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Contents
2002
Volume: 29 Issue 7
22 Article(s)
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Research Article
Matrix Series Method of the Raman-Nath Equation of Ultrasonic Light Diffraction and Its Application to the Optimum Design of Acousto-optics Modulator
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A universal and convenient matrix series method to solve the Raman Nath equation of normal ultrasonic light diffraction is presented. The results show that the diffraction efficiency for Bragg approach is only 97.5% at Q=4.1π, and that for asymmetry incidence, there is large error in previous Raman Nath approach. TheA universal and convenient matrix series method to solve the Raman Nath equation of normal ultrasonic light diffraction is presented. The results show that the diffraction efficiency for Bragg approach is only 97.5% at Q=4.1π, and that for asymmetry incidence, there is large error in previous Raman Nath approach. The formula of the optimum length of the acousto optics modulator is given. Increasing the ratio of acoustical frequency to optical frequency is a effective way to improve the diffraction efficiency..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 29, Issue 7, 595 (2002)
Temperature Tracking Compensation of Fiber Optic Voltage Sensor
[in Chinese], and [in Chinese]
The output characteristic of fiber optic voltage sensor is analyzed. It is found that the response of the voltage sensor is nonlinear and the sensor suffers from the influence of temperature over a wide measuring range. A method for temperature tracking compensation of fiber optic voltage sensor based on artificial neuThe output characteristic of fiber optic voltage sensor is analyzed. It is found that the response of the voltage sensor is nonlinear and the sensor suffers from the influence of temperature over a wide measuring range. A method for temperature tracking compensation of fiber optic voltage sensor based on artificial neural network is presented in this paper. In order to realize temperature tracking compensation over a full range, the neural network is trained to properly represent the nonlinear mapping between the sensor reading and their represented output accurately at different environmental temperature. It is revealed from the computer simulation result that not only the influence of temperature fluctuation can be eliminated effectively, but also a desired linear relationship between the sensor input and the neural network output can be obtained..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 29, Issue 7, 600 (2002)
Beat Frequency Character and Its Application for Optic-fiber Couplers
[in Chinese], [in Chinese], and [in Chinese]
A new structure of all fiber interferometer is constructed based on the analysis of beat frequency character of 2×2 optic fiber. The interferometer can be used for adjustment the alternate interference signal and used wide in the field of test for vibration character, length of optic fiber and speech signal collecA new structure of all fiber interferometer is constructed based on the analysis of beat frequency character of 2×2 optic fiber. The interferometer can be used for adjustment the alternate interference signal and used wide in the field of test for vibration character, length of optic fiber and speech signal collection..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 29, Issue 7, 605 (2002)
Biomedical Photonics and Laser Medicine
Study on Kinetics of Thermally Induced Damage of Rat Liver with Light Scattering Technique
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Kinetics of thermally induced damage of rat liver at different constant temperature (55～95℃) were studied with continuous wave transillumination technique. It showed that thermal damage could be described by scattering coefficient. According to the relation of change in scattering coefficient and time at different tempKinetics of thermally induced damage of rat liver at different constant temperature (55～95℃) were studied with continuous wave transillumination technique. It showed that thermal damage could be described by scattering coefficient. According to the relation of change in scattering coefficient and time at different temperature, the activation energy (E=135 2 (kJ/mol)) and entropy of activation (Δ S=116 7 (J/K·mol)) were calculated. The thermal damage of rat liver was analyzed. This work provides a new method to measure thermal damage properties..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 29, Issue 7, 667 (2002)
Holography and Information Processing
Effect of Initialization Conditions on the Reflectivity and CNR of Ge2Sb2Te5 Phase-change Optical Disk
[in Chinese], [in Chinese], and [in Chinese]
The initialization conditions have great effect on the reflectivity contrast and CNR of Ge 2Sb 2Te 5 phase change optical disk. It is indicated that the reflectivity contrast increases at low velocity, while decreases at high velocity, as the initialization power increases and the reflectivity contrast decreases as theThe initialization conditions have great effect on the reflectivity contrast and CNR of Ge 2Sb 2Te 5 phase change optical disk. It is indicated that the reflectivity contrast increases at low velocity, while decreases at high velocity, as the initialization power increases and the reflectivity contrast decreases as the initialization velocity increases. Also the reflectivity contrast is very different when the measurement wavelength changes from 400 to 900 nm. The CNR of Ge 2Sb 2Te 5 phase change optical disk first increases and then decreases when the initialization power and velocity increase. The most favorable initialization conditions are those that power ranges from 1100 to 1300 mW and velocity ranges from 3.0 to 4 2 m/s..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 29, Issue 7, 643 (2002)
