Journals >Chinese Journal of Lasers
Contents
2008
Volume: 35 Issue s1
49 Article(s)
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Research Article
An Edge-Bevel-Pumped Thermally Bonded Planar Waveguide Solid-State Laser
Zhang Haitao, Kang Hongxiang, Wang Dongsheng, and Gong Mali
By thermal bonding technology the single-clad YAG/Nd:YAG/YAG planar waveguide crystal has been fabricated. The geometry of the waveguide crystal is 12 mm×5 mm×1 mm, and Nd:YAG core is 0.2 mm thick and symmetry claddings are 0.4 mm thick. A novel pump scheme is employed——edge-bevel pumping: A 12 mm long edge iBy thermal bonding technology the single-clad YAG/Nd:YAG/YAG planar waveguide crystal has been fabricated. The geometry of the waveguide crystal is 12 mm×5 mm×1 mm, and Nd:YAG core is 0.2 mm thick and symmetry claddings are 0.4 mm thick. A novel pump scheme is employed——edge-bevel pumping: A 12 mm long edge is chamfered as a 0.3 mm wide bevel, the pump light from the fast-axis-collimated laser diode (LD) is focused and coupled into the crystal through the edge bevel. The pump efficiency is 82%, when the transmittance of the output mirror is 6.6% and the diode pump power is 49.5 W, the output power is 13.6 W with flat-flat cavity, the optical-optical conversion efficiency is 27.5%, and the transverse M2 factor is 1.9. The laser achieves a relatively high optical-optical conversion efficiency and excellent beam quality in transverse direction..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 1 (2008)
Tm:YLF Laser at 1.9 μm Double-End Pumped by Laser Diode
Duan Xiaoming, Yao Baoquan, He Wanjun, and Wang Yuezhu
Continuous wave (CW) Tm:YLF solid laser at 1.9 μm using laser diode (LD) double-end pumping is reported. The mechanism of the Tm3+-doped laser and the energy conversion loss is analyzed theorically. The slope efficiency of Tm:YLF laser calculated is 50%. In this experiment, fiber-coupled LD at 792 nm is used to pump thContinuous wave (CW) Tm:YLF solid laser at 1.9 μm using laser diode (LD) double-end pumping is reported. The mechanism of the Tm3+-doped laser and the energy conversion loss is analyzed theorically. The slope efficiency of Tm:YLF laser calculated is 50%. In this experiment, fiber-coupled LD at 792 nm is used to pump the Tm:YLF crystal .The LD output is divided into two beams with the same power to the two double-end pumping crystal in a folded resonator. The Tm:YLF crystal with the dimension of 3 mm×3 mm×12 mm is doped with 4% Tm3+. The wavelength of the laser with different transmittances of output mirrors is measured. When the output mirror transmittance is 26%, the continuous wave output power of 20.1 W at 1.9 μm is obtained with 75W pumping power, and the threshold is 9 W. At the same time, the slope efficiency of 34% and the optical-to-optical efficiency of 27% are achieved..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 5 (2008)
Low Voltage Driving Coupled-Cavity Electro-Optically Q-Switched Microchip Lasers
Wang Yunxiang, Huang Lei, Gong Mali, and Zhang Haitao
Coupled-cavity electro-optically Q-switched microchip lasers are integrated solid-state lasers with advantages of small size, fundamental transverse mode, single longitudinal mode, linear polarization, high repetition rate, and short pulse duration. They are ideal seed sources for high repetition rate, high beam qualitCoupled-cavity electro-optically Q-switched microchip lasers are integrated solid-state lasers with advantages of small size, fundamental transverse mode, single longitudinal mode, linear polarization, high repetition rate, and short pulse duration. They are ideal seed sources for high repetition rate, high beam quality MOPA systems. Experimental and theoretical study of the lasers is demonstrated. From theoretical analysis, long electric material and high end-face reflectivity lead to narrow Fabry-Pérot etalon transmission bandwidth, and low driving voltage. Two experimental setups are designed for low voltage driving. The gain medium and the electric material are Nd:YVO4 and LiTaO3, respectively. The cavity size is smaller than 3 mm×3 mm×2.5 mm. In the first setup, the output characteristics are studied through changing the length of electric material. Pulse repetition rates as high as 300 kHz is achieved with 184 mW pump power and 240 V driving voltage. The pulse width and peak power are 10 ns and 9.4 W, respectively. In the second setup, 1 MHz pulse rate is achieved in a short time period, by increasing the end-face reflectivity..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 9 (2008)
Quasi-Three-Level Operation of Nd:GdVO4 Laser Pumped by 879 nm Laser Diode
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
By use of novel 879 nm Laser Diode (LD), quasi-three-level transition in Nd:GdVO4 crystal at room temperature is realized. For the crystal with Nd doped concentration of 0.2% and 3 mm×3 mm×3.8 mm in size, wavelength of 912 nm. The 912 nm laser with output powe of 2.5 W when the pump power is 33 W, correspondiBy use of novel 879 nm Laser Diode (LD), quasi-three-level transition in Nd:GdVO4 crystal at room temperature is realized. For the crystal with Nd doped concentration of 0.2% and 3 mm×3 mm×3.8 mm in size, wavelength of 912 nm. The 912 nm laser with output powe of 2.5 W when the pump power is 33 W, corresponding to a slope efficiency of 11% with respect to the pump power and a slope efficiency 38% with respect to the absorbed pump power. For the crystal with Nd doped concentration of 0.2% and 3 mm×3 mm×5 mm in size. The 912 nm laser with output power of 3.0 W is obtained when the pump power is 33 W, corresponding to a slope efficiency of 16% with respect to the pump power and a slope efficiency 45% with respect to the absorbed pump power. For the acousto-optic (A-O) Q-Switched regime, average output power of 660 mW and pulse duration of 22 ns is achieved at the repetition rate of 10 kHz, the peak power is up to 3 kW. The relationship between lasing threshold and the length and Nd doped concentration of crystal are theoretically analyzed. The influence of reabsorption loss on laser′s operation is discussed and the saturation effect of reabsorption loss is observed..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 13 (2008)
Injection-Locking 2 μm Solid-State Laser
Wang Zhenguo, Ju Youlun, Li Yufeng, Wu Chunting, and Wang Yuezhu
Injection-locking solid-state laser is studied to obtain the laser light for 2 μm coherent doppler lidar. Tm,Ho:YLF microchip crystal with both ends coated is used for the master laser. In order to obtain pulse laser, the structure of slave laser is toroidal and an infrared fused silica is used as acousto-optic Q-switcInjection-locking solid-state laser is studied to obtain the laser light for 2 μm coherent doppler lidar. Tm,Ho:YLF microchip crystal with both ends coated is used for the master laser. In order to obtain pulse laser, the structure of slave laser is toroidal and an infrared fused silica is used as acousto-optic Q-switch. The master laser as a seed is injected into the slave laser. Via injection-locked and amplification, the single longitudinal-mode and frequency-stabilization pulse 2 μm laser is obtained. A Q-switch output energy is 2 mJ at 20 Hz with a pulse width of 146 ns, and 4 mJ with a pulse width of 86 ns. The wavelength of the output is 2.067 μm. The feasibility is demonstrated that the injection-locking laser is used for 2 μm coherent doppler lidar. The initial optical field in the ring laser is discussed..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 17 (2008)
Narrow Pumping Width Technology in Miniature High-Repetition Diode-Pumped Solid-State Laser
Xu Liujing, Zhao Hong, Zhang Dayong, Zhu Chen, Li Yao, and Jiang Dongsheng
There is always a contradiction between the heat-sinking capability and the volume in the engineering applications of the micro-diode-pumped solid-state laser (DPL). Using of narrow pumping width technology not only improves the products in the quality of photoelectric technology, but also decreases the heat output in There is always a contradiction between the heat-sinking capability and the volume in the engineering applications of the micro-diode-pumped solid-state laser (DPL). Using of narrow pumping width technology not only improves the products in the quality of photoelectric technology, but also decreases the heat output in key parts of apparatus to 30% of original level. It effectively solves the problem which is the heat output of the tiny parts of apparatus and improves the overall performance of the laser. Under the conditions of repeat frequency 2.5 kHz and pumping duration 120 μs, it achieves the peak power of 12.1 kW, impulse width of 7.7 ns and the laser beam quality factor M2 1.7 in pulse output while the laser works stably from -55 ℃ to ＋75 ℃. The technology greatly improves the developable space for equipment system. Clients could increase the repeat frequency to 5 kHz or even higher if needed..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 21 (2008)
