Journals >Chinese Journal of Lasers
Contents
2009
Volume: 36 Issue s1
81 Article(s)
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Research Article
Millisecond-Long-Pulse Solid-State Laser Pumped by Common Laser Diode Arrays
Ou Qunfei, Zhong Ming, Ren Gang, Yi Xuebin, Liu Wenbing, and He Hengxiang
A new approach to obtain millisecond-level long-pulse solid-state laser, pumped by some common pulsed high-power laser diode(LD) arrays with the pump pulse width of several hundreds microseconds, has been carried out. The long-pulse laser runs with high repetition rate and long life time. The pump laser diode arrays arA new approach to obtain millisecond-level long-pulse solid-state laser, pumped by some common pulsed high-power laser diode(LD) arrays with the pump pulse width of several hundreds microseconds, has been carried out. The long-pulse laser runs with high repetition rate and long life time. The pump laser diode arrays are six dual-line bars with a total peak power of 1.2 kW and duty cycle of 5%, which are divided into two groups. Based on time division pumping technology, NdYAG laser rod is pumped by the two groups successively. An average output power of 11.2 W and laser pulse width of about 1 ms have been obtained under pump electric current of 85 A..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 7 (2009)
Time-Varying Characteristic of Thermal Effect in Diode Laser Pumped Solid-State Lasers
Song Xiaolu, Guo Zhen, Li Bingbin, Wang Shiyu, Cai Defang, and Wen Jianguo
In laser diode (LD) pumped solid state laser, spatial and time distribution of temperature both exist in crystal, spatial distribution is discussed much more than time distribution in many papers. The time distribution of temperature lies on the pumped mode of laser such as CW pumped and pulsed pumped, time-varying proIn laser diode (LD) pumped solid state laser, spatial and time distribution of temperature both exist in crystal, spatial distribution is discussed much more than time distribution in many papers. The time distribution of temperature lies on the pumped mode of laser such as CW pumped and pulsed pumped, time-varying process exists in pulsed condition. Analytic method and finite element software are both used in the calculation of temperature time-varying distribution in laser diode pumped solid state laser, the influences of heating and cooling process are analyzed. The results show that heating process is influenced by pumped and cooling conditions, but mainly by pumped conditions such as pumped power and beam waist, cooling process is influenced by crystal radius, thermal physical parameters and cooling condition. Under the condition of pulsed laser diode pumped, radial temperature gradient and the resonator periodically change with time. After reasonable designing the resonator, lasers can periodically work in steady and unsteady states, which can obtain specifically laser output..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 10 (2009)
Research on Thermal Effect in Laser Diode-End-Pumped Nd∶Glass Laser Amplifier
Wang Mingzhe, Luo Yimin, Li Mingzhong, Ding Lei, Deng Qinghua, Tang Jun, and Jing Feng
As laser diode-end-pumped laser amplifier of moderate aperture can realize repeated-rate high energy output and good beam quality, it is paid more attention as inertial fusion energy (IFE) driver and directional energy weapon (DEW). Ndglass as laser medium has many advantages, such as easy to manufacture, high storage As laser diode-end-pumped laser amplifier of moderate aperture can realize repeated-rate high energy output and good beam quality, it is paid more attention as inertial fusion energy (IFE) driver and directional energy weapon (DEW). Ndglass as laser medium has many advantages, such as easy to manufacture, high storage energy, moderate emission cross section. However, its thermal conductivity is low and thermal effect is serious. Therefore, through analysis for the performance features of laser diode-end-pumped Ndglass laser amplifier, a ray tracing and finite element thermal model is established, and 3D and transient distributions of temperature and thermal stress in Nd:glass are simulated. The impacts of pump power, cooling parameter and repeat rate are mentioned, the mechanism of thermal fracture is also analyzed. The results are helpful of designing laser diode-end-pumped repeated-rate Nd∶glass laser amplifier..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 16 (2009)
High Average Power and High Beam Quality Intracavity Frequency Doubled Green Laser
Ma Yi, Cui Lingling, Wang Weimin, and Gao Jianrong
Preliminary influence factor analysis of beam quality of high-average-power and high-beam-quality intracavity frequency doubled green laser is presented. The methods of improving beam quality such as optimal design of resonator cavity and compensation of thermal effects are described. The corresponding experimental resPreliminary influence factor analysis of beam quality of high-average-power and high-beam-quality intracavity frequency doubled green laser is presented. The methods of improving beam quality such as optimal design of resonator cavity and compensation of thermal effects are described. The corresponding experimental research is done. With the control of beam quality, the green laser power of 63.7 W is obtained in a 8 mm×8 mm×12 mm KTP crystal with an M2 value of 9.65 and an optical-to-optical conversion efficiency of 9.7% at a pulse repetition rate of 10 kHz, and the green laser power of 79 W is generated in a 8 mm×8 mm×30 mm LBO crystal with an M2 value of 6.46 and an optical-to-optical conversion efficiency of 9.8% at a pulse repetition rate of 15 kHz..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 22 (2009)
Researching of High Power Ringed Diode Laser Module
Gao Songxin, Shi Yong, Lei Jun, Wei Bin, Wu Deyong, and Tang Chun
The distribution of optic gain,the stress in Nd∶YAG rod and the speciality of cooler are analyzed in this paper, the relation among the uniformity of optic gain, the distance between diode laser (DL) and center of Nd∶YAG,and the central wavelength of DL is identified. The model of pumping moudle is designed. 1～16 kW DLThe distribution of optic gain,the stress in Nd∶YAG rod and the speciality of cooler are analyzed in this paper, the relation among the uniformity of optic gain, the distance between diode laser (DL) and center of Nd∶YAG,and the central wavelength of DL is identified. The model of pumping moudle is designed. 1～16 kW DL pumping moudles are packaged and tested. The result of measurement shows that it can work at a duty cycle of 20%. The uniformity of optic gain is 85% with input current of 120 A and 25 ℃ of cooling water temperature the small signal gain is 0.148 cm-1..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 26 (2009)
Picosecond Laser System Combined with Nd∶YVO4 and Nd∶YAG Amplifiers
Peng Runwu, Guo Lin, Zhang Xiaofu, Li Fangqin, Cui Qianjin, Bo Yong, Peng Qinjun, Cui Dafu, Xu Zuyan, and Tang Lijun
A high average power and high beam quality picosecond laser system combined with diode-end-pumped Nd∶YVO4 and laser diode-side-pumped Nd∶YAG amplifier is described. The system combines the advantages of Nd∶YVO4 crystal having large stimulated-emission cross section and Nd∶YAG crystal having good thermal conductivity. TA high average power and high beam quality picosecond laser system combined with diode-end-pumped Nd∶YVO4 and laser diode-side-pumped Nd∶YAG amplifier is described. The system combines the advantages of Nd∶YVO4 crystal having large stimulated-emission cross section and Nd∶YAG crystal having good thermal conductivity. The diode-end-pumped Nd∶YVO4 amplifier allows the laser from the oscillator to obtain high gain so that the laser can amplify rapidly and the diode-side-pumped Nd∶YAG amplifier benefits to obtain high output power. The Nd∶YAG amplifier is designed as double-pass form to increase the efficiency of the amplifier. Spatial filters are adopted between amplifiers to ensure good beam quality and mode matching. Picosecond laser with average power of 43.4 W and good beam quality factor M2<1.7 is generated from this laser system..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 30 (2009)
Power-Balance Integrated Analytic Model of High-Power Solid-State Laser
Wang Wenyi, Su Jingqin, Li Yangchun, Wang Fang, Mo Lei, Liu Lanqin, and Li Keyu
High-power solid-state laser facility should provide careful power balance among beams for satisfying physical experiment requirement. To study effects of a number of differences on the output power balance, the power-balance integrated analytic model of high-power solid-state laser has been established. First, the detHigh-power solid-state laser facility should provide careful power balance among beams for satisfying physical experiment requirement. To study effects of a number of differences on the output power balance, the power-balance integrated analytic model of high-power solid-state laser has been established. First, the detailed description was made for that how the model was built, and the main algorithms. The model was developed based on the amplification, propagation and frequency conversion of narrow-band pulse laser. The model can solely analyze the influence of system deviation, or of random deviation on the output power balance, or together. Finally, the output-power-balance results at three conditions were analyzed by Haan pulse shape to meet 10% rms power imbalance requirement of the largest solid-state laser facility which is now building in our country, as well as the subsystem random-deviation specification was preliminarily allocated. The model was first used to obtain a basic understanding of the factors that determine the power balance for shaped pulse. It was a powerful tool to analyze the problem of the power balance of large solid-state laser facility..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 33 (2009)
Comparisons between Stable Resonator and Unstable Resonator with Variable Reflectivity Mirror for Slab Solid State Lasers
Qi Enyu, Shu Bohong, Xu Xiaojun, Wang Xiaobo, and Liu Liang
In order to obtain both high average output power and good beam quality in slab solid state laser, research on comparisons between the stable and unstable resonators was carried out through theoretical analysis and experimental study. For stable resonator, the laser had output power of 107 W when the pump power was 428In order to obtain both high average output power and good beam quality in slab solid state laser, research on comparisons between the stable and unstable resonators was carried out through theoretical analysis and experimental study. For stable resonator, the laser had output power of 107 W when the pump power was 428 W, which indicated M2x=8.35, M2y=32.29. However, the beam quality was poor in width direction. For unstable resonator, the beam quality could be significantly improved when an one-dimensional variable reflectivity mirror was used..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 40 (2009)
Study of Thermal-Stress-Induced Depolarization Loss in Conduction Cooled End-Pumped Slab Amplifiers
Liu Liang, Guo Shaofeng, Lu Qisheng, and Xu Xiaojun
The thermal-stress-induced depolarization is analyzed by numerical simulation in conduction cooled end-pumped YAG slab of finite dimensions with its length along the crystalline ［111］ axes. Simulation results show that the depolarization loss will be underestimated under plane-strain approximation. The alignment of theThe thermal-stress-induced depolarization is analyzed by numerical simulation in conduction cooled end-pumped YAG slab of finite dimensions with its length along the crystalline ［111］ axes. Simulation results show that the depolarization loss will be underestimated under plane-strain approximation. The alignment of the crystal’s axes with respect to the slab dimensions and the bounce number of the light in zigzag propagation are shown to significantly determine the depolarization loss. It’s not a reasonable solution to increase the bounce number of the light in zigzag propagation for minimizing depolarization loss in spite of the cut angle. Nevertheless, it is feasible for the slab with its width along ［101］ axes and the signal light can not be completely filled with the end of the slab..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 43 (2009)
Theoretical and Experimental Investigation of over 1 W Single-Mode Yb-Doped Fiber Laser at 980 nm
Zou Shuzhen, Li Pingxue, Wang Linghao, Chen Meng, and Li Gang
Based on rate equations, this paper gives expressions of the output power, the pump power threshold, the slope efficiency, and the fiber optimal length of the quasi-three-level Yb-doped fiber laser. The laser gain relationship between quasi-three-level mode and four-level mode in Yb-doped fiber laser is also given, whiBased on rate equations, this paper gives expressions of the output power, the pump power threshold, the slope efficiency, and the fiber optimal length of the quasi-three-level Yb-doped fiber laser. The laser gain relationship between quasi-three-level mode and four-level mode in Yb-doped fiber laser is also given, which provides a theoretical basis for suppressing the four-level transmissions and determining the range of the fiber length. In the experiment, a plano-plano cavity consisting of two 0° fiber ends is adopted as cavity mirrors. A quasi-three-level Yb-doped single-mode fiber laser totally emitted 1.32 W of single-mode laser output at 980 nm from two ends with the slope efficiency of 75.3% when the fiber length is 36.5 cm. The corresponding optical conversion efficiency is 66% from incidence pump power at 946 nm to the laser power at 980 nm. Besides, a total power of 15 mW at 490.8 nm is obtained by frequency doubling the laser at 980 nm with BIBO with the conversion efficiency of 1.1%..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 48 (2009)
Single-Longitudinal Mode Fiber Laser and the High Speed Transmission