Phase Unwrapping Using the Least Cross-section-difference
[in Chinese], [in Chinese], and C. Quan
Phase unwrapping is an ill posed problem. A new 2 D phase unwrapping method, based on the global continuity of the physical information, is proposed in this paper. The method, which is derived from the least cross section difference of the physical quantity, has shown to produce a reliable result in the presence of errPhase unwrapping is an ill posed problem. A new 2 D phase unwrapping method, based on the global continuity of the physical information, is proposed in this paper. The method, which is derived from the least cross section difference of the physical quantity, has shown to produce a reliable result in the presence of error sources, such as noise, phase discontinuity more than π and insufficient sampling, etc. In addition, the algorithm is very simple and fast..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 29, Issue 7, 647 (2002)
Laser Manufacturing
Development of Laser Cladding Materials with Crack Resistance and Wear Resistance in Clad Layer of Grey Iron
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
To avoid the forming of cracks in iron based laser cladding, the volume fractions of austenite and cemetite in cladding layers were adjusted through adjusting the contents of Ni. The claddings were produced on gray irons without preheating. Based on the optimum parameters of laser processing, the effects of Ni contentsTo avoid the forming of cracks in iron based laser cladding, the volume fractions of austenite and cemetite in cladding layers were adjusted through adjusting the contents of Ni. The claddings were produced on gray irons without preheating. Based on the optimum parameters of laser processing, the effects of Ni contents on the volume fraction of austenite and surface cracking were investigated, the cracking mechanisms were revealed, and a sort of Fe C Si Ni cladding material was obtained which could form crack free 25 pass cladding layers on iron. By adding Ti powders into the Fe C Si Ni cladding material, endogenous TiC could form in cladding layers. The effects of endogenous TiC on wear resistance of cladding layers were also investigated. As a result, Fe C Si Ni Ti cladding materials were obtained which could improve the cracking and wear resistance significantly..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 29, Issue 7, 652 (2002)
Technique and Performance of Laser Welding Diamond Core Drill Bit
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
This paper reported a technique of adopting laser welding to joint the diamond core drill segments and canister which improved the coalescent intensity compared with common brass solder. The laser welding technique and the structure performance of welding line were investigated. It showed that the laser welding diamondThis paper reported a technique of adopting laser welding to joint the diamond core drill segments and canister which improved the coalescent intensity compared with common brass solder. The laser welding technique and the structure performance of welding line were investigated. It showed that the laser welding diamond core drill bit can conquer the defect of segments desquamate, can adapt more work conditions, and can increase the using time by 25%～108%..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 29, Issue 7, 657 (2002)
Faint Signal Digital Correlation Detection of Laser Ranging:Study and Simulation
[in Chinese], and [in Chinese]
The SNR of faint signal is very low in the long distance laser ranging or bad circumstance laser ranging, so it is very difficult to recognize the echo wave. This paper introduces digital correlation detection method and uses it to process the signal. Single signal correlation and multi signal correlation are simulatedThe SNR of faint signal is very low in the long distance laser ranging or bad circumstance laser ranging, so it is very difficult to recognize the echo wave. This paper introduces digital correlation detection method and uses it to process the signal. Single signal correlation and multi signal correlation are simulated and calculated with laser ranging radar and a good results is got. This study will help to greatly improve the ability of laser ranging radar..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 29, Issue 7, 661 (2002)
Laser Physics
All-solid-state Single-frequency Ring Nd:YVO4 Tunable Lasers
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The influence of the etalon effect of the two plano plano face Nd∶YVO 4 crystal on the frequency tuning characteristics of single frequency laser is investigated. Using the 1° wedged Nd∶YVO 4 on one face and mode selection property of the etalon inserted inside laser resonator, the precise frequency tuning of LD pThe influence of the etalon effect of the two plano plano face Nd∶YVO 4 crystal on the frequency tuning characteristics of single frequency laser is investigated. Using the 1° wedged Nd∶YVO 4 on one face and mode selection property of the etalon inserted inside laser resonator, the precise frequency tuning of LD pumped single frequency ring Nd∶YVO 4 laser has been demonstrated experimentally by means of adjusting the inclined angle of the etalon. The maximum tunable frequency range is about 100 GHz..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 29, Issue 7, 577 (2002)
Single-longitudinal-mode, High Magnification Nd:YAG Amplifier
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The design and experiment results of MOPA single longitudinal mode Nd∶YAG laser are introduced. The seeder laser with 1 μJ, 22 ns is amplifed for six times. More than 100 mJ, near diffraction limited laser beam is obtained.The design and experiment results of MOPA single longitudinal mode Nd∶YAG laser are introduced. The seeder laser with 1 μJ, 22 ns is amplifed for six times. More than 100 mJ, near diffraction limited laser beam is obtained..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 29, Issue 7, 580 (2002)
