2006)
Auto-Controller of Laser Chopper
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A laser chopper auto-controller was designed to automatically adjust the output pulse of laser. The technology of pulse-width modulation (PWM) was used to establish the control system of servo motor of laser chopper. Based on Visual C++ language, the system user interface was made.A laser chopper auto-controller was designed to automatically adjust the output pulse of laser. The technology of pulse-width modulation (PWM) was used to establish the control system of servo motor of laser chopper. Based on Visual C++ language, the system user interface was made..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 183 (2006)
Principle and Application of Infrared Imaging Simulation Based on Sinda/G
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The simulation means of the target surface radiation equilibrium temperature field, in real-time infrared imaging simulation founded to supply high quality infrared image to evaluate IR detection image processing system in laboratory, is issued. For the target models based on the finite difference theory the lumped parThe simulation means of the target surface radiation equilibrium temperature field, in real-time infrared imaging simulation founded to supply high quality infrared image to evaluate IR detection image processing system in laboratory, is issued. For the target models based on the finite difference theory the lumped parameter thermal analysis means is adopted to make targets and environments dispersed-to several nodes with thermal capacitance property, which describe thermal system transient processing. The three modes in the thermal system, heat fulx, convection, radiation are abstracted to heat-resistance connected with every node, which reflects heat-exchange ability, so the heat flux description for the whole target infrared radiation and the equilibrium temperature field for the surface radiation are obtained. Infrared imaging simulation system based on professional thermal analysis software Sinda/G with the advantage of the thermal analysis means by adopting lumped parameter also works in the finite element post treatment after processor software femap's figure demonstration function. The color of nodes renders temperature results, and uses the nephogram and cartoon technology to display steady and transient temperature distribution conveniently to achieve the target infrared imaging simulation..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 183 (2006)
Intracavity KTP Doubly Resonant Optical Parametric Oscillator Pumped by Nd:YAG Laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The application prospect and production methods of the high-repetition-rate, high average power 2 μm laser were reported. With the KTP crystal refractive index ellipse and the Sellmeier equations, the tuning characteristic of the crystal about the cutting angle was analyzed when the 1.064 μm continuous Nd:YAG laser pumThe application prospect and production methods of the high-repetition-rate, high average power 2 μm laser were reported. With the KTP crystal refractive index ellipse and the Sellmeier equations, the tuning characteristic of the crystal about the cutting angle was analyzed when the 1.064 μm continuous Nd:YAG laser pumped the type Ⅱ phase matching KTP crystal. The cutting angle tuning curve was also calculated. As a result, when the cutting angle was 52.6°, the signal and the idler were degenerated at 2.128 μm with perpendicular polarization. To restrain the dispersion effect, the authors combined the intracavity optical parametric oscillator (OPO) with the short crystals connecting external OPO and designed an experimental set of intracavity doubly resonant optical parametric oscillator with two short KTP crystals connecting, with which high-repetition-rate 2 μm laser output was readized with acoustic-optic Q-switch. Finally, the threshold, the converting efficiency, the crystal dispersion length and the linewidth were numerically simulated..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 189 (2006)
Experimental Investigation on Backward Scattering Characteristic in SF6 Pumped by a KrF Laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The characteristics of the backward scattering phenomena generated by the 81 cm-1 bandwidth KrF laser pumping SF6 medium are explored. The spot patterns of the backward scattering light does not change with the pumping light spot, but its size is enlarged with the increase of the focal length of the lens. There exists The characteristics of the backward scattering phenomena generated by the 81 cm-1 bandwidth KrF laser pumping SF6 medium are explored. The spot patterns of the backward scattering light does not change with the pumping light spot, but its size is enlarged with the increase of the focal length of the lens. There exists maximum for the pulse width and the energy of the scattering light, which rise and then fall, with the rise of the gas pressure of the medium. The energy reflectivity is 1%～3%, and there exists pulse width compression effect for the backward scattering light, related with gas pressure of the medium. With the focusing lens and the medium pool replacing the back mirror, auto cavity-forming and laser output are realized..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 192 (2006)
Parameter Change Law of the Polishing Powder and Its Influence on the Polishing Effect During the Optical Manufacture
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
In view of the phenomena that the easy appearance of serious roughness and surface defects, the polishing mechanism and the influence of the main parameters on the polishing quality are researched. The research indicates: the superficial hydrolysis layer on the polishing surface has the vital significance to the formatIn view of the phenomena that the easy appearance of serious roughness and surface defects, the polishing mechanism and the influence of the main parameters on the polishing quality are researched. The research indicates: the superficial hydrolysis layer on the polishing surface has the vital significance to the formation of ultra smooth surface. The super big and hard grains of the polishing powder are the main reason of the surface defects. According to the variational law of the polishing powder's main parameters with polishing time, the concept of polishing cycle and the method of pretreatment on the polishing powder are proposed. viz. the polishing powder is pretreated on the initial stage period and the workpiece is polished on the intermediate stage. The experimental result indicates: this method can truly reduces surface roughness and the surface defect, and the polishing quality and efficiency are effectively enhanced..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 196 (2006)
Absolute Calibration Method for Single-Photon Detectors
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Introduced an absolute calibration method of quantum efficiency for single-photon detectors. Entangled photons produced by spontaneous parametric down conversion are used in absolute calibration of quantum efficiency for single-photon detectors in this method. It could allow an uncertainty comparable with traditional mIntroduced an absolute calibration method of quantum efficiency for single-photon detectors. Entangled photons produced by spontaneous parametric down conversion are used in absolute calibration of quantum efficiency for single-photon detectors in this method. It could allow an uncertainty comparable with traditional methods. Furthermore, it makes that possible for realization of standard-less radiometric calibration..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 200 (2006)
Beam Transmission
980 nm Optical Pumped Semiconductor Vertical External Cavity Surface Emitting Semiconductor Laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Using period resonance gain structure, a laser diode (LD) pumped 980 nm vertical external-cavity surface-emitting laser (VECSEL) with active region of InGaAs/GaAsP/AlGaAs system is developed. The characteristic parameters such as longitudinal confinement factor, threshold gain, optical gain and output power etc. are caUsing period resonance gain structure, a laser diode (LD) pumped 980 nm vertical external-cavity surface-emitting laser (VECSEL) with active region of InGaAs/GaAsP/AlGaAs system is developed. The characteristic parameters such as longitudinal confinement factor, threshold gain, optical gain and output power etc. are calculated through theoretical model. With the optimized characteristic parameters, the structure of VECSEL is designed. Theoretical calculations show that the output power of a LD-pumped VECSEL can be higher than 1.0 W..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 240 (2006)
M2 Factor and Propagation Properties of Beams Generated by Gaussian Mirror Resonator
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The expression of the M2 factor of the beam generated by Gaussian mirror resonator is derived based on the two-order matrix method, and the effects of the peak reflectivity value and the radius of the light spot on the film of the Gaussian mirror on the M2 factor are explored. The curves of the M2 factor are plotted wiThe expression of the M2 factor of the beam generated by Gaussian mirror resonator is derived based on the two-order matrix method, and the effects of the peak reflectivity value and the radius of the light spot on the film of the Gaussian mirror on the M2 factor are explored. The curves of the M2 factor are plotted with different peak reflectivity values and the radii of the light spot on the film. Integrating the whole beams from the Gaussian mirror resonator, the propagation property of the beam through an ABCD system with the diaphragm effect neglected is discussed, based on scalar diffraction theory and matrix optics theory. The curve of normalized optical intensity distribution versus different positions in free-space propagation is plotted..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 244 (2006)
Spectral Properties of Partially Coherent Flat-Topped Light Beams Propagating
[in Chinese], [in Chinese], and [in Chinese]
Based on the flat-topped beam model proposed by Li and the partially coherent light theory, the spectral propagating expression of the partially coherent flat-topped beam is derived, and its variation of spectral properties is studied quantitatively in the free space. The variation rule of the on-axis spectrum of the fBased on the flat-topped beam model proposed by Li and the partially coherent light theory, the spectral propagating expression of the partially coherent flat-topped beam is derived, and its variation of spectral properties is studied quantitatively in the free space. The variation rule of the on-axis spectrum of the flat-topped light beam for different orders in the propagating process is analyzed in detail. The effects of the source's spectrum width and the spatial coherence parameter on the spectral properties are discussed. It shows that when the partially coherent flat-topped beam propagates in the free space, the light source parameters have more effects on the value of the relative frequency shift than on the total change trend of the spectrum along the propagation distance, which is primarily determined by the order of flat-topped beam..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 248 (2006)
Calculate and Analysis Curved Optical Waveguide with FDTD
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The intrinsic field of the waveguide by numeric solution is calculated. The mathematical model of bend waveguide refractive index is given. The curved optical waveguide is calculated analyzed with FDTD. By numeric calculation, the evolution of the pulse entering the bend waveguide, the pulse propagating in bend waveguiThe intrinsic field of the waveguide by numeric solution is calculated. The mathematical model of bend waveguide refractive index is given. The curved optical waveguide is calculated analyzed with FDTD. By numeric calculation, the evolution of the pulse entering the bend waveguide, the pulse propagating in bend waveguide and its energy loss in the condition of different bend radius are obtained. The smaller the bend radius is, the more noticeable of the pulse moves and deforms, the more serious the energy loss. The bended waveguide is widely used to integrate optics and optical detection. etc..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 252 (2006)
Research on Temporal Smoothing Characteristics of Frequency-Modulated Light
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Laser driven fusion requires a high degree of uniformity in laser energy deposition in order to achieve the high density compression required for sustaining a thermonuclear burn. While, filamentation severely affects laser irradiation uniformity, which often encountered in indirect-drive research. Therefore, a proper sLaser driven fusion requires a high degree of uniformity in laser energy deposition in order to achieve the high density compression required for sustaining a thermonuclear burn. While, filamentation severely affects laser irradiation uniformity, which often encountered in indirect-drive research. Therefore, a proper smoothing method must be adopted. With smoothing by spectral dispersion (SSD), the size of focal spot increases greatly for the introduction of phase plate, and pinhole closure will likely happen when the light injected into the hohlraum. To solve this problem, angular spectral dispersion of stacked chirped pulse is proposed here to decrease the target nonuniformity of scale 10 μm to 100 μm. By analyzing the propagating characteristics of frequency-modulated light, mathematical representations are deduced. Simulation indicates, compared with one-dimensional SSD [without random phase plate (RPP)], chirped pulse stacking is more effective in diminishing high frequency modulations on target plane, and the size of smoothed area is dependent on the bandwidth of the stacked pulse in the dispersing direction. These advantages make the technique a promise in promising method laser irradiation uniformity..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 256 (2006)
Simulation of Satellite Optical Characteristic Based on Tracepro
[in Chinese], [in Chinese], and [in Chinese]
The way to simulate the visible signal and infrared signal from satellite in space based on TracePro is intraduced. First, the satellite position's coordinate, satellite surface's coordinate and the earth's coordinate are converted to one unite coordinate, then the temperature model from Sinda/G is insertedThe way to simulate the visible signal and infrared signal from satellite in space based on TracePro is intraduced. First, the satellite position's coordinate, satellite surface's coordinate and the earth's coordinate are converted to one unite coordinate, then the temperature model from Sinda/G is inserted in Tracepro, and the surface properties, such as the reflectivity and emissivity are built. The infrared characteristic of satellite radiation is obtained, using the gray radiation in the software. The distances between the satellite, the earth and the sun are determined by the above conversion. This simulation could directly show the optical action on the satellite surface, is propitious to analyze the process and improve the precision..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 260 (2006)