Passively Mode-Locked Side-Pumped Nd:YAG Laser with Semiconductor saturable Absorption Mirrors
Li xiao, and Xu xiaojun
Semiconductor saturable absorption mirrors (SESAMs) have become the important components in the compact mode-locking solid-state lasers. we designed a side-pumped folded cavity Nd:YAG solid laser mode-locking with SESAM and got the highest average output power of about 4.7 W. The single pulse has about 85 nJ energy andSemiconductor saturable absorption mirrors (SESAMs) have become the important components in the compact mode-locking solid-state lasers. we designed a side-pumped folded cavity Nd:YAG solid laser mode-locking with SESAM and got the highest average output power of about 4.7 W. The single pulse has about 85 nJ energy and 55 MHz repeat frequency. The spectrum is measured and the full wavelength at half maximum (FWHM) is about 0.1 nm, and the M2 factor is about 1.2. Significantly, with exactly measurement about the thermal focus length, special cavity can be designed to control the mode radius. Although the laser was pumped by high power LDs (over hundreds watts), but it still has very well beam quality(nearly the diffraction-limited beam). From this work, it get closer towards the high power mode-locking solid laser..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 25 (2008)
Experimental Research of Laser Diode Pumped Tm:YAP
Han Long, Wei Lei, Wu Junyong, Zheng Yi, Chen Junwei, and Wang Keqiang
The application of 2 μm laser source is introduced, and the energy level diagram and absorption spectrum of Tm:YAP crystal are analyzed. A laser diode end-pumped Tm:YAP laser is reported. A high efficient 2 μm laser is attained at room temperature. The CW output power is 6.5 W with the laser diode output power of 19 W,The application of 2 μm laser source is introduced, and the energy level diagram and absorption spectrum of Tm:YAP crystal are analyzed. A laser diode end-pumped Tm:YAP laser is reported. A high efficient 2 μm laser is attained at room temperature. The CW output power is 6.5 W with the laser diode output power of 19 W, the optical-to-optical efficiency is up to 34% and the slope efficiency is 47.5%. While acoustic-optical (AO) Q-switch is working at modulation mode, the output power of 2 μm at the repetition of 10 kHz is 5.4 W, single pulse width is 70 ns, optical-to-optical efficiency is 28% and the slope efficiency is tested to be 42%..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 29 (2008)
An Intermittent Oscillation Dual-Wavelength Diode Pumped Nd:YAG Laser
Fan Xiuwei, He Jingliang, Huang Haitao, and Xue Lin
A dual-wavelength diode side-pumped Nd:YAG laser is generating intermittent laser action at the wavelengths of 1064 nm and 1319 nm was demonstrated. By this means, the population inversion is distributed efficiently, mode competition of both laser lines can be avoided, the effect resulted from the accuracy of the coatiA dual-wavelength diode side-pumped Nd:YAG laser is generating intermittent laser action at the wavelengths of 1064 nm and 1319 nm was demonstrated. By this means, the population inversion is distributed efficiently, mode competition of both laser lines can be avoided, the effect resulted from the accuracy of the coating process can be reduced and the stable output of dual-wavelength is easily obtained. Furthermore, under different operation conditions, the ratio of the output powers can be controlled by changing the delay time. For the input current 22 A, the pulse repetition rate 4 kHz and the delay time 10 μs, the output powers are 6.2 W for 1319 nm and 5.1 W for 1064 nm, respectively. The numerical simulation of the performance of the dual-wavelength laser has been considered basing on the rate equations of intermittent oscillation dual-wavelength laser and the theoretical analysis corresponds to the experimental result..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 33 (2008)
Short-Term Frequency Stability Measurement of 2 μm Tm,Ho:YLF Microchip Laser
Wang Zhenguo, Zhang Yunjun, Shao Xiaowei, Ju Youlun, Li Yufeng, and Wang Yuezhu
Through using the self-beat of fiber delay method, we measured the short-term frequency stability of Tm,Ho:YLF microchip laser cooled by liquid nitrogen. When the single longitudinal mode output laser power is 10 mW and the delayed fiber length is 100 m, 200 m, 300 m, 400 m and 500 m (delayed time ranging from 0.5～2.5 Through using the self-beat of fiber delay method, we measured the short-term frequency stability of Tm,Ho:YLF microchip laser cooled by liquid nitrogen. When the single longitudinal mode output laser power is 10 mW and the delayed fiber length is 100 m, 200 m, 300 m, 400 m and 500 m (delayed time ranging from 0.5～2.5 μs), respectively, the short-term frequency stability linearly increase from 1.5～4.75 kHz, and the linear slope coefficient is 1.48 kHz/μs. The oscilloscope′s Fourier integral time is about 40 ms, when the stability is measured. The laser can be the signal source for 2μm frequency stabilized laser..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 38 (2008)
Improvement of Thermal Effect of Laser Crystal Using Multi-Channel and Indium-Soldered Technique
Zhang Wenping, Yu Xin, Gao Jing, Li Xudong, and Yu Junhua
To solve the thermal dissipation problem in laser diode (LD) end pumped solid state lasers, a novel heatsink was developed based on multi-channel and indium-soldered technique. Under 28 W pump power, 8.7 W (in traditional indium-wrapped heat-sink), 10.5 W (in indium-wrapped multi-channel heat-sink) and 11.9 W (in indiuTo solve the thermal dissipation problem in laser diode (LD) end pumped solid state lasers, a novel heatsink was developed based on multi-channel and indium-soldered technique. Under 28 W pump power, 8.7 W (in traditional indium-wrapped heat-sink), 10.5 W (in indium-wrapped multi-channel heat-sink) and 11.9 W (in indium-soldered multi-channel heat-sink) output were obtained with the Nd:GdVO4 laser crystal, respectively. Corresponding optical-optical efficiencies are 31%, 38% and 44%, and the slope efficiencies are 36%, 42% and 49%, respectively. In addition, 17.5 W output was achieved under 40 W incident pump power when the indium-soldered multi-channel heatsink was used, and no saturation was observed. From the aspects of maximum output power,optical-optical efficiency and slope efficiency, the indium-soldered multi-channel heat-sink showed best performance among three kinds of heatsinks. And the advantage was further certified by measuring the length of thermal lens and fundamental mode output power..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 41 (2008)
Self-Pulsing Behaviors of Yb-Doped Fiber Lasers
Hu Shuling, Zhang Chunxi, Wang Shouchao, Hu Hanwei, and Ou Pan
It is common to use Yb-doped double-clad fibers as gain material for high power fiber lasers. It is found that these fibers are similar to the general un-doped telecommunication fiber. Because of small core size, only from several microns to tens of microns, it is much easier to cause self-pulsing effects in the fiber It is common to use Yb-doped double-clad fibers as gain material for high power fiber lasers. It is found that these fibers are similar to the general un-doped telecommunication fiber. Because of small core size, only from several microns to tens of microns, it is much easier to cause self-pulsing effects in the fiber lasers. It is presented the experimental study of self-pulsing behavior of Yb-doped fiber lasers. The result shows that under the high power condition without concentration effect, large core Yb-doped double-clad fiber are the same to three-level ion systems that self-pulsing behavior is the result of relaxed oscillation. To Yb-doped fiber laser, saturated absorption effect, stimulated Brillouin scattering and stimulated Raman scattering cannot be ignored..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 45 (2008)
Resonance Characteristics and Frequency Stabilization in Brillouin Fiber Ring Laser
Lü Yuelan, Cheng Li, and Chong Xueqing
