Journals >Chinese Journal of Lasers
Contents
2010
Volume: 37 Issue 3
56 Article(s)
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Research Article
High Efficiency PPMgLN Optical Parametric Oscillator Infrared Laser with 62 W Output Power
Peng Yuefeng, Wang Weimin, Liu Dong, Wei Xingbin, Wu Deyong, and Li Deming
The experimental results of a high-efficiency infrared-laser are demonstrated on a quasi-phase-matched (QPM) single-resonated optical parametric oscillator (OPO) in PPMgLN (5% MgO-doping) pumped by a 1064 nm laser of an elliptical beam. Theoretical analyses of the PPMgLN temperature tuning are presented. The pump sourcThe experimental results of a high-efficiency infrared-laser are demonstrated on a quasi-phase-matched (QPM) single-resonated optical parametric oscillator (OPO) in PPMgLN (5% MgO-doping) pumped by a 1064 nm laser of an elliptical beam. Theoretical analyses of the PPMgLN temperature tuning are presented. The pump source was an acousto-optically Q-switched continuous wave (CW)-diode-side-pumped Nd∶YAG laser,the pump beam polarization matches the e→e+e interaction in PPMgLN,thus maximal nonlinear coefficient d33 (27.4 pm/V) is effective and walk-off of beams can be avoided. When the pump power was 104 W with a repetition rate of 7 kHz and PPMgLN crystal temperature of 110 ℃,an average output power of 62.7 W was obtained with a slope efficiency of 71.7%,with 16.7 W at the mid-infrared wavelength of 3.84 μm and 46 W at the near-infrared wavelength of 1.47 μm..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 613 (2010)
Characteristics of RbTiOPO4 Electro-Optic Q-Switch Operation at High Repetition Rate
Feng Yutong, Zhu Xiaolei, Tang Hao, Meng Junqing, Zang Huaguo, and Chen Weibiao
The characteristics of RbTiOPO4 (RTP) electro-optic (EO) Q-switch are experimentally studied in an all-solid-state laser which is end-pumped by a continuous-wave laser diode. Stable pulse train is generated at repetition rate of 30 kHz with pump power of 24 W. The maximum average output power is 6.7 W,and the pulse widThe characteristics of RbTiOPO4 (RTP) electro-optic (EO) Q-switch are experimentally studied in an all-solid-state laser which is end-pumped by a continuous-wave laser diode. Stable pulse train is generated at repetition rate of 30 kHz with pump power of 24 W. The maximum average output power is 6.7 W,and the pulse width is 7.8 ns with corresponding peak power of 28.6 kW. The pulse energy fluctuation is less than 5%,and the slope efficiency is 34.9%. It is found that the laser performance is better when using the RTP EO Q-switch in cavity than using La3Ga5SiO14 (LGS) Q-switch. Furthermore,the driving voltage of RTP Q-switch is significantly lower than that of LGS. This high repetition rate,end-pumped all-solid-state laser with an RTP based EO Q-switch can be considered as a candidate for the three-dimensional (3D) imaging lidar transmitter..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 617 (2010)
Experimental Study on Er/Yb Co-Doped Double-Clad All Fiber Laser
Ren Fang, Xiang Wanghua, Zu Peng, Bai Yangbo, Li Nan, Wu Chengqiang, Shi Xiaozhou, and Zhang Guizhong
An all fiber ring laser with a small segment of Er3+/Yb3+co-doped double-clad fiber as gain medium,pumped by a stable 976 nm high power laser diode,is experimentally demonstrated. Using mode-locked mechanism by nonlinear polarization rotation technique,adjusting the polarization controllers orientations and pump,the stAn all fiber ring laser with a small segment of Er3+/Yb3+co-doped double-clad fiber as gain medium,pumped by a stable 976 nm high power laser diode,is experimentally demonstrated. Using mode-locked mechanism by nonlinear polarization rotation technique,adjusting the polarization controllers orientations and pump,the stable operations of passive Q-switched,Q-switched-mode-locked and continual mode-locked were obtained experimentally. The pulse repetition rate of Q-switched is from 7.583 kHz to 32.86 kHz and the pulse repetition rate of continual mode-locked is 8.843 MHz.We also observed ribbon spectrum and analyzed the result simply..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 622 (2010)
Polarization Properties of a Whispering-Gallery-Mode Fiber Laser Pumped by the Evanescent Wave of Skew Beam
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The polarization properties of a whispering-gallery-mode (WGM) fiber laser pumped by the evanescent wave of skew beam are studied. It is found from the experiments that when pump beam transmits in a bared optical fiber in skew way,both transverse electric (TE) wave and transverse magnetic (TM) wave exist in the laser eThe polarization properties of a whispering-gallery-mode (WGM) fiber laser pumped by the evanescent wave of skew beam are studied. It is found from the experiments that when pump beam transmits in a bared optical fiber in skew way,both transverse electric (TE) wave and transverse magnetic (TM) wave exist in the laser emission,and the wave-number difference between TE and TM waves decreases monotonely with the increase of the refractive index of cladding solution. Based on the excitation mechanics of evanescent-wave pumped WGM fiber laser and the analytic asymptotic formula to determine the resonant positions of a WGM,the observed experimental results are well explained..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 627 (2010)
Research on Phase-Locking Technique for 2-Channels Fiber Laser Coherent Beam Combination Based on Stochastic Parallel Gradient Descent Algorithm
Zheng Yi, and Shen Feng
The stochastic parallel gradient descent (SPGD) algorithm is introduced,and the 2-channels master oscillator power amplifier coherent beam combination (MOPA-CBC) system based on this algorithm is designed. This system adopts a 10 W stage ytterbium fiber amplifier to import the phase noise. And the LiNbO3 phase modulatoThe stochastic parallel gradient descent (SPGD) algorithm is introduced,and the 2-channels master oscillator power amplifier coherent beam combination (MOPA-CBC) system based on this algorithm is designed. This system adopts a 10 W stage ytterbium fiber amplifier to import the phase noise. And the LiNbO3 phase modulator is adopted to compensate the piston error. When loop is open,the phase noise is analyzed at different working stages of amplifier. After loop closed,the stable coherent combined beam is obtained,the intensity of which increases 1.5 times than before,and piston peak-to-valley (PV) value decreases to 100.8 nm. The precision of correction reaches 1/(10λ),and the bandwith is 100 Hz. The experimental results indicate that the control ability of SPGD algorithm is effective in phase-locking..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 631 (2010)
A Method of Measuring Flow Field Temperature for HF/DF Chemical Laser
Luo Wei, Yuan Shengfu, Lu Qisheng, Wang Hongyan, Zhang Xuanzhe, and Zhou Qiong
This article introduced a method of measuring temperature which was named absorption spectrum temperature-measurement method;the relationship between the absorption coefficient and the temperature of thermal equilibrium flow field for HF/DF chemical laser was analyzed by the theory of gas absorption. Used the 1p9 and 1This article introduced a method of measuring temperature which was named absorption spectrum temperature-measurement method;the relationship between the absorption coefficient and the temperature of thermal equilibrium flow field for HF/DF chemical laser was analyzed by the theory of gas absorption. Used the 1p9 and 1p8 spectral line of a discharge driving continuous wave (CW) single-line HF laser as detect light source,the transmittance of the flow field that behind the gain field of a discharge driving CW HF/DF laser was experimental measured,which changed with the flow rate of injected hydrogen gas. The flow rate of HF gas was estimated,combined with the pressure of flow field and other data,the temperature variety scope of the flow field was computed by the absorption coefficient formula. The result and error source were analyzed. This method can be used for measuring gas flow field temperature of gas flow laser and engine combustor..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 636 (2010)
Experimental Studies on Large Height/Width Ratio and Mini-Channel Radiator for High Power Density Laser Cooling
Liu Dong, Liu Minghou, Wang Yaqing, and Xu Kan
The radiators with different large height/width ratio mini-channels are designed for cooling high power density laser. Using deionized water as working fluid,it is found that the radiator with 3 mm height mini-channels can achieve heat dissipation of 3×106 W/m2 when surface temperature is 70 ℃ and flow rate is 58.The radiators with different large height/width ratio mini-channels are designed for cooling high power density laser. Using deionized water as working fluid,it is found that the radiator with 3 mm height mini-channels can achieve heat dissipation of 3×106 W/m2 when surface temperature is 70 ℃ and flow rate is 58.2 L/h. The detailed experimental results show that the heat dissipating capacity is linearly with surface temperature for all mini-channel radiators when coolant flow rate is fixed. A suitable mini-channel height is required for maximum heat dissipation for this kind of radiator. A general empirical formula is proposed to evaluate cooling performance of the radiators with consideration of Nussel number (Nu) as a faction of Reynolds number (Re),height/width ratio,length/diameter ratio,and Prandtl number (Pr). Compared with the experimental data,it is found that the formula can describe heat dissipation performance of mini-channels radiator well. The average heat resistance of the radiator decreases with increasing of flow rate in mini-channels,while the trend is affected by the channel height. For maximum heat removal purpose,the mini-channels radiators have optimum working flow rate and channel height..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 640 (2010)