Design of Crossed Double Strip Integrators for High Power Laser Beam Homogenizing
[in Chinese], [in Chinese], and [in Chinese]
Using geometrical optics theory and off-axis aberration analysis, a set of crossed double strip integrators for high power CO2 laser beam homogenizing has been designed. The uniformity of the power distribution on the working plane can be improved without being affected by the change of original laser beam. And becauseUsing geometrical optics theory and off-axis aberration analysis, a set of crossed double strip integrators for high power CO2 laser beam homogenizing has been designed. The uniformity of the power distribution on the working plane can be improved without being affected by the change of original laser beam. And because all the elements have reflecting surface, energy loss is not serious and water cooling can be easily used..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 264 (2006)
Influence of Aerosol Concentration Field Fluctuation to Light Wave in Limited Space
[in Chinese], [in Chinese], and [in Chinese]
The relation between particle movement and atmospheric turbulence is discussed starting from the particle movement function in the atmospheric turbulence. It is found that the longer the particle movement relaxation time, the more evident the inertial effect, and the more different the particle movement and atmosphericThe relation between particle movement and atmospheric turbulence is discussed starting from the particle movement function in the atmospheric turbulence. It is found that the longer the particle movement relaxation time, the more evident the inertial effect, and the more different the particle movement and atmospheric movement are. The mathematic model is set up by using physics image analysis, the expression of aerosol concentration field in limited space is derived, and the correspondent numerical analysis is carried out. The experimental data of visibility sensor in short time indicate the influence of the aerosol concentration field fluctuation on intensity and phase of light on the path of light propagation..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 268 (2006)
Numerical Analysis of 1ω Far-Field in High Power Laser System
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
High quality far-field determined by the phase and amplitude distribution of focal beam is necessary for inertial confinement fusion (ICF). To the high power laser system, the amplitude distribution of the output laser beam mainly derives from input beam, while phase distribution mainly come from the large aperture optHigh quality far-field determined by the phase and amplitude distribution of focal beam is necessary for inertial confinement fusion (ICF). To the high power laser system, the amplitude distribution of the output laser beam mainly derives from input beam, while phase distribution mainly come from the large aperture optical elements, especially for the Nd:glass amplifier slab. Nonlinear self-focusing of ripple can effect on far field in high energy too. Based on these factor, the transmit character of high power laser with fourth-pass amplifier was simulated, and the effect of amplitude and phase distribution on far field was analyzed by numerical was. The conclusion is that the most important effect factor on far field is phase distortion come from large aperture optics..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 272 (2006)
Energy Transmission in High Power Laser Amplifier
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
To high power laser driver, the disk amplifiers are the most important sources of energy and power. The energy transmission and conversion in high power laser disk amplifier are discussed. The energy transmission is achieved by the energy bank modules, pulse flash-lamp, pump cavity and gain medium. The effects of diffeTo high power laser driver, the disk amplifiers are the most important sources of energy and power. The energy transmission and conversion in high power laser disk amplifier are discussed. The energy transmission is achieved by the energy bank modules, pulse flash-lamp, pump cavity and gain medium. The effects of different energy transmission process on the whole performance of disk amplifiers are researched by simulation and experiments. Results show that the small signal gain coefficient of 5.0%cm-1 and energy storage efficiency of about 3.0% are achieved by primary optimization in technical integration line (TIL). But because of the quality of some key elements, the best results are not obtained. High efficiency does not only improves the disk amplifier performance, reduce the cost, but also improves the amplifier reliability and stability..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 276 (2006)
Application of Wavelet Transform in Background Processing of 2D Image
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Wavelet Transform is a new technique for singnal processing. Based on the principle and algorithm of wavelet transform and discrete wavelet transform, a method of fittering with localized protecting by wavelet transform coefficient is presented. The method is used to process a simulating image and some real images, andWavelet Transform is a new technique for singnal processing. Based on the principle and algorithm of wavelet transform and discrete wavelet transform, a method of fittering with localized protecting by wavelet transform coefficient is presented. The method is used to process a simulating image and some real images, and all the results show that the new method is quite suitable for two dimensional the image with single spot..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 280 (2006)
Numerical Simulation for Optical Beam Diffraction Propagation
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
In order to numerically simulate the diffraction propagation of convergence/divergence optical beams, the complex amplitude pulse response function of lens imaging is researched. A novel method called object-image conjugation translation is presented, in which the spherical wave phase factor in convergence/divergence bIn order to numerically simulate the diffraction propagation of convergence/divergence optical beams, the complex amplitude pulse response function of lens imaging is researched. A novel method called object-image conjugation translation is presented, in which the spherical wave phase factor in convergence/divergence beams is equivalent to a lens, and the spherical wave phase factor is removed in the diffraction propagation with the pulse response function and the object-image translation. This idea is simple but efficient, with a visual physical meaning. The simulation of the diffraction propagation of the optical beam with square aperture-lens assembly, proves the practicality and the validity of the idea..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 284 (2006)
Experiment on Laser Beam Propagation in the Atmosphere with Stimulated Brillouin Scattering Phase-Conjugated Compensation at Long Distance
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
An experiment of laser beam propagation in the atmosphere with stimulated Brillouin scattering (SBS) phase-conjugated compensation at long distance (10.5 km) is reported. On the normal atmosphere condition of a city, the conversion efficiency of the SBS phase-conjugated laser is about 4.4% through a 10.5 km distance, wAn experiment of laser beam propagation in the atmosphere with stimulated Brillouin scattering (SBS) phase-conjugated compensation at long distance (10.5 km) is reported. On the normal atmosphere condition of a city, the conversion efficiency of the SBS phase-conjugated laser is about 4.4% through a 10.5 km distance, which is 2.4 times than the normal laser transimission efficiency on the same condition. Meanwhile, the phase-conjugated laser neturns to the emission position through the original path, and assembles again..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 287 (2006)
Laser Manufacturing
Applications of Femtosecond Laser Micromachining
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The 800 nm, 150 fs, 1 kHz femtosecond laser micromachining for different materials under different processing conditions is studied. The diffraction-limited cutting on the gold and silver films is obtained, respectively. A 4×4 array holes with the diameter of 3 μm are drilled in the GaAs materials. The transmissioThe 800 nm, 150 fs, 1 kHz femtosecond laser micromachining for different materials under different processing conditions is studied. The diffraction-limited cutting on the gold and silver films is obtained, respectively. A 4×4 array holes with the diameter of 3 μm are drilled in the GaAs materials. The transmission gratings with the grating constant of 2.5 μm and 5 μm are fabricated into the ZK6 and LaF2 glasses at the machining speed of 400 μm/s..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 415 (2006)
Numerical Simulation of Laser Peen Forming Based on ABAQUS
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Laser peen forming (LPF) is a process that elongates the peened metal surface and bends the overall shape with a shockwave, which is formed by a pulsed laser beam shocking the metal surface, penetrates the metal and introduces a residual impress stress field in the surface and inside. The methods of LPF including multiLaser peen forming (LPF) is a process that elongates the peened metal surface and bends the overall shape with a shockwave, which is formed by a pulsed laser beam shocking the metal surface, penetrates the metal and introduces a residual impress stress field in the surface and inside. The methods of LPF including multi-full peening and multi-selective peen forming single curved face and saddle-saddle-shaped hyperboloid are studied. Mathematical mode of LPF is established, LPF of the sheet metal of different form and size is numerically simulated with the ABAQUS software and the availability of the analytical peen way is proved. The results show that different kinds of deformations can be obtained with diverse ways of peening. The simulation can offer accurate peening schemes for experiments, improve the efficiency and help replace the traditional test-peening with LPF..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 419 (2006)
High Power Ultraviolet Laser Precision Cutting
[in Chinese], [in Chinese], and [in Chinese]
In order to meet the demand of micro film apparatus in micro electronic industry, a series of experiments were carried out on the ultraviolet laser cutting thin metal film, and the effects of laser cutting parameters on the kerf width and quality were studied. Aiming at the high flexible coefficient and easy deformed eIn order to meet the demand of micro film apparatus in micro electronic industry, a series of experiments were carried out on the ultraviolet laser cutting thin metal film, and the effects of laser cutting parameters on the kerf width and quality were studied. Aiming at the high flexible coefficient and easy deformed etc. characteristics of thin metal film, a special clamp and cutting equipment was introduced. The results showed that during the process of the high power ultraviolet laser precise cutting, according to the kind and thickness of thin metal film, suitable ultraviolet laser power and cutting speed are selected to decrease the kerf width and good kerf quality is obtained; besides, suitable fixing method for the thin metal film is selected to ensure the thin film no distortion and improve the cutting precision and the success probability of the micro film apparatus machining effectively..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 423 (2006)
Voltage Decoupling of Micromachined Membrane Deformable Mirror
[in Chinese], [in Chinese], and [in Chinese]
Due to the coupling of micromachined membrane deformable mirror (MMDM) is much larger than that of the common deformable mirror. The voltage-decoupling model for a 37-channel MMDM is established through theoretically and experimentally analyzing the principle of fitting aberration of a continuous-surface deformable mirDue to the coupling of micromachined membrane deformable mirror (MMDM) is much larger than that of the common deformable mirror. The voltage-decoupling model for a 37-channel MMDM is established through theoretically and experimentally analyzing the principle of fitting aberration of a continuous-surface deformable mirror. The fitting error for the first 10-order Zernike mode is carried out by means of the measured influence function of and coupling among actuators. The index and width of Gaussian function which is used for fitting the influence function is calculated. The experiment result demonstrate that Zernike mode can be act as the control voltage decoupling algorithm for the adaptive optics system based on MMDM..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 427 (2006)
Numerical Simulation of Propulsive Force in Steam Laser Cleaning of Printed Circuit Board
[in Chinese], [in Chinese], and [in Chinese]
The explosion process of steam laser cleaning of printed circuit board (PCB) is simulated by using Ansys/Ls-Dyna finite element analysis software (FEA). Comparison with the theoretical adhere pressure of the particles and the propulsive pressure calculation are also carried out. The result shows that under the chosen cThe explosion process of steam laser cleaning of printed circuit board (PCB) is simulated by using Ansys/Ls-Dyna finite element analysis software (FEA). Comparison with the theoretical adhere pressure of the particles and the propulsive pressure calculation are also carried out. The result shows that under the chosen conditions (energy density 1 J/cm2) the propulsive pressure on the particles which is in micron size or submicron size is larger than their adhere pressure but less than the destroy pressure of the PCB, so the micron or submicron particles are rencoved effectively without damaging the PCB. This proves that the steam laser cleaning can be uesed to clean PCB. From the simulation result, it is found that for laser cleaning of PCB, the laser pulse duration should be no more than 100 ns..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 432 (2006)
Design of 980 nm High-Power Semiconductor Laser Therapeutic Equipment
[in Chinese], [in Chinese], and [in Chinese]
A kind of which includes high-power semiconductor laser therapeutic equipment is designed beam path, current source and protective circuit and constant temperature control unit. By comparing and analyzing the effects of GaAlAs, InGaAs and Nd:YAG lasers in medicine, InGaAs high-power semiconductor laser therapeutic equiA kind of which includes high-power semiconductor laser therapeutic equipment is designed beam path, current source and protective circuit and constant temperature control unit. By comparing and analyzing the effects of GaAlAs, InGaAs and Nd:YAG lasers in medicine, InGaAs high-power semiconductor laser therapeutic equipment with output wavelength at 980 nm is used as effective light source, 670 nm semiconductor laser as aiming beam. This equipment has the highest power of 3 W, with such virtues as high output power, small volume and long life span, and has a very good prospect of application to tumor, ear-nose-throat department and gynecology..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 435 (2006)