Based on investigations of resonance characteristics in Brillouin fiber ring resonator, a frequency stability system is developed, in which microprocessor is adopted as the central controller and piezolectric ceramics (PZT) as the frequency regulator. In order to eliminate effects of external factors, the idea of “numeBased on investigations of resonance characteristics in Brillouin fiber ring resonator, a frequency stability system is developed, in which microprocessor is adopted as the central controller and piezolectric ceramics (PZT) as the frequency regulator. In order to eliminate effects of external factors, the idea of “numerical average filter” is adopted, which has highly improved the accuracy of frequency-discrimination. Besides, in order to make full use of the high speed characteristic of the frequency stability system designed in this paper, the control idea of “equal step, small step and quick control” is adopted. Using this control idea can improve the control accuracy and still guarantee the tracking velocity, and the system will not be easy to lose locking because the control idea rejects control vibration. The measuring frequency time is about 500 μs, and frequency accuracy is about 0.5 MHz, the locking time is 30 min..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 49 (2008)
Design and Simulation of End-Pumped Coupling System for Large Aperture Laser Diode Arrays
Duan Wentao, Xu Meijian, Jiang Xinying, Jiang Dongbin, Wang Fang, and Yu Haiwu
Based on the ray tracing method, the design of coupling system for large aperture laser diode (LD) arrays applied in end-pumped solid state laser was investigated systematically. Combming the current hollow duct coupling system for large aperture LD arrays, we discuss the common rules in designing coupling system for lBased on the ray tracing method, the design of coupling system for large aperture laser diode (LD) arrays applied in end-pumped solid state laser was investigated systematically. Combming the current hollow duct coupling system for large aperture LD arrays, we discuss the common rules in designing coupling system for large aperture LD arrays from the coupling efficiency, energy distribution and propagation characteristics. Also, a new way to predigest the elements of coupling system for large aperture LD arrays by arranging small arrays spherically was introduced. For 100kW LD arrays, using only one hollow duct we obtained excellent results with large uniform pump field by arranging small arrays spherically, and the intensity was more than 20 kW/cm2 with fluctuation less than 5％. The total coupling efficiency is 98％, and around 90％ of energy was contained within the effective area of gain media..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 52 (2008)
TEA CO2 Laser with High Single Pulse Energy and Repetition
Lu Hong, Cheng Zuhai, Zuo Duluo, Zhu Haihong, and Yu Wenfeng
A novel TEA CO2 laser with high single pulse power and high repetive frequency was developed to fulfill the need of laser propulsion and the optoelectric countermeasures. The technique problems such as quick charging of high voltage capacitor, uniform discharge in high pressure large aperture zone, uniform flow of highA novel TEA CO2 laser with high single pulse power and high repetive frequency was developed to fulfill the need of laser propulsion and the optoelectric countermeasures. The technique problems such as quick charging of high voltage capacitor, uniform discharge in high pressure large aperture zone, uniform flow of high pressure gas, and laser resonator, high energy pulse output and high repetition pulse output, were solved by applications of ultraviolet (UV) preionization, two-circuit series and parallel discharge structure of graphite Ernst electrode, folded resonator that embodies super-thin water-cooled non-deforming mirror, closed circle direct cooling system of double loop and high-voltage high-current switch power supply. The highest pulse energy is 92 J, pulse repetition is 35 Hz, the divergence angle of output laser is 1.4 mrad, the stability of pulse energy is 0.8%, and the average output power is more than 3000 W..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 57 (2008)
Normal Water Cooled Heatsink's Inlet Design of Semiconductor Laser Pumping Source
Yao Shun, Ding Peng, Zhang Liang, Zhang Hui, Cao Yinhua, and Wang Zhiyong
Facing the problems of high thermal resistance and high temperature difference on the top surface of semiconductor laser arrays′ directional macro-channel liquid-cooled heat sinks inducing different lifetimes and hard controlling of spectral width, the temperature distribution of internal heat sinks through the finite Facing the problems of high thermal resistance and high temperature difference on the top surface of semiconductor laser arrays′ directional macro-channel liquid-cooled heat sinks inducing different lifetimes and hard controlling of spectral width, the temperature distribution of internal heat sinks through the finite element modeling is presented. The heat sink under consideration is made of copper with varying the area of coolant inlet. Established analysis and simulation models show that a heat sink with smaller inlet area provides a lower surface temperature gradient and a better capability of heat dissipate. A continuous wave (CW) 120 W output semiconductor laser arrays pump source (3 laser bars) is obtained by using this kind of small inlet macro-channel heat sink. The central wavelength is 807.7 nm with a full wavelength at half maximum (FWHM) of 2.8 nm..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 61 (2008)
Laser Linewidth Measurement Error Analysis and Correction on Fiber Delayed Self-Heterodyne Interferometer
Jia Yudong, Ou Pan, Zhang Chunxi, and Cao Bin
The linewidth measurement error of delayed self-heterodyne interferometer is described in detail. The fundamental using delayed self-heterodyne to measure laser linewidth is analyzed, the emulator is programmed and an experimental setup is constructed to measure laser linewidth, when shorter delayed fiber is adopted. TThe linewidth measurement error of delayed self-heterodyne interferometer is described in detail. The fundamental using delayed self-heterodyne to measure laser linewidth is analyzed, the emulator is programmed and an experimental setup is constructed to measure laser linewidth, when shorter delayed fiber is adopted. The result shows the measurement error result from the fluctuation of power term. From numerical analysis, the power spectrum resulting of self-heterodyne signal is Voigt profile and the 1/f frequency noise is shown to be approximately Gaussian. The effects of 1/f frequency noise on self-heterodyne detection are described and the results are applied to the problem of laser linewidth measurement, It is proved that method is an effective tool for reducing the measurement error. As the example, when the spectrum width of Gauss profile is 4.5 kHz, the Lorentzian spectrum width is 0.68 kHz, the improvement is abvious..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 65 (2008)
A Method of Measuring Quality Factor and Reverse Saturated Current of Photovoltaic Detector PN Junction
Li Hongqi, and Wang Huimin
The characteristic parameters quality factor and reverse saturated current of photovoltaic detectors have very big distinction since different manufacture handicraft and producing conditions. A indirect method of measuring semiconductor PN junction characteristic parameters is proposed, and the convergence property of The characteristic parameters quality factor and reverse saturated current of photovoltaic detectors have very big distinction since different manufacture handicraft and producing conditions. A indirect method of measuring semiconductor PN junction characteristic parameters is proposed, and the convergence property of the numerical computational method used in this method is proved. Two simplified analysis formulas on using open circuit voltage and short circuit current are proposed to calculate PN junction quality factor and reverse saturation current of the photocell. Compared with the results of the numerical computational method, the relative error of quality factor and the reverse saturated current calculated by the simplified analytical formula are 0.03% and 0.25%, respectively. Compared with experimental results, the relative errors of open-circuit voltage calculated with iterative method is not less than 0.3%..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 69 (2008)
Beam Transmission
Real-Time Measurement of Beam Quality Factor M2 Based on Defocus Gratings
Geng Yifeng, Xu Xiaojun, and Xi Fengjie