Application of Neural Networks in Design of Q-Switched Laser
Yang Yang, Cheng Yin, Xu Mingshun, Wang Shiyu, Guo Zhen, Cai Defang, and Li Bingbin
An optimized design model of Q-switched lasers is established with neural networks (NN). Obtain the laser outputs with the numerical solution for the rate equations when given cavity parameters and pumping parameters,and these data will form the training set of neural networks. A back-propagation (BP) neural network isAn optimized design model of Q-switched lasers is established with neural networks (NN). Obtain the laser outputs with the numerical solution for the rate equations when given cavity parameters and pumping parameters,and these data will form the training set of neural networks. A back-propagation (BP) neural network is established after being trained based on the relationship between the laser structure parameters,pumping parameters and laser outputs. A quick design of Q-switched laser with the network to predict the laser structure parameters and pumping parameters according to required laser outputs can be made while the training time is 2.96 s for computer configuration of Pentium 4 2.4 GHz. Test data and experimental results show that the design standard deviation of peak output power,beam quality and pulsewidth are respectively 3.1%,3.4% and 5.8%. The results give good agreement and the errors are small..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 646 (2010)
Correction Effect to Spectral Resolution of Spectrometer Caused by Counter Rotating of Sagnac Prism
Li Suning, Zhu Rihong, and Shen Hua
In the Sagnac static imaging spectroscopy,there would be impact on the spectral resolution of the spectrometer caused by counter rotating of the Sagnac prism,and even the fake spectrum would be brought in. In order to improve the spectral resolution of the spectrometer and remove the fake spectrum,the relationship betwIn the Sagnac static imaging spectroscopy,there would be impact on the spectral resolution of the spectrometer caused by counter rotating of the Sagnac prism,and even the fake spectrum would be brought in. In order to improve the spectral resolution of the spectrometer and remove the fake spectrum,the relationship between the counter rotating angle brought in when balsaming of the two semi-pentagonal prisms and the shearing displacement caused by which is deduced,the effect on spectral resolution caused by counter rotating error is analyzed,the correction method to the error using Forman convolution is discussed. The experiment was carried out using hydrogen lamp,the result shows that,the spectral resolution of the spectrum reconstructed after correction can be improved and the fake spectrum can be restrained dramatically,the correction result is good..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 652 (2010)
Electrons Intervalley Transfer Gain in Bulk GaAs
Ni Zhengji, Chen Lin, Wang Shuling, Zhang Dawei, He Boyong, and Zhu Yiming
By using time-domain terahertz (THz) spectroscopy,the THz waveforms emitted from bulk GaAs photoexcited by femtosecond laser pulses under very high electric fields at 10 K have been recorded. It is clearly seen that the THz emission waveforms show a bipolar feature i.e.,an initial positive peak and a subsequent negativBy using time-domain terahertz (THz) spectroscopy,the THz waveforms emitted from bulk GaAs photoexcited by femtosecond laser pulses under very high electric fields at 10 K have been recorded. It is clearly seen that the THz emission waveforms show a bipolar feature i.e.,an initial positive peak and a subsequent negative dip. Terahertz intervalley transfer gain under step-function-like input electric fields F has been obtained by calculating Fourier spectrum of the measured THz trace under various biased electric fields. We found it can reach 750 GHz for F> 50 kV/cm at 10 K. Furthermore,from the temperature dependence of the cutoff frequency for the gain,it is found that the cutoff frequency is governed by the energy relaxation process of electrons from L to Γ valley via successive longitudinal-optical phonon emission. The estimated cutoff frequencies,at 10 K by considering the time for electrons ballistic acceleration in Γ valley,intervalley transfer,relaxation in Γ valley via longitudinal-optical phonon scattering match the experimental results very well..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 658 (2010)
Study of Laser Projection Display Based on Micro-Opto-Electro-Mechanical System Grating Moving Light Modulator
Zhang Zhihai
A novel micro-opto-electro-mechanical system(MOEMS)-based light modulator for laser project display is proposed,which is called grating moving light modulator (GMLM). It can modulate light by diffraction,and has a simple fabrication process and projection optical system. The light modulation theory and the projection oA novel micro-opto-electro-mechanical system(MOEMS)-based light modulator for laser project display is proposed,which is called grating moving light modulator (GMLM). It can modulate light by diffraction,and has a simple fabrication process and projection optical system. The light modulation theory and the projection optical system of GMLM are introduced. The optical model of GMLM is found to deduce the Fraunhofer diffraction pattern through the projection optical system based on the scalar diffraction method. The static and dynamic projection experiments of GMLM array are completed by the projection demo system. The results demonstrate the operation and projection principle of GMLM..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 663 (2010)
Dynamical Wave-Front Distortion Correction Experiment Based on Stochastic Parallel Gradient Descent Algorithm for 61-Element Adaptive Optics System
Zhang Jinbao, Chen Bo, Wang Caixia, and Li Xinyang
The stochastic parallel gradient descent (SPGD) algorithm is a promising control algorithm for adaptive optics (AO) system without wave-front sensor. In this paper,a 61-element laser beam focusing AO system for correcting dynamical wave-front distortion was established,which used a hot-wind experimental atmospheric turThe stochastic parallel gradient descent (SPGD) algorithm is a promising control algorithm for adaptive optics (AO) system without wave-front sensor. In this paper,a 61-element laser beam focusing AO system for correcting dynamical wave-front distortion was established,which used a hot-wind experimental atmospheric turbulence generator and SPGD algorithm controller based on field programmable gate array (FPGA). Up to one thousand iterations per second′s speed of the controller and the sub-millisecond response time of the deformable mirror and tilt mirror provided quick compensation for dynamic wave-front distortion induced by the hot-wind experimental atmospheric turbulence generator. The experimental results demonstrated that this AO system can significantly improve the laser beam quality with 30 times′ increase of the averaged performance metric and 10 times′ increase of the peak-values of far-field intensity distributions. The spectral analysis of performance metric showed that the AO system had an effective bandwidth of 10 Hz..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 668 (2010)
Design on Athermalised Middle Wavelength Infrared Optical System with Large Relative Aperture
Liu Lin, Shen Weimin, and Zhou Jiankang
Based on uncooled detector,an optical system is designed with 100 mm focal length,1 F number,±2.5°field of view ,working in the 3-5 μm wave band. The optical system has the advantages of large relative aperture and compact construction. While working under the condition of -20 ℃-60 ℃ the system can keep high Based on uncooled detector,an optical system is designed with 100 mm focal length,1 F number,±2.5°field of view ,working in the 3-5 μm wave band. The optical system has the advantages of large relative aperture and compact construction. While working under the condition of -20 ℃-60 ℃ the system can keep high quality image. With the Petzval objective,carefully selected optical material and reasonable optical power distribution,passive optical athermalization can be realized by using this system. The hybrid lens is used to simplify construction and decrease the volume and weight of the optical system. Also,large back focal length is another feature of the optical system..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 675 (2010)
Research of High Light Collection Efficiency of LED Parabolic Reflector Based on Non-Imaging Optics
Jin Ji, Yu Guiying, and Lin Min
Based on the theory of non-imaging optics,the geometric parameters of light-emitting diode (LED) parabolic reflector and the impact of rotation angle of LED around the axis which is perpendicular to propagation direction on the efficiency of light collection are analysed in energy transfer aspect,and eventually unifiedBased on the theory of non-imaging optics,the geometric parameters of light-emitting diode (LED) parabolic reflector and the impact of rotation angle of LED around the axis which is perpendicular to propagation direction on the efficiency of light collection are analysed in energy transfer aspect,and eventually unified closed relationships between efficiency of light collection of a parabolic reflector with the geometric parameters and the rotation angle are established. The results show that using étendue to evaluate the efficiency of energy collection of LED parabolic reflector is reasonable,and rotating the LED can further improve the efficiency,and for each different sets of geometric parameters,the best rotation angle is different. The simulation results are according with the theoretical analysis..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 680 (2010)