Wang Tianshu, Qian Sheng, Zhou Xuefang, Qi Yongmin, and Li Qiliang
A single-longitudinal mode fiber laser with fiber saturable absorber is designed. Tunable fiber Bragg grating as the wavelength selector is in the ring cavity with a 2 m-long unpumped erbium-doped fiber. A section of high concentration erbium-doped fiber is pumped by a 980 nm laser diode and the standing-wave interfereA single-longitudinal mode fiber laser with fiber saturable absorber is designed. Tunable fiber Bragg grating as the wavelength selector is in the ring cavity with a 2 m-long unpumped erbium-doped fiber. A section of high concentration erbium-doped fiber is pumped by a 980 nm laser diode and the standing-wave interference is produced in the saturable absorber. Single-longitudinal mode laser at 1.55 μm band is observed and the output range is 42 nm. The optical bistable is observed because the absorption for laser reduces with the increasing of the pump power. Only one laser simultaneously pumps fiber amplifier and laser through a splitter for enhancing stability and decreasing noise. The output power exceeds 24 mW and the stability is less than ±0.005 dB. The laser slope efficiency is 18.5%. A 12.5 Gb/s codes rate is used in the fiber laser transmission experiment. The signal is transmitted in 42 km without regeneration. This fiber laser has potential applications in the field of the high capacity communications..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 52 (2009)
Experimental Study on the Nonlinear Polarization Rotation Mode-Locking Fiber Laser
Ren Fang, Xiang Wanghua, Bai Yangbo, Li Nan, and Shi Xiaozhou
A passively mode-locked fiber ring cavity laser with a small segment of Er3+/Yb3+co-doped fiber as gain medium, pumped by stable 976 nm laser diode and mode-locked by the nonlinear polarization rotation technique, experimentally demonstrated. By adjusting the polarization controllers orientation and pump power, the staA passively mode-locked fiber ring cavity laser with a small segment of Er3+/Yb3+co-doped fiber as gain medium, pumped by stable 976 nm laser diode and mode-locked by the nonlinear polarization rotation technique, experimentally demonstrated. By adjusting the polarization controllers orientation and pump power, the stable operations of continual fundamental wave mode-locked with the repetition rate of 15.90 MHz and the spectral bandwidth of 7.4 nm, Q-switched-mode-locked with the spectral bandwidth of 4.84 nm, passive Q-switched with the repetition rate of 147.06 kHz and the spectral bandwidth of 1.8 nm, high-order harmonically mode-locked regimes in a ring cavity Er3+/Yb3+co-doped fiber laser have been obtained experimentally. Compared with Er3+ fiber as gain medium, the experiment accomplished by using Er3+/Yb3+co-doped fiber as gain medium shows a better output of mode-locking..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 56 (2009)
The Impact of Stimulated Raman Scattering and Polarization Effect on the Gain of Fiber Optical Parametric Amplifier
Li Qiliang, Zhu Yinfang, and Jin Jing
We study the impact of stimulated Raman scattering (SRS) and polarization effect on the gain of fiber optical parametric amplifier. We find that the gain spectrum is asymmetrical because of the Raman scattering, contemporaneously, the gain peak value in SRS case is larger than that in no SRS case. When the difference oWe study the impact of stimulated Raman scattering (SRS) and polarization effect on the gain of fiber optical parametric amplifier. We find that the gain spectrum is asymmetrical because of the Raman scattering, contemporaneously, the gain peak value in SRS case is larger than that in no SRS case. When the difference of two pumps is increased, the gain peak value decreases and the gain flatness is worse. When the Raman response delay time decreases is, the gain peak value increases. The greater birefringence coefficient is, the smaller gain peak value is. Moreover, the polarization effect is considered, the signal gain and the signal power are dependent on the signal polarized angle, namely, the signal gain and the signal power reach maximum if the signal and the pumps are horizontally polarized, but they reach minimum if the signal and the pumps are orthogonally polarized..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 61 (2009)
Analysis of Wavelength Conversion of Picosecond Pulses Based on Four-Wave Mixing in Microstructure Fibers
Zhang Xia, Li Jiajian, Huang Yongqing, and Ren Xiaomin
All optical wavelength conversion based on four-wave mixing (FWM) is experimentally demonstrated in 80-m dispersion-flatted high nonlinear microstructure fibers (MF). The pulsed signal with 10 GHz repetition rate and 1.6 ps pulse width is used as pump wave. In the experiments, both down- and up-conversion are obtained All optical wavelength conversion based on four-wave mixing (FWM) is experimentally demonstrated in 80-m dispersion-flatted high nonlinear microstructure fibers (MF). The pulsed signal with 10 GHz repetition rate and 1.6 ps pulse width is used as pump wave. In the experiments, both down- and up-conversion are obtained in this type of wavelength converter. Moreover, the relationship between conversion efficiency and the power of CW and pulsed wave is also experimentally analyzed. Both of the wavelength up-conversion and down-conversion is efficient and this efficiency decreases as the input power falls. The power of optical pulse’s impact on the down-conversion is obvious. In summary, we believe the high nonlinear dispersion-flattened microstructural fiber will play an important roll in all optical wavelength conversion..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 66 (2009)
Optimal Design of High-Power Ytterbium-Doped Double-Clad Fiber Amplifier
Leng Jinyong, Chen Shengping, Guo Shaofeng, Xu Xiaojun, Liu Zejin, and Zhao Yijun
The power distributions of signal and amplified spontaneous emission in continuous- wave high-power ytterbium-doped double-clad fiber amplifier are studied. The relationships between the output power and the signal power, pump power, pump schemes, fiber length are studied. The system of ytterbium-doped double-clad fibeThe power distributions of signal and amplified spontaneous emission in continuous- wave high-power ytterbium-doped double-clad fiber amplifier are studied. The relationships between the output power and the signal power, pump power, pump schemes, fiber length are studied. The system of ytterbium-doped double-clad fiber amplifier is set up and amplified laser of 48.2 W is obtained when the powers of signal and pump are 2 W and 72.9 W, respectively. The resoults of theoretical study and experiment are in good agreement. And the results of numerical simulation provide a theoretical guide to optimal design of continuous-wave high-power double-clad fiber amplifier..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 70 (2009)
Experimental Study of Supercontinuum Generation by Hundred Nanosecond Pulse in Highly Nonlinear Photonic Crystal Fiber
Zhang Shiqiang, Li Xiao, Xu Xiaojun, Chen Shengping, and Jing Chunyuan
The supercontinuum (SC) from 600 nm to 1500 nm is generated in the highly nonlinear photonic crystal fiber, pumped by acoustic-optic Q-switch pulses with a duration of 200 nm, a repetition rate of 3.3 kHz and tunable power. And the generation causes are also analysised. It is shown that when the pump wavelength overlapThe supercontinuum (SC) from 600 nm to 1500 nm is generated in the highly nonlinear photonic crystal fiber, pumped by acoustic-optic Q-switch pulses with a duration of 200 nm, a repetition rate of 3.3 kHz and tunable power. And the generation causes are also analysised. It is shown that when the pump wavelength overlaps with the zero- dispersion wavelength self-phase modulation and third-order dispersion plays an important role, the propagating pulses will oscillate. With the increasing of the peak power of pump pulse , the pectral width becomes wider..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 75 (2009)
Synchronous Output for RF Excited Waveguide CO2 Laser with Grating
Wang Jing, Sun Zhenghe, Sun Yude, Zhang Yanchao, Tian Zhaoshuo, and Wang Qi
In order to provide the ideal light source for difference frequency THz laser device, the methods of pulsed laser output synchronization have been studied for two 10 μm radio-frequency (RF) excited pulsed waveguide CO2 laser with grating. One method was to control the pulse triggering delay, and the other was to adjustIn order to provide the ideal light source for difference frequency THz laser device, the methods of pulsed laser output synchronization have been studied for two 10 μm radio-frequency (RF) excited pulsed waveguide CO2 laser with grating. One method was to control the pulse triggering delay, and the other was to adjust the voltage on the piezoceramics (PZT). The pulsed laser output synchronization could be realized by the two methods. It is helpful to obtain high efficiency THz generation. In the experiment, because of the ambient temperture, vibration and other external conditions, it is found the output pulsed laser synchronization maintains a relatively short time, but the pulsed laser can be re-synchronized by manually controling the pulse trigger delay or adjusting the PZT voltage..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 79 (2009)
High Power Pulsed TEA CO2 Laser with Unstable Resonator
Guo Ruhai, Zhang Laiming, Yang Guilong, and Li Shiming
High average power high repetition rate TEA CO2 lasers have many important applications such as laser manufacturing, laser ranging and military applications, especially its optical quality is the key point for its applications. Based on original high power TEA CO2 with stable resonator in this paper, three sets of teleHigh average power high repetition rate TEA CO2 lasers have many important applications such as laser manufacturing, laser ranging and military applications, especially its optical quality is the key point for its applications. Based on original high power TEA CO2 with stable resonator in this paper, three sets of telescopic positive-branch confocal resonators are designed and manufactured using unstable resonator scheme. The corresponding comparison experiments are performed with single-pulse energy and divergence angle. Experimental results indicate that using unstable resonator can largely improve the divergence angle and compress the pulse width as the same time to maintain the high single-pulse energy. The single-pulse energy 13.4 J, the divergence angle 1.2 mrad and pulse duration time 49.5 ns are obtained from the best unstable resonator. At the same time the output mirror freezing by change of state can guarantee the average power of laser greater than several kW at high repetition rate..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 82 (2009)
A Study of Cross-Polarization Modulation Characteristics of Dual-Channel PolSK Optical Transmission System
Zhang Chao, Wang Lutang, Fang Nian, and Huang Zhaoming
In this paper, based on the dual-channel polarization shift-keying (PolSK) optical transmission system in which two cascaded semiconductor optical amplifiers (SOAs) are employed; the cross-polarization modulation (XPolM) characteristics of the system were studied using different code types, bit rates and time delays foIn this paper, based on the dual-channel polarization shift-keying (PolSK) optical transmission system in which two cascaded semiconductor optical amplifiers (SOAs) are employed; the cross-polarization modulation (XPolM) characteristics of the system were studied using different code types, bit rates and time delays for the two data streams. The simulation results showed that the two polarization multiplexed channels of the system are completely independent, which can be used to transmit two data streams simultaneously with different code types, bit-rates and clock signals. Also the results showed that the system has good performances in the polarization multiplexing and de-multiplexing of the data, which are well agreed with those in our previous experimental system. Through the simulation, it was observed that the polarization-modulated signals at high bit-rate have complicated data pattern dependences and complicated optical frequency chirps which are resulted from the time varying of the phases of the optical signals..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 86 (2009)
Spontaneously generated coherence induced second-order susceptibility in atomic gases
Ni Cui, Yueping Niu, and Shangqing Gong
Second-order susceptibility which vanishes in the electric-dipole approximation for an atom is induced by the spontaneously generated coherence (SGC). The SGC considered in a lambda-type atomic system causes an indirect coupling between the lower two levels which acts equivalently as a direct current (DC) field and theSecond-order susceptibility which vanishes in the electric-dipole approximation for an atom is induced by the spontaneously generated coherence (SGC). The SGC considered in a lambda-type atomic system causes an indirect coupling between the lower two levels which acts equivalently as a direct current (DC) field and therefore makes possible the existence of second-order susceptibility..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 93 (2009)
Ultraslow solitons and soliton pairs in asymmetric quantum wells
Yihong Qi, Hui Sun, Yueping Niu, Ni Cui, and Shangqing Gong
Generation of ultraslow solitons and dynamic behaviors of soliton pairs with low intensity input pulse in semiconductor asymmetrical quantum wells (QWs) are investigated. It shows that the QWs structure can provide giant Kerr-type nonlinearity via resonant tunneling, therefore the group velocity dispersion can be balanGeneration of ultraslow solitons and dynamic behaviors of soliton pairs with low intensity input pulse in semiconductor asymmetrical quantum wells (QWs) are investigated. It shows that the QWs structure can provide giant Kerr-type nonlinearity via resonant tunneling, therefore the group velocity dispersion can be balanced, which results in the generation of the ultraslow solitons and soliton pairs, and the initial relative phase of the soliton pairs plays an important role in the propagation of soliton pairs in such a semiconductor QW system. These properties are very useful in practical applications, such as quantum information processing and optical buffers..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 96 (2009)