Crossed phase defocus gratings are designed and a new technique for real-time measurement of beam quality factor M2 is achieved. We can get the beam spots at 9 various positions to be measured simultaneously by using the defocus gratings closely connecting with a short-focal-length lens. The lens provides the majority Crossed phase defocus gratings are designed and a new technique for real-time measurement of beam quality factor M2 is achieved. We can get the beam spots at 9 various positions to be measured simultaneously by using the defocus gratings closely connecting with a short-focal-length lens. The lens provides the majority of the focusing power and the grating provides 9 separate optical axes and effectively modifies the focal length of each axis. The value of M2 is determined by calculating the beam diameters using the second moment method and curve-fitting. A He-Ne laser beam is measured by using the gratings designed and a M2 value of 5.775 is achieved. Compared with a conventional measurement, the error is 5.1%..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 98 (2008)
Spatial Shape the Laser Beams to Achieve the Uniform Irradiation Required for Laser Direct-Driven Fusion
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The nonuniformity of the irradiation on the target is eliminated by adjusting the intensity distribution on the cross section of the incident laser beams while keeping the position and direction of the beams that are used for indirect-driven laser fusion unchanged. A simulating program that can calculate the intensity The nonuniformity of the irradiation on the target is eliminated by adjusting the intensity distribution on the cross section of the incident laser beams while keeping the position and direction of the beams that are used for indirect-driven laser fusion unchanged. A simulating program that can calculate the intensity distribution on spherical target with several beams irradiating on it is written. The intensity distribution on the target and its nonuniformity are worked out according to the condition of the incident beams. Then the distribution on the focal plane of the beams is educed by using the principle of weighted average. Finally the laser′s electric field distribution before the lens that is necessary for the uniform irradiation is obtained based on the laser transmission theory..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 101 (2008)
Effect of Intracavity Perturbation on Mode Properties and Tilt-Aberrated Correction for Confocal Unstable Resonators
Zhang Xiang, Zhu Xinghua, and Xiang Anping
The influence on outcoupled phase mode by introducing intracavity tilt-perturbation in confocal unstable resonators is researched by adopting Fox-Li prony method. The distribution of wavefront has been analyzed by using Zernike aberration and mode reconstruction theory. The front 35-order Zernike aberration coefficientThe influence on outcoupled phase mode by introducing intracavity tilt-perturbation in confocal unstable resonators is researched by adopting Fox-Li prony method. The distribution of wavefront has been analyzed by using Zernike aberration and mode reconstruction theory. The front 35-order Zernike aberration coefficient, point spread function (PSF) and the integrated relative far-field intensity are obtained, so the beam quality can be known fully. The properties of mode distortion are also studied experimentally by adopting Hartmann-Shack (H-S) wavefront sensor. Finally, a set of control system for intracavity perturbation is constructed and the correction for intracavity low-order aberration is performed experimentally. The result of intracavity correction shows that the system can achieve good correction for static intracavity perturbation when the control loop is closed after tilt is introduced. The front 10-order Zernike aberration, the peak value (PV) and root-mean-square (RMS) error of the wavefront have been reduced remarkably..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 104 (2008)
Spatial Intensity Profile of Stimulated Brillouin Scattering Beam
Gong Huaping, Lü Zhiwei, and Lin Dianyang
Through focusing Q-switched laser pulses into FC-72 medium, the intensity profile of backward stimulated Brillouin scattering (SBS) spot is investigated experimentally by charge-coupled device (CCD) camera and digital image processing technology, and the rules of intensity profile and spot size versus pump energy are oThrough focusing Q-switched laser pulses into FC-72 medium, the intensity profile of backward stimulated Brillouin scattering (SBS) spot is investigated experimentally by charge-coupled device (CCD) camera and digital image processing technology, and the rules of intensity profile and spot size versus pump energy are obtained. The results show that the intensity profile of backward SBS spot turns from quasi-Gaussian to Gaussian profile when the pump energy increases. And the size of SBS spot decreases gradually in a whole with pump energy. When pump energy is near the SBS threshold, the size of SBS spot is maximum, and larger than that of pump spot. When pump energy is three times larger than the SBS threshold, the size of SBS spot is minimum and smaller than that of pump spot..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 111 (2008)
Self-Imaging of Waveguides and Its Potential Applications in Coherent Combining
Liao Suying, Gong Mali, and Zhang Haitao
This paper investigated the self-imaging properties of waveguides and its potential applications in laser power coherent combing. Based on phase propagation constant and mode propagation analysis method, the self-imaging formation process of waveguides was analyzed and simulated. The self-image lengths of several regulThis paper investigated the self-imaging properties of waveguides and its potential applications in laser power coherent combing. Based on phase propagation constant and mode propagation analysis method, the self-imaging formation process of waveguides was analyzed and simulated. The self-image lengths of several regular waveguides and corresponding requests were confirmed in detail. Its characteristics were also gathered up by the numbers. Two kinds of waveguides of square and equilateral triangle were used to simulate combining for multi-beams. The calculation results show applying self-imaging of waveguides to coherent combining will be propitious to exalt output power and keep high quality beam transmitting. It is a good approach to realize high power and high quality laser radiation..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 115 (2008)
Pulse-Shaping of Nanosecond Broadband KrF Laser
Wang Shuangyi, Lü Zhiwei, Lin Dianyang, Tang Xiuzhang, Gong Kun, and Gao Zhixing
Pulse-shaping of nanosecond broadband KrF laser is studied in this paper. Short pulse is obtained through the stimulated Brillouin scattering (SBS) pulse compression, and then the pulse-shaping is realized by using the pulses-stacking. According to the amplification of stacking-pulses in KrF laser amplifier, KrF laser Pulse-shaping of nanosecond broadband KrF laser is studied in this paper. Short pulse is obtained through the stimulated Brillouin scattering (SBS) pulse compression, and then the pulse-shaping is realized by using the pulses-stacking. According to the amplification of stacking-pulses in KrF laser amplifier, KrF laser amplifier has great influence on the shape of stacking-pulse. Through adjusting the shape of stacking-pulse, the anticipated shaped pulse can be gained after amplification. The energy of shaped-pulse reaches 50mJ after once amplification, and reaches 300mJ after twice amplifications. The theoretical analysis agrees well with the experimental results. The results show that the combined scheme of pulse-stacking and the amplification of amplifier have strong ability of pulse-shaping..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 121 (2008)
Design of Binary Optical Element Applied in Excimer Laser Wavefront Shaping
Liu Xun, Chen Tao, and Zuo Tiechuan
We designed a binary optic element (BOE) applying in the excimer laser wavefront shaping, which can obtain an optical field of Butterworth distribution. We employed the Gerchberg-Saxton (GS) algorithm for realizing the optimization and MATLAB was utilized to simulate the change of optical field. By comparing the simulaWe designed a binary optic element (BOE) applying in the excimer laser wavefront shaping, which can obtain an optical field of Butterworth distribution. We employed the Gerchberg-Saxton (GS) algorithm for realizing the optimization and MATLAB was utilized to simulate the change of optical field. By comparing the simulation results of iterative number with 10, 100 and 1000 respectively, we studied the impacts of iterative number on shaping effects in Gerchberg-Saxton algorithm. Through the shaping result by cimulating about 106 time′s iterations, the phase distribution of binary optic element was obtained. The results present that the distribution of emergent optic field is Butterworth whose energy is 75.62% of total energy and the root mean square (RMS) of uniformity is 0.1394%..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 125 (2008)