Elliptical Crystal Spectrometer Researched for Z-Pinch Plasma X-Ray by Using Au-Wire Arrays
Wang Hongjian, Xiao Shali, Shi Jun, Huang Xianbin, Cai Hongchun, and Xu Daolian
To diagnose the presence of electron beams in Z-pinch plasma in spectral range of 0.2-2 nm,two channel X-ray spectrometers respectively using have desirable properties for applications requiring broad spectral coverage,good spectral resolution,and minimized source broadening. A new space resolved focusing elliptical cuTo diagnose the presence of electron beams in Z-pinch plasma in spectral range of 0.2-2 nm,two channel X-ray spectrometers respectively using have desirable properties for applications requiring broad spectral coverage,good spectral resolution,and minimized source broadening. A new space resolved focusing elliptical curved crystal spectrometer has been developed and applied to diagnose X-ray of Z-pinch plasma based on focusing spectrograph spatial resolution (FSSR). An elliptical PET(002)crystal was employed with 1348 mm focal length,0.9480 eccentricity and 30°-67.5° Bragg angle. The first experiment was carried out on the Yang accelerator and aimed to investigate the characteristics of high-density plasma and the second did with the spectrometer rotated 90°. X-ray spectra in an absolute intensity scale were obtained from Au-wire Z-pinch plasmas recorded by half-circle X-ray film with radius of 50 mm. It was demonstrated experimentally that the two measured wavelength were same,with spectral resolution λ/Δλ of 300-600,and that spectrograph of elliptically bent PET crystal was a good tool for diagnosing Z-pinch plasmas..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 685 (2010)
Determining the Graded-Index Profiles of Channel Waveguides by Prism Coupling Method
Yang Tianxin, Zou Hao, Wang Lei, Li Rui, Wang Junlong, and Sang Mei
A method for determining the two-dimensional (2D) index profiles of channel waveguides by the datum of the effective indexes measured by prism coupling method is proposed. The channel waveguides are home-fabricated by ion-exchanged method on the substrate of phosphate glass with various diffusion times and various maskA method for determining the two-dimensional (2D) index profiles of channel waveguides by the datum of the effective indexes measured by prism coupling method is proposed. The channel waveguides are home-fabricated by ion-exchanged method on the substrate of phosphate glass with various diffusion times and various mask opening widths. The method for calculating the 2D index profiles is set up based on the theory of graded-index waveguides,such as Wentzel-Kramer-Brillouin (WKB) method and effective index method. First,an index profile function is supposed. Then its effective indexes calculated by a homemade program based on WKB method and effective index method are compared with the measured results of the effective index. Finally the best-fit index profile is reconstructed by modifying the supposed index profile until the calculated effective indexes are becoming very close to the measurement of the effective indexes. The relationships between the fabricating parameters,such as diffusion time and mask opening width,with index profile of waveguides can be set up. This work could be useful for optimizing the fabrication process of channel waveguides in order to obtain high quality waveguide lasers and photonic waveguide devices repeatedly and effectively..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 689 (2010)
Near Infrared Polarimeter Based on Liquid Crystal Variable Retardes
Zhang Zhiyong, Deng Yuanyong, Wang Dongguang, Sun Yingzi, and Xuan Weijia
Measuring the polarization states of the sunlight with a polarimeter,one can obtain the magnetic field information in the solar atmosphere using the principle of Zeeman effect and study the solar activities such as sun spots,flares and coronal mass ejection (CME). Near infrared polarization measurement has been becominMeasuring the polarization states of the sunlight with a polarimeter,one can obtain the magnetic field information in the solar atmosphere using the principle of Zeeman effect and study the solar activities such as sun spots,flares and coronal mass ejection (CME). Near infrared polarization measurement has been becoming the frontier and hot point in solar physics. Developing polarimeter at this wavelength can help us to get far more information than visible light and redound to resolving the basic problems of the solar physics. A newly developed near infrared Stokes polarimeter is presented in this paper. In this device,a λ/2 and a 1 λ liquid crystal variable retarders (LCVRs) are employed as the electro-optical modulators and a near infrared polarizer whose extinction ratio is about 10-5 as the analyzer and the temperature control system can keep the temperature within ±0.01 ℃,which satisfies the system designs. Compared to the commonly used KD*P electro-optical modulators,liquid crystal retarder can reach any retardation between 0 and maximum only with low modulating voltage and has better transmittance and lager aperture. Furthermore,without any movement units,the speed of alternating the Stokes parameters is significantly improved by 102. And theoretical analysis shows that the crosstalk of this design is limited in the order of 10-3..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 696 (2010)
Development of Synchronized Laser Discriminator in Quantum Key Distribution System
Cai Wenqi, Chen Tengyun, Liang Hao, and Jin Ge
The quantum key distribution (QKD) system and single-photon detector are introduced. For the reduction of the dark counts of the single-photon detector,a synchronized laser system which consists of a synchronized laser of the transmitter and a laser discriminator of the receiver is developed. The method of developing tThe quantum key distribution (QKD) system and single-photon detector are introduced. For the reduction of the dark counts of the single-photon detector,a synchronized laser system which consists of a synchronized laser of the transmitter and a laser discriminator of the receiver is developed. The method of developing the synchronized laser discriminator including photo electricity translator,preamplifier,voltage discriminator and level translator is shown detailedly. Test results show that the synchronized laser discriminator works stably by long time experiments. Error discrimination and fault discrimination can not be found. Now the synchronized laser discriminator has worked well on the QKD system. Transmitter and receiver are synchronized exactly. The dark counts of the single-photon detector are reduced effectively..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 703 (2010)
Terahertz Generation Based on Optical Fibers
Zhou Ping, and Fan Dianyuan
This paper proposes theoretically a novel terahertz source based on the conventional single-mode optical fibers. Utilizing four-wave-mixing effect in optical fibers and the dual-wavelength laser as the pump source,a compact,wide-tunable countinuous wave (CW) terahertz source is constructed. The four-wave mixing processThis paper proposes theoretically a novel terahertz source based on the conventional single-mode optical fibers. Utilizing four-wave-mixing effect in optical fibers and the dual-wavelength laser as the pump source,a compact,wide-tunable countinuous wave (CW) terahertz source is constructed. The four-wave mixing process has been discussed in detail through the coupled-wave theory,and the analytical expression of terahertz output power is obtained. It is shown that when the pump power is 1 kW,the terahertz peak power is about 60 mW. This scheme provides a possibility to realize a high-power and compact CW terahertz source..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 708 (2010)
Experimental Investigations on Magnetic Sensitivity in Four-Frequency Differential Laser Gyros
Wang Zhiguo, Long Xingwu, Wang Fei, and Huang Yun
To reduce magnetic sensitivity of four-frequency differential laser gyro (DILAG),an operating point control method is proposed. Moreover,the magnetic sensitivities of the same gyro with conventional frequency stabilization using light intensity comparison and with the new operating point control method are compared. InTo reduce magnetic sensitivity of four-frequency differential laser gyro (DILAG),an operating point control method is proposed. Moreover,the magnetic sensitivities of the same gyro with conventional frequency stabilization using light intensity comparison and with the new operating point control method are compared. In the range of 0-0.06 mT,the magnetic sensitivities of two experimental gyros are 62.7 and 111.3(°)/(h·mT),respectively,when the gyros are controlled with conventional frequency stabilization method. However,the magnetic sensitivities are improved to 0.9 and 1.6(°)/(h·mT) respectively,when they are controlled with a new operating point control method. The results indicate that electronic control means are of significance to the magnetic sensitivity. The residual magnetic sensitivity maybe arises from nonreciprocal effects induced by transverse magnetic field,which is going to be investigated in future work..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 713 (2010)
Study of Speckle Suppression by a Moving Diffuser in Liquid Crystal on Silicon Based Laser Projection System
Sun Mingjie, and Lu Zukang