Research of Optical Switch Temperature Control Technology Based on Digital Signal Processor
Wei Limin, Hu Shuling, Hu Hanwei, Zhang Xiaoqing, and Meng Zhaokui
Optical switch is the key function unit of fiber delay line, which will be influenced by optical switch. A whole digital temperature control system based on TMS320F2812 digital signal processor (DSP) of Texas Instruments (TI) Co. is designed to control the operating temperature of micro-electronic mechanical systems (MOptical switch is the key function unit of fiber delay line, which will be influenced by optical switch. A whole digital temperature control system based on TMS320F2812 digital signal processor (DSP) of Texas Instruments (TI) Co. is designed to control the operating temperature of micro-electronic mechanical systems (MEMS) optical switch, which utilizing DS18B20 to collect temperature and then sending it to DSP. In the DSP difference between the temperature to be measured and the temperature set as the input of proportioral integration differential (PID) algorithm, so control quantity produced through calculation is used to control DRV592 as to drive thermal electric cooler (TEC). This system has the characteristics of simple hardware circuit, high integration, high precision. The error of this system is ±0.1 ℃, temperature control domain is 0 ℃～70 ℃, so the optical switch can operate regularly..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 100 (2009)
Design and Analysis of Large-Scale Mirror Frame Based on Structure Stability Index
Zhang Junwei, Zhou Yi, Xie Na, Zhou Hai, Lin Donghui, and Chen Lin
Stability index distribution of high power solid laser facility requires that the rotation of all the optical elements in the facility can not exceed 0.46 μrad when excited by environmental random vibrations. According to the requirement of stability, back inference the nature frequency design requirement of switchyardStability index distribution of high power solid laser facility requires that the rotation of all the optical elements in the facility can not exceed 0.46 μrad when excited by environmental random vibrations. According to the requirement of stability, back inference the nature frequency design requirement of switchyard mirror frame by pseudo excitation method and random vibration theory, which is one of the large-scale mirror frame. Back inference result is that the nature frequency of switchyard mirror frame can not smaller than 14.88 Hz. Builds the 3-D model and analyses the mode of switchyard mirror frame, the result has a good agreement with the design calculation. Using the PSD as the excitation which had been measured for 24 hours on the install base level of the mirror frame to analyze random vibration response of the mirror frame by the PSD module of ANSYS, the response result is 0.2 μrad. The result indicates that designed mirror frame can meet the requirement of stability index and also indicate that according to the back inference result design the mirror frame is feasibility at the same time..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 105 (2009)
Study on Cs 852 nm Faraday Anomalous Dispersion Optical Filter
Liu Shuangqiang, Zhang Yundong, and He Zhusong
As an ultra-narrow bandwidth optical filter with unique character of high efficiency, Faraday anomalous dispersion optical filter (FADOF) has been focused on by both international and domestic researchers in recent years. In this thesis the theoretical and experimental studies on Cs 852 nm FADOF were done on the base oAs an ultra-narrow bandwidth optical filter with unique character of high efficiency, Faraday anomalous dispersion optical filter (FADOF) has been focused on by both international and domestic researchers in recent years. In this thesis the theoretical and experimental studies on Cs 852 nm FADOF were done on the base of reviewing the domestic and international development. A qualitative analysis on the magnetic field and temperature of the two main factors was given and the best working conditions were obtained. Hereby experiment was planned and at last a small-scale device was made..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 110 (2009)
Pulse Laser Technology Based on Coherently Phase-Wavelength Multiplexed Principle
Wang Xiaolin, Zhou Pu, Ma Haotong, Ma Yanxing, Xu Xiaojun, Liu Zejin, and Zhao Yijun
A new pulse laser technology based on coherently phased-wavelength multiplexed (CPWM) principle has been proposed, simulation has been done to analyze the effect of each parameters to the characteristic of the pulse laser. Base on the coherent combining of the multi-wavelength laser, several CW laser’s those hold the sA new pulse laser technology based on coherently phased-wavelength multiplexed (CPWM) principle has been proposed, simulation has been done to analyze the effect of each parameters to the characteristic of the pulse laser. Base on the coherent combining of the multi-wavelength laser, several CW laser’s those hold the same frequency interval are coherently combined, by effective phase control of each laser, pulse laser with adjustable parameter such as intensity, pulse width, pulse repetition rate can be generated. In theory, the combined pulse laser holds the same characteristic as the mode-locked laser, and the repetition rate is equal to the frequency interval. Apply a certain phase control to each laser; an anticipant pulse laser can be generated. As the development of the out-cavity phase controlling technology, this method can be an effective way to generate pulse laser with multi-parameter adjustable from a CW laser..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 114 (2009)
Beam Transmission
Focusing Characteristics of Partially Coherent Electromagnetic Vortex Beams
Liu Xiaoyun, Tang Hongliang, Li Qian, and Xu Songning
Based on the extended Huygens-Fresnel principle, the propagation formulas for focusing of partially coherent electromagnetic vortex beams by an aperture lens have been derived. Based on these formulas, the intensity distribution and the degree of coherence near the geometrical focus are investigated. It is found that tBased on the extended Huygens-Fresnel principle, the propagation formulas for focusing of partially coherent electromagnetic vortex beams by an aperture lens have been derived. Based on these formulas, the intensity distribution and the degree of coherence near the geometrical focus are investigated. It is found that the topological charges, normalized coherence lengths and the truncated parameter play an important role in controlling the size of the partially coherence vortex dark core and the distribution of coherence in the focal region. The size of the vortex dark core increases with increasing the topological charge and the normalized coherent length. Moreover, the intensity of the vortex bright ring moves to the aperture with decreasing the normalized coherent length and the perceptive parameter. The effective coherent length in the focal region decreases with increasing the normalized coherence lengths and topological charges. It is also found that the effective coherent length increases with increasing the propagating distance. Therefore, the desired vortex dark core near the geometrical focus can be achieved by choosing appropriate values of parameters..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 199 (2009)
A Coaxial Optical System for Holographic Disc Storage
Wang Ye, and Tao Shiquan
It is necessary to develop a miniaturization of the holographic disc storage systems for its practical and commercial application. A novel coaxial system of holographic disc driver was designed. One laser beam was used as information beam and reference beam simultaneously. The center part of the laser beam acts as the It is necessary to develop a miniaturization of the holographic disc storage systems for its practical and commercial application. A novel coaxial system of holographic disc driver was designed. One laser beam was used as information beam and reference beam simultaneously. The center part of the laser beam acts as the information beam. And the other part of the laser beam around the ring, which becomes a convergent beam after it is reflected by two annulus shaped mirrors, acts as the reference beam. The information beam and the reference beam interfere in the back focal plane of the first Fourier transform lens. The larger angle between the information beam and the reference beam can be obtained through optimizing the geometric parameters of the mirrors. Then the complex level of holographic storage is improved and the better selectivity is provided. This system has a compact profile and is useful to make a miniaturization holographic disc driver in the future..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 205 (2009)
Research on Novel Piezoelectric Fast Steering Mirror
Xiang Sihua, Chen Sihai, Wu Xin, Zheng Xiawei, Xiao Ding, and Dai Jun
A fast steering mirror based on novel piezoelectric actuator was designed. The size of the mirror was 20 mm×15 mm. The optical scanning angle reached ±0.7°. The first step resonance frequency was 1872 Hz. Fast steering mirror was based on two amplified piezoelectric actuator .The structure was analyzed bA fast steering mirror based on novel piezoelectric actuator was designed. The size of the mirror was 20 mm×15 mm. The optical scanning angle reached ±0.7°. The first step resonance frequency was 1872 Hz. Fast steering mirror was based on two amplified piezoelectric actuator .The structure was analyzed by finite element analysis software, and the frequency response was measured. The linearity of open loop scanning was improved by using the method of combining software which compensated the hysteretic behavior of piezoelectric actuator and notch filter circuit which restrained the structure resonance of the scanner. Accordingly, the triangle wave with high rate scanning was achieved. The sine wave with high precision scanning was realized by using the digital proportional-integral differential (PID) controller based on repetitive control principle. Test results shown that the scanner can steer the beam at high speed with high precision. The scanner also had other advantages such as small size and simple structure..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 208 (2009)
1+2-Dimensional Super Gaussian Nonlocal Spatial Soliton
Zeng Chunxiang, Wang Xinghua, Xie Liangxing, and Xie Yingmao
The propagation properties of the 1+2-dimensional super Gaussian shaped optical beam in strongly nonlocal nonlinear media are discussed by means of variational approach. A set of parameter evolution equations, a critical power and an approximate evolution law of the beam width are obtained. In the general case, the beaThe propagation properties of the 1+2-dimensional super Gaussian shaped optical beam in strongly nonlocal nonlinear media are discussed by means of variational approach. A set of parameter evolution equations, a critical power and an approximate evolution law of the beam width are obtained. In the general case, the beam width of the 1+2-dimensional super Gaussian shaped optical beam in strongly nonlocal media takes periodical oscillating variation with sine and cosine shape. But the beam width remains constant and the spatial optical soliton is formed when the input power equals the critical power. The critical power increases with the order of optical beam, but is independent on the order of phase factor. The speed of phase shift of the spatial optical soliton is related with the order of optical beam, the order of phase factor and the initial power. As the order of optical beam gets higher, the order of optical beam and the initial power plays more important role, and the effect of the order of phase factor can be ignored..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 213 (2009)
Crosstalk Characteristics of Concave Grating Demultiplexer
Guo Fuyuan, Li Lianhuang, and Wang Minghua
The crosstalk between two adjacent signal channels of concave grating demultiplexer is composed of the transverse mutual coupling efficiency between two output waveguides and the response efficiency of output waveguide for the central wavelength of adjacent signal channels. Under the condition of weak coupling approximThe crosstalk between two adjacent signal channels of concave grating demultiplexer is composed of the transverse mutual coupling efficiency between two output waveguides and the response efficiency of output waveguide for the central wavelength of adjacent signal channels. Under the condition of weak coupling approximation, based on the mutual coupling coefficient between two nonparallel rectangular waveguides which derived from the method of field distribution analysis, the mutual coupling characteristic between two identical structure output waveguides in concave grating demultiplexer is discussed, and the relationship between the crosstalk and the basic structure parameters of the output waveguides is clarified. As the spectral response efficiency which is derived from the diffraction factor of grating facet, emission factor of input waveguide and receive factor of output waveguide is employed, the relationship between the spectral response characteristic of the signal channel and the basic structure parameters of the Rowland circle structure concave grating demultiplexer is clarified. These results will provide theoretical support for designing the basic structure parameters of concave grating demultiplexer..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 217 (2009)
