Journals >Chinese Journal of Lasers
Contents
2010
Volume: 37 Issue 11
47 Article(s)
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Research Article
2 μm Pulsed Laser with 100 mJ Intracavity KTP Optical Parametric Oscillator
Wei Xingbin, Peng Yuefeng, Wang Weimin, Chen Xingwu, Liu Dong, and Li Deming
A high energy optical parametric oscillated (OPO) 2 μm pulsed solid-state laser is demonstrated. The 2 μm laser is generated through a doubly resonant intracavity KTP OPO pumped by an electro-optic (EO) Q-switched Nd:YAG laser. The OPO resonator is composed of a 2 μm high reflection mirror, two walk-off compensated KTPA high energy optical parametric oscillated (OPO) 2 μm pulsed solid-state laser is demonstrated. The 2 μm laser is generated through a doubly resonant intracavity KTP OPO pumped by an electro-optic (EO) Q-switched Nd:YAG laser. The OPO resonator is composed of a 2 μm high reflection mirror, two walk-off compensated KTP crystals and a 2 μm output mirror. OPO is realized by the typeⅡ phase matching(o→o+e). Both KTP crystals are cut as θ=53°, φ=0°, and have a volume of 8 mm×8 mm×15 mm. When the energy of the diode laser is 1.02 J and the repetition rate of the EO Q-switch is 30 Hz, the highest single pulsed energy of the 2.1 μm laser is 107 mJ, and the conversion efficiency from 808 nm to 2.1 μm is 10.5%. The beam quality M2 factor is M2x=2.38, M2y=1.56, respectively..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2762 (2010)
Laser Diode Stack End-Pumped Nd:YVO4 Slab Laser with Hybrid Resonator at 1064 nm and 1342 nm
Zhang Hengli, Yan Ying, Liu Yang, Li Jing, and Xin Jianguo
Laser diode stack end-pumped Nd:YVO4 slab lasers with hybrid resonator operating at both 1064 nm and 1342 nm are demonstrated. The size of the atomic fraction of 0.3% doped Nd:YVO4 slab crystal is 12 mm×10 mm×1 mm, which is cut along a axis and the c axis is parallel with the 12 mm direction. By using a stablLaser diode stack end-pumped Nd:YVO4 slab lasers with hybrid resonator operating at both 1064 nm and 1342 nm are demonstrated. The size of the atomic fraction of 0.3% doped Nd:YVO4 slab crystal is 12 mm×10 mm×1 mm, which is cut along a axis and the c axis is parallel with the 12 mm direction. By using a stable-positive confocal unstable resonator, 123 W at 1064 nm and 35.4 W at 1342 nm laser output are realized with M2 factor of 1.3 and the optical conversion efficiency of 46.6%, and its stability is better than 1%. With a stable-negative confocal unstable cavity, 35.4 W 1342 nm laser is obtained under the pump power of 139.5 W, with M2 factor less than 1.3 and the optical conversion efficiency of 25.4%..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2766 (2010)
Packaging of 808 nm 1500 W Continous Wave Operation Perpendicularity Laser Diode Stack
Xu Huiwu, Ren Yongxue, An Zhenfeng, Niu Jiangli, Ren Hao, and Yan Lihua
To meet the requirements of high power laser diode-pumped solid-state lasers, packaging of 808 nm 1500 W continuous wave (CW) operation perpendicularity laser diode stack is reported. Theoretically, the influences of packaging-induced stress, thermal resistance, and beam collimation on high power laser diode stack fabrTo meet the requirements of high power laser diode-pumped solid-state lasers, packaging of 808 nm 1500 W continuous wave (CW) operation perpendicularity laser diode stack is reported. Theoretically, the influences of packaging-induced stress, thermal resistance, and beam collimation on high power laser diode stack fabrication are explained detailedly. The origination, exhibition and reduction approach of the residual stress are illuminated. Simulation of temperature distribution of the micro-channel heat sink is depicted. Necessity of the beam collimation and the relation between soldering process and focusing optics system are illustrated. The residual stress is reduced by investigating and using indium-gold composite solder and optimizing the parameters of the soldering process, and the alignment precision is improved by designing collimation tools that a average value of 2 μm for the smile and 6 mrad for the divergence angle could be realized..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2769 (2010)
A Hexagonal Zigzag Slab Laser
Liu Liang, Guo Shaofeng, Lu Qisheng, and Xu Xiaojun
A method to design hexagonal slabs with zigzag optical path was presented. Compared with COFFIN slabs, the amplitude of thermal-induced wave-front distortion is lower and easier to be compensated in hexagonal slabs. Moreover, the laser beam enters the slab at Brewster angle when it is parallel to the slab length directA method to design hexagonal slabs with zigzag optical path was presented. Compared with COFFIN slabs, the amplitude of thermal-induced wave-front distortion is lower and easier to be compensated in hexagonal slabs. Moreover, the laser beam enters the slab at Brewster angle when it is parallel to the slab length direction, and covers the entire slab and the entrance aperture, which means the fill factor is 1 inside the slab..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2774 (2010)