Laser Manufacturing
10 kW Class CO2 Laser Welding of Thick Stainless Steel Plates
Zhang Song, Zhao Xudong, Wu Shikai, Chen Kai, and Xiao Rongshi
Laser welding of thick stainless steel with 20 kW CO2 laser was studied. The focal point shifts at high output power. For describing welding position the distance h between the center of focusing mirror and surface of test piece was used as the welding position reference, and the seam formation and welding depth were aLaser welding of thick stainless steel with 20 kW CO2 laser was studied. The focal point shifts at high output power. For describing welding position the distance h between the center of focusing mirror and surface of test piece was used as the welding position reference, and the seam formation and welding depth were also studied. Besides, high power laser welding was more sensitive to the focal system. The seam formation gave little differences at different welding positions when the focal length f was 300 mm while it was not the case when the f=200 mm. A good bead was got with one pass welding when f=200 mm, h=208 mm, laser power was 18 kW, and welding velocity was 2 m/min. The results illustrated that through optimizing welding parameters, without groove and filling materials, 12 mm thick stainless steel plate was butt welded with 20 kW laser and the seam formation was well..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 169 (2008)
Drilling in Micro-Sprinkler Irrigation Plastic Pipeline by Fiber Laser
Zhao Hongliang, Zhai Libin, Chen Jimin, Lü Yongshun, and Lü Jianmin
Holes with diameter from 0.3～1 mm need to be processed in micro-sprinkler irrigation plastic pipeline for agriculture. This requirement cannot be satified by traditional way of using mechanical punching. Laser drilling in such pipeline not merely brings some advantages such as good suitability in material, high efficieHoles with diameter from 0.3～1 mm need to be processed in micro-sprinkler irrigation plastic pipeline for agriculture. This requirement cannot be satified by traditional way of using mechanical punching. Laser drilling in such pipeline not merely brings some advantages such as good suitability in material, high efficiency in production and free burr on porthole but also improves product quality and increases variety of product. The CW fiber laser and pulsed fiber laser have been employed on drilling in micro-sprinkler irrigation plastic pipeline with ingredient of PE(Polyethylene) in the experiment. The dependence between laser power and hole diameter and the dependence between fluence and hole diameter have been achieved. Finally, holes for required diameter have been made in the pipeline by using CW fiber laser and pulsed fiber laser..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 173 (2008)
Distortion of Streak Tube and Its Effection to Multiple Streaks-Streak Tube Imaging Lidar
Liu Jinbo, Li Sining, Guang Yuhao, Zhao Daimin, and Wang Qi
A flash imaging lidar system based on multiple streaks (MS)-streak tube was designed. In the imaging process, the laser beam after expanding was irradiated on the target, and the light reflected by the target was focused on the fiber image transformer through receining antena. The line images transformed from plane imaA flash imaging lidar system based on multiple streaks (MS)-streak tube was designed. In the imaging process, the laser beam after expanding was irradiated on the target, and the light reflected by the target was focused on the fiber image transformer through receining antena. The line images transformed from plane image will be coupled to the photocathode of streak tube through an optical taper. The photoelectrons excitated by the line images are accelerated and deflected by the deflecting voltage: And then they were imaged on the phosphor of the streak tube and captured by a CCD camera. In order to remap the line images to area image, the distortion effect of streak tube must be corrected, for it will seriously affect the final image remapping. The reason and effect of the distortion is analyzed in this paper. Distoration of streak image and its effect to image remapping is simulated. The results show that 5% elongated or 0.5% local dip will seriously influence the remapped quality of target image..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 177 (2008)
Signal Extraction and Simulation for Coherent Wind Lidar
Xu Bo, Wang Chunhui, Zhang Jian, and Wang Qi
We discuss the methods to apply pulse integration in coherent lidar, and simulate the course of signal processing by Simulink softplat. According to the result of the simulation, under certain parameters set, signal-noise ratio (SNR) can achieve 22 dB at least, when the coherent integrated time is more than 0.028 s. IfWe discuss the methods to apply pulse integration in coherent lidar, and simulate the course of signal processing by Simulink softplat. According to the result of the simulation, under certain parameters set, signal-noise ratio (SNR) can achieve 22 dB at least, when the coherent integrated time is more than 0.028 s. If we process a shot-time coherent integration within 0.007 s at first, then process non-coherent integration, SNR can achieve 18 dB at least, when the total integrated time is more than 0.020 s..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 181 (2008)
Semiconductor Laser in Range-Gated Night Vision System
Xin Desheng, Zhang Jianjia, Wang Ling, Zhang Mengmeng, and Zhang Jiaying
Range-gated night vision system with semiconductor pulse laser is an active image-forming system, which takes high power semiconductor laser and shimmer tube as lighting source and receiving sensor, respectively. Night vision system of semiconductor laser introduced in this paper adopts high quality semiconductor laserRange-gated night vision system with semiconductor pulse laser is an active image-forming system, which takes high power semiconductor laser and shimmer tube as lighting source and receiving sensor, respectively. Night vision system of semiconductor laser introduced in this paper adopts high quality semiconductor laser lighting source technology and range-gated technology, whose key technology is the semiconductor laser beam shaping and proportion technique. The system can eliminate the impact of back scattering light and stray light brought by the pulse laser and increase signal-to-noise ratio. It can obtain plain night vision figures. Experiments prove that the range-gated night vision system can obtain plain night vision figures in bad weather condition. Its function distance can reach to 5 km. Not only can the night vision system of semiconductor laser be used in military field, but also in frontier defense, public security, searching rescue, monitor field, etc..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 185 (2008)
Application of Laser in the Measurement of Object Surface Coating Uniformity
He Ning, Liao Xin, and Ao Faliang
Aiming at the nonuniformity of object surface coating, laser is adopted in contactless measurement of object surface. By this way, online detection of microcosmic variations in the object surface is realized. Through scanning over the object surface with a light spot and analyzing the variation of intensity of reflecteAiming at the nonuniformity of object surface coating, laser is adopted in contactless measurement of object surface. By this way, online detection of microcosmic variations in the object surface is realized. Through scanning over the object surface with a light spot and analyzing the variation of intensity of reflected light, the relationship between reflected light intensity and object surface coating uniformity can be obtained. Uniformity of object surface coating is radom, and the reflectivity is different on the surface. The appearance features of object surface to be measured are emulated by computer, and the simulated results can reflect the change tendency of surface coationg uniformity. Experimental results prove that the measurement system has simple structure and intuitionisticprinciple, and precision of measurement value is less than 5 μm within an operation scope from 1～80 μm..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 189 (2008)
Sealing Glass Ampoule by CO2 Laser
Tang Wenlong, Wang Xinbing, Huang Yu, and Jiao Junke