Propagation of Polarized Light in Anisotropic Scattering Medium
Li Wei, Zeng Nan, Yun Tianliang, and Ma Hui
Many biological tissues consist of fibril structures. The scattered light of tissues provides abundant information about the properties of tissues. The polarization property of scattered light can reveal structure and type of tissue. Understanding the propagation property of polarirzed light in scattering medium is helMany biological tissues consist of fibril structures. The scattered light of tissues provides abundant information about the properties of tissues. The polarization property of scattered light can reveal structure and type of tissue. Understanding the propagation property of polarirzed light in scattering medium is helpful to improve imaging gating method and diagnosis technology. In this paper, the transmitted light from a section of dentin was measured. A linearly polarized He-Ne laser beam was incident on the sample, and the transmitted light is recorded. The image showed anisotropic spatial distribution, indicating the light propagating along the fibers. The polarization property of the scattered light was related to the polarization direction of the incident light. A Monte Carlo simulation considering cylindrical scatterers was utilized to model the scattering property of microstructure in dentin. The experimental results are compared with the simulation. The ordered fibers have influence on the spatial distribution and the polarization state of scattered light..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 222 (2009)
Reasearch of Wavefront Correction System in Laser Driver
Dai Wanjun, Hu Dongxia, Zhou Wei, Zhao Junpu, Zhang Kun, Jiang Xuejun, and Jing Feng
Based on the theoretical and experimental results of adaptive optics system application in SG-Ⅲ prototype facility, the main scientific and technical problems were researched and solved, the efficiency was verified by experiment. In order to fulfill need of future high power solid-state laser driver wavefront correctioBased on the theoretical and experimental results of adaptive optics system application in SG-Ⅲ prototype facility, the main scientific and technical problems were researched and solved, the efficiency was verified by experiment. In order to fulfill need of future high power solid-state laser driver wavefront correction, the scheme of combined adaptive optics system with continuous phase plate (CPP) was researched in theory. “One big deformable mirror (DM) with one CPP ”and “One small DM with two CPPs” schemes were analyzed by numerical modeling. The result showed that the latter scheme can achieve the goal of controlling the entire beam wavefront, and fulfill the need of focal spot size and uniformity for physics experiment. The results can also provide theoretical reference to design wavefront correction system in high power solid-state laser facility..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 225 (2009)
CAD of the Modeling Stray Light in the High Power Laser System
Mo Lei, Su Jingqin, Wang Fang, Wang Wenyi, and Liu Lanqin
According to the analysis of stray light in high power solid-state laser system, the ghost image was 3D demonstrated in the structure model of the facility by software Wildfire-PRO/E3.0. The simulation model to describe the ghost-image distribution was also established. The position of the one-or-more order ghost imageAccording to the analysis of stray light in high power solid-state laser system, the ghost image was 3D demonstrated in the structure model of the facility by software Wildfire-PRO/E3.0. The simulation model to describe the ghost-image distribution was also established. The position of the one-or-more order ghost image in the facility can be fully displayed in all directions so that the ghost-image harmfulness can be easily found. The hazard analysis of typical ghost-image was made and method to avoid the damage of ghost image was put forward. The research results will be in favor of stray light management..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 231 (2009)
Propagation Properties of Ultrashort Pulsed Bessel-Gaussian Beams Diffracted by an Circular Aperture
Zou Qihui, Zhu Hongyu, and Duan Xi
Based on the Fresnel diffraction integral, complex Gaussian function expansion and complex analytical signals method, the approximate analytical expression for ultrashort pulsed Bessel-Gaussian beams diffracted by an circular aperture in free space is derived. The normalized power spectrum, transversal intensity distriBased on the Fresnel diffraction integral, complex Gaussian function expansion and complex analytical signals method, the approximate analytical expression for ultrashort pulsed Bessel-Gaussian beams diffracted by an circular aperture in free space is derived. The normalized power spectrum, transversal intensity distribution, and optical pulse shape of ultrashort pulsed Bessel-Gaussian beam are studied in detail..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 235 (2009)
Design of Laser Beam Homogenizing Instrument for Ceramic Sintering on Double Sides
Li Zhi, Ji Lingfei, and Jiang Yijian
Using geometrical optics, a laser beam homogenizer for high power CO2 has been designed. Laser beam is homogenized by means of waveguide, separate beam with spectroscope, so the device can be used to sintering ceramics on double sides. The waveguide is composed of a square-section tube with four flat rectangular mirrorUsing geometrical optics, a laser beam homogenizer for high power CO2 has been designed. Laser beam is homogenized by means of waveguide, separate beam with spectroscope, so the device can be used to sintering ceramics on double sides. The waveguide is composed of a square-section tube with four flat rectangular mirrors, and its length is 200 mm, cross section 10 mm×10 mm. Two mirrors that has an angle with each other forms the spectroscope. The uniformity of the power distribution is stable without being affected by original laser beam. Using Fourier optics to analyze system, the method to improving the uniformity has been discussed. Because all the elements have reflecting surface, energy loss is not serious, optical path adjusting is convenient..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 240 (2009)
Focusing of Elliptically Polarized Vortex Beams through a High Numerical-Aperture Objective
Chen Baosuan, and Pu Jixiong
Based on Richards-Wolf vectorial diffraction integral, the focusing properties of elliptically polarized vortex beams through a high-numerical aperture objective is studied in this paper. The intensity, phase and orbital angular momentum distribution properties of tightly focused vortex beams are presented. The influenBased on Richards-Wolf vectorial diffraction integral, the focusing properties of elliptically polarized vortex beams through a high-numerical aperture objective is studied in this paper. The intensity, phase and orbital angular momentum distribution properties of tightly focused vortex beams are presented. The influence of corresponding parameters on the tight focusing properties is also investigated. It is shown that elliptical light spots of great application can be obtained near the focus. Moreover the elliptical spot may rotate and the size and shape of the spot may change with the change of certain parameters. It is also found that the spin angular momentum of the elliptically polarized vortex beam will convert to orbital angular momentum by the tight focusing. These properties are quite important for the applications of this kind of elliptically polarized vortex beams..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 244 (2009)
Extra Cavity Coherent Superposition for Generation of Radially Polarized Beam
Lin Huichuan, Liu Hui, and Pu Jixiong
Due to the extensive application of radially polarized beams, the generation and propagation of this kind of beam are investigated theoretically and experimentally in this paper. In theory, the generation of TEM01 and TEM10 beams and radially polarized light beam are simulated by the integral of scalar diffraction. In Due to the extensive application of radially polarized beams, the generation and propagation of this kind of beam are investigated theoretically and experimentally in this paper. In theory, the generation of TEM01 and TEM10 beams and radially polarized light beam are simulated by the integral of scalar diffraction. In experiment, by the use of phase step, two orthogonally polarized TEM00 beams are converted to TEM01 and TEM10 beams with orthogonal polarization respectively outside the cavity. Then the radially polarized light beam is obtained by coherent superposition of TEM01 and TEM10 beams. The influence of experimental error on the generation of radially polarized light beam, and the change of the light spot of radially polarized light beam in propagation are investigated. A longitudinal electric field and teeny focal spot can be generated by focusing the radially polarized light beam, therefore, it may have extensive application in many fields, such as particle acceleration, high-resolution microscopy and material processing etc..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 251 (2009)
Wavefront Distortion Tolerance of Continuous Phase Plate for Backlighter
Zhao Junpu, Hu Dongxia, Su Jingqin, Li Ping, Zhou Wei, and Dai Wanjun
The wavefront, such as power, astigmatism, coma and spherical aberration distortion etc., was currently generated by Zernike polynomial with the P-V value less than 5λ (1053 nm). Then with the generated wavefront added the continuous phase plate (CPP), which was designed for backlight with the methods of improved GerchThe wavefront, such as power, astigmatism, coma and spherical aberration distortion etc., was currently generated by Zernike polynomial with the P-V value less than 5λ (1053 nm). Then with the generated wavefront added the continuous phase plate (CPP), which was designed for backlight with the methods of improved Gerchberg-Saxton (G-S) algorithm, the focus process was simulated by fast Fourier transform (FFT) algorithm. The influences of wavefront distortion type and wavefront distortion value on the 3ω (351 nm) shaping focal spots were studied in details through three factors, energy efficiency, the uniformity of the 10～100 μm scale of focus and the size of the focal spot. The results showed it had a relatively wider tolerance for wavefront distortions due to the energy efficiency and the size of the focal spot, the variances will be no more than 5% as the P-V of the generated wavefront distortion was analogous with the CPP. The uniformity of the focal spot was very sensitive to wavefront distortion, with 1λ (1053 nm) wavefront distortion, the root-mean-square (RMS) of focal spots will be increased about 38.5%, from 0.325 to 0.45. Therefore, it indicates that it is necessary to control the wavefront distortions of the whole laser systems..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 257 (2009)
Improve the Adjusting Reliability of Optimum Matching Angular of the Frequency Tripling of High Power Laser by Laser Near Field CCD Diagnostic Device
Tang Shunxing, Ji Lailin, Ouyang Xiaoping, Huang Kuixi, Zhu Baoqiang, and Lin Zunqi
An online-offline program which is applied to find out the optimum matching angular of the frequency tripling of high power laser are intraduced in this paper. Comparing with determining the optimum matching angular by laser energy meter or naked eyes, the laser near field CCD diagnostic device is more reliable. The reAn online-offline program which is applied to find out the optimum matching angular of the frequency tripling of high power laser are intraduced in this paper. Comparing with determining the optimum matching angular by laser energy meter or naked eyes, the laser near field CCD diagnostic device is more reliable. The result shows that the adjusting precision of the optimum matching angular of the frequency tripling can reach 20″, which can meet the requirement of engineering application..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 262 (2009)
Laser Manufacturing
Mechanical Property of CO2 Laser Welded Joint of 1420 Aluminum-Lithium Alloy
Cai Hua, Xiao Rongshi, and Chen Kai
Aluminum-lithium alloys are ideal high-strength lightweight structural materials, which have extensive applications in aerospace, weapon and other hi-tech industrial areas. By using a Slab CO2 laser, 1420 aluminum-lithium alloy has been welded. The mechanical properties of the welded joint have been studied after addinAluminum-lithium alloys are ideal high-strength lightweight structural materials, which have extensive applications in aerospace, weapon and other hi-tech industrial areas. By using a Slab CO2 laser, 1420 aluminum-lithium alloy has been welded. The mechanical properties of the welded joint have been studied after adding different wires and postweld heat treatment process..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 122 (2009)
Key Technologies of Auto Programming for Laser Planar Cutting
Bao YongW, u Qiang, Wang Xibing, and Zuo Tiechuan
The original objects dealt with in laser planar cutting are numerous curve segments out of order, while the processing itself is sequential. The key of auto programming for laser planar cutting is how to convert such curve segments to ordered cutting traces and generate numerical control (NC) codes at last. According tThe original objects dealt with in laser planar cutting are numerous curve segments out of order, while the processing itself is sequential. The key of auto programming for laser planar cutting is how to convert such curve segments to ordered cutting traces and generate numerical control (NC) codes at last. According to the characteristics of laser planar cutting, the key technologies of auto-programming are discussed and the solutions to every key steps are given here. NC programs of laser planar cutting can be automatically generated from unordered curve segments through such key steps, namely “auto extraction of traces”, “auto analysis of relations between traces”, “auto creation of laser-on points” and “auto plan of the shortest path”..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 126 (2009)