Impact of Radial and Tangential Thermal Lens Effect on Output Characteristics of High-Brightness Lasers
Ding Xin, Li Xue, Sheng Quan, Li Bin, Zhou Rui, Wen Wuqi, Wang Peng, Yao Jianquan, Song Feng, Yu Xuanyi, and Zhang Guangyin
Gentle zones were found in all output power curves of laser-diode (LD) side-pumped solid-state lasers. Through the calculation of the radial and tangential thermal lens effect, the gentle zones were found at the boundary of the radial stability zones, going through the gentle zone, the output power increased continuousGentle zones were found in all output power curves of laser-diode (LD) side-pumped solid-state lasers. Through the calculation of the radial and tangential thermal lens effect, the gentle zones were found at the boundary of the radial stability zones, going through the gentle zone, the output power increased continuously and reached its highest value at the boundary of the tangential stability zone with the lowest M2 value. The gentle zones were thought to be due to the combined effects of the radial and tangential stability zones and high-brightness lasers can be obtained at the stable power point. Based on this, a simple high-brightness laser with a cavity length of 200 mm was designed to operate at the boundary of the tangential stability zone, and laser at 1064 nm with output power of 50 W and theoretical beam factor M2=2 was achieved when the pump power was 220 W..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2780 (2010)
Design and Experimental Study of Two-Cavity Dual-Frequency All-Solid-State Laser with Large Frequency Difference
Jiao Mingxing, Xing Junhong, Liu Yun, Yang Yun, and Ma Shaohua
In order to obtain the output of dual-frequency laser with large frequency difference, a new birefringent filter consisting of a polarizing beam splitter and a half wave-plate has been designed as a laser longitudinal mode selector. When the birefringent filter is included in a laser-diode(LD)-pumped Nd:YAG laser cavitIn order to obtain the output of dual-frequency laser with large frequency difference, a new birefringent filter consisting of a polarizing beam splitter and a half wave-plate has been designed as a laser longitudinal mode selector. When the birefringent filter is included in a laser-diode(LD)-pumped Nd:YAG laser cavity, the laser is enforced to oscillate in single longitudinal mode. When the angle between the fast axis of the half wave-plate and the polarizing plane of the polarizing beam splitter is changed by rotating the half wave-plate around the laser cavity axis, the output power of the single axial mode laser varies periodically with a period of approximately π/2. A LD-pumped two-cavity dual-frequency Nd:YAG laser with large frequency difference has been designed and experimentally investigated, which has both straight and right angle standing-wave cavities sharing the same gain medium and the longitudinal mode selector. The p-and s-component of 1064 nm laser light oscillate simultaneously in single longitudinal mode in the straight and right angle cavities, respectively. The resonant frequency of the single longitudinal mode oscillated in each resonant cavity can be tuned by changing each cavity-length so that the frequency difference of the dual-frequency laser is tuned. It has been observed experimentally that the frequency difference of the orthogonally and linearly polarized dual-frequency laser at 1064 nm is tunable in a range from 27 to 113.4 GHz..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2784 (2010)
Fourth Harmonic Generation Ultraviolet Laser Output Characteristics from Laser Diode Side-Pumped Two Nd:YAG Rods in Resonator
Pan Sunqiang, Liu Chong, Zhao Zhigang, Dong Yantao, Ge Jianhong, Mao Qianmin, Xiang Zhen, and Chen Jun
An 1.85 W laser diode (LD)-side-pumped Nd:YAG extra-cavity fourth harmonic generation (FHG) all-solid-state 266 nm ultraviolet laser is reported. The high-beam-quality high-stability linear-polarized 1064 nm fundamental frequency laser is obtained from thermal-induced birefringence-compensated resonator with two Nd:YAGAn 1.85 W laser diode (LD)-side-pumped Nd:YAG extra-cavity fourth harmonic generation (FHG) all-solid-state 266 nm ultraviolet laser is reported. The high-beam-quality high-stability linear-polarized 1064 nm fundamental frequency laser is obtained from thermal-induced birefringence-compensated resonator with two Nd:YAG rods. The type-Ⅰnoncritical phase-matched LBO and type-Ⅰphase-matched BBO crystals are used as the extra-cavity frequency doubled and FHG crystal respectively. 1.85 W ultraviolet laser of 266 nm is obtained at the pulse repetition rate of 10 kHz with the conversion efficiency of 13.3% from green to ultraviolet light. The self-heating effect of BBO crystal on FHG phase-matched angle is studied, and the result that the self-heating effect can be reduced by adjusting the angle of BBO is proposed..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2790 (2010)