The technology of sealing glass ampoule by preheating, melting and sealing by CO2 laser was presented in this paper. The ANSYS software was used to simulate the temperature and thermal stress distributions considering the influences of surface convection and the variation of the physical properties of the glass with teThe technology of sealing glass ampoule by preheating, melting and sealing by CO2 laser was presented in this paper. The ANSYS software was used to simulate the temperature and thermal stress distributions considering the influences of surface convection and the variation of the physical properties of the glass with temperatures. The relationships between temperature and the thickness and rotating velocity of the ampoule were obtained. The results show that the surface temperature decreases with the increase of thickness; the temperature of the outer surface will reach almost the same value at different rotating velocities, if the laser interaction time is the same. The main cause of the ampoule broken is the tensile stress during the cooling..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 193 (2008)
Application Research of Range-Gated Technique in Underwater Laser Imaging System
Chen Mingsong, Li Tiansong, and He Zhiyi
The report provides the principle and advances of range-gated underwater laser imaging technology. A novel prototype underwater laser imaging system has been designed and developed. The range-gated technique is one of the effective methods to decrease the backward scattering of the water. By using the lower attenuationThe report provides the principle and advances of range-gated underwater laser imaging technology. A novel prototype underwater laser imaging system has been designed and developed. The range-gated technique is one of the effective methods to decrease the backward scattering of the water. By using the lower attenuation window for the water in the visible light spectrum, pulse laser with the blue-green wavelength has been adopted as an illumination source and CCD as the receiver. The range-gated underwater laser imaging system has been successfully fulfilled. The system can decrease the influence of backward scattering and at the same time the system can improve target luminance. The detail schematic principle and realization scheme have been analyzed. It has been found that the range-gated underwater laser imaging system could improve the imaging quality and the imaging distance by conveniently adjusting the pulse delay and the pulse width. It has been become one of the key techniques in underwater laser imaging research field..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 197 (2008)
One-Dimensional Thermal Pattern Simulation of Resin Based Composites Subjected to Pulse Laser Beam
Wang Yizhong, and Zhao Guomin
One-dimensional (1D) temperature field model is built to simulate the effects of resin based composites subjected to continuous laser beam. “Phase change enthalpy method” is put forward to deal with the problem of additional heat absorbed during resin decomposition and moving decomposition surface, which simplifies theOne-dimensional (1D) temperature field model is built to simulate the effects of resin based composites subjected to continuous laser beam. “Phase change enthalpy method” is put forward to deal with the problem of additional heat absorbed during resin decomposition and moving decomposition surface, which simplifies the solving process; then, the model is adjusted using “highest historical temperature pursue method” to revise the model of enthalpy method, which settles the argument between bidirectional change of temperature and irreversible decomposition process. Then, FORTRAN compute program is compiled after discreting the equtions with difference method. Results from calculation and references agree well. Using the model, the relationship between laser parameters and composites temperature is studed at last..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 204 (2008)
Laser Physics
Solid State Dye Laser Based on Copolymer of Methyl Methacrylate with 2-Hydroxyethyl Methacrylate
Fan Rongwei, Li Xiaohui, Xia Yuanqin, Liu Wei, and Chen Deying
Polymers are a kind of attractive hosts for laser dyes with advantages such as superior optical homogeneity, high transparency in pumping and lasing range, good chemical compatibility with organic dyes, easy control of the chemical process, low cost, and so on. PM567-doped solid dye samples based on copolymer of methylPolymers are a kind of attractive hosts for laser dyes with advantages such as superior optical homogeneity, high transparency in pumping and lasing range, good chemical compatibility with organic dyes, easy control of the chemical process, low cost, and so on. PM567-doped solid dye samples based on copolymer of methyl methacrylate (MMA) with 2-hydroxyethyl methacrylate (HEMA) were prepared. The influence of the volume percentage of HEMA on the properties of solid dye samples was studied. Pumping the samples longitudinally with the second harmonic generation (SHG) of Q-switched Nd:YAG laser at the pulse rate of 10 Hz, the output properties were studied. The lasing threshold was lower than 10 mJ/cm2. There was an optimal volume ratio of MMA to HEMA for the highest slope efficiency. And the highest efficiency 56.2% was obtained in the sample with volume ratio 1:1. The photostability of samples was studied through pumping the samples by 17.5 mJ/pulse (the fluence was 0.02 J/cm2) at 10 Hz repetition rate. The useful lifetime of 123000 shots was obtained before the output fell to half of its initial value, and normalized stability was 10.8 GJ/mol..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 73 (2008)
Impacts of Relative Velocity Distribution between Two Colliding Atoms on Laser-Induced Collisional Energy Transfer
Zhang Hongying, Chen Deying, Lu Zhenzhong, Xia Yuanqin, and Fan Rongwei
The distribution function of relative velocity between two colliding atoms in three-dimensional space is obtained based on Maxwell velocity distribution function under thermal equilibrium condition. Considering this distribution function in the computation of laser-induced collision cross section, one laser-induced colThe distribution function of relative velocity between two colliding atoms in three-dimensional space is obtained based on Maxwell velocity distribution function under thermal equilibrium condition. Considering this distribution function in the computation of laser-induced collision cross section, one laser-induced collisional energy transfer (LICET) process in Eu-Sr system both in weak and strong field is numerically calculated by integrating the motion equation based on the four-level model, and profiles of laser-induced collision cross section at given temperature are obtained. Impacts of relative velocity distribution on laser-induced collision process are analyzed by comparing the presenting numerical results with the former theoretical research. It is shown that although statistical distribution of relative velocity between two atoms has no impacts on the line shape of LICET spectrum, it has certain impacts on the peak value of collision cross section. The conclusions we came to in this paper are consistent with the theoretical predictions of former investigation, showing the validity of our numerical calculations..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 77 (2008)
Concept Design of Three-Line Capillary: Possible Source for Extreme Ultraviolet Lithography
Zhang Xingqiang, Cheng Yuanli, and Wang Qi
Extreme ultraviolet lithography (EUVL) technology, the extensional technology of 193 nm immersion lithography, would breakthrough the 30 nm node or below and become the main technology of the next generation lithography (NGL). Although the capillary discharge extreme ultraviolet (EUV) source could provide efficient andExtreme ultraviolet lithography (EUVL) technology, the extensional technology of 193 nm immersion lithography, would breakthrough the 30 nm node or below and become the main technology of the next generation lithography (NGL). Although the capillary discharge extreme ultraviolet (EUV) source could provide efficient and convenient light for EUVL investigation, its low power confines the development of EUVL. The concept design of three-line capillary discharge EUV source will be essentially different from conventional capillary discharge channel, which will also make a great difference of dynamical mechanism. The circular loop band plasma column of three-line capillary discharge EUV source irradiates more EUV power than conventional capillary discharge device does and the optimal divergence angle of the former will be improved too. The concept design plan of three-line capillary discharge will not only create a new area for EUVL research technically, but also help to produce light sources industrially and economically..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 81 (2008)