Single Frequency Yb3+-doped Fiber Laser Operating at 1053 nm
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Single frequency Yb 3+ doped fiber lasers operating at 1053 nm pumped by laser diode have been achieved. Characteristic of the lasers was researched in this paper. The power of 18 mW with F P cavity, and 1.3 mW with the structure of phase step DFB were obtained, respectively.Single frequency Yb 3+ doped fiber lasers operating at 1053 nm pumped by laser diode have been achieved. Characteristic of the lasers was researched in this paper. The power of 18 mW with F P cavity, and 1.3 mW with the structure of phase step DFB were obtained, respectively..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 29, Issue 7, 583 (2002)
Noncollinear Phase and Group-velocity Matching of Femtosecond Optical Parametric Amplification Based on Periodically Poled Lithium Niobate
[in Chinese], and [in Chinese]
Noncollinear phase and group velocity matching of femtosecond OPA based on periodically poled lithium niobate were discussed, which differ from that based on birefringent phase matched traditional crystals such as BBO. The noncollinear phase matching was investigated in noncritical phase matched PPLN and tilted PPLN.Noncollinear phase and group velocity matching of femtosecond OPA based on periodically poled lithium niobate were discussed, which differ from that based on birefringent phase matched traditional crystals such as BBO. The noncollinear phase matching was investigated in noncritical phase matched PPLN and tilted PPLN..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 29, Issue 7, 586 (2002)
Theoretical Study on the Beam Quality of Strip Buried Heterostructure Laser
[in Chinese], [in Chinese], and [in Chinese]
Based on waveguiding mode theory and non paraxial vectorial moment theory, the beam quality of TE 00 mode propagating in GaAs/AlxGa1-x As strip buried heterostructure semiconductor laser is investigated theoretically, and the emphasis is laid on the variational relation between the beam quality factor in the direction Based on waveguiding mode theory and non paraxial vectorial moment theory, the beam quality of TE 00 mode propagating in GaAs/AlxGa1-x As strip buried heterostructure semiconductor laser is investigated theoretically, and the emphasis is laid on the variational relation between the beam quality factor in the direction parallel to the junction plane M2y and the active layer width W. The results show that M2y fluctuates with the active layer width W, which is useful for the proper design of the active layer width..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 29, Issue 7, 591 (2002)
Measurement and Metrology
Study on APV Optical Road Arrangement in Measurement Water Mist
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
On the basis of the light scattering theory of spherical particles and the characteristic of the water mist, by theoretical computation and experiment study, the lay out parameters of the APV (adaptive phase/Doppler velocimeter) system are given. Experiment measurement and analysis are carried out to study the characteOn the basis of the light scattering theory of spherical particles and the characteristic of the water mist, by theoretical computation and experiment study, the lay out parameters of the APV (adaptive phase/Doppler velocimeter) system are given. Experiment measurement and analysis are carried out to study the characteristic parameters of the particles in the water mist flow field. The particle size and the velocity distribution and the water mist volume flux flow field are obtained from the experiments..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 29, Issue 7, 616 (2002)
Experimental Investigation on Heat Wave, Shock Wave and Rarefaction Wave in Aluminum Driven by "XGⅡ" Laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Aluminum targets with three kinds of thickness (6,10 and 20 μm) were driven by laser at 0 35 μm wavelength on "Xingguang Ⅱ" facilities. Shock wave images were recorded by optical streak camera, heat wave and rarefaction wave images were measured using X ray streak camera. The experimental investigation on theAluminum targets with three kinds of thickness (6,10 and 20 μm) were driven by laser at 0 35 μm wavelength on "Xingguang Ⅱ" facilities. Shock wave images were recorded by optical streak camera, heat wave and rarefaction wave images were measured using X ray streak camera. The experimental investigation on the interactions among shock wave, heat wave and rarefaction wave was made. Through several measure technique, the three wave interaction physical images were obtained in which shock wave early heat wave was late and rarefaction wave was last..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 29, Issue 7, 621 (2002)
Long Range Straightness/Coaxiality Measurement System Using Dual-frequency Laser
[in Chinese], [in Chinese], and [in Chinese]
In this paper, a novel straightness/coaxiality measurement system using transversal Zeeman dual frequency laser is introduced. In contrast to longitudinal Zeeman system, the size of instrument is shortened and the non linearity error generated from quarter wave plate is avoided. The system is self adaptive and quite reIn this paper, a novel straightness/coaxiality measurement system using transversal Zeeman dual frequency laser is introduced. In contrast to longitudinal Zeeman system, the size of instrument is shortened and the non linearity error generated from quarter wave plate is avoided. The system is self adaptive and quite resistant to air turbulence. Phase measurement can reach 0.1 degree equivalent to 1 μm. Measuring component can be removed from light path during measuring process. Using 8098 singlechip computer to stabilize the beat frequency intelligently, experiment has shown that the change of beat frequency is less than 0.5 kHz in 10 hours. The measuring stability is about 2 μm/h. Correlation coefficient of linearity of indicating value is better than 0 9999. It realizes the straightness/coaxiality measurement of long range..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 29, Issue 7, 625 (2002)