Thin-Disk Laser at 515 nm with Good Beam Quality
Wang Chunhua, Wang Weimin, Ma Yi, and Lei Jun
16-passes pump system for thin-disk laser was designed. The thin-disk was made inland with the diameter of 10 mm, thickness of 200 μm and doping atom fraction of 10%. A micro-channel cooler was used to cool the thin-disk effectively. Based on the system , a Z type cavity was designed in this experiment. An LBO crystal 16-passes pump system for thin-disk laser was designed. The thin-disk was made inland with the diameter of 10 mm, thickness of 200 μm and doping atom fraction of 10%. A micro-channel cooler was used to cool the thin-disk effectively. Based on the system , a Z type cavity was designed in this experiment. An LBO crystal was used as the nonlinear crystal for intracavity frequency doubling. Using an acousto-optic Q-switcher, with pulse repetition rate of 5 kHz , a green laser of TEM00 mode with an output power of 10.2 W at 515 nm was achieved, with M2x of 1.3 and M2y of 1.6 at the optical-to-optical conversion efficiency of 12.5%. The pulse duration was 150 ns..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2795 (2010)
Study on High-Power Laser Diodes as Pumping Source at High Operating Temperature
Chen Hongtai, Che Xianghui, Xu Huiwu, Zhang Shizu, Lin Lin, Ren Yongxue, and An Zhenfeng
Based on the theoretical analysis for the influence of operating temperature on the operating wavelength electro-optical conversion efficiency and lifetime of the device, the high-power 808 nm quasi-continuous wave (QCW) laser diode array was fabricated with the technology of wavelength compensating, Al-free active regBased on the theoretical analysis for the influence of operating temperature on the operating wavelength electro-optical conversion efficiency and lifetime of the device, the high-power 808 nm quasi-continuous wave (QCW) laser diode array was fabricated with the technology of wavelength compensating, Al-free active region epitaxial material with high characteristic temperature and integrative soldering. When the heat sink temperature was 70 ℃, a CW output power of 65 W of a single bar was achieved at a driving current of 80 A. A characteristic temperature of a single bar in the range of 20 ℃～70 ℃ was estimated to be about 145 K. Under quasi-continuous wave (2% duty factor) operation condition, the laser diode array stacked with 10 bars achieved an electro-optical conversion efficiency of 53%, and a lifetime in excess of 109 shots..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2799 (2010)
Laser Diode-Pumped Continuous-Wave Mode-Locked Yb,NaCaF2 Laser
Ge Wenqi, Chai Lu, Yan Jie, Hu Minglie, Wang Qingyue, Su Liangbi, Li Hongjun, Zheng Lihe, and Xu Jun
The demonstration of a laser diode (LD)-pumped continuous-wave (CW) mode-locked Yb,NaCaF2 laser is presented. By employing a semiconductor saturable absorber mirror (SESAM) for initiating the passively mode locking and a pair of SF10 prisms for the dispersive compensation, a pulse series with a duration of 406 fs and aThe demonstration of a laser diode (LD)-pumped continuous-wave (CW) mode-locked Yb,NaCaF2 laser is presented. By employing a semiconductor saturable absorber mirror (SESAM) for initiating the passively mode locking and a pair of SF10 prisms for the dispersive compensation, a pulse series with a duration of 406 fs and a repetition frequency of 94.8 MHz is obtained. With 1% output coupler, the maximum of average output power centered at 1043 nm is 80 mW under the absorbed pumping power of 9 W..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2803 (2010)
Investigation on Thermal Effect of High Power Slab Laser with 11 kW
Wang Chao, Tang Xiaojun, Xu Liujing, Liu Lei, Liang Xingbo, Liu Gang, Du Tao, Zhao Hong, and Chen Sanbin
Thermal effect of Nd:YAG slab gain medium is studied for solid slab high power amplifier. The investigation uses the finite element method to simulate the distribution of temperature and stress of Nd:YAG slab gain medium with edge pump by high power laser diode array, considering uneven pump distribution in gain mediumThermal effect of Nd:YAG slab gain medium is studied for solid slab high power amplifier. The investigation uses the finite element method to simulate the distribution of temperature and stress of Nd:YAG slab gain medium with edge pump by high power laser diode array, considering uneven pump distribution in gain medium. The result shows that the temperature and stress of the bonding part of doped and undoped YAG are the highest. It is the weakness of the slab gain medium and should be designed optimum for avoiding slab Nd:YAG damage . Refer to the result, the power amplifier is designed. The laser chain is built, and the seed laser of 2.5 W power is amplified by a four-pass pre-amplifier and four stage double-pass power amplifier. The laser chain achieves 11 kW laser average power. The temperature distribution of slab gain medium with high power pump is measured in the experiment. The experimental result agrees well with the simulation..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2807 (2010)