Artificial Media Based Low-Pass Spatial Filters
Xiang Yuanjiang, Tang Zhixiang, Wen Shuangchun, and Dai Xiaoyu
By using the transfer matrix method and finite difference time domain (FDTD) method, the propagation characteristics of artificial media based low-pass spatial filters were numerically simulated and analyzed. Two schemes were presented, and the method controlling the cutoff wave-vector of the spatial filters was obtainBy using the transfer matrix method and finite difference time domain (FDTD) method, the propagation characteristics of artificial media based low-pass spatial filters were numerically simulated and analyzed. Two schemes were presented, and the method controlling the cutoff wave-vector of the spatial filters was obtained. Numerical calculations show that spatial filtering utilizing the indefinite metamaterial or low effective index photonic crystal processes near filed components and is inherent compact. It consists of multilayer of thin slabs, which are only a few wavelengths thick. The spatial filters based on the artificially media is significant in the high-power laser, which can decrease the spaces occupied by the conventional spatial filters..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 85 (2008)
A 100 J Laser System with Stimulated Brillouin Scattering Phase Conjugating Mirror
Wang Yulei, Lü Zhiwei, He Weiming, Zheng Zhenxing, and Wang Shuangyi
A high-power phosphate Nd: glass laser system with 100J energy was developed. In the laser design process, the optimization of the optical layout was considered and the amplification gain of laser media was simulated. In the laser system, image relaying and stimulated Brillouin scattering (SBS) are employed to improve A high-power phosphate Nd: glass laser system with 100J energy was developed. In the laser design process, the optimization of the optical layout was considered and the amplification gain of laser media was simulated. In the laser system, image relaying and stimulated Brillouin scattering (SBS) are employed to improve the quality of the output beam. A single-longitudinal mode laser pulse provided by a Nd:YLF front-end was amplified by two dual pass amplifiers and a booster amplifier, and the output energy of 106 J was obtained. In view of the requirements of SBS phase conjugating mirror employed to the high energy and high power laser system with large diameter, a new design of the SBS phase conjugating mirror was described. It is fully applicable to the high energy and high power dual pass amplification laser system..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 90 (2008)
Degenerate Four-Wave Mixing for Iodine Vapor under the Condition of Normal Atmosphere and Room Temperature
Wang Weibo, Chen Deying, Fan Rongwei, and Yang Jun
Forward degenerate four-wave mixing (DFWM) by using self-stability spilt-beam system has been demonstrated in iodine vapor. It is found that there is no laser-induced fluorescence (LIF) existing because of collision quenching at atmospheric pressure and room temperature, however strong DFWM spectroscopy of iodine vaporForward degenerate four-wave mixing (DFWM) by using self-stability spilt-beam system has been demonstrated in iodine vapor. It is found that there is no laser-induced fluorescence (LIF) existing because of collision quenching at atmospheric pressure and room temperature, however strong DFWM spectroscopy of iodine vapor can be obtained. DFWM spectrum (554～556 nm) of iodine vapor has been measured by forward geometry of DFWM at atmospheric pressure and room temperature. This technique without suffering severe quenching problems at atmospheric pressure and room temperature is of importance to trace atom, molecular and radical in combustion diagnosis..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 95 (2008)
Materials and Thin Films
Research on Peculiarity of All-Optical Poling for the Azo Adulterant Polymer Spin Film
Li Yun, Wang Wenjun, Liu Yunlong, and Gao Xuexi
It has been an important trend for searching materials with quicker second harmonic generation (SHG) and some excellent poling conditions. In this paper, the properties of SHG were investigated for spin coating films of the Azo host-guest adulterant dye by using all-optical poling way. The experiment results show that It has been an important trend for searching materials with quicker second harmonic generation (SHG) and some excellent poling conditions. In this paper, the properties of SHG were investigated for spin coating films of the Azo host-guest adulterant dye by using all-optical poling way. The experiment results show that the saturation time of all optical poling was different for the same guest (NBMR) adulterated to different hosts. The poling time of whose hostis PMMA was about 15 min quicker than PA. For the same sample, poling condition Iω/I2ω=9 is better than Iω/I2ω=30. The rule of all-optical poling were basically same for the spin coating films with the same host (PMMA), different guests (NBAR and NBMR) and different thicknesses. The longer of the poling time, the stronger of the SHG intensity during the poling first stageis . But the SHG intensity no longer increases adding when the samples′ SHG intensity reaches a certain saturation value. Then it would be slightly receded with the increasing of poling time, and at last it would reach to a stable value..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 153 (2008)
Study of High-Luminescence Semiconductor Laser′s Film
Wang Hongming, Fu Xiuhua, and Zhang Enjie
One major method to decrease threshold current density of the semiconductor laser and enhance the deferential exterior of the quantum-efficiency is choosing desirable reflectance of light on both ends of light-emitting chip. This paper provides the contents of optimizing coating system based on optical thin film designOne major method to decrease threshold current density of the semiconductor laser and enhance the deferential exterior of the quantum-efficiency is choosing desirable reflectance of light on both ends of light-emitting chip. This paper provides the contents of optimizing coating system based on optical thin film design theories. The design of optical thin film is prepared with desirable materials, assisted with electron-beam evaporation technology. The optical dielectric film was deposited on two end surfaces of light-emitting chip which has 100 μm stripe width and 1mm length in semiconductor laser. Through the process, it obtains the specific properties of optical spectrum as well as obtuse light emitting vertical cavity surface. It decreases material absorption and enhances laser damage thresholds through optimizing parameters of optical film deposition. After testing, the output power of the high-luminous semiconductor laser′s luminous CMOS chip is improved to 3.7 W. The power has been raised by 2.8 to 3.1 times than the uncoated apparatus..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 157 (2008)
Thin Films Thickness Calculation of Vanadium Dioxide Using as Laser Protection Material
Tian Xuesong, Liu Jincheng, Li Lianjiang, Liu Jinbo, and Wang Qi
Vanadium dioxide thin films can be used in laser protection for it has the closest phase transition temperature to the room temperature. Before phase transition, its transmittance is high, and the detector can work. Phase transition occurs when the attack laser′s energy is absorbed, then transmittance decrease, and theVanadium dioxide thin films can be used in laser protection for it has the closest phase transition temperature to the room temperature. Before phase transition, its transmittance is high, and the detector can work. Phase transition occurs when the attack laser′s energy is absorbed, then transmittance decrease, and the detector can be protected. The film thickness has large influence on transmittance. Its influence can be analyzed by eigenmatrix method of absorbing thin film, calculating the transmittance before and after phase transition using refract index n and extinction index k. For the transmittance 75% before and 5% after phase transition by calculating the thickness, combining with the calculation of sputtering yield and sputtering rate, preparing time can be gotten. VO2 thin films were prepared on zinc selenide, the transmittance was measured by IR spectrophotometer, 79.2% before and 12.3% after phase transition. The thickness was measured by profile meter, and the result fits the calculation well. The calculation about thickness is doable..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 161 (2008)