Slab CO2 Laser Welding of 7075-T6 High Strength Aluminum Alloy
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Experimental study of slab CO2 laser bead-on-plate welding and filling wire welding 7075-T6 high strength aluminum alloy of 2.4 mm thickness has been completed. The mechanical properties of welding joints have been analysed. Through analysis of influence of laser power, focal length, welding velocity, working gas and sExperimental study of slab CO2 laser bead-on-plate welding and filling wire welding 7075-T6 high strength aluminum alloy of 2.4 mm thickness has been completed. The mechanical properties of welding joints have been analysed. Through analysis of influence of laser power, focal length, welding velocity, working gas and shielding gas on weld shaping and welding stability, filling wire welding of 7075-T6 high strength aluminum alloy is put forward. On the basis of the optimization of feeding direction, feeding angle, feeding velocity and feeding position, filling wire welding of 7075-T6 alloy is completed successfully with slab CO2 laser. The tensile strength of as-welded welds with AlSi12 is 360.8 MPa and with AlMg4.5MnZr 414.6 MPa. The tensile strengths of welds after heat treatment are 404.2 MPa (75 percents of base-metal) and 482.6 MPa (88 percents of base-metal) for AlSi12 and AlMg4.5MnZr, respectively..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 439 (2006)
Influence of Beam-Focusing Characteristics on Laser Welding
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Focal spot shape and size, beam power intensity distribution, convergence angle and depth of focus which are determined by beam quality and focus system describe the characteristics of focal beam. The influences of these parameters on depth and width of weld seam are studied in theory and experiment. Results shown thatFocal spot shape and size, beam power intensity distribution, convergence angle and depth of focus which are determined by beam quality and focus system describe the characteristics of focal beam. The influences of these parameters on depth and width of weld seam are studied in theory and experiment. Results shown that enough power intensity is the precondition of realizing laser penetration welding. Depth and width of weld seam rely on energy penetrating into materials. With the same processing parameters, focal spot size decides the acquired power intensity, depth of focus decides the algnment distance and convergence angle has effect on Fresnel absorption in keyhol wall. All in all, beam-focusing characteristics have effect on results of laser welding with different energy acquired at different focus beam cross section. In reality application, laser system, focus system and focal spot position should be selected according to the practical requirements in order to acquire ideal quality of processing..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 445 (2006)
Analysis on Microstructure and Tensile Property of Laser Welding 1Cr18Ni9Ti
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Laser welding is an indispensable advanced manufacture technology in the modern production, and it has excellent welding performance compared with the conventional welding ways. However, it can reduce the performance of the welding-joints if the inappropriate welding parameters are adopted. Therefore, it is important tLaser welding is an indispensable advanced manufacture technology in the modern production, and it has excellent welding performance compared with the conventional welding ways. However, it can reduce the performance of the welding-joints if the inappropriate welding parameters are adopted. Therefore, it is important to select the right welding technical parameters to get excellent welding properties. The effects of welding parameters on the welding properties are studied. The laser welding of austenitic stainless steels is studied experimentally and a smooth, good-looking welding-joint is obtained by controlling welding power, welding velocity, flux of protective gas and facula diameter. However, its tensile strength is just 63.5% of that of the basal body, which is greatly lower than the reported data (99.4%). The main factors to affect the welding properties by the micro-morphological analysis of the welding-joints include lower laser output power, slower welding velocity, and a rather large heat-affected-zone (HAZ)..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 450 (2006)
Laser Physics
kW-Class Laser Diode Pumped Yb:YAG Slab Lasers
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
This work analyses the temperature and thermal stress distributions inside Yb:YAG slab crystals with high pump power. The focal lengths of thermal lenses in both thickness and width directions inside the laser crystal are calculated. The hybrid resonator using one-dimensional VRM is designed and the thermal-lensing effThis work analyses the temperature and thermal stress distributions inside Yb:YAG slab crystals with high pump power. The focal lengths of thermal lenses in both thickness and width directions inside the laser crystal are calculated. The hybrid resonator using one-dimensional VRM is designed and the thermal-lensing effects in the slab are considered. The kilo-watts composite Yb:YAG/YAG slab laser pumped by laser diode is presented, in which the corner-pumped scheme is used, with slope efficiency of 43% and optical-to-optical efficiency of 35%. A slab laser scheme with ten kilo-watt output is designed out..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 1 (2006)
Reliability of High Power Diode Laser Stack
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The reliability of packaging technique about diode laser (DL) unit and the defect characteristics of high power DL stack and pumping module are analyzed. Testing methods for the reliability of high power DL unit and stack is made. Random samples selected from the lasers passing the reliability tests were used for lifetThe reliability of packaging technique about diode laser (DL) unit and the defect characteristics of high power DL stack and pumping module are analyzed. Testing methods for the reliability of high power DL unit and stack is made. Random samples selected from the lasers passing the reliability tests were used for lifetime test. Under the conditions of cooling water temperature of 20 ℃, current of 150 A, and duty cycle of 15% (500 Hz, 300 μs), the experimental results led to an estimated lifetime of 5×109 shots. No defect was found during the lifetime test. It was demonstrated that the reliability of diode lasers could be assured after filtrating..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 6 (2006)
Laser Diode Array High-Order Lateral Modes Phase Locking in External Cavity
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
It is theoretically found that phase locking high-order lateral modes of laser diode array (LDA) with a short external cavity can be realized. The far field pattern, which comprises a main lobe and side lobes, is observed for a LDA positioned in a short external cavity. There are structures composed of peaks and valleyIt is theoretically found that phase locking high-order lateral modes of laser diode array (LDA) with a short external cavity can be realized. The far field pattern, which comprises a main lobe and side lobes, is observed for a LDA positioned in a short external cavity. There are structures composed of peaks and valleys, symbolizing phase locking, within the side lobes. From these results, it can be concluded that the phase locking of high-order lateral modes of LDA exists when the external cavity is short enough..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 10 (2006)
Energy Extract Efficiency of the Nd:YAG Two Rods Pumped by Diode Laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Diode laser pumped Q-switch green laser is described. The energy extract efficiency of two Nd:YAG rods pumped by diode laser is experimentally investigated and simulated. The output energy and extract efficiency of the pre- and master amplification in different input energy are analyzed by theory and experiment. SingleDiode laser pumped Q-switch green laser is described. The energy extract efficiency of two Nd:YAG rods pumped by diode laser is experimentally investigated and simulated. The output energy and extract efficiency of the pre- and master amplification in different input energy are analyzed by theory and experiment. Single pulse energy 1.27 J is output at the frequency of 400 Hz, and energy extract efficiency is 63%,and optical-optical efficiency is 16%..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 13 (2006)
Thermodynamics Analysis in Diode-Laser Side-Pumped Nd:YAG Disk Laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Based on conduction model of even heat source, cooling underside and making the other sides adiabatic, the three-dimensional distributions of temperature, displacement and Von Mises stress of disk gain medium are calculated. The calculation results indicate that: even heat source, low heat power, thin medium and reasonBased on conduction model of even heat source, cooling underside and making the other sides adiabatic, the three-dimensional distributions of temperature, displacement and Von Mises stress of disk gain medium are calculated. The calculation results indicate that: even heat source, low heat power, thin medium and reasonable cooling can realize one-dimensional temperature distribution and decrease the temperature, displacement and Von Mises stress inside the disk..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 16 (2006)
LD Pumped Laser System of High Frequency and High Energy
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The laser diode (LD) pumped MOPA system with high frequency, large energy, high beam quality is presented. The main techniques in the LD pumped MOPA system are researched systematically. Combined computer simulation and practical application, the LD uniformly side pumped laser structure is designed, and the performanceThe laser diode (LD) pumped MOPA system with high frequency, large energy, high beam quality is presented. The main techniques in the LD pumped MOPA system are researched systematically. Combined computer simulation and practical application, the LD uniformly side pumped laser structure is designed, and the performance of the laser is estimated theoretically. The measures to compensate the thermal induced birefringence effect, maintain high beam quality, avoid spontaneous irradiation and improve the damage threshold are taken in the amplification process. While the repetition is 100 Hz, the single pulse energy output reaches 5 J, the pulse width is about 20 ns and the beam quality is 5 times of the diffraction limit..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 20 (2006)
Short Wavelengh Wide-Spectrum Superluminescent Diode
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Non-uniform well-thickness multi-quantum wells materials were adopted to widen the output spectrum of superluminescent diodes. 850 nm high-power, wide-spectrum, low-divergence superluminescent diodes with large optical cavity structure were fabricated. The spectral width (FWHM) of 26 nm, continuous wave (CW) output powNon-uniform well-thickness multi-quantum wells materials were adopted to widen the output spectrum of superluminescent diodes. 850 nm high-power, wide-spectrum, low-divergence superluminescent diodes with large optical cavity structure were fabricated. The spectral width (FWHM) of 26 nm, continuous wave (CW) output power of 6 mW were achieved at operating current of 120 mA. The pigtail output power when coupled with single-mode polarization maintaining fiber reached 1.0 mW..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 23 (2006)
Diffusive Reflector-Type Laser Diode Side-Pumped Nd:GdVO4 Rod Laser with Line Polarization Output of 45 W
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The pumping unit consists of three 40 W CW laser diode bars mounted on modular silicon micro-channel cooled heat sinks. Two pumping units are used to assemble one pump head with a Nd:GdVO4 crystal rod of 3 mm×60 mm side-pumped. The laser with parallel-plane optical resonator emits 45 W CW laser beam with TEM01* mThe pumping unit consists of three 40 W CW laser diode bars mounted on modular silicon micro-channel cooled heat sinks. Two pumping units are used to assemble one pump head with a Nd:GdVO4 crystal rod of 3 mm×60 mm side-pumped. The laser with parallel-plane optical resonator emits 45 W CW laser beam with TEM01* mode pattern and line polarization. When the laser has 10 W output, the mode pattern is TEM00 with 3.9 mm diameter measured by scan method of micro-duct and near Gaussian radial intensity distribution..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 26 (2006)
Research of Transient Temperature Distribution of Nd:GGG Gain Medium in Solid-State Heat Capacity Laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The transient temperature distribution of 18 mm×18 mm×10 mm slate Nd:GGG gain medium of the solid-state heat capacity laser pumped by a 104 W laser diode array is numerically calculated to analyze the influence of the large scale temperature variation on the specific heat of Nd:GGG crystal. Through comparing The transient temperature distribution of 18 mm×18 mm×10 mm slate Nd:GGG gain medium of the solid-state heat capacity laser pumped by a 104 W laser diode array is numerically calculated to analyze the influence of the large scale temperature variation on the specific heat of Nd:GGG crystal. Through comparing the calculated results with the experimental data, which is achieved with the HR-2 thermal infrared imager from the end face and the side face of the Nd:GGG crystal, valuable conclusions are obtained..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 30 (2006)
Single Pulse Energy 8.5 J High Peak Power Solid State Laser Using Polarized Combination
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The primary technical issues of high peak power and large energy Nd:YAG solid state laser are researched. A pair of Nd:YAG rods are used to realize the above laser, and some techniques are discussed in detail. Characteristics of the Q-switch of pulse drives with KD*P crystals and the double-channel 6-step traveling-wavThe primary technical issues of high peak power and large energy Nd:YAG solid state laser are researched. A pair of Nd:YAG rods are used to realize the above laser, and some techniques are discussed in detail. Characteristics of the Q-switch of pulse drives with KD*P crystals and the double-channel 6-step traveling-wave power amplifier are presented, inspectively. The 45° beam polarized combination of two Nd:YAG lasers using polarization coatings are completed. The experimental results are presented: at 20.0 Hz, output energy exceeding 8.5 J per pulse, pulse width 13.9 ns, beam quality M2≤3.99 and energy unstabllity degree less than 0.5%..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 34 (2006)