Single-Frequency Nd:YAG Ring Laser
Zhao Weifang, Hou Wei, Li Gang, Lin Xuechun, and Li Jinmin
A Nd:YAG crystal was end-pumped by a fiber-coupled laser diode(FCLD). The four-mirror bow-tie ring cavity with a Faraday rotator and a half wave plate was applied to eliminate the spatial hole-burning effect. A solid etalon was inserted into the cavity to obtain the narrow line width single frequency output. The maximuA Nd:YAG crystal was end-pumped by a fiber-coupled laser diode(FCLD). The four-mirror bow-tie ring cavity with a Faraday rotator and a half wave plate was applied to eliminate the spatial hole-burning effect. A solid etalon was inserted into the cavity to obtain the narrow line width single frequency output. The maximum output was 2 W and the slope efficiency was 37% with 7 W of the incident power. The line width of the single frequency was 50 MHz, and the M2 factor was about 1.2..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2810 (2010)
Least Square Phase Retrieval Algorithm Based on Defocusing Grating
Li Fei, and Rao Changhui
The wavefront sensor based on defocusing grating has a great potential in the field of wavefront sensing, which attributes to many advantages such as fully optical measurement, simple configuration, ease to use, insensitivity to vibration and so on. However, traditional algorithms are suitable for point target and scarThe wavefront sensor based on defocusing grating has a great potential in the field of wavefront sensing, which attributes to many advantages such as fully optical measurement, simple configuration, ease to use, insensitivity to vibration and so on. However, traditional algorithms are suitable for point target and scarcely for extended object. To widen the application of this technology, a least square phase retrieval algorithm is proposed, which is suitable not only for point target but also for extended target, and the object can be restored simultaneously. Numerical simulations of phase retrieval using the proposed method demonstrate that the root mean square error is 0.18% without the consideration of noise. Additionally, the main factors which affect the retrieval accuracy are analyzed and some comparisons with traditional algorithms are carried out. Results show that the least square phase retrieval algorithm can accurately retrieve the wave-front of a point target or an extended target..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2813 (2010)
Continuous-Wave Tunable Intra-Cavity Optical Parametric Oscillator and Orange-Red Source
Sheng Quan, Ding Xin, Chen Na, Li Xue, Yu Xuanyi, Wen Wuqi, Wang Peng, and Yao Jianquan
We report a continuous-wave tunable optical parametric oscillator (OPO) which is intra-cavity pumped by a laser diode (LD) end-pumped Nd:YVO4 laser and utilize a periodically-poled lithim niobate (PPLN) crystal as nonlinear medium. Cavities are carefully designed and intra-cavity pumping schemes are adopted to realize We report a continuous-wave tunable optical parametric oscillator (OPO) which is intra-cavity pumped by a laser diode (LD) end-pumped Nd:YVO4 laser and utilize a periodically-poled lithim niobate (PPLN) crystal as nonlinear medium. Cavities are carefully designed and intra-cavity pumping schemes are adopted to realize continuous-wave operation. 1406～1513 nm signal output and 3.66～4.1 μm mid-infrared idler output are obtained with the maximum power of 820 mW at 1500 nm and 195 mW at 3.86 μm, corresponding conversion efficiencies versus 10.9 W LD power are 7.5% and 1.8%. 606～624 nm continuous-wave tunable orange-red output is also obtained by intra-cavity sum-frequency generating of 1064 nm pump wave and 1.4～1.5 μm signal wave of the OPO in a BBO crystal. The maximum output power is 120 mW at 624 nm, with conversion efficiency of 1.1%..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2821 (2010)
2.5 W Picosecond Pulse Regenerative Amplifier with 100 kHz Repetition Rate
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The use of RTP crystals as electro-optical crystals, laser diode (LD) end-pumped Nd:GdVO4 crystal pulse mode-locked picosecond regenerative amplifier is reported. Geometric parameters of the laser cavity are optimized to achieve the best mode matching between picosecond seed and regenerative amplifier by ABCD matrix. LThe use of RTP crystals as electro-optical crystals, laser diode (LD) end-pumped Nd:GdVO4 crystal pulse mode-locked picosecond regenerative amplifier is reported. Geometric parameters of the laser cavity are optimized to achieve the best mode matching between picosecond seed and regenerative amplifier by ABCD matrix. Laser pulses are provided at pump power 7.5 W with a pulse duration of 12 ps, a peak power of 2.08×106 W, a repetition rate of 100 kHz, optical-optical conversion efficiency of 33.3%, energy gain of 4.8×103 times. And TEM00 mode is achieved with the beam quality factor M2 less than 1.2 and the long-term stability root mean square (RMS) is less than 3%..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2825 (2010)