When coherent light scattered from a rough surface,speckle is detected by an intensity detector. Speckle severely affects the image quality and therefore must be suppressed. Speckle suppression can be achieved by averaging a number of speckle configurations produced by vibrating a diffuser. The method is applied in a lWhen coherent light scattered from a rough surface,speckle is detected by an intensity detector. Speckle severely affects the image quality and therefore must be suppressed. Speckle suppression can be achieved by averaging a number of speckle configurations produced by vibrating a diffuser. The method is applied in a liquid crystal on silicon (LCoS) based laser projection system,and experiments are performed to study the relation between speckle contrast and diffuser movement. After suppression,speckle contrast on detector is reduced from 0.49 to 0.065. Experimental results indicate that larger amplitude and frequency of diffuser vibration,as well as smaller diffuse phase unit size,can reduce speckle contrast on the detector..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 718 (2010)
Periodic Microstructures On Chromium Film Induced by Femtosecond Laser
Wu Tengfei, Zhou Changhe, and Zhu Linwei
The surface periodic microstructures on chromium film were induced by the nanojoule femtosecond laser. We analyzed the distribution of temperature on the chromium film surface with the theory of interference between the incident laser and the excited surface plasmons wave and the principles of periodic surface structurThe surface periodic microstructures on chromium film were induced by the nanojoule femtosecond laser. We analyzed the distribution of temperature on the chromium film surface with the theory of interference between the incident laser and the excited surface plasmons wave and the principles of periodic surface structures were explained. Experimental results are in coincidence with numerical simulation. The periodic microstructures formed on the chromium film should be helpful for us to understand the physical mechanism of the interaction between the chromium film and the femtosecond laser..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 722 (2010)
Brillouin Optical Time-Domain Analyzer Based on Orthogonal Polarization Control for Long-Distance Distributed Optical-Fiber Sensors
Song Muping, Bao Chong, and Ye Xianfeng
For the standard single-mode optical-fiber,the frequency shift of Brillouin scattering light is the function of the temperature or strain. So,the temperature or strain of the optical-fiber can be obtained,when Brillouin frequency shift is able to be detected. Brillouin optical time-domain analyzer (BOTDA) is suitable fFor the standard single-mode optical-fiber,the frequency shift of Brillouin scattering light is the function of the temperature or strain. So,the temperature or strain of the optical-fiber can be obtained,when Brillouin frequency shift is able to be detected. Brillouin optical time-domain analyzer (BOTDA) is suitable for long-distance distributed sensing,but the stimulated Brillouin scattering is polarization related,which makes it hard to stably detect the Brillouin optical frequency shift. A method named with the orthogonal polarization control is adopted to reduce the effect of the optical-polarization-related problem. A laboratorial system of 25 km distributed Brillouin optical time-domain analyzer is achieved,with 2 ℃ in temperature resolution,30 με in strain resolution,and 5 m in spatial resolution..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 757 (2010)
Analysis of Magnetic Field Sensor with Phase-Shifted Grating Based on the Polarization Properties
Feng Kui, Zhu Yong, Su Yang, and Peng Hui
The magnetic field measurement mechanism with phase-shifted grating is presented by using transfer matrix approach. The effects of grating parameters on the sensing performance are analyzed by simulations. It shows that the bandwidth and transmission rate of the stop-band transmission window in phase-shifted grating haThe magnetic field measurement mechanism with phase-shifted grating is presented by using transfer matrix approach. The effects of grating parameters on the sensing performance are analyzed by simulations. It shows that the bandwidth and transmission rate of the stop-band transmission window in phase-shifted grating have great effects on the measurements. The results are compared with fiber Bragg grating (FBG) scheme. The simulations and experiments show that the phase-shifted grating with narrow bandwidth and high transmission rate can improve the accuracy and sensitivity of the magnetic sensor system..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 763 (2010)
Beam Transmission
Propagation of Off-Axis Gaussian-Schell Model Electromagnetic Beams Beyond the Paraxial Approximation
Xing Yan, and Lü Baida
Based on the generalized Rayleigh-Sommerfeld diffraction integrals,the analytical expression for the 3×3 cross-spectral density matrix of nonparaxial off-axis Gaussian-Schell model (GSM) electromagnetic beams propagating in free space is derived and used to formulate the spectral density (intensity),degree of polaBased on the generalized Rayleigh-Sommerfeld diffraction integrals,the analytical expression for the 3×3 cross-spectral density matrix of nonparaxial off-axis Gaussian-Schell model (GSM) electromagnetic beams propagating in free space is derived and used to formulate the spectral density (intensity),degree of polarization and spectral degree of coherence of electromagnetic beams at the z plane. Nonparaxial on-axis GSM electromagnetic beams and nonparaxial off-axis Gaussian electromagnetic beams can be treated as special cases of our results. The effect of off-axis parameter,self- and cross-correlation lengths on the intensity,the degree of polarization and the spectral degree of coherence of electromagnetic beams are stressed. The results are illustrated by numerical examples..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 726 (2010)
Propagation Efficiency of Various Combined Beams in Turbulent Atmosphere
Zhou Pu, Ma Yanxing, Wang Xiaolin, Ma Haotong, Xu Xiaojun, and Liu Zejin
Propagation properties of four combined beams,i.e.,coherently combined single mode laser,incoherently combined single mode laser,coherently combined multi-mode laser and incoherently combined multi-mode laser,in turbulent atmosphere are analyzed by using extended Huygens-Fresnel principle. The propagation efficiency anPropagation properties of four combined beams,i.e.,coherently combined single mode laser,incoherently combined single mode laser,coherently combined multi-mode laser and incoherently combined multi-mode laser,in turbulent atmosphere are analyzed by using extended Huygens-Fresnel principle. The propagation efficiency and effective range are numerically evaluated. The calculating results show that there is no significant difference in propagating efficiency and effective range of coherent or incoherent beam combining,and the single mode laser array has advantages in propagation efficiency over multi-mode beams. The advantage of coherent beam combining decreases with an increase in the intensity of turbulence,and there is no difference between coherent and incoherent combining in strong turbulence. The adaptive phase-locked single mode laser array that can correct tilted aberration is the best choice for developing a 100 kW tactical laser system..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 733 (2010)
Effect of Primary Coma Aberration on Focusing of a Circularly Polarized Vortex Bessel-Gaussian Beams
Zhao Zhaoxiong, and Liu Yong
Based on Richards and Wolf vectorial diffraction integral,three-dimensional light field complex amplitude function is presented when circularly polarization vortex Bessel-Gaussian beam passes through a high numerical-aperture system with primary coma aberration. The highly-focusing fields with different comatic aberratBased on Richards and Wolf vectorial diffraction integral,three-dimensional light field complex amplitude function is presented when circularly polarization vortex Bessel-Gaussian beam passes through a high numerical-aperture system with primary coma aberration. The highly-focusing fields with different comatic aberration coefficients are presented. The results show that the presence of primary coma aberration makes the pattern and position of light distribution change. The pattern of light distribution does not depend on sign of comatic aberration coefficient. As for intensity distribution along the optical axis,primary coma aberration does not change its symmetry,but affects its form..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 739 (2010)
Biomedical Photonics and Laser Medicine
Effects of Laser and Electric Field on Related Physiological and Biochemical Parameters of Rice
Fan Shuguo, Chen Kai, Li Yang, Qiu Lu, Yang Haiyan, Li Guoshu, Li Yizhou, and Xie Meihua
To compare the related physiological and biochemical parameters of “Sanjiao fragrant glutinous rice from Yao’an county” and its induced variety treated by laser and electric field. To measure the content of chlorophyll a,chlorophyll b,Lys,Pro under low temperature treatment and soluble sugar;the activity of amylase,catTo compare the related physiological and biochemical parameters of “Sanjiao fragrant glutinous rice from Yao’an county” and its induced variety treated by laser and electric field. To measure the content of chlorophyll a,chlorophyll b,Lys,Pro under low temperature treatment and soluble sugar;the activity of amylase,catalase and nitrate reductase;seed vigor and respiratory rate. The activity of catalase and nitrate reductase,respiratory rate,and the content of Lys did not change so much;the activity of amylase declined;but the content of chlorophyll a,chlorophyll b,soluble sugar and seed vigor increased by laser and electric field treatment. The related physiological and biochemical parameters of “Sanjiao fragrant glutinous rice from Yao’an county” and its induced variety treated by laser and electric field have changed,some of them increased,whereas some of them decreased..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 891 (2010)