589 nm Sum-Frequency Laser
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A diode laser (DL)-pumped Nd:YAG all-solid-state sum-frequency laser is presented. Efficient sum-frequency mixing 1064 nm and 1319 nm in a 4 mm×4 mm×20 mm LBO crystal (x-cut, θ＝90°,＝0°) is obtained by extra-cavity sum-frequency. Type I noncritical-phase-match (NCPM) is realized by controlling the tA diode laser (DL)-pumped Nd:YAG all-solid-state sum-frequency laser is presented. Efficient sum-frequency mixing 1064 nm and 1319 nm in a 4 mm×4 mm×20 mm LBO crystal (x-cut, θ＝90°,＝0°) is obtained by extra-cavity sum-frequency. Type I noncritical-phase-match (NCPM) is realized by controlling the temperature of the LBO crystal. By injecting 1.23 W and 1.50 W of 1064 nm and 1319 nm Q-switched radiation into the LBO crystal, respectively, 500 mW of sum-frequency maximum output is generated with a pulse repetition rate of 500 Hz and pulse duration of about 25 ns, efficiency up to 18.5%, beam quality M2 less than 3. By carefully adjusting the tilt angle of etalon in each oscillator, the wavelength of sum-frequency output is tuned to the sodium D2 line..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 37 (2006)
Study on Solid-State Heat Capacity Laser Technology with Exchangeable Gain Medium
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The feasible schemes for solid-state laser to realize high average-power output are compared, and the development and the current status of heat capacity laser are described. The basic principle of the solid-state heat capacity laser (SSHCL) is introduced, and the advantage and the disadvantage of the SSHCL are analyzeThe feasible schemes for solid-state laser to realize high average-power output are compared, and the development and the current status of heat capacity laser are described. The basic principle of the solid-state heat capacity laser (SSHCL) is introduced, and the advantage and the disadvantage of the SSHCL are analyzed. A new type laser with rapid gain medium exchange is proposed, and simulated experiments are carried out to test it..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 41 (2006)
E-mail: Effect of Stress-Birefringence in Nd:YAG on Conversion Efficiency and Beam Profile in Combined Disks Laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Stress birefringence resulted from the growth defect of YAG crystal is tested and analyzed using the photoelastic stress theory. Combined with the test result, the effect of the stress birefringence on the conversion efficiency of large aperture multi-disks YAG laser is calculated. The result indicates that it causes 3Stress birefringence resulted from the growth defect of YAG crystal is tested and analyzed using the photoelastic stress theory. Combined with the test result, the effect of the stress birefringence on the conversion efficiency of large aperture multi-disks YAG laser is calculated. The result indicates that it causes 36.3% wasting in average where stress exists, which is a spatial modulated function, in the range of 0～0.9997. The static transmission rate and the near field spot distribution are measured in the experiment and validate the calculation..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 45 (2006)
13.2 W Continuous Wave Output 1540 nm Semiconductor Laser Array Module
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
InGaAsP/InP double-step gradient refractive index (GRIN) separated-confinement-heterostructure multi-quantum-well (SCH MQW) structure laser module with an emission wavelength of 1540 nm was grown. Laser bars with a stripe width of 100 μm and a filling factor of 20% was fabricated. The back high-reflection (HR) coating InGaAsP/InP double-step gradient refractive index (GRIN) separated-confinement-heterostructure multi-quantum-well (SCH MQW) structure laser module with an emission wavelength of 1540 nm was grown. Laser bars with a stripe width of 100 μm and a filling factor of 20% was fabricated. The back high-reflection (HR) coating is 3(Si/Al2O3) and the front anti-reflection (AR) coating is Al2O3. The module's continuous wave (CW) output power reaches to 13.2 W at a current of 50 A. The threshold current is 10 A and the central wavelength is 1535.5 nm with a FWHM of 6.5 nm. Characteristic temperature T0 of 68 K is obtained when the temperature of the active region is in the range of 20～50 ℃..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 49 (2006)
High Performance 1.3 μm InGaAsN Quantum Well Semiconductor Lasers
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
InGaAsN triple-quantum-well strain-compensated lasers grown by metal organic chemical vapor deposition were fabricated with pulsed anodic oxidation. Laser output power reached 962 mW in continuous wave mode at room temperature from 100 μm stripe lasers with a wavelength of 1297 nm and a maximum slope efficiency of 0.42InGaAsN triple-quantum-well strain-compensated lasers grown by metal organic chemical vapor deposition were fabricated with pulsed anodic oxidation. Laser output power reached 962 mW in continuous wave mode at room temperature from 100 μm stripe lasers with a wavelength of 1297 nm and a maximum slope efficiency of 0.42 W/A at 1.5 A current. The threshold current density was 256 A/cm2. The characteristic temperature of the lasers was 138 K in the linear region (20～80 ℃). The lasers operated up to 100 ℃..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 53 (2006)
808 nm Output from a Single-Fiber-Coupled Laser Diode Array
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
808 nm wavelength 25-stripe laser diode arrays (LDAs) have been fabricated with 200 μm-wide emitters whose center-to-center space is 400 μm. 40 W continuous wave (CW) output power is achieved with Cu-microchannel cooler packaged devices. Step-mirror method is adopted to shape the output beam symmetrically and a square 808 nm wavelength 25-stripe laser diode arrays (LDAs) have been fabricated with 200 μm-wide emitters whose center-to-center space is 400 μm. 40 W continuous wave (CW) output power is achieved with Cu-microchannel cooler packaged devices. Step-mirror method is adopted to shape the output beam symmetrically and a square beam pattern is obtained. The focused output beam is coupled into a multi-mode fiber. 30 W output power is obtained from the fiber with core diameter of 600 μm and numerical operture of 0.22, the total coupling efficiency of about 75% is achieved..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 56 (2006)
Super-Mode Far-Field Lobes and Spikes of External Cavity Phase Locked Laser Diode Array
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Far fields of super-modes (SMs) from an external cavity phase locked high power laser diode array (LDA) are studied. The super-mode far-field lobes shows periodical distribution, and there are spikes with the equivalent spacing between two lobes. The intensity of the spike is generally much less than that of the lobe. Far fields of super-modes (SMs) from an external cavity phase locked high power laser diode array (LDA) are studied. The super-mode far-field lobes shows periodical distribution, and there are spikes with the equivalent spacing between two lobes. The intensity of the spike is generally much less than that of the lobe. The angular spacing between two neighboring pairs of lobes is equal to the ratio of lasing wavelength λ to the distance d between the centers of two adjacent emitters, and the angular spacing of the lobes of each pair depends on the order of super-mode. For the lowest order super-mode (LSM) and highest order super-mode (HSM), there are even larger spikes between two closely spaced lobes resulting in composite lobes so that the number of lobes is reduced to a half of that of the other orders super-modes. For other super-modes, the intensity of the spike nearer to the lobe is larger and that of the farther is smaller. The far-field distribution of the lowest order super-mode is similar to that of the highest order one but of an angular diapalcement of λ/(2d)..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 59 (2006)
Study of End Pumped Double Clad Fiber Laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
End pumping is a simple pumping method in double clad fiber laser. According to rate and heat conduction equations, the distribution of power and temperature in end pumped Yb3+ doped double clad fiber laser is studied. It is shown that the maximum output power can be obtained for backward pump, the distribution of tempEnd pumping is a simple pumping method in double clad fiber laser. According to rate and heat conduction equations, the distribution of power and temperature in end pumped Yb3+ doped double clad fiber laser is studied. It is shown that the maximum output power can be obtained for backward pump, the distribution of temperature in fiber is the flattest for bidirectional pump, when no severe thermal effect happens, higher laser power can be obtained for backward pump, when fiber laser works at high power level, thermal effects can be reduced for birectinal pump, and backward pump power can be properly increased to acquire higher laser power. The results provide a good reference for designing end pumped high power double clad fiber laser..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 62 (2006)
E-mail: Analysis of Two Aspheric Micro-Lens in Collimating High-Power LD
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
There is a large divergence angle of the fast-axis output beam of high power diode laser (HPDL) and the great differences between the fast-axis and slow-axis beam limit the direction application of HPDL. The mathematical model of the LD collimation lens' surface is researched and by using aplanatic principle and coThere is a large divergence angle of the fast-axis output beam of high power diode laser (HPDL) and the great differences between the fast-axis and slow-axis beam limit the direction application of HPDL. The mathematical model of the LD collimation lens' surface is researched and by using aplanatic principle and considering the position of microlens, two equations of two types of quadratic-vertical surfaces-elliptical surface and hyperbolic surface-are established in a practice way. These two models are simulated in ZEMAX software and the conclusion is elicited; the effect of these two collimation lens are much better than the regular spherical surfaces..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 66 (2006)
Thermal-Lens Effect and Influence on Laser Output and Stability of Resonator in the All-Solid-State Laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
By using of matrix method and ABCD law for Gaussian beam, the resonator parameters of the YAG laser have been analyzed and computed under considering of the thermal-lens effect. The thermal lens effect as the function of the pump current is measured by “unstable resonator” method. The influences of the dynamic thermal By using of matrix method and ABCD law for Gaussian beam, the resonator parameters of the YAG laser have been analyzed and computed under considering of the thermal-lens effect. The thermal lens effect as the function of the pump current is measured by “unstable resonator” method. The influences of the dynamic thermal lens effect on the laser output and their stabilities are discussed and verified by experiments..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 70 (2006)
Key Technologies of High Power Pulsed CO2 Laser
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Electrically excited high power pulsed CO2 laser is one of the favorable lasers in novel applications such as laser propulsion. The performances of power and beam quality of the existed lasers cannot fulfill the requirements of these applications. The improvements of these performances are decided by the technologies oElectrically excited high power pulsed CO2 laser is one of the favorable lasers in novel applications such as laser propulsion. The performances of power and beam quality of the existed lasers cannot fulfill the requirements of these applications. The improvements of these performances are decided by the technologies of quick charging of high voltage capacitor, uniform discharge in high pressure large aperture zone, uniform flow of high pressure gas, and laser resonator, etc.. The technology of serial resonant switch mode power supply realizes the quick charging of high voltage capacitor with charging current of 807 mA, charging voltage of 50 kV for one unit. The inductor isolated Marx high voltage pulse generator is tested for the purpose of uniform discharge with a high pressure large aperture zone. By use of this method, the reliable working pressure of helium-free gas is increased from 2×104 Pa to 3×104 Pa, and the highest pulse energy is increased from 64 J to 115 J..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 74 (2006)
Pulse Characteristics of High-Pressure CO2 Lasers
[in Chinese], and [in Chinese]
Output pulse characteristics of high-pressure CO2 lasers are theoretically investigated. The dynamical mechanism of pulsed electric discharge CO2 lasers is described by means of six-temperature multifrequency dynamical model, which takes into account the effects of the collision-dependent overlap of rotational lines, hOutput pulse characteristics of high-pressure CO2 lasers are theoretically investigated. The dynamical mechanism of pulsed electric discharge CO2 lasers is described by means of six-temperature multifrequency dynamical model, which takes into account the effects of the collision-dependent overlap of rotational lines, hot bands, and sequence bands on the gain spectrum, and non-Lorentzian line overlap. The calculations present the influence of specific input energy or output laser energy on laser build-up time and pulse width at different pressures. Theoretical results are consistent with experimental measurements at 400 kPa, 600 kPa, 800 kPa and 1000 kPa, respectively. The pulse width decreases from 120 ns to 35 ns and laser build-up time from 1000 ns to 400 ns, as output laser energy increases from 250 mJ to 1000 mJ. These data are helpful for the design of high-pressure pulsed CO2-N2-He-CO system..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 78 (2006)
10 J Level of Optically Pumping XeF(C-A) Laser Operating on Repetition Mode
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A 10 J level of optically pumping XeF(C-A) laser has been developed which can be operated on repetition mode. The laser system consists of a laser device and a XeF2 generator. The laser chamber is 167 cm in length, 20 cm in height and 13 cm in width with an aperture of 5 cm×5 cm. The irradiation from a sectioned sA 10 J level of optically pumping XeF(C-A) laser has been developed which can be operated on repetition mode. The laser system consists of a laser device and a XeF2 generator. The laser chamber is 167 cm in length, 20 cm in height and 13 cm in width with an aperture of 5 cm×5 cm. The irradiation from a sectioned surface discharge is used to photolysis XeF2. Lasing is investigated by employing a stable resonator with the length of 210 cm and the output coupling of 10%. The active mixed gases with XeF2 concentration of (0.6～1.2)×1017 cm-3 can be obtained from XeF2 generator. The lasing experiments have been performed and the laser can be operated in the repetitive rate of 0.2～1 Hz. At present, the maximum output energy of first pulse is 18.7 J and the total conversion efficiency of 2.5‰ is obtained. The duration of laser pulse is about 1 μs..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 83 (2006)