Model of Measuring Capillary Blood Flow by Using Auto-correlation of Diffusion Light
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
In this paper, a model was put up to non invasively measure capillary blood flow using diffusion light auto correlation. The influences of the Brownian motion of scatterers and the capillary blood flow on the auto correlation of diffusion light were theoretically analyzed. The theoretical and Monte Carlo simulation resIn this paper, a model was put up to non invasively measure capillary blood flow using diffusion light auto correlation. The influences of the Brownian motion of scatterers and the capillary blood flow on the auto correlation of diffusion light were theoretically analyzed. The theoretical and Monte Carlo simulation results show that the characteristic correlation time exponentially decays as the mean square velocity of capillary blood flow increases..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 29, Issue 7, 631 (2002)
Nonlinear Optics
Experimental Study on Broadband SRS in Fused Silica Fibers Excited by Single-frequency Laser
[in Chinese], [in Chinese], [in Chinese], and Ken-ichi Ueda
The frequency doubled output of a single frequency Nd∶YVO 4 laser centered at λ0=532 nm was used as input pump to excite single mode fused silica fibers with length of 250 m and 920 m, respectively. The study on broadband SRS Stokes spectrum within range of visible spectrum in fused silica fibers was made. The first orThe frequency doubled output of a single frequency Nd∶YVO 4 laser centered at λ0=532 nm was used as input pump to excite single mode fused silica fibers with length of 250 m and 920 m, respectively. The study on broadband SRS Stokes spectrum within range of visible spectrum in fused silica fibers was made. The first order to the fourth order SRS Stokes spectra were obtained, and frequency shift peak was at 450 cm-1, 1064 cm-1, 1610 cm-1 and 2168 cm-1, respectively..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 29, Issue 7, 609 (2002)
Specify Steady-state Self-focusing Behaviors of Circular Gaussian Beamstravelling inside Absorptive Keer Medium
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Equations describing circular Gaussian beams (CGB) propagating inside the absorptive Keer medium have been derived from nonlinear paraxial equation. Based on these equations, an evolution equation of the beam waist has been obtained. The evolution equation indicates that, depending on the beam and material parameters, Equations describing circular Gaussian beams (CGB) propagating inside the absorptive Keer medium have been derived from nonlinear paraxial equation. Based on these equations, an evolution equation of the beam waist has been obtained. The evolution equation indicates that, depending on the beam and material parameters, the circular Gaussian beams may be convergent or divergent when travelling inside the nonlinear medium. There is a special threshold beam whose waist approaches zero at the point where the self focusing can just compensate for the diffraction. After solving the evolution equation, the threshold intensity and threshold focal length of the threshold beam have also been specified..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 29, Issue 7, 613 (2002)
Optical Communication
Analytical Investigation on Noise Characteristics of Distributed Fiber Raman Amplifiers under Complex Conditions
[in Chinese], and [in Chinese]
Analytical expressions of equivalent noise figure and other noise characteristics of distributed fiber Raman amplifier (DFRA) are derived under complex conditions. These conditions include difference in polarization state and attenuation coefficients between pump and signal light as well as multiple wavelength pumping.Analytical expressions of equivalent noise figure and other noise characteristics of distributed fiber Raman amplifier (DFRA) are derived under complex conditions. These conditions include difference in polarization state and attenuation coefficients between pump and signal light as well as multiple wavelength pumping. Accordingly, their impact on DFRA performance and optical signal to noise ratio improvement (ΔOSNR) of concatenated DFRA+EDFA is investigated. With increasing DFRA on off gain, ΔOSNR increases first linearly and then logarithmically, resulting in saturation. Results of this work agree well with numerical simulation of existing work..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 29, Issue 7, 635 (2002)
Impact of Phase Error on Crosstalk of AWGs
[in Chinese], [in Chinese], and [in Chinese]
The impacts of phase errors induced by the fabrication errors on the transmission characteristics of an AWG are studied in this paper. The non random phase error makes the central wavelength of the channels shift, the studies show that when the 0 02 μm change of the width of the waveguide will cause 0 1 nm shift of theThe impacts of phase errors induced by the fabrication errors on the transmission characteristics of an AWG are studied in this paper. The non random phase error makes the central wavelength of the channels shift, the studies show that when the 0 02 μm change of the width of the waveguide will cause 0 1 nm shift of the central wavelength. The random phase error deteriorates the crosstalk of an AWG, the studies show that the maxium random error of 0 00004 rad/μm will make the crosstalk increase 42 dB..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 29, Issue 7, 639 (2002)
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