Holography and Information Processing
A New Approach for Removing the Gibbs-Like Artifacts in Image Denoising
Guo Baolong, Wu Xiaoyue, and Li Leida
A new algorithm for removing the Gibbs-like artifacts in image denoising is presented. The original image is decomposed by using the nonsubsampled pyramid filter (NSPF) and the decomposed image model is built based on total variation model. Then the preliminary denoised image is produced by reconstruction. A detail comA new algorithm for removing the Gibbs-like artifacts in image denoising is presented. The original image is decomposed by using the nonsubsampled pyramid filter (NSPF) and the decomposed image model is built based on total variation model. Then the preliminary denoised image is produced by reconstruction. A detail compensation image is further obtained by using the difference between the preliminary denoised image and the original image. Finally,the denoised image can be obtained by adding the compensation image to the reconstructed image. Experiments show that the proposed scheme can remove Gibbs-like artifacts and image noise effectively. This algorithm outperforms the existing schemes in regard of both the peak-signal-to-noise-ratio (PSNR) and the edge preservation ability..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 769 (2010)
A Novel Image Retrieval Method Based on Interest Points Matching and Distribution
Fu Xiang, and Zeng Jiexian
The main deficiency of traditional interest points-based image retrieval methods is that the accuracy is influenced by the dissimilar interest points in the non-interest regions. A novel algorithm for image retrieval based on interest points was presented. By comparing the Euclidean distance of each interest point’s loThe main deficiency of traditional interest points-based image retrieval methods is that the accuracy is influenced by the dissimilar interest points in the non-interest regions. A novel algorithm for image retrieval based on interest points was presented. By comparing the Euclidean distance of each interest point’s local Zernike moments based on its local gray information,the best matching pairs of interest points were computed and the dissimilar points were eliminated. Then,the spatial cohesion of interest points was used to discriminate the similarity between two images. With robustness to rotation and translation,the algorithm avoided the shortcoming of traditional methods. Experimental results show that this algorithm is simple and improves the image retrieval accuracy efficiently..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 774 (2010)
Digital Holography Experiment on the Measurement of Particle Size and Size Distribution of Diesel Spray
Lü Qieni, Zhao Chen, Ma Zhibin, Ge Baozhen, Gao Yan, and Zhang Yimo
An experimental system of digital holography for digitally recorded dynamic spray particle field is proposed. Hologram of dynamic particle field is recorded based on digital in-line holography arrangement with continuous wave (CW) laser and a high-speed charge coupled device (CCD),and the reconstructed images with diffAn experimental system of digital holography for digitally recorded dynamic spray particle field is proposed. Hologram of dynamic particle field is recorded based on digital in-line holography arrangement with continuous wave (CW) laser and a high-speed charge coupled device (CCD),and the reconstructed images with different times are reconstructed numerically. The reconstructed images of a hologram of particle field are approached by adaptive filtering,and in-focus images of particle in the volume are integrated into a plane and binarized,and the edge of particle image by Roberts is extracted,then Hough transform and sub-pixel precision computing are completed,so the size and the position of particle are obtained. Digital holograms of diesel spray under different pulse widths of the injector and different measuring locations are given,and the three-dimensional (3D) distribution of particle field,and mass distribution and distribution of Sauter mean diameter (SMD) of the spray field along x-axis and y-axis are also given when pulse width of the injector is 8 ms..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 779 (2010)
A Three-Dimensional Reconstructed Method of Big Scale Objects Based on the Maximum of an Area Modulation Sum
Cheng Xusheng, Cao Yiping, and He Yuhang
A novel and high precise three-dimensional (3D) reconstructed method of big scale objects is proposed. The sub-shapes of the experimental object are measured with phase measuring profilometry (PMP),height matching is carried out in the modulation maximum area with an algorithm due to maximum correlativity. The method sA novel and high precise three-dimensional (3D) reconstructed method of big scale objects is proposed. The sub-shapes of the experimental object are measured with phase measuring profilometry (PMP),height matching is carried out in the modulation maximum area with an algorithm due to maximum correlativity. The method saves matching time by computer compared to using the whole height data of the sub-objects,and the mosaic precision is improved. Finally the whole shape of objects is obtained by the mosaic method. Binarization templates of modulation are generated in order to draw out the object from background and shadow,and image mosaic is carried out by using the overlapping position obtained from the above height matching. The results show that the repeatability precision of our method is superior to 20 μm,and the mosaic precision is beyond100 μm,which is an effective method to reconstruct big scale objects..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 784 (2010)
Image Restoration Based on Hybrid Wiener/Projection Onto Concex Sets Algorithm
Liu Yang, and Cui Jiwen
In order to improve the resolution of the restored image in the original context of projections onto convex sets (POCS),and suppress the features of edge oscillating and enlargement of noise,a motion blurred restoration approach based on hybrid Wiener/POCS algorithm is proposed. Estimated original image f0 and super-reIn order to improve the resolution of the restored image in the original context of projections onto convex sets (POCS),and suppress the features of edge oscillating and enlargement of noise,a motion blurred restoration approach based on hybrid Wiener/POCS algorithm is proposed. Estimated original image f0 and super-resolution restored image fi of the original POCS are respectively bounded by a Wiener set,which is noise normalized and complete convergence,and three other bounded local variance sets are also incorporated into POCS. Some experiments based on restoration of image are given to demonstrate the effectiveness of the hybrid Wiener/POCS algorithm. As a result,the bounded Wiener variance set using in complete convergence is better than any other,and in the evaluation of quality of super-resolution restoration image,the normalized co-correlation function (NCCF) improves 7.28%,the peak signal-to-noise ratio (PSNR) improves 32.35% as the largest,which effectively suppress the ringing ripples and improve the resolution..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 789 (2010)
Laser Manufacturing
Detection of Powder Stream Concentration Field in Robot Laser Remanufacturing
Chen Xiuping, and Yang Xichen
A low power,portable,cheap and high precision detection system is developed to measure the concentration field of powder steam,and it is suitable to requirement of laser robot repair. The system mainly consists of 532 nm,100 mW semiconductor laser,sheet of lens,charge coupled device (CCD) camera and analysis software. A low power,portable,cheap and high precision detection system is developed to measure the concentration field of powder steam,and it is suitable to requirement of laser robot repair. The system mainly consists of 532 nm,100 mW semiconductor laser,sheet of lens,charge coupled device (CCD) camera and analysis software. It is shown that the consistency in the detection of volume of concentration distribution of metal powder stream and the theoretical calculation is very good. The system could be an effective guiding significance for the design of co-axial nozzle and the determination of powder stream parameter in robot laser repair..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 842 (2010)
Research on Microstructure of TC17 Titanium Alloy Fabricated by Laser Solid Forming
Wang Junwei, Chen Jing, Liu Yanhong, Zhao Xiaoming, Zhang Fengying, and Huang Weidong
The influences of different heat treatments on the microstructure of TC17 alloy fabricated by laser solid forming (LSF) are investigated,while the alloy in three states of as-deposited,after relief annealing and aging treatment. The results indicate that the microstructure of as-deposited sample consists of coarse coluThe influences of different heat treatments on the microstructure of TC17 alloy fabricated by laser solid forming (LSF) are investigated,while the alloy in three states of as-deposited,after relief annealing and aging treatment. The results indicate that the microstructure of as-deposited sample consists of coarse columnar grains which grow epitaxially from the substrate along the deposition direction z. The microstructure within the columnar grain showstypical α+β structure. The original β grains are composed of extremely fine basketweave microstructure. And the α phase has lath morphology,its length and width are 1-3 μm and 0.1-0.2 μm,respectively. After furnace cooling (FC) annealing treatment following 1 h holding at 600 ℃,the length and width of the α lath both increased while the length/width ratio decreased,but no other changes can be observed. The equiaxed α phase will be observed on the β matrix after air cooling (AC) annealing treatment following 4 h holding at 550 ℃. During aging treatment,the α laths coarsen continuously as the aging time increases,whereas their length/width ratio gradually decreases. When the holding time reaches 8 h,most of the α laths are spheroidized,only a few left..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 847 (2010)