Application of CO2 Laser Seamless Glass Cutting
Wang Zhong, Chen Zeming, Li Yi, He Li, and Lu Feixing
Assisted-CO2 laser glass cutting method has been introduced. 0.8 mm thick borosilicate glass has been cut with 100 W slab CO2 laser, 450 mm/s speed. With suitable heating/cooling technic, high speed, high quality, precision and accurate cutting of glass have been achieved. Side intensity of glass cut by laser method isAssisted-CO2 laser glass cutting method has been introduced. 0.8 mm thick borosilicate glass has been cut with 100 W slab CO2 laser, 450 mm/s speed. With suitable heating/cooling technic, high speed, high quality, precision and accurate cutting of glass have been achieved. Side intensity of glass cut by laser method is obviously higher than traditional method. The cutting speed model has been reported and calculated, the same as experimental results. The parameters which affect cutting have been discussed. It’s feasible to increase cutting speed by output power enhancement..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 130 (2009)
Vital Problems on Laser Remanufacturing Gears
Dong Shiyun, Xu Binshi, Wang Zhijian, and Zhang Xiaodong
Gears are important components in mechanism, which take roles of transfering power and speed. Their failures are mainly caused by tooth fracture and abrasion. However, reparation of the damaged gears is still a popular and hard problem in machinery industry. In this paper, as to remanufacturing or repairing the damagedGears are important components in mechanism, which take roles of transfering power and speed. Their failures are mainly caused by tooth fracture and abrasion. However, reparation of the damaged gears is still a popular and hard problem in machinery industry. In this paper, as to remanufacturing or repairing the damaged gear-tooth, it introduced connotation and technical characters of remanufacture engineering, stated connotation and technical processes of laser remanufacture. Then it devided the damage of gear tooth into three sorts, and discussed the vital problems on laser remanufacturing of the damaged gear tooth from various aspects such as remanufacturing processing, performance and shape of the remanufactured teeth. With practical samples, it intepreted the laser remanufacturing methods for the fracture, tooth-surface abrasion and tooth-end abrasion gears individually. At last, it points out that laser remanufacturing is great practical technology for damaged gear repair, which shows great prosperous applications..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 134 (2009)
Investigation on Laser Sintering of Bi4Ti3O12 Ceramics
Gao Yi, Ji Lingfei, and Jiang Yijian
The investigation on laser sintering of Bi4Ti3O12 ceramics is reported. The green patch of Bi4Ti3O12 ceramic was sintered by a CO2 laser, with power density 20～30 W/cm2 and sintering temperature around 1000 ℃. Compared with that sintered by conventional solid-state reaction technique ,the density of Bi4Ti3O12 ceramic sThe investigation on laser sintering of Bi4Ti3O12 ceramics is reported. The green patch of Bi4Ti3O12 ceramic was sintered by a CO2 laser, with power density 20～30 W/cm2 and sintering temperature around 1000 ℃. Compared with that sintered by conventional solid-state reaction technique ,the density of Bi4Ti3O12 ceramic sintered by laser is higher, reaches 95% of the theoretical one ,the piezoelectric constant was increased by 60% , the decrease of coercive field and easier polarization indicated that the enhancement of the ferroelectric properties. By using the X-ray diffraction (XRD), scanning electron microscope (SEM), the phase, microstructure, and the mechanism of property modification in laser sintered Bi4Ti3O12 ceramics were analyzed. It’s indicated that the measure of laser sintering could be regarded as one of the ways to sinter the functional ceramics..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 139 (2009)
Laser Application in Processing Brittle Materials
Zhu Yinbo, Zhou Jianzhong, Huang Shu, Fan Yujie, and Jiang Suqin
Brittle materials have been applied more and more popularly because of their special properties, relativing to machining technique of metal materials, there is little study on processing for nonmetal brittle materials, and effective machining tools lack. With the development of laser technology, laser is becoming a potBrittle materials have been applied more and more popularly because of their special properties, relativing to machining technique of metal materials, there is little study on processing for nonmetal brittle materials, and effective machining tools lack. With the development of laser technology, laser is becoming a potential processing tool for brittle materials. The principle of processing, characteristics and research status on brittle materials with laser separation, laser bending and laser peening are reviewed. Affecting factors of processing quality in laser separation and bending, such as laser energy, scanning velocity and beam mode, are discussed, the theory of dislocation is used to explain the performance improved in brittle materials after laser peening. Finally, some problems of laser application in nonmetal brittle materials processing are pointed out and future developments are forecasted..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 143 (2009)
Dissimilar Metal Laser Welding of Cast Ni-Based Superalloy K418 Turbo Disk and Alloy Steel 42CrMo Shaft
Pan Ming, Tan Jiansong, Wang Jianping, Wu Bo, Xie Zhimin, Hu Dingyun, and Yu Gang
Dissimilar metal laser welding of cast Ni-based superalloy K418 turbo disk and alloy steel 42CrMo shaft was studied. Microstructure of the welded seam was characterized by optical microscopy (OM) and scanning electron microscopy (SEM). Results showed that side-blow shielding gas was warped in the melt pool with excessiDissimilar metal laser welding of cast Ni-based superalloy K418 turbo disk and alloy steel 42CrMo shaft was studied. Microstructure of the welded seam was characterized by optical microscopy (OM) and scanning electron microscopy (SEM). Results showed that side-blow shielding gas was warped in the melt pool with excessive flow rate of shielding gas by progressively reducing of heat input of laser. Bubble defect of seam ending can be inhibited by optimizing flow rate of side-blow shielding gas. Microstructure of the weld and base metal interface is mainly composed of dendrites whose growing direction is nearly parallel to the negative heat-transfer direction. Distribution of Laves phase have discrepancy in different region of the welded seam because of different mixing proportion of K418 and 42CrMo,and different solidifying velocity in different region of the melting pool..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 147 (2009)
Characterization and Measurement of Bonding Strength of Soft Coating Based on Laser Thermal Stress
Kong Dejun, Luo Kaiyu, Zhang Leihong, and Song Guangshan
A device measuring bonding strength of soft coating based on laser thermal effect was established, and the mechanism and method for characterizing interfacial bonding strength of coating by residual stress under laser action were analyzed, which is suited for measuring bonding strength of soft coating. The experimentalA device measuring bonding strength of soft coating based on laser thermal effect was established, and the mechanism and method for characterizing interfacial bonding strength of coating by residual stress under laser action were analyzed, which is suited for measuring bonding strength of soft coating. The experimental results show that residual stresses of the coating are changed under laser thermal stress, and residual stress in the node can be used to measure the interfacial bonding strength of the coating. Tradition pulling method can be replaced by the method of coating interfacial bonding strength with laser thermal stress, and the real time measurement of coating bonding strength was realized in the real-time way..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 151 (2009)
Laser Transmission Welding of Thermoplastic Polyurethane Films
Liu Huixia, Li Pin, Xing An, Yuan Xiaoming, Xiang Baozhen, and Wang Xiao
0.12 mm thick films of thermoplastic polyurethane (TPU) are welded using laser transmission welding technology. The effect of main welding parameters including laser average power, welding speed on welding quality is investigated. The results show that using Clearweld resins, the color of welding seam is similar to par0.12 mm thick films of thermoplastic polyurethane (TPU) are welded using laser transmission welding technology. The effect of main welding parameters including laser average power, welding speed on welding quality is investigated. The results show that using Clearweld resins, the color of welding seam is similar to parent material’s, and colorless welding is obtained. The experimental results show that at the welding speed of 100 mm/min, with increasing of laser average power from 0.31 W to 8.11 W, the seam width increases from 0.86 mm to 4.10 mm. When the laser average power is lager than 2.30 W, the material is decomposed in the weld seam. When the laser average power is lager than 7.15 W, the material is ablated. And the peeling strength is all more than 1.3 N/mm during the laser average power from 0.6 W to 5.89 W. Adjusting welding speed and fixing the laser average power, parameter window for laser transmission welding is obtained. The results show that with the matching of laser average power and welding speed, the welding speed can be increased by the premise of guarantee of weld seam quality..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 156 (2009)
Design and Analysis of Diffractive Optical Element on Laser Transmission Welding Based on Diffraction
Wang Xiao, Li Pin, Chen Cheng, Xing An, Xiang Baozhen, and Liu Huixia
Laser transmission welding of plastics based on diffraction is a new technology of simultaneous welding. This paper introduces the principle of laser transmission welding of plastics based, and tells a laser simultaneous welding technology based on diffractive optical element. Diffractive model is established and basedLaser transmission welding of plastics based on diffraction is a new technology of simultaneous welding. This paper introduces the principle of laser transmission welding of plastics based, and tells a laser simultaneous welding technology based on diffractive optical element. Diffractive model is established and based on the weighted G-S algorithm, the influence of the size of weighted factor on the design of diffractive optical element (DOE) is numerically simulated, at the same time, the influence of the size of weighted factor on the welding is analyzed by using Matlab. The simulation results indicate that with the weighted factor increasing, the diffractive efficiency is improved that means the light intensity in the emitting region is enhanced, and meanwhile, sun of square error (SSE) is improved that means the uniformity of the spot is decreased after reshaping, and the light intensity in the emitting region may be non-uniform. Finally, the experiment of modulation and reshaping of DOE is carried out, the pre and post spot shapes are acquired, attaining the expected pattern..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 161 (2009)
Intensity Distribution Optimal Design for Laser-Dominated Thermal Loading
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To accomplish laser-induced thermal loading simulation tests for pistons, space intensity distribution of laser is changed by diffractive optical element (DOE),and time distribution of laser is controlled with the help of computer. It is necessary to know proportion of intensity distribution for design and process of DTo accomplish laser-induced thermal loading simulation tests for pistons, space intensity distribution of laser is changed by diffractive optical element (DOE),and time distribution of laser is controlled with the help of computer. It is necessary to know proportion of intensity distribution for design and process of DOE. Finite mode of intensity distribution is established. Results show temperature distributing of piston is agreement with target temperature distributing when power proportion from center circle to outer circle is 0.03,0.01 and 9.96. Thermal loading of high cycle and low cycle can be simulated by optimization DOE..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 166 (2009)
Precision Green Laser Trimming in Application of Film Pressure Sensor
Chen Zeming, Wang Zhong, Lu Feng, Min Dayong, and Lu Feixing
Precision green laser trimming system was Introduced. The system composition structure was analyzed. The system includes laser system, laser focus and optical localization system, precise numerical control system and automation test system. The application of green laser trimming in diaphragm pressure sensor was descriPrecision green laser trimming system was Introduced. The system composition structure was analyzed. The system includes laser system, laser focus and optical localization system, precise numerical control system and automation test system. The application of green laser trimming in diaphragm pressure sensor was described. The main craft of green laser trimming which is used in the film pressure sensor was analyzed, the key craft is the laser energy real-time control and laser beam size. Through the high performance laser, focus, supervisory and precise motion control system, trimming technology was successfully applied in the film pressure sensor production. Sensor’s zero point error has been controlled between -80～+80 μV, and zero temperature drift is smaller than 0.02% ℃, the non-compensatory of sensor was achieved..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 170 (2009)