Stress Characteristic of Photonic Crystals Sensor Made by GaAs Pillars in Air with Graphite Lattice
Li Yan, Fu Haiwei, Zhen Yankun, and Li Xiaoli
The photonic energy bands of the two-dimensional photonic crystal made by GaAs pillars in air with graphite lattice is calculated by finite difference time domain (FDTD) method. The result shows that there is a complete photonic band gap in the normalized frequency zone between 0.53 to 0.58 within this kind of photonicThe photonic energy bands of the two-dimensional photonic crystal made by GaAs pillars in air with graphite lattice is calculated by finite difference time domain (FDTD) method. The result shows that there is a complete photonic band gap in the normalized frequency zone between 0.53 to 0.58 within this kind of photonic crystal. Based on it, a model of two-dimensional photonic crystals stress sensor made by GaAs pillars in air with graphite lattice is designed. The TEy mode formant wavelength of the sensor resonant cavity changing along with x and y directions stress and the stress environment are calculated by FDTD method. The result shows that there is a good linear characteristic between the formant wavelength and the stress, the sensor sensitivity responding to stress is 0.0111 nm/MPa, meanwhile, it is found that the sensor sensitivities along x and y directions are the same..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2829 (2010)
Optical Performance of Photonic Crystal Filter with Liquid Crystal Layer
Song Litao, He Jie, Wang Hualei, Han Yiang, and Li Tao
A tunable photonic crystal filter was proposed with parallel nematic liquid crystal as defect layer. Optical performance and the eigenmodes were analyzed by 4×4 matrix method. The results show that there are two kinds of transmission modes when the voltage is low. Different modes can be selected by rotating the fiA tunable photonic crystal filter was proposed with parallel nematic liquid crystal as defect layer. Optical performance and the eigenmodes were analyzed by 4×4 matrix method. The results show that there are two kinds of transmission modes when the voltage is low. Different modes can be selected by rotating the filter axially. Peaks of two modes merge into one and the polarization sensitive performance disappears as the applied voltage increases. Photonic bandgap is insensitive to voltage. Tunable range of the filter is 87 nm. The positions and number of transmission peaks depend on the thickness of defect layer sensitively..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2834 (2010)
Simulations of Chemical Atomic Iodine Generator Based on NCl3/I2
Li Liucheng, and Duo Liping
A chemical method of iodine atoms generation based on NCl3 is proposed. Iodine atoms are generated by the reaction of iodine donors with chlorine atoms produced from the combustion of NCl3. A chemical model for NCl3/I2 reaction system is developed. Simplified one-dimensional numerical simulations are carried out with aA chemical method of iodine atoms generation based on NCl3 is proposed. Iodine atoms are generated by the reaction of iodine donors with chlorine atoms produced from the combustion of NCl3. A chemical model for NCl3/I2 reaction system is developed. Simplified one-dimensional numerical simulations are carried out with a developed Matlab code. The results indicate that the number density and yield of iodine atoms are significantly influenced by the molar flow rate ratio of I2 to NCl3, and the optimum ratio decreases with the total pressure. The optimum yield of iodine atoms decreases with the total pressure, which indicates that this method favorites direct injection into the main gas flow to produce iodine atoms. The optimum ratio of I2 to NCl3 is 0.62 at the pressure of 666.61 Pa with iodine atom yield of 117% versus NCl3 and 189% versus I2. The modeling results show that the NCl3/I2 reaction system is an effective method to produce iodine atoms..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2838 (2010)
Fabrication and Characteristics of Bi3+-Ga3+-Al3+ Codoped High Concentration Er3+-Doped Silica-Based Fiber
Peng Jian, Liu Lisong, Fu Yongjun, Wei Huai, Zheng Kai, and Jian Shuisheng