Research on Continuous/Pulse Laser Cladding Superalloy K403
Zhong Rutao, and Xiong Zheng
Aiming at the special requirement of laser cladding on aereoengine blade, the influences of continuous/pulse beam on cladding performance for K403 substrate was studied experimentally on a transverse CO2 laser and its processing system,compared with continuous laser beam,by using pulse laser beam,the hardness of claddiAiming at the special requirement of laser cladding on aereoengine blade, the influences of continuous/pulse beam on cladding performance for K403 substrate was studied experimentally on a transverse CO2 laser and its processing system,compared with continuous laser beam,by using pulse laser beam,the hardness of cladding layer increased for about 5%,while the duty rate and area of heat-affected zone decreased for about 20% and about 50%,respectively. Cladding with pulse laser beam could weaken the gathering of alloy elements and the formation of low melting eutectic structure,resulting in the absence of liquid state membrane on grain boundary. In addition,the tension stress in solidification is greatly reduced during pulse laser cladding due to the less deform of substrate,and a higher degree of superheat induced fully mixing of the melting pool and decreased the brittleness of substrate,so,the heat cracking behavior of K403 substrate under continuous laser beam cladding was avoided under pulse laser beam cladding..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 852 (2010)
Erosive Wear Resistance Behavior of Laser Cladding Al2O3+13%TiO2 Coating Prepared by Plasma Spraying on Titanium Alloy Surface
Gao Xuesong, Huang Yinhui, Tian Zongjun, Liu Zhidong, Shen Lida, and Wang Dongsheng
A ceramic coating on a matrix of titanium alloy was prepared with powdered Al2O3+13%TiO2 (mass fraction) by using laser cladding of plasma-sprayed process. Erosive wear resistance of the ceramic coating was tested with an erosion-blasting machine. The worn surface of coating was observed through a three-dimensional vidA ceramic coating on a matrix of titanium alloy was prepared with powdered Al2O3+13%TiO2 (mass fraction) by using laser cladding of plasma-sprayed process. Erosive wear resistance of the ceramic coating was tested with an erosion-blasting machine. The worn surface of coating was observed through a three-dimensional video microscope. The coating’s composition before and after laser cladding was analyzed by X-ray diffraction (XRD). The results show that during the course of laser cladding,the composition of ceramic coating is distributed uniformly and densely,therefore enhancing the coating’s anti-erosion performance. The experimental findings explain why with erosion angle increasing,there is more weight-loss in laser cladding coating than in plasma-sprayed coating. The empirical equations of the erosion weight-loss were also obtained..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 858 (2010)
Generation of 5-Axis Laser Cutting Path Based on STL Model
Zhu Hu, Fu Jianhui, and Liu Zhijun
A method for automatically generation of 5-axis 3D laser cutting path was proposed based on automatic recognition of incision features. Automatic selection of incision features was realized through automatic recognition of incision features using STL (stereo lithography) model. The laser beam radius compensation was doA method for automatically generation of 5-axis 3D laser cutting path was proposed based on automatic recognition of incision features. Automatic selection of incision features was realized through automatic recognition of incision features using STL (stereo lithography) model. The laser beam radius compensation was done by offsetting of the edge loop of incision. The positions of laser beam focal points were decided according the discrete points on the edge loop of incision. The laser head posture was determined using the normal vector of triangle face on which the laser beam focal points was located. The case studies indicate that the method can automatically select incision features and carry out laser beam radius compensation automatically,at the same time can ensure the laser head perpendicular to the surface of workpiece all the time. The operation of software system is stable and reliable..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 863 (2010)
Experimental Research on Formation of Laser Sintering WC Particles Reinforced Ni-Base Alloy Bulk
Chen Jinsong
Theory of preparation of sub-micro WC particles reinforced Ni-base super alloy matrix composite using direct metal laser sintering (DMLS) is introduced. The effects of processing parameters ,such as laser power,scanning speed on the microstructures,composition and microhardness of the laser sintered samples were characTheory of preparation of sub-micro WC particles reinforced Ni-base super alloy matrix composite using direct metal laser sintering (DMLS) is introduced. The effects of processing parameters ,such as laser power,scanning speed on the microstructures,composition and microhardness of the laser sintered samples were characterized by X-ray diffraction (XRD),scanning electron microscope (SEM ) and microhardness tester. The result shows that the examples prepared by laser sintering have better performance and higher density under the laser power of 900 W,scanning speed of 0.7 m/min,for WC particles melt as dendrites disperse evenly in the matrix and can be captured by solid-liquid interface. The compact metal bulks with high hardness are fabricated successfully by DMLS with optimized processing parameters..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 868 (2010)
Thermal Characteristic Analysis of Laser Diode Side-Pumped Regenerative Amplifier for kHz Picosecond Laser
Chang Liang, Chen Meng, Li Gang, Ma Yunfeng, Fan Zhongwei, Niu Gang, Yu Jin, Liu Yang, and Zhang Xue
The influence of heat effect produced by gain medium and electro-optic crystal working at high repetition rate on a regenerative amplifier is investigated in this paper. Depolarization loss induced by heat generated in Nd∶YAG crystal and thermal absorption of KD*P electro-optic crystal were measured,and a compensating The influence of heat effect produced by gain medium and electro-optic crystal working at high repetition rate on a regenerative amplifier is investigated in this paper. Depolarization loss induced by heat generated in Nd∶YAG crystal and thermal absorption of KD*P electro-optic crystal were measured,and a compensating element to compensate the loss of thermal depolarization was used effectively. A BBO Pockel cell for regenerative amplifier was designed by ourself,and effective amplification is obtained. An output pulse energy at 1064 nm is obtained from the picosecond laser pulse regenerative amplifier by laser diode (LD) side-pumped with 3 mJ each pulse and amplification radio of 3×106 at 1 kHz repetition rate..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 873 (2010)
Plasma Characteristics of Metal Fe Ablated by Pulsed Laser
Gao Xun, Guo Kaimin, Song Xiaowei, Tan Yong, Li Baozeng, Li Haijun, and Lin Jingquan
Laser-induced plasma spectroscopy of Fe target in air is investigated. Time and space-resolved spectra in the wavelength range of 380.0-420.0 nm are measured at different laser pulse energies. Under the model of local thermodynamic equilibrium,electronic temperature of Fe plasma is deduced to be around 104 K with assisLaser-induced plasma spectroscopy of Fe target in air is investigated. Time and space-resolved spectra in the wavelength range of 380.0-420.0 nm are measured at different laser pulse energies. Under the model of local thermodynamic equilibrium,electronic temperature of Fe plasma is deduced to be around 104 K with assistance of Saha equation. Electron density of Fe plasma is obtained to be about 1017 cm-3 by use of the full-width at half maximum (FWHM) of Fe spectral lines. Spatio-temporal evolution,electron temperature as well as electron density near the target are presented..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 877 (2010)
Synthesis and Photoluminescence of Silicon Nanoparticles Fabricated by Pulse Laser Ablation
Zhu Shiwei, Wang Lei, Chen Xing, Tu Hailing, and Du Jun