Research Status and Application of Laser Cleaning
Wang Min, Zhou Jianzhong, Huang Shu, and Hu Lingling
Laser cleaning is a novel and effective cleaning technique,which uses the excellent directionality and high brightness of laser to clean the contaminants on the surface of materials, while does not destroy the substrate. In this paper, the main three cleaning principles with laser ablation, dry laser cleaning and wet lLaser cleaning is a novel and effective cleaning technique,which uses the excellent directionality and high brightness of laser to clean the contaminants on the surface of materials, while does not destroy the substrate. In this paper, the main three cleaning principles with laser ablation, dry laser cleaning and wet laser cleaning are introduced, the mechanisms and influencing factors for dry laser cleaning and wet laser cleaning are analyzed detailedly. The laser cleaning applications in the fields of precise components, cultural relics and upsize components are also presented . Finally, an evaluating system for laser cleaning is introduced and the evaluating criterion of cleaning quality is established..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 174 (2009)
An All-Solid-State Quasi-Continuous-Wave Widely Tunable Blue-Violet Laser Scan and Control System
Li Pingxue, Huang Daobo, Zhang Dapeng, Chen Meng, and Li Gang
An all-solid-state quasi-continuous-wave (QCW) tunable Ti∶sapphire laser system from 697 nm to 942 nm by using single output mirror is reported, which was pumped by an intra-cavity frequency doubling Nd∶YAG laser at 532 nm. Under the pump power of 18W at 532 nm with the repetition rate of 3.9 kHz, the average output poAn all-solid-state quasi-continuous-wave (QCW) tunable Ti∶sapphire laser system from 697 nm to 942 nm by using single output mirror is reported, which was pumped by an intra-cavity frequency doubling Nd∶YAG laser at 532 nm. Under the pump power of 18W at 532 nm with the repetition rate of 3.9 kHz, the average output power of 3.5 W at 795 nm with an optical conversion efficiency of 20% was yielded. Through extra-cavity frequency doubling with the nonlinear crystal LBO (LiB3O5, 3 mm×6 mm×20 mm), cut for critical type I phase matching (Θ=90°,Φ=33.2°) at room temperature, tunable second-harmonic generation (SHG) from 350 nm to 465 nm was achieved. The average output power at 400 nm was 540 mW. Through the design of laser focus system , the scan and control system, the whole laser can be used to expose the CTP material. In this way, the capability of the CTP material can be valued..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 178 (2009)
Frequency-Domain Optical Coherent Tomograph and the Application in Ophthalmology
Wang Weichao, Liu Yujia, Tobias Braeuler, Xi Peng, Zhou Chuanqing, Jiang Minshan, and Ren Qiushi
Optical coherence tomography (OCT) is a high resolution, contact-free and non-invasive optical imaging approach. By measuring the interference signal of the backscattering light of the tissues, OCT can obtain the interior structure of the tissues. As a diagnostic technique, OCT has been widely used in medical examinatiOptical coherence tomography (OCT) is a high resolution, contact-free and non-invasive optical imaging approach. By measuring the interference signal of the backscattering light of the tissues, OCT can obtain the interior structure of the tissues. As a diagnostic technique, OCT has been widely used in medical examination, especially in ophthalmological imaging diagnosis. Frequency-domain OCT (FD-OCT) has a better performance in the imaging speed than that of time-domain OCT (TD-OCT), as it can obtain the characteristic information of the whole depth without mechanical scanning. Therefore, it is more applicable to ophthalmology. We constructed a fiber based FD-OCT imaging system, of which the axial resolution is less than 10 μm and scanning speed is more than 24000 times per second. The system can image the retinal tissue structure for clinical diagnosis..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 181 (2009)
Health-Enhancing Low Level Laser Irradiation
Yuan Jianqin, Liu Chengyi, Wu Min, Li Xiaoguang, Xu Xiaoyang, and Liu Songhao
Photobiomodulation (PBM) is a green approach to maintain human health, and is often used in disease prevention or treatment. Its health enhancement, especially exercise-induced fatigue treatment with intranasal low intensity laser therapy, will be discussed. Function-specific homeostasis (FSH) is a negative-feedback rePhotobiomodulation (PBM) is a green approach to maintain human health, and is often used in disease prevention or treatment. Its health enhancement, especially exercise-induced fatigue treatment with intranasal low intensity laser therapy, will be discussed. Function-specific homeostasis (FSH) is a negative-feedback response of a biosystem to maintain the function-specific conditions inside the biosystem. An individual system might be classified as FSH-essential system (FES) and FSH-non-essential system (FNS) which homeostasis can be written as FESH and FNSH for short, respectively. FSH quality might be enhanced by study or training (SOT). Extraordinary SOT disrupts the formal FSH and establishes FESH. Ordinary SOT maintains FESH and establishes FNSH and then a new FSH, and then maintains the new FSH. The cellular rehabilitation of low level laser irradiation or monochromatic light might promote the establishment of FESH, FNSH and FSH, shorten SOT period and then promote health..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 185 (2009)
Cellular Model Studies of Brain-Mediated Monochromatic Phototherapy on Alzheimer′s Disease
Zhu Ling, Liu Chengyi, Hu Binna, Li Xiaoyun, and Wang Yongqing
Alzheimer’s disease (AD) is now the most common neurodegenerative disease. As drugs approved are not very effective, the brain-mediated monochromatic phototherapy is one of therapeutic candidate approaches. The cellular model studies of AD have been conducted in our laboratory and will be reviewed in this paper. GenetiAlzheimer’s disease (AD) is now the most common neurodegenerative disease. As drugs approved are not very effective, the brain-mediated monochromatic phototherapy is one of therapeutic candidate approaches. The cellular model studies of AD have been conducted in our laboratory and will be reviewed in this paper. Genetic studies have shown that dysfunction of amyloid-β (Aβ) or tau is sufficient to cause AD. Aβ or hydrogen peroxide (H2O2) induced neuron apoptosis might be a cellular model of AD. We found red light at 640±15 nm from light emitting diode array (RLED640) might inhibit PC12 cell apoptosis induced by Aβ25-35 and apoptosis of differentiated PC12 cell (dPC12) induced by H2O2, which might be mediated by cAMP and tyrosine hydroxylase, respectively. The dysfunction of tau might be mimicked by colchicine. We found H2O2 and colchicines might lead to dPC12 abortive apoptosis, and the abortive apoptosis might be inhibited with RLED640. The rhythm dysfunction in AD might be mimicked by tumor necrosis factor α(TNF-α). We also found low intensity 810 nm laser irradiation might rehabilitate inhibition of circadian gene expression of NIH 3T3 fibroblasts induced by the TNF-α..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 190 (2009)
Monte Carlo Simulation of Energy Distribution in Port Wine Stain Skin Model
Xu Lanqing, Wang Ying, and Li Hui
Laser irradiation is the most acceptable therapy for port-wine stain (PWS) patient at present time. Its efficacy is highly dependent on the energy deposition rules in skin. To achieve optimal PWS treatment parameters a better understanding of light propagation in PWS skin is indispensable. In this paper the structure oLaser irradiation is the most acceptable therapy for port-wine stain (PWS) patient at present time. Its efficacy is highly dependent on the energy deposition rules in skin. To achieve optimal PWS treatment parameters a better understanding of light propagation in PWS skin is indispensable. In this paper the structure of normal skin and the pathological character of PWS skin was analyzed in detail and the true structure were simplified into a hybrid layered mathematical model to character two most important aspects of PWS skin: layered structure and overabundant dermal vessels. The basic laser-tissue interaction mechanisms in skin were investigated and the optical parameters of PWS skin tissue at 532 nm was calculated which the therapeutic wavelength of our clinical treatment is. Monte Carlo (MC) based techniques were choused to calculate the energy deposition in the skin and blood vessel; results can be used in choosing optical dosage. Further simulations can be used to predict optimal laser parameters to achieve high-efficacy laser treatment of PWS..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 194 (2009)
Materials and Thin Films
Analysis of Permitted Parameters and Angle Tuning ZnGeP2-OPO Mid-Infrared Laser
Li Guang, and Wang Li
The optical permitted parameters and angle tuning characteristics of ZnGeP2 (ZGP)-OPO were numerically simulated based on the dispersion equation of ZGP and the momentum and energy conservation in type-I and type-II. The angle tuning ranges of 50.7°～57° in accordance with wavelength tuning from 2.4 μm to 11 μThe optical permitted parameters and angle tuning characteristics of ZnGeP2 (ZGP)-OPO were numerically simulated based on the dispersion equation of ZGP and the momentum and energy conservation in type-I and type-II. The angle tuning ranges of 50.7°～57° in accordance with wavelength tuning from 2.4 μm to 11 μm in type-I, and the wavelength tuning ranges of 2.4～11.5 μm (in-continuity 3～6 μm)with angle tuning 58°～87° in type-II have researched. The acceptance angle and walk-off angle in the process of angle tuning were also numerically simulated. Furthermore, the permitted parameters of ZGP were compared with AGS and AGSe crystal. The conclusions showed that ZGP is the optimum mid-infrared crystal..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 314 (2009)
Dynamic Population Process of Upconversion Luminescence of ErP5O14 Crystal Excited by 650 nm Laser
Chen Xiaobo, He Chenjun, Song Zengfu, Guo Jinghua, Yang Guojian, Zhou Hongyu, Wang Yafei, Tian Qiang, Zhou Jing, Peng Fanglin, Wang Huaying, Liu Dahe, Wu Zhenglong, Ma En, Ouyang Jie, Chen Ying, and Li Hui
Dynamic population process of ErP5O14 crystal described by rate equations is reported in the present manuscript. All dynamic process and pumping power influence have been calculated out for ErP5O14 crystal when excited by 650nm laser. Established rate equations has included spontaneous emission rates, absorption of pumDynamic population process of ErP5O14 crystal described by rate equations is reported in the present manuscript. All dynamic process and pumping power influence have been calculated out for ErP5O14 crystal when excited by 650nm laser. Established rate equations has included spontaneous emission rates, absorption of pumping photon, relative stimulated emission rates, nonradiative multiphonon relaxation rates, all possible energy transfer rates and back energy transfer rates. It is found that upconversion luminescence intensity is very strong and upconversion luminescence behaviour is very good when 650 nm laser pumping power reaches 103～105 W. The stable population probability of 4I15/2 state can be reduced to 0.0617 small extent. The population probability of 4F9/2 state can be first enhanced to 0.362 fast and then reduced to 0.0374 stable value smoothly. It means that the population of 4F9/2 state has been upconversioned to higher level. The very good results have emerged at that the population probability of 4S3/2 state may be as high as 0.212, which will results in the strong 543 nm upconversion luminescence. It is more significant that the population probability of 4G9/2 state may be as high as 0.160, which will results in the strong 379 nm upconversion luminescence..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 319 (2009)
Design and Fabrication of Multilayer SiO2/CeO2-TiO2/SiO2 Coatings with UV Absorption and High Quality Transparence Properties
Jiamiao Ni, Qingnan Zhao, and Xiujian Zhao
New transparence and ultraviolet (UV) absorption coatings having the sandwich structure of SiO2/CeO2-TiO2/SiO2 were deposited on the soda-lime silicate glass by radio frequency (R.F.) magnetron sputtering. The computer aid simulation for optical characterization has been used to optimize multilayer coatings to obtain hNew transparence and ultraviolet (UV) absorption coatings having the sandwich structure of SiO2/CeO2-TiO2/SiO2 were deposited on the soda-lime silicate glass by radio frequency (R.F.) magnetron sputtering. The computer aid simulation for optical characterization has been used to optimize multilayer coatings to obtain high transparent and good UV absorbing properties. Optimum thickness of SiO2 and CeO2-TiO2 films were obtained. Several analytical tools such as spectrophotometer, scanning electron microscopy, and digital camera were used to characterize possible changes in optical properties. These results suggest that the single addition of inner layer SiO2 film has no distinct effect on improving transmittance and decreasing reflection rate in the visible light range, whereas the main function of this layer film is to improve the adhesion of the coating to glass substrate. In contrast, the outer layer SiO2 film plays a main role on diminishing the interference yellow coloring and increasing transparence. Therefore the three-layered SiO2(113 nm)/CeO2-TiO2(342 nm)/SiO2(113 nm) films show good UV absorption (>99%) properties, high transparence (average value of ～89%) and low average reflection rate (as low as ～9%) in the visible light range..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 324 (2009)
Production and Application of Optical Diamond-Like Carbon Films