High-concentration erbium-doped fiber plays a very important role in optical transmission and related devices based optical-fiber. On the grounds of characteristic of modified MCVD technique, the preforms were manufactured by "online" solution doping technique. The fabrication process of Er3+-Bi3+-Ga3+-Al3+ cHigh-concentration erbium-doped fiber plays a very important role in optical transmission and related devices based optical-fiber. On the grounds of characteristic of modified MCVD technique, the preforms were manufactured by "online" solution doping technique. The fabrication process of Er3+-Bi3+-Ga3+-Al3+ codoped fiber by using modified furnace round heating MCVD was discussed. Especially, the depositing temperature of porous core layer was very significant, the best value was 1560 ℃～1600 ℃. The action mechanism of bismuth was also discussed. The effect of increasing concentration of Er3+ by codoped Bi3+, Ga3+ and Al3+ was analyzed. The core areas performances were detected by scanning electron microscope (SEM) and the mole ratio of different ingredients of fabricated fibers were measured by electro-probe micro analyzer (EPMA). The highest absorption coefficient at 1530 nm was about 60 dB/m. The concentration of Er3+ in the fiber was about 3.84×1025 m-3..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2879 (2010)
Influence of Coupling Coefficients on Filtering Characteristics of Series Coupled Two-Microring Resonators
Liu Xin, Kong Mei, and Wen Quan
Compound of several optical waveguide microring resonators can extend the free spectral range and improve the filtering properties. For series coupled two-microring resonators, the perfect coupling condition is derived when the coupling coefficients between the two rings and the straight waveguides are not limited to bCompound of several optical waveguide microring resonators can extend the free spectral range and improve the filtering properties. For series coupled two-microring resonators, the perfect coupling condition is derived when the coupling coefficients between the two rings and the straight waveguides are not limited to be equal. When the light is input through the straight waveguide coupled with the smaller ring under perfect coupling condition, the changing of main resonance peak bandwidth, shape factor, and peak transmittance of the spurious modes with the coupling coefficients are calculated. The influence patterns of the coupling coefficients on these filtering characteristics are demonstrated. Calculation and analysis show that when the coupling coefficients between the two rings and the straight waveguides are different, balanced filtering characteristics can be realized, and more flexibility of design can be provided..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2885 (2010)
Demodulation Method of Distributed Fiber Bragg Grating Sensor Using Blazed Fiber Bragg Grating
Ying Chaofu, Peng Baojin, Ren Zhijun, Wan Xu, Zhu Yinyan, and Pang Hui
A new system on demodulation of distributed fiber Bragg grating (FBG) sensor is built using blazed fiber Bragg grating (BFBG). In order to eliminate the temperature effect on strain measurement, two adjacent FBGs (one for sensing, the other for reference) with similar central wavelength and different lengths as a probeA new system on demodulation of distributed fiber Bragg grating (FBG) sensor is built using blazed fiber Bragg grating (BFBG). In order to eliminate the temperature effect on strain measurement, two adjacent FBGs (one for sensing, the other for reference) with similar central wavelength and different lengths as a probe by parallel connection are utilized. Both ends of the BFBG are connected to a piezoelectric (PZT)．A saw-tooth function voltage with 10 Hz signal is supplied to the PZT. The spectrum signal from the probe can be demodulated by the main mode and the side mode of BFBG periodically offset in the same direction. The transmitted light intensity is converted to electric current by a photodiode which is processed by a computer to display the detected strain in real time. Experimental results show that it is feasible to demodulate action spectrum by BFBG with the resolution of micro-strain detection of 5 με. The cross of FBG for temperature and strain is solved. It is testified that the system is stable, reliable, and less-expensive..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2891 (2010)
Dual Wavelength Filtering Properties of Phase-Shifted Fiber Bragg Grating and Sampled Fiber Bragg Grating
Tian Li, and Zhang Ailing
Phase-shifted fiber Bragg grating and sampled fiber Bragg grating with dual wavelength filtering properties are designed and their properties with transmission matrix method are studied. As a result, both multi- π phase-shifted grating and π phase-shifted sampled grating have dual wavelength reflective profile. MoreovePhase-shifted fiber Bragg grating and sampled fiber Bragg grating with dual wavelength filtering properties are designed and their properties with transmission matrix method are studied. As a result, both multi- π phase-shifted grating and π phase-shifted sampled grating have dual wavelength reflective profile. Moreover, the side lobe of reflective profile of π phase-shifted sampled grating is lower than that of multi- π phase-shifted grating. By adjusting the duty cycle of π phase-shifted sampled grating in the range of 0.66～0.8, better dual wavelength filtering profile is obtained, especially the side lobe reflective index is lowest when the duty cycle is 0.75..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 37, Issue 11, 2896 (2010)