The buffer gas pressure is one of the most important parameters which influence the size of nanoparticles in the synthesized process by pulse laser ablation (PLA). Usually speaking,the size of nanoparticles increases with the increase of buffer gas pressure. In this report,according to the scanning electron microscopy The buffer gas pressure is one of the most important parameters which influence the size of nanoparticles in the synthesized process by pulse laser ablation (PLA). Usually speaking,the size of nanoparticles increases with the increase of buffer gas pressure. In this report,according to the scanning electron microscopy (SEM) measurements and corresponding statistic results for particles size of about 10 nm,it can be obtained that,the size of silicon nanoparticles decreases with the increasing of the gas pressure in the range of 50-100 Pa,and a relative expression between the gas pressure and the size of the silicon nanoparticles can be given,which describes the experimental phenomenon properly. The photoluminescent (PL) properties of silicon nanoparticles are investigated by photoluminescence spectroscopy with a wavelength of 280 nm at room temperature,and the violet and blue emissions are gained. A double peak structure at 372 nm and 445 nm appears in the sample synthesized by the gas pressure of 50 Pa. While the gas pressure increases to 70 Pa or 100 Pa,the peak in blue region disappears and the peak in violet region shifts to 379 nm and 393 nm corresponding to the samples synthesized by gas pressure of 70 Pa and 100 Pa respectively. These photoluminescent emissions are attributed to the surface state effect from the oxidized layer at the surface of the silicon nanoparticles..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 882 (2010)
Study on Microstructure and Mechanical Properties of Laser Repaired 1Cr12Ni3MoVN Alloy
Xue Lei, Lu Penghui, Chen Jing, Lin Xin, and Huang Weidong
In the present paper,1Cr12Ni3MoVN alloy was repaired by laser repair (LR) with 1Cr11Ni2W2MoV. A very good metallurgical bond between the repaired zone and the substrate was achieved. The microstructure of the laser repaired zone (LRZ) is composed by martensite and tempered martensite,and a quenching phenomenon was obseIn the present paper,1Cr12Ni3MoVN alloy was repaired by laser repair (LR) with 1Cr11Ni2W2MoV. A very good metallurgical bond between the repaired zone and the substrate was achieved. The microstructure of the laser repaired zone (LRZ) is composed by martensite and tempered martensite,and a quenching phenomenon was observed in heat affected zone (HAZ). Micro-hardness values decreased from LRZ to substrate zone (SZ),the maximum value happened in the HAZ close to the melting line. The results of room temperature tensile tests show that the strength of LRZ is 1280-1380 MPa,while the strength of laser repaired sample is 965-980 MPa. Fractures were observed on casting substrate during tensile test..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 887 (2010)
Materials and Thin Films
Synthesis of 10-Hydroxybenzo[h] quinoline (Bq) and Study on Its Luminescence Characteristics
Cheng Zhiming, Zhang Fujun, and Xu Zheng
A new kind of organic luminescent material 10-Hydroxybenzo[h]quinoline (Bq) was synthesized. The band gap of this material is about 1.98 eV measured by electrochemical cyclic voltammetery. The photoluminescence emission peak was about 616 nm,which was in accordance with the cyclic voltammetry experimental results. The A new kind of organic luminescent material 10-Hydroxybenzo[h]quinoline (Bq) was synthesized. The band gap of this material is about 1.98 eV measured by electrochemical cyclic voltammetery. The photoluminescence emission peak was about 616 nm,which was in accordance with the cyclic voltammetry experimental results. The electron cloud of the highest occupied molecular orbit and the lowest unoccupied molecular orbit were calculated by Gaussian 03 software. The organic material Bq and polymer poly(N-vinylcarbazole) (PVK) were dissolved into chloroform according to the weight ratio of 3%. Two kinds of devices ITO/PVK:Bq/BCP/Alq3/Al and ITO/PVK:Bq /Al were fabricated. There was not only 616 nm emission from Bq exaction,but also a peak at 500 nm emission in the electroluminescence spectra. The emission peak at 500 nm should be attributed to the electroplex emission (bimolecular emission) from PVK and Bq molecule. Based on the multilayer devices,the white emission was obtained under different driving voltages and the emission coordinate was about (x=0.37,y=0.38)..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 832 (2010)
Study and Synthesis of Large Section Soft Image Transfer Fiber Photonic Material
Zhou Dechun, Yu Fengxia, Tan Fang, Lu Jingjuan, Yang Jun, and Cui Yuan
Image transfer fiber photonic material is one of the most active research object in the photoelectric functional material field. This material has many virtues:fine single fiber diameter,best softness properties,imaging clearly and so on. This material has wide application perspective in all kinds of high image definitImage transfer fiber photonic material is one of the most active research object in the photoelectric functional material field. This material has many virtues:fine single fiber diameter,best softness properties,imaging clearly and so on. This material has wide application perspective in all kinds of high image definition instruments and industrial automate detection fields. This article prepared high optical quality core and clad glasses with physicochemical matching properties. On the base of end strengthen and optical cold work,we tested and evaluated soft image transfer fiber. It gained large section image transfer fiber photonic material,of which the diameter is 6.18 mm,single fiber diameter is 8±1 μm,resolution is 55 line pair /mm,visible light transmittance is more than 38%/m,core/clad glass concentricity error is 0.01% and numerical aperture is 0.65..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 836 (2010)
Measurement and Metrology
Radial Hartmann Method for Measuring Large Optical System
Tang Guomao, He Yumei, and Liao Zhou
A new Hartmann test method and principle based measurement of radial wavefront slop are presented,and structure of an 800 mm aperture Hartmann test system based on this method is built. Test on a 700 mm aperture telescope using this system is performed,and the testing results show that it can be used to test the opticaA new Hartmann test method and principle based measurement of radial wavefront slop are presented,and structure of an 800 mm aperture Hartmann test system based on this method is built. Test on a 700 mm aperture telescope using this system is performed,and the testing results show that it can be used to test the optical quality of large telescope and aspheric mirror indoor without using large flat mirror..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 795 (2010)
Inertial Confinement Fusion Experiment Target Gestur Estimation Technology
Liu Guodong, Wu Huilan, Hu Tao, and Pu Zhaobang
In order to deal with the problem of the slow on-line testing speed which is caused by the traditional regression model that is not sparse enough,a method based on the relevance vector machine (RVM) regression is proposed in the inertial confinement fusion (ICF) experiment target gesture estimation. In the experiment,tIn order to deal with the problem of the slow on-line testing speed which is caused by the traditional regression model that is not sparse enough,a method based on the relevance vector machine (RVM) regression is proposed in the inertial confinement fusion (ICF) experiment target gesture estimation. In the experiment,the algebra features extracted by the principal component analysis (PCA) is used as the sample features of the RVM,which can deal with the bluer problem caused by the small depth of field. A comparison between the commonly used regression algorithms such as support vector regression (SVR),K-nearest neighbor (KNN) and least mean square (LMS) has been done in this paper,the result shows that the testing error square of the RVM and SVM are the smallest,and the testing accuracy of them are the highest also. The testing time of the RVM is the lowest in the several algorithms,which shows that the RVM is more suitable for on-line testing..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 800 (2010)
Testing Method of Laser Equipment Based on Multi-Wavelength Simulated Laser Source Technique
Chen Zhibin, Xue Mingxi, Hou Zhangya, and Li Yizhao
Using the simulated laser source for optoelectronic instrument testing and calibrating is one of the important methods of optoelectronic equipment fault diagnosis and protection. Under the same platform,for testing laser equipments with different wavelengths,a single wavelength laser source is difficult to meet the reqUsing the simulated laser source for optoelectronic instrument testing and calibrating is one of the important methods of optoelectronic equipment fault diagnosis and protection. Under the same platform,for testing laser equipments with different wavelengths,a single wavelength laser source is difficult to meet the requirements of them.In this paper,by using independently developed muliti-wavelengh simulated laser source and the optoelectronic testing platform with the function of optoelectronic testing and controlment,information collection,analysis and processing,a testing method of laser equipments with several different wavelengths is proposed. Experiment shows,the method is appropriate to detect the laser sources with multi-wavelength and different pulse widths,such as 1.06 μm,0.9 μm and 1.55 μm,etc. Due to high integration and small bulk,the operation of testing is convenient in field condition..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 804 (2010)
Wavefront Testing of Large-Aperture Continuous Phase Plate
Chai Liqun, Yu Yingjie, Shi Qikai, Xu Qiao, Wen Shenglin, and Hou Jing