Discharge-Pumped XeCl Excimer Laser with X-Ray Preionzation
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A discharge-pumped XeCl excimer laser (PEL) with X-ray preionization was introduced. The capacitance lines were charged pulsed mode, and the energy stored in PFL was transfered to mixture medium by a multi-channel rail switch. As the source of X-ray, the vacuum diode produced X-ray during the time of about 500 ns earliA discharge-pumped XeCl excimer laser (PEL) with X-ray preionization was introduced. The capacitance lines were charged pulsed mode, and the energy stored in PFL was transfered to mixture medium by a multi-channel rail switch. As the source of X-ray, the vacuum diode produced X-ray during the time of about 500 ns earlier before the discharge of electrodes. The maximum output energy of 2 J was obtained experimentally with the charging voltage of 50 kV, the gas mixture of HCl:Xe:Ne＝1:2.5:2000, and the pressure of 3.546×105 Pa..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 83 (2006)
Operation Condition Optimization of Laser Media Heat-Capacity Laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
In order to optimize the operation condition of laser media employed in the heat capacity laser, numerical simulation about temperature distribution and stress distribution within the media are carried out according to different thickness and doping concentration. The principle to optimize parameters of lasing media haIn order to optimize the operation condition of laser media employed in the heat capacity laser, numerical simulation about temperature distribution and stress distribution within the media are carried out according to different thickness and doping concentration. The principle to optimize parameters of lasing media have been gotten by minimizing the gradient of temperature and stress. Then the pumping coupling way of laser media is analyzed and some current progress in heat capacity laser system is introduced..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 89 (2006)
Theoretical Research on Output Performance of Laser Resonator at Heat Capacity Model
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A three-dimensional thermo-elasto-optical distortion model for the laser disk has been constructed, the temperature and stress distributions under different work conditions on a laser disk of a heat capacity laser have been simulated by using ANSYS software, and the effect of the stress on the beam quality with nonunifA three-dimensional thermo-elasto-optical distortion model for the laser disk has been constructed, the temperature and stress distributions under different work conditions on a laser disk of a heat capacity laser have been simulated by using ANSYS software, and the effect of the stress on the beam quality with nonuniform pump has been analyzed. An demonstration experiment is done, and the results are accordant to the simulation results. The results show that at the heat capacity mode, the thermal induced birefringence is the main reason to affect the output beam properties..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 93 (2006)
Self-Compensated Thermal Effect Phenomenon of Laser Rods
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Extremity ground (end cap) method is better means to compensate thermal lens effect in laser rod. The self-compensated thermal lens (SCTL) effect phenomenon was found from the deduced equation of radius ground. Based on that the laser rod is equivalent to gradient index rod (GRIN), a new thermal lens focal length expreExtremity ground (end cap) method is better means to compensate thermal lens effect in laser rod. The self-compensated thermal lens (SCTL) effect phenomenon was found from the deduced equation of radius ground. Based on that the laser rod is equivalent to gradient index rod (GRIN), a new thermal lens focal length expression was achieved. From it the effect of self-compensated thermal lens was found, and analyzed..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 98 (2006)
Nonlinear Imbert-Fedorov Effect for Reflective Light Beam
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Nonlinear Imbert-Fedorov (I-F) effect was discussed theoretically. Only Kerr nonlinear optical medium was discussed. The results appear that nonlinear Imbert-Fedorov effect; near the critical angle, in negative Kerr effect nonlinear optical medium is smaller than linear Imbert-Fedorov effect in the linear optical mediuNonlinear Imbert-Fedorov (I-F) effect was discussed theoretically. Only Kerr nonlinear optical medium was discussed. The results appear that nonlinear Imbert-Fedorov effect; near the critical angle, in negative Kerr effect nonlinear optical medium is smaller than linear Imbert-Fedorov effect in the linear optical medium. With increasing of light intensity, Imbert-Fedorov effect decrease gradually and emerge negative shift..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 203 (2006)
Dynamic Model for CuBr UV Laser
[in Chinese], [in Chinese], and [in Chinese]
The dynamic process of Ne-CuBr UV laser in nanosecond pulsed longitudinal discharge is analyzed, and a comprehensive self-consistent physical model is developed. The temporal evolutions of discharge parameters, main particle densities, electron and gas temperatures, and the laser pulse intensity are numerically calculaThe dynamic process of Ne-CuBr UV laser in nanosecond pulsed longitudinal discharge is analyzed, and a comprehensive self-consistent physical model is developed. The temporal evolutions of discharge parameters, main particle densities, electron and gas temperatures, and the laser pulse intensity are numerically calculated. The process of population inversion between the upper and the lower laser levels as well as the lasing mechanism are illustrated. The influences of the tube radius and discharge parameters on the laser output characteristic are also explained quantificationally..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 206 (2006)
Measurement of Enhanced Near Field and Resonant Enhancement of Goos-Hnchen Shift
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
It is predicted that the Goos-Hnchen (GH) shift of both reflected and transmitted light beams in the sketch of thin-film frustrated total reflection can be resonantly enhanced .At same time the evanescent wave field in the medium of lower refractive index is still enhanced. In order to measure enhanced evanescent waveIt is predicted that the Goos-Hnchen (GH) shift of both reflected and transmitted light beams in the sketch of thin-film frustrated total reflection can be resonantly enhanced .At same time the evanescent wave field in the medium of lower refractive index is still enhanced. In order to measure enhanced evanescent wave field, sketch of frustrated total reflection is used. The results indicate that the GH shifts of reflected and transmitted wave beams can be modulated by changing incident angle and the thickness of the thin film. When the thickness of the vacuum layer satisfies some condition, the GH shift of transmitted beams are half approximately of the reflected beam..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 210 (2006)
Chirped Fiber Grating with the Apodization of Parabola Squared Function for Dispersion Compensation of Chirped Gaussian Pulses
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Theoretical research and numeric model of dispersion compensation of chirped super Gaussian pulses are presented, using chirped fiber grating with the apodization of parabola squared function. It shows that pulses, after transmitting in a fiber length, will become broadened because of dispersion. When using chirped fibTheoretical research and numeric model of dispersion compensation of chirped super Gaussian pulses are presented, using chirped fiber grating with the apodization of parabola squared function. It shows that pulses, after transmitting in a fiber length, will become broadened because of dispersion. When using chirped fiber grating with the apodization of parabola squared function, pulses can be compensated with the results that the width of pulses is more narrow and the max-power is higher ,compared with using chirped fiber grating with the apodization of Gaussian function. The pulses are distorted after being compensated. The max-power has something to do with the order of Gaussian pulses..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 213 (2006)
Amplification of the Broadband Chirped Pulse in Inhomogeneously Broadening Medium
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The amplification of highly chirped pulse with broadband in inhomogeneously broadening amplifier is investigated. Based on the analysis of the properties of the pulse with a very big chirp in which the pulse in time domain and frequency domain shares the same profile and time and frequency are linearly related, a theorThe amplification of highly chirped pulse with broadband in inhomogeneously broadening amplifier is investigated. Based on the analysis of the properties of the pulse with a very big chirp in which the pulse in time domain and frequency domain shares the same profile and time and frequency are linearly related, a theoretical model for the amplification of highly chirped pulse is built in inhomogeneously broadening medium. The amplification performance of the broadband linearly chirped pulse in the inhomogeneously broadening medium and the feasibility of the shaping compensation of the pulse amplification are explored..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 216 (2006)
Widely Tunable Mid-Infrared Generation in a Quasi-Phase Matched Optical Parametric Oscillator
[in Chinese], and [in Chinese]
A widely tunable mid-infrared generation in a quasi-phase matched optical parametric oscillator with a periodically polarized MgO-doped lithium niobate crystal is reported. Because of the lower coercive force and high damage threshold, the crystal is chosen and designed for six period patterns. In the quasi-phase matchA widely tunable mid-infrared generation in a quasi-phase matched optical parametric oscillator with a periodically polarized MgO-doped lithium niobate crystal is reported. Because of the lower coercive force and high damage threshold, the crystal is chosen and designed for six period patterns. In the quasi-phase matched optical parametric oscillator, the broadly tunable mid-infrared wavelength is realized by translating the position of the pattern in the nonlinear crystal without realignment adjustment. The experimental results show that the idler light lies in 3.649～4.115 μm when the pump wavelength is 1.064 μm. And the grating period of the crystal and the threshold pump energy of the optical parametric oscillator in this experiment are nearly consistent with the corresponding theoretical value, respectively..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 219 (2006)
Theoretical Design of 3～4 μm KTA Optical Parametric Oscillator
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The background and the meaning of studying on 3～4 μm KTiOAsO4 (KTA) optical parametric oscillator (OPO) were clarified. The researching status at present and the developing direction in the future of the KTA OPO were introduced too. The phase-matching mode, the temperature tuning characteristic and the structure of OPOThe background and the meaning of studying on 3～4 μm KTiOAsO4 (KTA) optical parametric oscillator (OPO) were clarified. The researching status at present and the developing direction in the future of the KTA OPO were introduced too. The phase-matching mode, the temperature tuning characteristic and the structure of OPO cavity were calculated and theoretically analyzed. At the same time, some problems which should be considered, such as the best length of the KTA crystal, the effect of pumping power, the coating of the OPO cavity mirror, the structure and cavity length of the OPO, the mode matching between the pump source and OPO, were discussed. The designed 3～4 μm KTA OPO pocessed the repeating frequency of 1～40 Hz, the pulse-width less than 20 ns and the single pulse energy more than 30 mJ..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 222 (2006)
Laser Pulse with Duration Shorter than 1/4 of Hypersound Oscillation Period of Medium Achieved by Stimulated Brillouin Compressor
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
An 8 ns laser pulse is compressed with the stimulated Brillouin scattering (SBS) two-step compressor in the experiment, the shortest 153 ps SBS pulse is obtained with FC-75 as the medium, and the average pulse is 177.6±11.9 ps statistically, which is shorter than the 1/4 of hypersound oscillation period of FC-75. An 8 ns laser pulse is compressed with the stimulated Brillouin scattering (SBS) two-step compressor in the experiment, the shortest 153 ps SBS pulse is obtained with FC-75 as the medium, and the average pulse is 177.6±11.9 ps statistically, which is shorter than the 1/4 of hypersound oscillation period of FC-75. And the effects of the pump energy and the focal length of the lens on the SBS pulse compression process are studied experimentally..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 226 (2006)
Time-Resolved Spectra of 240 nm at Argon Third Continuum and Kinetics Analysis
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
With electron beam, the third continuum of argon, which centers at 240 nm, has been obtained. Then photomultiplier has been used to measure the temporal evolution of 240 nm. The results show that the width of the temporal evolution at 240 nm is larger than the width of the current waveform. In theory, the kinetics modeWith electron beam, the third continuum of argon, which centers at 240 nm, has been obtained. Then photomultiplier has been used to measure the temporal evolution of 240 nm. The results show that the width of the temporal evolution at 240 nm is larger than the width of the current waveform. In theory, the kinetics model of the argon ionic excimer pumped by electron beam is built. And the relation between density of argon ionic excimer and time is obtained. The effect of the reactions on production of ionic excimer is discussed. The results of theory and experiment show that the time behavior of 240 nm is same as the density of Ar+2 ionic excimer. Therefore, the spectrum around 240 nm should be emitted by Ar+2 ionic excimer..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 229 (2006)
Response of PC Type HgCdTe Detectors Irradiated by Femtosecond Pulses Laser