Beam Transmission
Effect of Reflection on High Power Small-Scale Self-Focusing
Li Xiaoyan, Zhang Yanli, Ouyang Xiaoping, Zhang Yan, Sun Pingping, and Zhu Jianqiang
Parasitic reflection is one of the most important fact impacts the laser′s near-field quality. Based on Bespalov-Talanov theory, the small-scale self-focusing caused by parasitic reflection and the parameter′s contribution to the growth of ripple in wedged optical device of high power system are discussed. By analyzingParasitic reflection is one of the most important fact impacts the laser′s near-field quality. Based on Bespalov-Talanov theory, the small-scale self-focusing caused by parasitic reflection and the parameter′s contribution to the growth of ripple in wedged optical device of high power system are discussed. By analyzing the interference field caused by the main beam and the reflected beam, the expression of small-scale modulated gain spectrum in no-linear media is found. The laws that the maxium gain of small-scale modulation grows with the window′s wedged angle of Nd-glass slab amplifier when the media gain or propagation distance changed are concluded. The influence of the length and wedge angle of amplifier window on the gain of perturbation is analyzed, additionally variation relation between the gain of perturbation and the width of the pulse with fixed window is derived..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2844 (2010)
M2 Factor of Partially Coherent Cosh-Gaussian Beams in Turbulent Atmosphere
Ai Yangli, Dan Youquan, and Ming Delie
Based on the extended Huygens-Fresnel principle and the method of second moments of the Wigner distribution function, the analytical formulas for the root-mean-square (RMS) spatial width, the RMS angular width, and the M2-factor of the partially coherent cosh-Gaussian (ChG) beam in turbulent atmosphere have been deriveBased on the extended Huygens-Fresnel principle and the method of second moments of the Wigner distribution function, the analytical formulas for the root-mean-square (RMS) spatial width, the RMS angular width, and the M2-factor of the partially coherent cosh-Gaussian (ChG) beam in turbulent atmosphere have been derived, which can be applied to cases of different spatial power spectra of the refractive index fluctuations of the turbulent atmosphere. It can be shown that the RMS angular width, M2 factor and relative M2 factor of a partially coherent ChG beam in turbulence increase with the propagation distance and depend on the waist width, wavelength, coherent parameter, decentered parameter, and spatial power spectrum of the refractive index fluctuations. The RMS angular width as a function of the decentered parameter has a minimum at any given propagation distance. For long propagation distance, the M2-factor as a function of the decentered parameter also has a minimum, and the beams with a larger decentered parameter are less affected by the turbulence..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2849 (2010)
Reflecting Intensity Distribution on the Angle-Tuned Filter in Oblique Incidence
Yu Kan, Huang Dexiu, Zhou Kun, Yin Juanjuan, Bao Jiaqi, and Chang Jin
Based on the multi-beam interference principle and Gaussian beam transmission equation in the free space, the intensity expression of a Gaussian beam incidenting obliquely on an angle-tuned narrowband filter has been derived. According to the result, the influence and relationship of the incident angle on the reflectioBased on the multi-beam interference principle and Gaussian beam transmission equation in the free space, the intensity expression of a Gaussian beam incidenting obliquely on an angle-tuned narrowband filter has been derived. According to the result, the influence and relationship of the incident angle on the reflection of a Gaussian beam have been investigated theoretically. The calculation and experiment results show that the size of the transmitting beam spot will be brodened obviously when the incident angle is increasing. However, the size of reflecting beam spot will be a little brodened for a relatively large incident angle, which extent is much less than that of the transmitting beam. The reflecting port of the angle-tuned narrowband filter does not need facular-shaping fitting as the transmitting port within its tuanble range..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2855 (2010)
Biomedical Photonics and Laser Medicine
Research on Synthetic Aperture Technique for Endoscopic Ultrasound Imaging
Yu Daoyin, Li Ming, Li Yan, Wang Yi, and Chen Xiaodong