Continuous phase plate(CPP) is critical diffractive optical element used for beam shaping in high-power laser system. But the large-aperture interferometer is unsuitable for testing it for its spatial period with several millimeters and the large phase gradient. A sub-aperture stitching method by small-aperture and higContinuous phase plate(CPP) is critical diffractive optical element used for beam shaping in high-power laser system. But the large-aperture interferometer is unsuitable for testing it for its spatial period with several millimeters and the large phase gradient. A sub-aperture stitching method by small-aperture and high lateral-resolution interferometer is proposed to realize wavefront testing of CPP. A novel interpolation algorithm is developed for circular aperture and the equipment is set up. It tests a CPP with size of 330 mm×330 mm.The experimental result shows that the maximum testable slope of this CPP reaches 3 μm/cm with millimeter period,while the testing repeatability is 6 nm(root mean square). The simulated spot diagram result of far field based on tested wavefront is in good agreement with tested result in high-power laser system..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 809 (2010)
Time-Resolved Spectral Characteristics of Carbon Emission for Diamond-Like Film Prepared by Pulsed Laser Deposition
Lin Xiaodong, Hu Juguang, Liu Yi, and Zhang Lei
Time-resolved plasma emission spectrum measurement system is established for pulsed laser deposition (PLD) device. In diamond-like carbon film deposition,the intensity of CII(426.7 nm) and CIII(229.7 nm) emission is observed. The result is that the intensity decreases with deposition time,and depends strongly on targetTime-resolved plasma emission spectrum measurement system is established for pulsed laser deposition (PLD) device. In diamond-like carbon film deposition,the intensity of CII(426.7 nm) and CIII(229.7 nm) emission is observed. The result is that the intensity decreases with deposition time,and depends strongly on target′s surface. Keeping pulse energy and frequency constant,when the target is held,the emission intensity decreases more quickly than that when the target is rotated. The ratio of CIII emission intensity to that of CII is found increasing with time..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 815 (2010)
Fabrication of Novel Integrated Optical Young Interferometer Sensor
Zhao Shukai, Chen Fang, and Qi Zhimei
Two parallel three-dimensional single-mode channel waveguides spacing of 75 μm were prepared on glass substrate by standard photolithography combined with K+-Na+ ion exchange. By use of sputtering technique,a tapered film of TiO2 with thickness < 30 nm was then deposited on the middle region of one channel to form aTwo parallel three-dimensional single-mode channel waveguides spacing of 75 μm were prepared on glass substrate by standard photolithography combined with K+-Na+ ion exchange. By use of sputtering technique,a tapered film of TiO2 with thickness < 30 nm was then deposited on the middle region of one channel to form a composite optical waveguide. On the basis of the tapered velocity coupling theory,the fundamental transverse electric mode can propagate through the TiO2-covered region with a low attenuation,leading to a significantly enhanced evanescent field in this region. Therefore,the composite waveguide can serve as the sensing arm and the naked channel waveguide as the reference. With the prism-coupling method the linearly polarized He-Ne laser light was simulatenously launched into the two channels,and the divergent light emitted from the two channels are superposed to yield the Young′s interference pattern. The interferometer signal was interrogated using a slit-photodetector system. Such a novel integrated optical Young interferometer is applicable to the ultra-trace detection of chemical and biological measurands..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 819 (2010)
Effects of Thermal Annealing on the Properties of GaN Metal-Semiconductor-Metal UV Photodetectors
Zhao Man, Zhao Mei, Fan Xiuying, Zhou Maiyu, Gu Feng, Zhang Yong, and Bao Jinhe
Metal-semiconductor-metal structured GaN ultraviolet photodetectors are fabricated on sapphire substrates by metalorganic chemical vapor deposition. The properties of GaN photodetectors are improved through thermal annealing. With a 3 V bias,the very low dark current is about 200 pA,the maximum responsivity of 0.19 A/WMetal-semiconductor-metal structured GaN ultraviolet photodetectors are fabricated on sapphire substrates by metalorganic chemical vapor deposition. The properties of GaN photodetectors are improved through thermal annealing. With a 3 V bias,the very low dark current is about 200 pA,the maximum responsivity of 0.19 A/W is achieved at 362 nm,and the corresponding detectivity is 1.2×1011cm·Hz1/2/W. The physical mechanism about the effects of thermal annealing is studied,which is attributed to the introducing Au by the thermal annealing..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 822 (2010)
A Corneal Topography Based on Hartmann-Shack Sensor
Yang Jinsheng, Rao Xuejun, and Rao Changhui
A methodology for designing corneal topographier based on Hartmann-Shack sensor is described in this paper. Then,applying this method,an instrument is developed for measurement of corneal topography. In the system,the focus of an objective lens is precisely positioned on cornea′s curve center. Wavefront reflected from A methodology for designing corneal topographier based on Hartmann-Shack sensor is described in this paper. Then,applying this method,an instrument is developed for measurement of corneal topography. In the system,the focus of an objective lens is precisely positioned on cornea′s curve center. Wavefront reflected from the surface of cornea can be measured by the H-S sensor which is conjugated to the cornea plane. Then,the surface data of cornea can be acquired by algorithms for reconstructing. The repeatability and precision of the instrument are also validated. And the difference between errors measured by the instrument and those measured by ZYGO interferometer is less than 0.0818λ (RMS). Data of human corneal topography was also measured..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 826 (2010)
Optical Communication
Influence of Spot Noise in Inter-Satellite Optical Communications and Suppression Algorithm
Chen Xinglin, Zheng Yanhong, and Wang Yan
The inter-satellite laser communication system that implements for acquisition,pointing and tracking (APT) process,is a switch system which influences the continuity of communication widely. The switch sequence and the active subsystem are determined by the spot image collected by charge coupled device(CCD). In this paThe inter-satellite laser communication system that implements for acquisition,pointing and tracking (APT) process,is a switch system which influences the continuity of communication widely. The switch sequence and the active subsystem are determined by the spot image collected by charge coupled device(CCD). In this paper,the process of APT is analyzed in detail. Based on the whole workflow,the switch system model is represented. And the influence of spot noise which mixed into spot image to system performance is verified. The suppression algorithm that cascaded by average value wave filtering,Otsu method and selecting connected area method is proposed for the noise elimination. The simulation indicates that the algorithm is effective for pepper salt noise,Gaussian noise and stellar background noise,and the continuous communication can be got..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 743 (2010)
Phase-Shifted Photonic Analog-to-Digital Converter by Using Fiber Squeezer
Peng Yue, Zhang Hongming, Wu Qingwei, Fu Xin, and Yao Minyu
In this paper,a novel phase-shifted photonic analog-to-digital conversion (PADC) scheme is presented. In order to realize the phase-shifted quantization,the phase difference between two polarizations is produced by press-induced birefringence in fiber squeezer. A 4-bit optical phase-shifted analog-to-digital system is In this paper,a novel phase-shifted photonic analog-to-digital conversion (PADC) scheme is presented. In order to realize the phase-shifted quantization,the phase difference between two polarizations is produced by press-induced birefringence in fiber squeezer. A 4-bit optical phase-shifted analog-to-digital system is demonstrated experimentally with 10 GS/s sampling rate,and 2.5 GHz sinusoidal electrical signal is sampled and quantized,achieving a signal-to-noise of 23.9 dB and an effective number of bits of 3.68 bits. Comparing with existing PADC methods,this scheme has a simple structure,and only needs one phase modulator,which avoids the problem of input signal synchronization;using the fiber squeezer as phase-shift module,the quantization resolution of higher than 6-bit can be achieved with high control precision and low cost;this scheme has the potential to realize higher sampling rate with optical pulses multiplex technology..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 748 (2010)
Research on the Fabrication and Coupling Characteristic of Symmetrical Twin-Core Fiber
Liu Lisong, Peng Jian, Yao Lei, Zheng Kai, Wei Huai, and Jian Shuisheng
The relation between coupling characteristic and numerical parameter of twin-core fiber (TCF) was analyzed with coupling mode theory. It’s proposed that the coupling characteristic of two different twin-core fibers can be the same so that the parameter of twin-core fibers can be optimized according to their applicationThe relation between coupling characteristic and numerical parameter of twin-core fiber (TCF) was analyzed with coupling mode theory. It’s proposed that the coupling characteristic of two different twin-core fibers can be the same so that the parameter of twin-core fibers can be optimized according to their application. Meanwhile,an improved fabrication method of twin-core fiber was presented. Twin-core fiber was fabricated by modified chemical vapor deposition (MCVD) and photonic crystal technology. Then,its numerical parameter was measured..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 3, 752 (2010)
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