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The output signal and out-of-service time of the PC type HgCdTe detectors are obtained when irradiated with femtosecond laser at the repetition rate of 1 kHz, and repetition rate of 10 Hz, respectively. When irradiated with the 1 kHz repetition rate femtosecond laser at the fluence of 0.024 mJ/cm2, the output signal isThe output signal and out-of-service time of the PC type HgCdTe detectors are obtained when irradiated with femtosecond laser at the repetition rate of 1 kHz, and repetition rate of 10 Hz, respectively. When irradiated with the 1 kHz repetition rate femtosecond laser at the fluence of 0.024 mJ/cm2, the output signal is distorted and the reference signal can be perceived, and the reference signal vanished, the detector disabled when the laser fluence increased to 0.60 mJ/cm2. While irradiated with the femtosecond laser of 10 Hz repetition rate, the out-of-service time of the detector was increasing with the irradiated fluence and the out-of-service time of 520 μs is obtained at the fluence of 2.03 mJ/cm2. The output signal indicates that the temperature of the detector is ascending while irradiated with femtosecond laser pulses continuously, which results in the resistance increasing..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 232 (2006)
Analyses Theoretically on Negative Refraction in One-Dimensional Photonic Crystals
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Negative refraction can exist in photonic crystals, and the physical significance of negative refraction in one-dimensional photonic crystals is discussed theoretically. The analytical expressions of the photonic band structure, the group velocity and the power transmittance are obtained. The frequency bands for negatiNegative refraction can exist in photonic crystals, and the physical significance of negative refraction in one-dimensional photonic crystals is discussed theoretically. The analytical expressions of the photonic band structure, the group velocity and the power transmittance are obtained. The frequency bands for negative refraction are found. There is a beam negative transverse position shift at the transmission surface when negative refraction occurs, which is analyzed in detail..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 236 (2006)
Materials and Thin Films
Recent Developments of Laser Crystals
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Recent developments and research status of laser crystals for high-power and large-energy lasers at around 1 μm for advanced fabricating techniques and novel laser weapons were reviewed.Recent developments and research status of laser crystals for high-power and large-energy lasers at around 1 μm for advanced fabricating techniques and novel laser weapons were reviewed..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 290 (2006)
Self-Q-Switched Laser Properties of Cr,Yb:YAG Crystal
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Using a fiber-coupled laser diode as the pumping source, the 1.03 μm self-Q-switched laser in the Cr,Yb:YAG crystal is demonstrated. The output Q-switched pulses are very stable, the threshold pumping power is 680 mW, the pulse duration is as short as 3.3 ns, the mean output power of 156 mW is obtained and the slope efUsing a fiber-coupled laser diode as the pumping source, the 1.03 μm self-Q-switched laser in the Cr,Yb:YAG crystal is demonstrated. The output Q-switched pulses are very stable, the threshold pumping power is 680 mW, the pulse duration is as short as 3.3 ns, the mean output power of 156 mW is obtained and the slope efficiency is about 18.5%. With the rise of the pump power, the repetition rate increases linearly, the pulse width decreases very slowly and the pulse energy and peak power increase slowly with absorbed pump power. The beam quality factor M2 is measured to be 1.17..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 294 (2006)
Nd3+:LaB3O6 Cleavage Microchip Laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
End-pumped by a Ti:sapphire laser at 871 nm, quasi-cw laser around 1060 nm with power up to 395 mW and slope efficiency near to 52% has been obtained from a Nd3+:LaB3O6 cleavage microchip placed in a plano-plano resonator. The influence of the ratio between the cavity mode and pump beam area on the laser performances aEnd-pumped by a Ti:sapphire laser at 871 nm, quasi-cw laser around 1060 nm with power up to 395 mW and slope efficiency near to 52% has been obtained from a Nd3+:LaB3O6 cleavage microchip placed in a plano-plano resonator. The influence of the ratio between the cavity mode and pump beam area on the laser performances and laser spectra at various output powers have been investigated. The experimental results show that the cleavage technique may be a novel method to obtain the microchip laser medium easily and directly..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 298 (2006)
Simulation of Thermodynamics of Electro-Optic Switches for High Average Power
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The thermodynamics of electro-optic switch materials such as LiNbO3, DKDP and KDP used in high average power laser systems is analyzed by use of finite element methods. The results show that when the power of input laser with the facular of 20 mm×20 mm gets up to 2 kW under the radiation time of 10 s, the maximum The thermodynamics of electro-optic switch materials such as LiNbO3, DKDP and KDP used in high average power laser systems is analyzed by use of finite element methods. The results show that when the power of input laser with the facular of 20 mm×20 mm gets up to 2 kW under the radiation time of 10 s, the maximum temperature rises of the three materials are 0.45 K, 7.04 K and 76.02 K, respectively, and the maximum thermal stresses are 0.528 MPa, 4.78 MPa, 47 MPa, respectively..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 301 (2006)
Self-Q-Switched and Passively Mode-Locked Laser of Laser Diode-Pumped Yb3+,Na+:CaF2 Crystal
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Laser performances of a new Na+,Yb3+:CaF2 crystal under laser diode pumping were demonstrated. This crystal only operated in the self-Q-switched scheme, with laser wavelength of 1.05 μm, and minimum pump absorbed power of 30 mW corresponding to power density of 0.60 kW/cm2. On 5 W incident power, the repetition rate anLaser performances of a new Na+,Yb3+:CaF2 crystal under laser diode pumping were demonstrated. This crystal only operated in the self-Q-switched scheme, with laser wavelength of 1.05 μm, and minimum pump absorbed power of 30 mW corresponding to power density of 0.60 kW/cm2. On 5 W incident power, the repetition rate and width of the self-Q-switched pulses reached 28 kHz and 1.5 μs, respectively. By using a semiconductor saturable absorber mirror (SESAM), simultaneous transform-limited 1 ps passively mode-locked pulses, with the average output power of one laser beam 180 mW and the repetition rate of 183 MHz, were obtained under the self-Q-switched envelope induced by the laser medium. The corresponding pulse peak power arrived at 27 kW, indicating the promising application of Yb3+,Na+-codoped CaF2 crystals in achieving ultra-short pulses and high pulse peak power..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 306 (2006)
Thermal-Lens Effect of Nonlinear Optical Crystals
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A discuss on the thermal-lens effect of three nonlinear optical crystals of great commercial value——LBO, KTP and BBO was given in the paper. The curve that the focal length of three crystals mentioned above varying with the spot size of fundamental frequency delivered on the face of the nonlinear optical crystals was aA discuss on the thermal-lens effect of three nonlinear optical crystals of great commercial value——LBO, KTP and BBO was given in the paper. The curve that the focal length of three crystals mentioned above varying with the spot size of fundamental frequency delivered on the face of the nonlinear optical crystals was also given. At the same time, KTP thermal focal length was calculated 852 mm on the condition that the incident spot size w=368 μm according to 20 W output green laser which used KTP crystal as its double frequency crystal, which agrees well with the experimental data..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 310 (2006)
Growth of Large-Sized Nd:GGG Crystal with Automatic Control of Diameter and Flat Interface
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Nd:GGG crystal with large size and good optical quality is required to applied for solid-state heat capacity laser (SSHCL), and the major way to obtain the crystals is to grow with flat interface by the method of Czochralski. In this paper large-sized Nd:GGG crystal of 75 mm diameter and 60 mm length is successfully grNd:GGG crystal with large size and good optical quality is required to applied for solid-state heat capacity laser (SSHCL), and the major way to obtain the crystals is to grow with flat interface by the method of Czochralski. In this paper large-sized Nd:GGG crystal of 75 mm diameter and 60 mm length is successfully grown by the flat interface growth technique in the furnace equipped with automatic diameter control appliance. And the crystal is absent of scattering particles and shows good optical homogeneity..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 313 (2006)
Second-Harmonic Generation in Biaxial Crystal KNbO3 for Optical Communication Systems
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Characteristics of second-harmonic generation (SHG) in biaxial crystal KNbO3 were studied. The phase-matching angles and effective second-order nonlinear coefficients for the communication wavelength of 1550 nm were calculated, and the optimum phase-matching parameters were obtained. The influences of walk-off angle onCharacteristics of second-harmonic generation (SHG) in biaxial crystal KNbO3 were studied. The phase-matching angles and effective second-order nonlinear coefficients for the communication wavelength of 1550 nm were calculated, and the optimum phase-matching parameters were obtained. The influences of walk-off angle on effective second-order nonlinear coefficient and SHG efficiency were also analyzed..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 316 (2006)
Study of Thermal Conductivity of Lennard-Jones Materials by Molecular Dynamic Method
[in Chinese], [in Chinese], and [in Chinese]
Method of molecular dynamics has been proposed which exhibits the development of films damage from micro angle in virtue of computer in detail. It can make the development of damage more visualized which cannot be observed in experiment. With Lennard-Jones potential function, pre-correct integrates method and dummy-forMethod of molecular dynamics has been proposed which exhibits the development of films damage from micro angle in virtue of computer in detail. It can make the development of damage more visualized which cannot be observed in experiment. With Lennard-Jones potential function, pre-correct integrates method and dummy-force-restrict-demarcate method are used. The effect of the density and temperature of the films on the thermal conductivity is simulated. With the radial distribution function and long distance distribution function, the structure characteristics of system have been analyzed. Besides, the high-temperature-size-effect has been studied by using different simulating sizes. The results show that the thermal conductivity increases when density or temperature increases which cannot be obtained from experimental methods. This kind of simulation can provide some useful data for research..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 320 (2006)
Broad and Dual-Band UV Optical Coatings for Application to Storage-Ring Free Electron Laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
An “HfO2/SiO2+Al2O3/SiO2” optical coating with broad-band or dual-band has been investigated experimentally for the resonator mirror of storage-ring free electron laser (SR-FEL). It was deposited by the electron-beam evaporation. Based on the measured transmittance spectrum, it was shown that the range of the tunable wAn “HfO2/SiO2+Al2O3/SiO2” optical coating with broad-band or dual-band has been investigated experimentally for the resonator mirror of storage-ring free electron laser (SR-FEL). It was deposited by the electron-beam evaporation. Based on the measured transmittance spectrum, it was shown that the range of the tunable wavelength is from 320 nm to 390 nm, and the measured transmittance is T(355 nm)=0.097%, measured absolute reflectivity is R(355 nm)=99.349% for the broad-band mirror coating. For the dual-band mirror coatings, the bands are located at 320 nm to 375 nm and 200 nm to 274 nm. The measured transmittance is as T(198 nm)=1.275%, T(248 nm)=0.028%, T(266 nm)=0.100%, T(355 nm)=0.194%. The measured absolute reflectivity is R(248 nm)=98.423%, R(266 nm)=98.298%, R(355 nm)=99.651% at the different wavelength..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 324 (2006)
Vanadium Dioxide Thin Films Depositing on ZnSe Substrate and Thermo Nonlinear Absorption Character Research
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The ZnSe crystal in the infrared wave band 10.6 μm neighbor transmissibility is 70%, is a suitable substrate for vanadium dioxide thin films used in the laser protection domain. The VO2 thin films are deposited by magnetron sputtering methods, the films and the ZnSe bond not well, the substrate need special clean. The The ZnSe crystal in the infrared wave band 10.6 μm neighbor transmissibility is 70%, is a suitable substrate for vanadium dioxide thin films used in the laser protection domain. The VO2 thin films are deposited by magnetron sputtering methods, the films and the ZnSe bond not well, the substrate need special clean. The deposit temperature was 450 ℃. The ratio of O2 and Ar is a key parameter, lots of experiments were done between 0.104 and 0.117. The results showed that when the ratio is 0.11, the VO2 is easily deposited. The VO2 content is 51.7%, is higher than films prepared by other methods. The transmittance can be higher than 60% at 10.6 μm..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 327 (2006)
Mechanism Laser Induced Damage for Sol-Gel Single Layers Optical Coatings
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
According to the damage appearances of single layer of ZrO2 and SiO2 thin films, the causing was analyzed. The damage mechanisms of two kinds of materials on sol-gel thin films can be made out that heat shocking leads to the damage of ZrO2 thin film and heat absorption is mostly the damage cause of SiO2 thin films. TheAccording to the damage appearances of single layer of ZrO2 and SiO2 thin films, the causing was analyzed. The damage mechanisms of two kinds of materials on sol-gel thin films can be made out that heat shocking leads to the damage of ZrO2 thin film and heat absorption is mostly the damage cause of SiO2 thin films. The method was taken out to improve the damage threshold of two kinds of materials..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 330 (2006)
Second-Harmonic Genaration Properties of Push-Pull Azobenzene in Langmuir-Blodgett Films