Guo Yanlong, Wang Shuyun, Wang Xiaobing, Cheng Yong, Lu Changyong, and Sun Bin
The merits and performance of optical diamond-like carbon (DLC) films are generalized. The most popular production methods for DLC films are pulsed laser deposition, filtered arc deposition, radio frequency plasma chemical vapor deposition, magnetron sputtering, radio frequency sputtering and ion beam deposition. The pThe merits and performance of optical diamond-like carbon (DLC) films are generalized. The most popular production methods for DLC films are pulsed laser deposition, filtered arc deposition, radio frequency plasma chemical vapor deposition, magnetron sputtering, radio frequency sputtering and ion beam deposition. The principle, character, research process of those methods and the performance and application on various optical materials and fields of the DLC films deposited by those methods are summarized. Through analyzation of domestic and overseas research progress, wide application prospect and huge practical value of optical DLC films are revealed..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 330 (2009)
Investigation of n-Si and p-Si Semiconductors by Terahertz Time-Domain Spectroscopy
Jin Bin, Li Tong, Zhou Qingli, Shi Yulei, and Zhang Cunlin
Two kinds of semiconductor substrates, n-Si and p-Si, are investigated by the terahertz (THz) time-domain spectroscopy. The reference signals of free space and the sample signals are measured, and a series of optical parameters of these two samples in the range of 0.5～2.0 THz are calculated. The refractive index and reTwo kinds of semiconductor substrates, n-Si and p-Si, are investigated by the terahertz (THz) time-domain spectroscopy. The reference signals of free space and the sample signals are measured, and a series of optical parameters of these two samples in the range of 0.5～2.0 THz are calculated. The refractive index and real part of complex relative permittivity of n-Si are independent of frequencies, as well as p-Si. The extinction coefficient and imaginary part of complex relative permittivity of p-Si decrease with the increasing frequency, and this phenomenon is much more obvious than that of n-Si. The complex conductivity and dielectric loss also have been calculated. The obtained results indicate that n-Si and p-Si have good dielectric properties and can be used to work in the THz range..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 337 (2009)
Research on Amorphous Silicon Solar Cell Scribing with 1064 nm/523 nm 4-Way Light Splitter System
Min Dayong, Chen Zeming, He Li, Wang Zhong, and Lu Feixing
Through the discussion of tandem amorphous silicon (a-Si∶H) film solar cell processing, suitable laser and process parameters are given. Character of scribing area which scribed by 40 kHz, 1.2 m/s scribing speed, 16 W 1064 nm laser, 4 W single way power and 3 W 532 nm laser, 0.75 W single way power with 4-way light splThrough the discussion of tandem amorphous silicon (a-Si∶H) film solar cell processing, suitable laser and process parameters are given. Character of scribing area which scribed by 40 kHz, 1.2 m/s scribing speed, 16 W 1064 nm laser, 4 W single way power and 3 W 532 nm laser, 0.75 W single way power with 4-way light splitter focus system are discussed. Factors which cause heat-affected zone and lead to the decrease of efficiency are analyzed. Key process parameters which affect scribing line obviously and which needed to be accurately controlled are given..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 341 (2009)
Effect of Multi-Waveband Antireflective Coating on Laser Induced Damage Threshold of MgO Doped LiNbO3
Wang Ying, Zhang Yueguang, Shen Weidong, Liu Xu, and Gu Peifu
Multi-spectral antireflective coating (AR) was deposited by electron beam evaporation on MgO doped LiNbO3 crystal, and the transmission band of the coating is 1.064 μm, 1.4～1.6 μm and 3.5～4.3 μm. The laser induced damage threshold (LIDT) of un-coated and AR-coated samples were measured. The AR-coated samples have a betMulti-spectral antireflective coating (AR) was deposited by electron beam evaporation on MgO doped LiNbO3 crystal, and the transmission band of the coating is 1.064 μm, 1.4～1.6 μm and 3.5～4.3 μm. The laser induced damage threshold (LIDT) of un-coated and AR-coated samples were measured. The AR-coated samples have a better LIDT than un-coated crystal..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 346 (2009)
Spectroscopic Properties of Er3+/Yb3+ Co-Doped Sr3Y2(BO3)4 Crystal
Zhou Haifang, and Wang Guofu
The growth and spectral properties of Er3+/Yb3+∶Sr3Y2(BO3)4 crystal were reported in this paper. Er3+/Yb3+∶Sr3Y2(BO3)4 crystal with high quality and dimensions of 25 mm×35 mm has been grown by the Czochralski method. The spectral properties of Er3+/Yb3+∶Sr3Y2(BO3)4 were investigated. Based on the Judd-Ofelt (J-O)The growth and spectral properties of Er3+/Yb3+∶Sr3Y2(BO3)4 crystal were reported in this paper. Er3+/Yb3+∶Sr3Y2(BO3)4 crystal with high quality and dimensions of 25 mm×35 mm has been grown by the Czochralski method. The spectral properties of Er3+/Yb3+∶Sr3Y2(BO3)4 were investigated. Based on the Judd-Ofelt (J-O) theory, the spectral parameters were calculated. The oscillator intensity parameters were Ω2=14.10×10-20 cm2,Ω4=1.69×10-20 cm2,Ω6=1.72×10-20 cm2, and the emission cross section was 8.24×10-21 cm2 at 1534 nm. The fluorescence lifetime and radiative lifetime of the Er3+ (4I13/2→4I15/2 transition) were 0.650 ms and 3.873 ms, respectively. The result shows that the Er3+/Yb3+∶Sr3Y2(BO3)4 crystal may be become 1.55 μm laser materials..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 349 (2009)
Supercontinuum Generation Using 120 fs Femtosecond Pulse Laser in a Dispersion Flattened Photonic Crystal Fiber
Wang Qiuguo, Zhang Hu, Zhang Xia, Li Wei, and Yang Bojun
Supercontinuum generation using femtosecond pulse in a nonlinear dispersion flattened photonic crystal fiber is experimentally demonstrated. The photonic crystal fiber with a nonlinearity of about 11 W-1·km-1 is characterized by flattened chromatic dispersion. The chromatic dispersion varies less than 1.2 ps/(nm&#Supercontinuum generation using femtosecond pulse in a nonlinear dispersion flattened photonic crystal fiber is experimentally demonstrated. The photonic crystal fiber with a nonlinearity of about 11 W-1·km-1 is characterized by flattened chromatic dispersion. The chromatic dispersion varies less than 1.2 ps/(nm·km) between 1500 nm and 1650 nm. By injecting 120 fs optical pulses into an 40 m-long dispersion-flattened photonic crystal fiber, the supercontinuum with a broadened spectrum of 480 nm (at 20 dB level) is achieved, it has important applications, such as supercontinuum source and optical wavelength conversion..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 353 (2009)
Monolithically Integrated Si-Based Wavelength-Selective Photodetector Operating at Long Wavelength
Huang Hui, Ren Xiaomin, Lü Jihe, Huang Yongqing, Wang Qi, and Cai Shiwei
A monolithically integrated wavelength-selective photodetector operating at long wavelength was reported in this paper. The photodetector, which consists of an GaAs-based Fabry-Pérot filter and an InP-based p-i-n absorption structure, was grown on a Si substrate by heteroepitaxy technology. A crack-free and high-qA monolithically integrated wavelength-selective photodetector operating at long wavelength was reported in this paper. The photodetector, which consists of an GaAs-based Fabry-Pérot filter and an InP-based p-i-n absorption structure, was grown on a Si substrate by heteroepitaxy technology. A crack-free and high-quality GaAs epilayer was obtained by using mid-patterned growth. The photodetector with a spectral linewidth of 1.1 nm (FWHM) and a quantum efficiency of 9.0% was demonstrated, and its absorption layer thickness is 300 nm..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 356 (2009)
Morphological and Composition of Defects of Optical Coatings
Guo Peitao, Xue Yiyu, Zhao Lixin, Xia Zhilin, Huang Caihua, and Zhang Guangyong
Optical thin films greatly constrain the performance improvement of optical systerm. The defects of optical thin films are highlight point both in theory and experiment. Choose TiO2,SiO2 as original materials and the typical defects of multilayer films which made by electron beam evaporation as research object. The morOptical thin films greatly constrain the performance improvement of optical systerm. The defects of optical thin films are highlight point both in theory and experiment. Choose TiO2,SiO2 as original materials and the typical defects of multilayer films which made by electron beam evaporation as research object. The morphology and composition were measured by scanning electron microscope (SEM). The result shows that the nodule defect is semisphere and composition correspond with the original material; defect formed by original material sputtering is pit and the content of Ti is much higher than nodule defect; one of the defects adhered on surface is irregular colloid contain with C which means this defect is organism; the other defects adhered on surface is block with arris and correspond with the original material..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 360 (2009)
Effect of Annealing on the Optical Properties of Ta2O5 Films Prepared by Electron Beam Evaporation
Huang Caihua, Xue Yiyu, Peng Hua, Xia Zhilin, and Guo Peitao
The Ta2O5 optical thin films were deposited on glasses with the Ta2O5 as coating material by electron beam evaporation. The Ta2O5 optical thin films were annealed in air and argon atmosphere respectively. Measured the transmittance by spectrophotometer while the refractive index calculated by the minimum value of the tThe Ta2O5 optical thin films were deposited on glasses with the Ta2O5 as coating material by electron beam evaporation. The Ta2O5 optical thin films were annealed in air and argon atmosphere respectively. Measured the transmittance by spectrophotometer while the refractive index calculated by the minimum value of the transmittance. The structure of Ta2O5 optical thin films were measured by XRD. Optical properties of Ta2O5 optical thin films as a function of holding temperature, holding time and the atmosphere were studied. The results show that: the transmittances of Ta2O5 optical thin films are stable after 300～600 ℃/2 h annealing; the ultraviolet transmittance peak of Ta2O5 optical thin films are decreased, the visible transmittance peak and the refractive index increased after 400 ℃/(2 h,4 h) annealing in the atmosphere of argon; all the Ta2O5 films annealing at the temperature 300～600 ℃ are amorphous..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 364 (2009)
Anti-Resonant Reflecting Optical Waveguide Model for MetallicPhotonic Crystal Fibers
Liu Wei, Hou Jing, Lu Qisheng, and Liu Yonggui
To predict effectively the coupling positions of surface plasmon polaritons modes and guided modes within metallic photonic crystal fibers (MPCF), in this paper anti-resonant reflecting optical waveguide model (ARROW) for metallic photonic crystal fibers has been put forward based on ARROW model for photonic crystal fiTo predict effectively the coupling positions of surface plasmon polaritons modes and guided modes within metallic photonic crystal fibers (MPCF), in this paper anti-resonant reflecting optical waveguide model (ARROW) for metallic photonic crystal fibers has been put forward based on ARROW model for photonic crystal fibers and spiraling model for surface plasmon polaritons modes. Afterwards, we obtain the matching points of silver and gold metallic photonic crystal fibers using the model presented and the results we get is approximately equal to some experimental results that have been published..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 369 (2009)
Measurement and Metrology
Study about Data Processing of the Measurement of Laser Scattering Wetness Sensor
He Guizhen, Liu Haibo, Mei Chengqiang, and Zhou Huimin
Using the laser scattering wetness sensor, the data processing method of turbine last stage wetness measuring in the thermal power station has been researched. Firstly, we calculate the results of the vapor phase function using Mie scattering theory, and get the most probable radius of liquid water droplets at the end-Using the laser scattering wetness sensor, the data processing method of turbine last stage wetness measuring in the thermal power station has been researched. Firstly, we calculate the results of the vapor phase function using Mie scattering theory, and get the most probable radius of liquid water droplets at the end-turbine by the method of the look-up table and inversion fitting; Then according to the generalized Gamma distribution of the steam condensation water under the particle size, using the most probable radius of liquid water droplets we get before and using some related spectrum parameters to calculate the of liquid water content at the end-turbine; then using the pressure and temperature in the steam turbine and according to the ideal gas equation to calculate the dry steam content, the temperature and pressure is measured by temperature sensor and pressure sensor in the turbine; At the end, use the liquid water content, dry steam content and the definition of dryness fraction to calculate the dryness fraction at end-turbine..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 265 (2009)
A Method for Decreasing the Impact of Depth-of-Focus to Accurate Location of Particle
Li Zhibin, Zheng Gang, Zhang Lixin, and Xia Fei