Improvement of Cavity Films and Catastrophic Optical Damage on 980 nm Semiconductor Laser
Lu Peng, Liu Guojun, Bo Baoxue, Wang yuxia, and Wang chongyang
One serious problem impairing semiconductor laser quality is the catastrophic optical damage (COD), and different cavity film have different devices COD. Ion beam assisted deposition (IBAD) can make the surface of substrate more cleanly, make the film more firmly and compactly, then decrease the loss of absorption and One serious problem impairing semiconductor laser quality is the catastrophic optical damage (COD), and different cavity film have different devices COD. Ion beam assisted deposition (IBAD) can make the surface of substrate more cleanly, make the film more firmly and compactly, then decrease the loss of absorption and scatter. And making cavity films in a N2 atmosphere can can improve the threshold of COD. Using the 980 nm semiconductor, we found a improving COD from aging test in different technologies and different materials..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 164 (2008)
Optical Communication
Influence of Spherical Aberration and Coma on Far-Field Behavior of Signal Bean in Intersatellite Optical Communications
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In intersatellite communications, wave front aberration is main factor in affecting far-field behavior of signal beam. In this paper the influence of coma and spherical aberration on the far-field distribution and antenna receiving power is analyzed, in which aberration attenuation factor is introduced and the relationIn intersatellite communications, wave front aberration is main factor in affecting far-field behavior of signal beam. In this paper the influence of coma and spherical aberration on the far-field distribution and antenna receiving power is analyzed, in which aberration attenuation factor is introduced and the relation of it to root mean square (RMS) of wavefront aberration is given. The results show that the deeper coma and spherical aberration are, the heavier the influence on receiving power is. In the condition of the antennae being aligned correctly, receiving power becomes half of that for signal beam without aberration, when the values of root mean square for coma and spherical aberration are 0.120λ and 0.135λ, respectively. The influence of coma on receiving power is mainly caused by the moving of the intensity peak, and for spherical aberration it is the increasing of secondary intensity peak..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 129 (2008)
Supercontinuum Spectra Generation in the Highly Nonlinear Liquid-Core Photonic-Crystal Fiber
Zhang Hui, Guo Peng, Chang Shengjiang, and Yuan Jinghe
A novel method to realize a highly nonlinear photonic crystal fiber (PCF) is reported. In this method, the core of the hollow core-PCF (HC-PCF) is filled with highly nonlinear liquids, such as carbon disulfide, chloroform and methylbenzene. The transmitting characteristics, fundamental mode distribution and dispersion A novel method to realize a highly nonlinear photonic crystal fiber (PCF) is reported. In this method, the core of the hollow core-PCF (HC-PCF) is filled with highly nonlinear liquids, such as carbon disulfide, chloroform and methylbenzene. The transmitting characteristics, fundamental mode distribution and dispersion features of the liquid-filled PCFs are studied by using the full-vector finite element method. Numerical results indicate that the zero-dispersion wavelength of the liquid-filled PCF can be tuned around 800 nm. And the propagation of femtosecond pulses laser with central wavelength at 800 nm through the liquid-filled PCF in its anomalous dispersion regime is numerically simulated. As the liquid-filled PCF demonstrates highly nonlinear coefficient, the liquid-filled PCF is capable to generate dramatically broadened supercontinuum about 1000 nm through several micrometers distance..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 134 (2008)
Numeric Analysis of Butterfly Multimode Interference Couplers
Yan Chaojun, Wan Junli, Jiang Binghua, Xiang Liu, and Ling Jie
The structural parameters of butterfly multimode interference (MMI) coupler need to be determined according to the special ratio of power splitting when the device is designed. The coupling length, as a characteristic parameter of rectangular MMI coupler, is determined by the finite difference beam propagation method (The structural parameters of butterfly multimode interference (MMI) coupler need to be determined according to the special ratio of power splitting when the device is designed. The coupling length, as a characteristic parameter of rectangular MMI coupler, is determined by the finite difference beam propagation method (FD-BPM) which is applied to the modeling of symmetrical interference rectangular MMI coupler and then the structural parameters of butterfly MMI coupler are designed by the formulas of mode propagation analyse (MPA) method which is an approximate method. Finally the FD-BPM is used to correct the parameters of butterfly MMI couplers, including the structural parameters and the ratio of power splitting. It is indicated by an example of practical device in SOI wafer that the length of butterfly MMI coupler obtained by simulation is more than the length expected by MPA theory within the range of two to four micrometers. The actual power splitting ratio is lower than the predicted values of MPA theory. And the further the shape of butterfly MMI coupler departures from the shape of rectangular MMI coupler, the more deviation grows between these two values..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 139 (2008)
Storage Energy from High Energy Pulsed Fiber Amplifiers under the Influence of Amplified Spontaneous Emission
Zhou Jie, Yan Ping, Ye Changgeng, Yu Haijuan, and Gong Mali
In the high energy pulsed fiber amplifiers, due to the long gain region of fiber, amplified spontaneous emission (ASE) builted during the space of successive pulses is the most important limitation of the increase of storage energy and extraction capabilities. An analytic model is developed to evaluate the ASE, storageIn the high energy pulsed fiber amplifiers, due to the long gain region of fiber, amplified spontaneous emission (ASE) builted during the space of successive pulses is the most important limitation of the increase of storage energy and extraction capabilities. An analytic model is developed to evaluate the ASE, storage energy, gain and extractable energy from low frequency, high pumped fiber amplifiers for various numerical apertures, overlap integrals, reflection index, core radius, fiber length and pump power. This model could reflect the physics essence compared to numerical model. The model provides a good assessment for the maximum extractable energy and gain from high energy pulsed amplifiers..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 143 (2008)
Fiber Characteristics under High Power Density Measurement System Design
Tian Ning, Wang Dongsheng, Huang Lei, and Gong Mali
Tian Ning,Wang Dongsheng,Huang Lei,Gong MaliAiming at solving special requirements of fiber device suited for fiber laser under high power density operation, a new measurement system was designed to meet these special requirements. After comprehensive analysis and comparison with truncation method, backward scattering Tian Ning,Wang Dongsheng,Huang Lei,Gong MaliAiming at solving special requirements of fiber device suited for fiber laser under high power density operation, a new measurement system was designed to meet these special requirements. After comprehensive analysis and comparison with truncation method, backward scattering method and insertion loss method, a new dual optical path measurement system of fiber was proposed. The system can measure the insertion loss of tested fiber and reference fiber at the same time to monitor and calibrate the input optical signal power, so it can achieve higher accuracy. Theoretical consequence and explanation for the measuring method and parameters in this new system are discussed in this paper. The transmission efficiency and measuring accuracy of the system is analyzed, which meet the need of design (Insertion loss ≤0.5 dB, return loss≥50 dB)..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue s1, 149 (2008)
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