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The Langmuir-Blodgett (LB) film and the second-order nonlinear optical properties of a new azo compound were investigated by using means of second harmonic generation (SHG). Stable monolayer of 4-(carboxylic)-4-(amidogen)-azobenzene molecular formed on water surface could be transferred to solid substrate and built LB The Langmuir-Blodgett (LB) film and the second-order nonlinear optical properties of a new azo compound were investigated by using means of second harmonic generation (SHG). Stable monolayer of 4-(carboxylic)-4-(amidogen)-azobenzene molecular formed on water surface could be transferred to solid substrate and built LB multilayers. The SHG signal intensity was very strong. The hyperpolarizability of the molecule was about 1.17×10-26 esu..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 334 (2006)
Diamond-Like Carbon Thin Films Deposited by kHz Femtosecond Pulsed Laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Diamond-like carbon (DLC) thin films have been deposited with kHz femtosecond pulsed laser in different temperatures and the optical, mechanical and physicochemical properties of the deposited DLC are evaluated. The laser used in the experiment is a Ti:sapphire laser with the pulse width of 50 fs, wavelength of 800 nm,Diamond-like carbon (DLC) thin films have been deposited with kHz femtosecond pulsed laser in different temperatures and the optical, mechanical and physicochemical properties of the deposited DLC are evaluated. The laser used in the experiment is a Ti:sapphire laser with the pulse width of 50 fs, wavelength of 800 nm, single pulse energy of 0.5～1.5 mJ and repetition rate of 1kHz. DLC on different substrates, such as quarts, optical K9 glass, is deposited with the focused laser beam ablating the graphite target with the purity of 99.999% at laser pulse energy between 0.5 mJ and 1.5 mJ. Raman spectrum indicates that the DLC have a structure of D band and G band located at 1346 cm-1 and 1574 cm-1, respectively. The infrared transmission of the DLC thin film on the quartz is more than 87% between 1075 nm and 2700 nm with the highest transmission of 90% around 2000 nm, and the apparent transmission-enhanced performance is observed. After dipped into the 10% vitriol for several days and wiped with absorbent cotton, no damage and scratch are found on the DLC thin films..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 336 (2006)
Measurement and Metrology
Submarine Objects Detection Based on Stimulated Brillouin Scattering
[in Chinese]
The principle of detecting submarine objects based on stimulated Brillouin scattering (SBS) is proposed. It is based on signal disappearance to determine the position of submarine objects, and temporal difference of pump signal and echo signal to calculate the distance submarine object. When laser is focused into the wThe principle of detecting submarine objects based on stimulated Brillouin scattering (SBS) is proposed. It is based on signal disappearance to determine the position of submarine objects, and temporal difference of pump signal and echo signal to calculate the distance submarine object. When laser is focused into the water, SBS occurs as the laser intensity is over the SBS threshold. On the other hand, SBS does not occur when some objects appear before the focus. Theoretically, within diffraction limitation, it can detect objects farther than 100 m with pulse energy of 1 J, pulse width 10 ns and emission diameter 1 m; experimentally, the measurment error is less than 10 cm within 2 m, which is determined by the pulse width and does not change with the detecting distance..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 339 (2006)
Measurement of Large-Aperture Laser Beam Parameters by Array-Lens
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The parameters of laser beam is important to laser and laser optical system. The difficulties and price of measure system are increase with the aperture of laser beam increases. In this article an approach to measure the large-aperture laser beam parameters by using large array lens is given, the principle of measuremeThe parameters of laser beam is important to laser and laser optical system. The difficulties and price of measure system are increase with the aperture of laser beam increases. In this article an approach to measure the large-aperture laser beam parameters by using large array lens is given, the principle of measurement and the structure of system are introduced, the parameters of array lens and imagine system are discussed. A experimental equipment of large-aperture laser beam wavefront measurement system is designed, the wavefront aberration of a laser beam is measured and compared by array-lens and interferometer. The feasibility of the method is jestified by result of experiment..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 342 (2006)
Using Precision Fabry-Perot Interferometer to Measure Refractive Index of Aqueous Solution
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The design and application of a sensing device, based upon Fabry-Perot interferometer, for measuring refractive index of aqueous solution or concentration are presented. It is manifested by a successful measurement of the refractive index of ethanol solution, with fairly high precision, by utilizing a single-mode fiberThe design and application of a sensing device, based upon Fabry-Perot interferometer, for measuring refractive index of aqueous solution or concentration are presented. It is manifested by a successful measurement of the refractive index of ethanol solution, with fairly high precision, by utilizing a single-mode fiber for laser transmission and a two-unit CCD for image acquisition. Theoretically, the measurement principle and the feasibility of the device are analyzed; and the experimental devices are constructed with a He-Ne laser, a segment of single-mode fiber, an F-P cavity and a CCD head. Through counting the number of the concentric interference rings, with calculation the refractive index and the solution concentration are retrieved with high precision. The dynamic evolution of these rings is demonstrated, corroborating the measurement process. A refractive index change of 10-5 and a corresponding concentration variation of about 0.04% are inferred from the measured image data..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 345 (2006)
Regression Arithmetic of Trace Gas Concentration Based on Tunable Diode-Laser Absorption Spectroscopy
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Trace gas analyzers based on the tunable diode-laser absorption spectroscopy (TDLAS), combined with the long-path absorption cell, provide high sensitivity, high precision and fast response measurements of trace gases. The interferences caused by laser noise, electronic noise and optical niose, result in measurement erTrace gas analyzers based on the tunable diode-laser absorption spectroscopy (TDLAS), combined with the long-path absorption cell, provide high sensitivity, high precision and fast response measurements of trace gases. The interferences caused by laser noise, electronic noise and optical niose, result in measurement error of the second harmonic signals. Characteristics of the second harmonic signal with TDLAS are analyzed. Mathematical model of the second harmonic signal is set up. Linear regression method is used to deal with the second harmonic signal of the measured trace gas using the signal of high concentration gas as the standard. The relationship between concentrations and corresponding correlation coefficients is also studied. Some measurements of CO and CO2 are presented, and the validity of the arithmetic is proved..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 349 (2006)
Measurement Method of Laser Scattering
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The measurement method of the bidirectional reflectance distribution function (BRDF) of the object surface is explored. The changes of the incident angle and the output angle of the laser in the measurement system are studied based on the spatial position relation of the parameters of the BRDF. With the three axes circThe measurement method of the bidirectional reflectance distribution function (BRDF) of the object surface is explored. The changes of the incident angle and the output angle of the laser in the measurement system are studied based on the spatial position relation of the parameters of the BRDF. With the three axes circumrotation method, the position of the incident laser is unchanged, and the conversion from the complicate three-dimensional spatial position relation into a two-dimensional plane is realized, by adjusting the relative positions of the detector and the target with certain spatial conversion relation. A sample platform easy to adjust and build is set up, based on which the BRDF measurement system is completed with the wave chopper, phase lock-in amplifier and data collection system. The BRDF of a certain type missile surface is obtained with the incident angle 0～80°, reflective angle 0～80° and reflective azimuth 0～360°..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 353 (2006)
New-Style Intelligent Detection System of Laser Range Finder
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Considering of the characteristics of military equipment, an intelligent laser detection instrument is developed by using a simple, practical ranging-precision detection technology and an off-line simulation technology et al.. This system can not only detect the optical performance in any kind of weather conditions, buConsidering of the characteristics of military equipment, an intelligent laser detection instrument is developed by using a simple, practical ranging-precision detection technology and an off-line simulation technology et al.. This system can not only detect the optical performance in any kind of weather conditions, but also diagnose the circuit faults automatically and locate the fault to a single component. It has the advantages of real-time, accuracy, convenience and reliability..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 357 (2006)
Time of Flight Measurements with Picoseconds Resolution in Laser Altimetry
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A pulsed time-of-flight laser radar operates by transmitting a short laser pulse to an optical visible target and detecting the reflected pulse by an optical detector. The measured distance is calculated from this flight time. So the accuracy of laser time interval is a basic beacon to measure its system capability. ByA pulsed time-of-flight laser radar operates by transmitting a short laser pulse to an optical visible target and detecting the reflected pulse by an optical detector. The measured distance is calculated from this flight time. So the accuracy of laser time interval is a basic beacon to measure its system capability. By using two tapped differential delay lines working in a matrix mode with delay locked loop (DLL), to gether with counter, high precision measurement in flight time is realized in an entire digital way with all measurement construction located in a single field programmable gate array (FPGA). The single-shot precision of the time digital converter (TDC) is better than 250 ps, the drifts of TDC units remain within±30 ps over a temperature range -10～+50 ℃. The concrete design of transmit and receive circuits is discussed to improve the accuracy of the TDC. Because of the high integration, low power, light weight and stable performance the prototype reaches the request of the laser altimeter..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 361 (2006)
Calibration Technique of Light Beam Quality Measurement System
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Beam quality is always an important parameter to value the output quality of laser beam, and many methods are developed. For high intensity laser beam with center obscuration, beam quality far field measurement method is used presently. The beam quality factor β is used to judge the performance parameters of the beam qBeam quality is always an important parameter to value the output quality of laser beam, and many methods are developed. For high intensity laser beam with center obscuration, beam quality far field measurement method is used presently. The beam quality factor β is used to judge the performance parameters of the beam quality in the application of beam transport efficiency field, and it is obtained by CCD far field measurement. In order to advance measurement precision of the CCD far field beam quality factor β measurement system, the key parameters in optical elements and data collecting and processing courses are analyzed, and different calibration methods are used for different parameters. The calibration methods used in practice are explained, and the sources of the system measurement uncertainty are analyzed and determined quantificationally. The research of calibration methods promotes the advance of the measurement method, and the application of the calibration method benefits the improvement of the veracity and reliability of the measurement results in the practical measurement work..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 365 (2006)
Retroreflector Array Effect on Measurement Precision of Hartmann-Shack Wavefront Sensor
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The theory of retroreflector array used as pseudophase conjugator was presented. The simulation about the ability that Hartmann-Shack wavefront sensor reconstruct wavefront was done when Hartmann-Shack wavefornt sensor was affected by outline of single retroreflector and the beam-size reduced error of wavefront sensor The theory of retroreflector array used as pseudophase conjugator was presented. The simulation about the ability that Hartmann-Shack wavefront sensor reconstruct wavefront was done when Hartmann-Shack wavefornt sensor was affected by outline of single retroreflector and the beam-size reduced error of wavefront sensor etc. The circular retroreflector array possessed relatively better wavefront fidelity. Meanwhile the reconstruction precision of Hartmann-Shack wavefront sensor was analyzed when it was affected by its surface shape error and the correction method was presented..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 369 (2006)
Veracity Analysis on Measurement Results of Cavity Ring-Down
[in Chinese]
Different capability laser has different pulse width, which influences the figure of ring-down waveform in the cavity ring-down system (CRDS), and makes measurement result relative departure from true reflectivity.According to propagation equation of Gaussian beam and overlap-add of signal, a theory model is set up by Different capability laser has different pulse width, which influences the figure of ring-down waveform in the cavity ring-down system (CRDS), and makes measurement result relative departure from true reflectivity.According to propagation equation of Gaussian beam and overlap-add of signal, a theory model is set up by data fitting to research the influence of pulse laser on its ring-down signal and its metrical results. The change of ring-down waveform is numerically simulated in different cases by this model, and it is also calculated how the measurement result varies with the true reflectivity. Based on this, it is analyzed that relation between waveform of the laser and measured reflectivity of the CRDS. Results show that current data processing can not acquire exact measured reflectivity. and a collating ways for measured reflectivity is put forward..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 373 (2006)