The particle fields is generally measured by digital in-line holographic technique. But the resolution of particle axial position is lower due to the impact of zero-order image, twin-image noise and the depth of focus(DOF). Generally, DOF is tens of times as many as particle diameter. The large DOF has been a vexing prThe particle fields is generally measured by digital in-line holographic technique. But the resolution of particle axial position is lower due to the impact of zero-order image, twin-image noise and the depth of focus(DOF). Generally, DOF is tens of times as many as particle diameter. The large DOF has been a vexing problem in extraction of particle position from digital in-line holograms. DOF is affected by some recording parameters, i.e. NA of recording system, size of CCD, recording distance and the wavelength. Resolution of particle axial position can be improved by reducing depth of focus and recording distance. In this paper, an auto-focusing algorithm based on the most gradient for accurate location of particle by selecting proper window in accordance with particle size is proposed. At present, there are a lot of auto-focusing algorithms based on gradient, which calculate the gradient value only in appointed fixed directions, but the real gradient direction may not be the appointed direction. In order to solve the problem, an auto-focusing algorithm based on the most gradient and threshold is proposed. The gradients in all possible directions are calculated, then compare all of the possible gradients, and choose the largest gradient as the result. At the same time, in order to improve the precision and stability of auto-focusing algorithm, another threshold parameter is introduced. Through simulations and experiments, the algorithm has the characteristics such as strong single peak feature and good stability, which could decrease the impact of DOF to resolution of particle axial position..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 270 (2009)
Terahertz Focal-Plane Multiwavelength Phase Imaging
Zhang Liangliang, Zhang Yan, Zhong Hua, and Zhang Cunlin
A terahertz focal-plane phase imaging method with multiwavelength is presented. This novel approach can image object with larger optical length compared to using the largest wavelength in the terahertz spectrum and does not involve the usual phase unwrapping in the detection of phase discontinuity. Furthermore, this teA terahertz focal-plane phase imaging method with multiwavelength is presented. This novel approach can image object with larger optical length compared to using the largest wavelength in the terahertz spectrum and does not involve the usual phase unwrapping in the detection of phase discontinuity. Furthermore, this technique can effectively reduce the noise background and improve the accuracy of the reconstructive images. The validity of this new method can be demonstrated by processing the reflective two dimensional (2D) image data of a metal washer and Nikon camera’s lens cap. The measurements show that the multiwavelength phase imaging is a straightforward and efficient phase data processing method in terahertz imaging application..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 276 (2009)
Research on Laser Temporal Profile Measurement By Beam Sampling Grating
Peng Zhitao, Song Zhihong, Liu Hua, Xu Longbo, Fu Xuejun, Hu Dongxia, Wang Chao, Tang Jun, Xia Yanwen, and Yuan Haoyu
Beam sampling by a fused-silica grating, which sampling the full-aperture beam, is focused on a diagnostics sensor to measure the laser pulse shape of technical integration lines of Shenguang-Ⅲ. The optical path of sampling beam at focus spots is not equal, so the pulse shape is different from the original pulse. ReseaBeam sampling by a fused-silica grating, which sampling the full-aperture beam, is focused on a diagnostics sensor to measure the laser pulse shape of technical integration lines of Shenguang-Ⅲ. The optical path of sampling beam at focus spots is not equal, so the pulse shape is different from the original pulse. Research on laser temporal profile measurement by means of grating are reported. The model to reconstruct the pulse shape is developed to study the superposition of sampling pulse, and spatial uniformity and optical path are considered. Simulation indicated that sampling has only a small impact on the pulse shape of beam, which aperture is 290 mm×290 mm, pulse duration is more than 1 ns, focus length of sampling beam is 1380 mm, and the angle is 11.5°. The calibration results show that the diagnostic technology of sample with grating is feasible for laser measurement. The technology is a great success in the laser temporal diagnostic of technical integration lines of Shenguang-Ⅲ..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 280 (2009)
Identification of Terahertz Absorption Spectra of Medicines Using Support Vector Machines
Zhao Shusen, Liang Meiyan, and Shen Jingling
On the base of absorption spectra obtained in the range from 0.2 to 2 THz of six different medicines using terahertz time-domain spectroscopy (THz-TDS) technique, the THz absorption spectra of medicines were identified successfully by support vector machines (SVM). Firstly, absorption spectra of the six different medicOn the base of absorption spectra obtained in the range from 0.2 to 2 THz of six different medicines using terahertz time-domain spectroscopy (THz-TDS) technique, the THz absorption spectra of medicines were identified successfully by support vector machines (SVM). Firstly, absorption spectra of the six different medicines, which were pretreated by normalized unit, were used to train libsvm program. Secondly, absorption spectra of the medicines which were measured on different date, pretreated by normalized unit too, were identified by the libsvm and the identification rate of 100% was achieved. The results indicated that it is feasible to apply SVM on identification of medicines and providing an effective method in the secure inspection and identification for medicines..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 283 (2009)
Analysis of Twin-CGH by Extended Absolute Measurement of Sphere
Wang Qing, Ma Jun, and Dong Linlin
An analysis of a multiplex computer-generated hologram (Twin-CGH) is presented, with the extended absolute measurement of spherical surfaces. By means of the five-position test, the pattern error and figure error of Twin-CGH operated in spherical modes with two different optical power are separated respectively, and inAn analysis of a multiplex computer-generated hologram (Twin-CGH) is presented, with the extended absolute measurement of spherical surfaces. By means of the five-position test, the pattern error and figure error of Twin-CGH operated in spherical modes with two different optical power are separated respectively, and internal relations between two different holograms are proved. This relations is based on the relations of the spatial frequencies corresponding to two different phase functions. In this article, two kinds of errors in different modes are derived from each other. The derivative results are compared with experimental ones, and the residual error are less than λ/40 (PV, λ=632.8 nm). The results demonstrate the feasibility of error transfer in Twin-CGH. It shows that the aspherical reflective surface with known errors can be obtained using a Twin-CGH which reconstructs a spherical wavefront as well as an aspherical wavefront. The aspherical reflective surface can calibrate null grating..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 286 (2009)
A Method of Fast Edge Direction Detection Based on Low-Frequency Coefficients
Zhang Rongfu, Ma Lingguan, and Zhang Jun
Edge detection can be used both in spatial and frequency infomation. However, the calculation complexity detection in spatial domain is much greater than that in frequency domain. To compressed image, it is more obvious because the processing should include two parts: frequency to spatial and spatial to frequency. So iEdge detection can be used both in spatial and frequency infomation. However, the calculation complexity detection in spatial domain is much greater than that in frequency domain. To compressed image, it is more obvious because the processing should include two parts: frequency to spatial and spatial to frequency. So it cannot satisfy the dealing-in-time for video. Discrete cosine transform (DCT) is widely used in image processing and compression for its characteristics of low calculation complexity, orthogonality and fixed primary function. Based on the relation between DCT coefficients and spatial information, a fast edge detection method is proposed. In the method, main edge direction is detected by using only two low frequency coefficients F(1,0) and F(0,1)..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 290 (2009)
Research of Optimizing Linearity of Laser Energy Detecting
Tang Ling, Li Xiaoqun, Wang Chao, Chen Ji, Chen Dehuai, Sun Zhihong, and Dang Zhao
In large-scale high-power laser system, real time detecting is of great importance to laser energy transmission. There are a large number of beams and they are distributed in a large area, furthermore, intensive electromagnetic disturbing affects the linearity of the laser energy detecting severely. A method of measuriIn large-scale high-power laser system, real time detecting is of great importance to laser energy transmission. There are a large number of beams and they are distributed in a large area, furthermore, intensive electromagnetic disturbing affects the linearity of the laser energy detecting severely. A method of measuring laser energy is introduced in this paper, which uses thermopile to change the laser energy, and analogue digital module to process the signal. Subtracting the background and compensating the potential to overcome the effects of the temperature drift is focused on. Optimizing linearity result is achieved in this paper. The linearity of laser energy measurement has been optimized to more than 2% in our method..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 293 (2009)
Laser Diagnostic System Applied in Ultra-Short Pulse Facility
Li Xiaoyan, Fan Hongjia, Ouyang Xiaoping, Tang Shunxing, Xu Guang, Wang Tao, Zhu Baoqiang, and Zhu Jianqiang
It needs a down-collimator to convert big beams of a large laser facility into smaller beams in diameter to fit measurement instruments in diagnostic system. Because ultra-short pulses have wide spectrum, dispersion will be important to measurement. This paper provides some advice about diagnostic system designed by anIt needs a down-collimator to convert big beams of a large laser facility into smaller beams in diameter to fit measurement instruments in diagnostic system. Because ultra-short pulses have wide spectrum, dispersion will be important to measurement. This paper provides some advice about diagnostic system designed by analyzing the down-collimator’s characteristic and group velocity dispersion of the sampling mirror. The result shows that the edged sampling mirror and the edged vacuum window can be treated as a pair of prisms, which generates negative group velocity dispersion. And the group velocity dispersion increases with the edged angle and the optical path. When input pulse width is above 50 fs, the output one will not change. So we can obtain the work range of this diagnostic system..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 298 (2009)
Method to Control FM-to-AM Conversion Using Spectrum Shaping Guided by Waveform Measuring
Geng Yuanchao, Su Jinqin, Zhang Rui, Mo Lei, Wang Fang, Liu Lanqing, and Wang Wenyi
In the transmission process, broadband optical pulses generated through sinusoidal phase modulation, as a result of changes in spectral composition, will lead to FM-to-AM, resulting in pulse intensity modulation in the time domain. It is difficult to measure the microstructure of spectrum accurately due to the narrow sIn the transmission process, broadband optical pulses generated through sinusoidal phase modulation, as a result of changes in spectral composition, will lead to FM-to-AM, resulting in pulse intensity modulation in the time domain. It is difficult to measure the microstructure of spectrum accurately due to the narrow spectrum bandwidth (about 0.3nm). In order to control this effect, the paper presents a compensation method of spectral shaping guided by waveform measurement. By measuring the waveform before and after transmission, the shaping pulse spectrum will be calculated using G-S iterative method. Liquid crystal spatial modulator is used for spectrum shaping in order to compensate FM-to-AM effect. By numerical simulation, the details of the methods are improved and requirements for measuring instruments are proposed. The results show that, under certain transmission conditions, this method can effectively control the FM-to-AM effect, to resolve the issue of time-domain intensity modulation..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 302 (2009)
Research on the Measurement of M2 Factor Based on Crossed Defocus Gratings
Ma Haotong, Xi Fengjie, Zhou Pu, Wang Xiaolin, Xu Xiaojun, and Liu Zejin
M2 factor measuring system which based on crossed defocus gratings is theatrical analyzed. This instrument can get nine intensity distributions of different positions near the beam waist. The M2 factor is determined by calculating the beam waist using the second moment method and curve-fitting. According to the theory M2 factor measuring system which based on crossed defocus gratings is theatrical analyzed. This instrument can get nine intensity distributions of different positions near the beam waist. The M2 factor is determined by calculating the beam waist using the second moment method and curve-fitting. According to the theory of Gaussian beam propagation and transformation; using the zeroth-order and multi-modes Gaussian beam, measured errors as functions of beam waist, positions and modes distribution are analyzed. If zeroth-order Gaussian beam waist radius or the zeroth-order Gaussian beam waist radius corresponding to multi-modes beam was properly controlled, the measuring system can work well in a large range. The guidance for the M2 factor measuring system is provided by this analysis..
Chinese Journal of Lasers
- Publication Date: Aug. 12, 2021
- Vol. 36, Issue s1, 309 (2009)
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