Detection of Mid-Infrared Laser Signal with Low Amplitude and Short Pulse Width
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A detection method in presented for mid-infrared laser signals with 4 kHz repeat frequency, 20 ns pulse width and 1 W average power. The long distance between the detector to the source resuts in weak energy output from the detector 30～60 μV, and the loop gain of the single stage of the amplifier can not exceed 100 timA detection method in presented for mid-infrared laser signals with 4 kHz repeat frequency, 20 ns pulse width and 1 W average power. The long distance between the detector to the source resuts in weak energy output from the detector 30～60 μV, and the loop gain of the single stage of the amplifier can not exceed 100 times. Otherwise, overage gain will brings poor frequency characteristic, instability and high noises. So three-stage amplifier is designed, the total loop gain is 1000～15000 times, furthermore, an offset adjustment placed on the noninverting input to avoid the distortion of signal source, and high-pass filter is designed to reduce the noise of under 100 kHz and depress and attenuate the disturbing signals caused by high gain. Lastly, the effective and unusual method of data acquisition is put forward aiming at the characteristics of the mid-infrared short pulses..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 376 (2006)
Achromatic Focal Spot Measurement of the High Power Laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Result of the focal spot measurement on the high power laser with single lens imaging method is reported in this paper. Focal spot of the high power laser is sampled by an ellipsoid concave mirror, and after passing through a single lens, it is imaged on the CCD system. With testing data to be processed, reliable focalResult of the focal spot measurement on the high power laser with single lens imaging method is reported in this paper. Focal spot of the high power laser is sampled by an ellipsoid concave mirror, and after passing through a single lens, it is imaged on the CCD system. With testing data to be processed, reliable focal spot shape and intensity distribution are obtained. In this way, real time test with the focal spot of the high power laser is realized. The testing result has been validated in other way..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 379 (2006)
Two-Dimensional Micro-Fluidic Detection Technique of Suspension Array Based on Fluorescence Encoding
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A two-dimensional micro-fluidic detection technique was studied. Micro-fluidic device designed distinguishingly was fabricated through methods of laser ablation, laser lithography and chemical etching. Continuous laser is used to excite fluorescence from the microprobes passing the detection area and molecules reactionA two-dimensional micro-fluidic detection technique was studied. Micro-fluidic device designed distinguishingly was fabricated through methods of laser ablation, laser lithography and chemical etching. Continuous laser is used to excite fluorescence from the microprobes passing the detection area and molecules reaction information of suspension array is obtained by using highly sensitive cooling CCD freezing imaging technology. Two-dimensional micro-fluidic detection technique of suspension array, with high sensitivity and speediness and nicety, was validated by experiment..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 382 (2006)
Heat Radiation Analysis of Space Target with Combination of Sinda/G and Nevada
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
As a standard software used by NASA of USA, Sinda/G and Nevada are successfully used in the field of space target heat radiation analysis. The target with spherical surface is modeled by FEMAP of Sinda/G lite. Its orbit parameters is setup by Nevada. The simulation is executed by combination of Sinda/G and Nevada. The As a standard software used by NASA of USA, Sinda/G and Nevada are successfully used in the field of space target heat radiation analysis. The target with spherical surface is modeled by FEMAP of Sinda/G lite. Its orbit parameters is setup by Nevada. The simulation is executed by combination of Sinda/G and Nevada. The simulation results show that the heat balance is achieved within 10 minutes. While the target fly on its orbit, there are rapid changing of temperature and its distribution of target surface..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 385 (2006)
Computation on Spectral and Spatial Distribution Characteristics of Infrared Radiation of Plume
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The study on spectral and spatial distribution characteristics of infrared radiation of plume is useful for the demand of detection or defense mechanism of aircraft. The absorption spectrums of gas molecule are obtained by Curtis-Godson approximation. The spectral and spatial distribution characteristics of infrared raThe study on spectral and spatial distribution characteristics of infrared radiation of plume is useful for the demand of detection or defense mechanism of aircraft. The absorption spectrums of gas molecule are obtained by Curtis-Godson approximation. The spectral and spatial distribution characteristics of infrared radiation of plume are computed by solution of radiation transfer equation. The plume radiation intensity of a certain observation direction is obtained by integral on all parallel sample lines of sight. The calculation is reduced by adoption of adaptive coordinates method. There is strong plume radiation in the two bands of 2.7 μm and 4.3 μm due to molecular emission bands of high temperature CO2 and H2O, while the radiation intensity in the two bands greatly decreases after atmosphere propagation. The plume spectrum distribution and radiation intensity vary versus the observation direction. There are two distinct radiation bands of 2.7 μm and 4.3 μm when observed from the front. When observed in the backside, the radiation is much stronger and the characteristic of selective radiation is not so clear..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 388 (2006)
High Sensitive Laser Absorption Spectrometer Using in Greenhouse Gas Monitoring
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
It is a pop field using molecular character of absorption spectrum in infrared and tunable diode laser absorption spectroscopy to study many atmospheric trace gases absorption spectrum. Most of the molecular characteristic absorption is very weak, and the absorption line width is very narrow that can't be measured It is a pop field using molecular character of absorption spectrum in infrared and tunable diode laser absorption spectroscopy to study many atmospheric trace gases absorption spectrum. Most of the molecular characteristic absorption is very weak, and the absorption line width is very narrow that can't be measured by traditional methods. Laser has become the perfect light source using in the atmosphere monitoring due to its monochromatic, directional and high power. The key technique of the tunable diode laser absorption spectroscopy (TDLAS) is the diode laser's character of high resolution and ability of tunable, it can even obtain the concentration of trace gas by measuring a single absorption line without interferes from others. A sensitive and precise atmosphere greenhouse gas continuous monitor is developed by combining the TDLAS with multi-pass cell and weak signal detect technique. The detect limit is lower than 0.087 mg/m3, and it can up to 17.5 mg/m3, that is enough for the ambient methane detection (1.16 mg/m3 in the air)..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 391 (2006)
Application of Electronic Speckle Pattern Interferometry in Heat Reliability Research on Very Large Scale Integration Package
[in Chinese], [in Chinese], and [in Chinese]
Based on the principle that it is possible to test minuteness displacement and deformation with electronic speckle pattern interferometry (ESPI), the heat reliability of very large scale integration (VLSI) is tested. The speckle pictures of two different CPU under different heat load are obtained experimentally. By usiBased on the principle that it is possible to test minuteness displacement and deformation with electronic speckle pattern interferometry (ESPI), the heat reliability of very large scale integration (VLSI) is tested. The speckle pictures of two different CPU under different heat load are obtained experimentally. By using the approximate formula of off-surface displacement. The off-surface displacement values are calculated and the simulation curve of off-surface displacement with heat is plotted. Through analyzing the changes of curve, the heat reliability and the stability of CPU are expressed. Because this test means is fast nondestructive and with high reliability, it can not only fit for heat reliability test of VLSI package, but also for package reliability test of many other electronic and photo-electronic devices..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 395 (2006)
Laser-Induced Air Plasma Spectra Used in Atmospheric Surveillance
[in Chinese], [in Chinese], and [in Chinese]
A system of atmospheric surveillance is brought forward by studying the spectra of gas plasma induced by a pulsed Nd:YAG laser. The system can avoid shortcomings of other existing air pollution detection methods, and carry out an on-line quantitative analysis. By adjusting the experimental setup, the concentrations of A system of atmospheric surveillance is brought forward by studying the spectra of gas plasma induced by a pulsed Nd:YAG laser. The system can avoid shortcomings of other existing air pollution detection methods, and carry out an on-line quantitative analysis. By adjusting the experimental setup, the concentrations of pollutions in the air can be tested. The primary plasma spectra evolution is presented. The method can be also applied in remote controlling the particular components in certain condition..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 398 (2006)
Wavefront Reconstruction by Means of a New Extrapolation Method of Fringe-Prolongation
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
There are noticeable errors at the border of the pattern when the traditional Fourier transform method (FTM) is used to evaluate the carrier fringe pattern. A new extrapolation of fringe prolongation method based on the shift theorem of Fourier transform is proposed. Numerical simulations are performed to evaluate the There are noticeable errors at the border of the pattern when the traditional Fourier transform method (FTM) is used to evaluate the carrier fringe pattern. A new extrapolation of fringe prolongation method based on the shift theorem of Fourier transform is proposed. Numerical simulations are performed to evaluate the performance of the method which reduces the errors at the borders of the pattern. An accuracy of the phase evaluation of approximately 3.3 mrad is obtained. In order to verify the methode, a radial shearing interferometer system has been set up. The surface of a plano-convex lens has been measured. Wavefront traversing the sample is reconstructed by means of the new extrapolation method of fringe prolongation. The results show that errors are reduced in the processing of shearing wavefront testing..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 401 (2006)
Tunable Diode Laser System for Flue Gas CO Detection
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Continuous and in-situ monitoring of flue gas CO is an effective way to optimize combustion efficiency and reduce pollutant emission. Tunable diode laser absorption spectroscopy (TDLAS) a trace gas detection technique with a high sensitivity, high selectivity and fast time response, based on the tunability and narrow lContinuous and in-situ monitoring of flue gas CO is an effective way to optimize combustion efficiency and reduce pollutant emission. Tunable diode laser absorption spectroscopy (TDLAS) a trace gas detection technique with a high sensitivity, high selectivity and fast time response, based on the tunability and narrow linewidth features of diode laser. It can implement fast gas concentration measurement through an single isolated absorption line. Flue gas CO detecting system based on open-path near infrared tunable diode laser spectroscopy has been experimentally studied. Using a telecom distributed-feedback (DFB) diode laser as optical source, a rotational-vibratinal line of CO near 1.58 μm has been used for real time CO concentration measurement. Open dual-path optical configuration has been adopted in this system. Influence of optical extinction coefficient fluctuation has been avoided by background fitting and subtracting. The system detection limit is about 0.125 g/m2 (path integrated concentration), and can meet the demands of in situ measurements of combustion flue gas CO in industrial environments..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 405 (2006)
Atmosphere Backscattering Experiment of TEA-CO2 Difference Absorption Lidar
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The theory of optical heterodyne of coherent detection is introduced, which is used in TEA-CO2 differential absorption lidar (DIAL) technique to detect backscattering light of atmosphere. And the correlative optical setup is emphasised. The atmosphere backscattering experiment is carvied out based on the theory. The reThe theory of optical heterodyne of coherent detection is introduced, which is used in TEA-CO2 differential absorption lidar (DIAL) technique to detect backscattering light of atmosphere. And the correlative optical setup is emphasised. The atmosphere backscattering experiment is carvied out based on the theory. The result shows that the distance of detection of the lidar reaches over 15 km with 7 km altitude of detection. Compared with short-wavelength lidar (detection range is 3～4 km), the long-wavelength lidar has more powerful detection capability..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 408 (2006)
Laser Detecting System for the Ointment Content of the Plaster
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The system based on laser transmission method to measure the plaster ointment content was introduced in this paper. The principle and structure of the system were reported in detail. The relation of the system output and the plaster ointment content was established, and this result was compared with the results by the The system based on laser transmission method to measure the plaster ointment content was introduced in this paper. The principle and structure of the system were reported in detail. The relation of the system output and the plaster ointment content was established, and this result was compared with the results by the use of commercial β-ray instrument. Both systems can detect 0.1 g variation of the ointment content, but the optoelectronic system is safer and more compact, and can be used in the plaster industry..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 33, Issue suppl, 412 (2006)
© Copyright 2018-2021 | Chinese Laser Press. All Rights Reserved 沪ICP备15018463号-20