Synthetic aperture focusing, widely used in radar system, is introduced into endoscopic ultrasound imaging system in this paper. Based on the features of synthetic aperture focusing (SAF), a method of synthetic aperture imaging for ultrasonic endoscope is presented, using the rotation effect of a probe with single tranSynthetic aperture focusing, widely used in radar system, is introduced into endoscopic ultrasound imaging system in this paper. Based on the features of synthetic aperture focusing (SAF), a method of synthetic aperture imaging for ultrasonic endoscope is presented, using the rotation effect of a probe with single transducer, transmitting and receiving the echoes at different time and different locations during the rotation, synthesizing a large transmitting aperture equivalently to enhance the signal to noise ratio and the resolution of the ultrasonic images. The principle of synthetic aperture technique was analyzed, which is used for endoscopic ultrasound imaging with single transducer probe, and then the longitudinal and lateral compression were implemented according to the coded and linear frequency modulated characteristics of the echoes. Finally, an experiment was completed, using a transducer, with the center frequency of 8 MHz, to detect a pigskin sample, the target with the size of 0.8 mm×2 mm could be identified, and the signal to noise ratio had an improvement of 9.38 dB..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2693 (2010)
Laser Immunotherapy: Novel Modality to Treat Cancer through Specific Antitumor Immune Response
Xiaosong Li, and Wei R.
Treatment of metastatic cancer remains a great challenge and needs novel approaches. Combining a selective photothermal therapy with an active immunological stimulation, laser immunotherapy (LIT) was developed to induce systemic immune responses through local intervention. LIT consists of three major components: a nearTreatment of metastatic cancer remains a great challenge and needs novel approaches. Combining a selective photothermal therapy with an active immunological stimulation, laser immunotherapy (LIT) was developed to induce systemic immune responses through local intervention. LIT consists of three major components: a near-infrared laser, a light-absorbing agent, and an immunological stimulant. Its effect relies on two major interactions: a selective photothermal interaction and an active immunological stimulation. The selective photothermal interaction can reduce the tumor burden and at the same time release the tumor antigens, which can induce specific antitumor immune response. The expression of heat shock protein and the application of immunoadjuvant further enhance the host immunity. It has been proved in pre-clinical studies that LIT could not only eradicate treated local tumors but also regress and eliminate untreated metastases at distant sites. Moreover, LIT is well tolerated and has shown to have many advantages for cancer treatment compared with other traditional modalities..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2698 (2010)
Hydration of fingernail investigated by optical coherence tomography
Hao Zhang, Yaoyong Meng, Wenjuan Ou, Xiaoyan Zhang, and Songhao Liu
Optical coherence tomography (OCT) is used to investigate the microstructure changes of human fingernail induced by hydration. Images of nail plate are obtained to display the morphology of fingernail and to disclose the keratinization of basal cells of nail plate. Combined with digital vernier caliper, this imaging teOptical coherence tomography (OCT) is used to investigate the microstructure changes of human fingernail induced by hydration. Images of nail plate are obtained to display the morphology of fingernail and to disclose the keratinization of basal cells of nail plate. Combined with digital vernier caliper, this imaging technology is used to evaluate thicknesses and changes of nail in vitro after immersion with time. OCT images of nails show that the dorsal and ventral layers of nails have similar thicknesses which are much thinner than intermediate layer. The total thickness of fingernail exponentially increases with immersion time, and the saturating phenomenon appears at about 12 min. Three layers show different contributions to the total increase of the thickness of 17.4%. Microstructure changes in vivo are similar to the results in vitro. The changes of optical path length also could be evaluated by this method. OCT is capable of reflecting precise microstructure changes, and it has the potential to provide physician with a modern and objective diagnostic standard for nail inspection (NI) and to monitor disorders in Chinese traditional medicine (CTM) clinical practice and research..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2703 (2010)
Detecting Early Artificial Caries by Using Optical Coherence Tomography
Meng Zhuo, X. Steve, Yao Hui, Liu Tiegen, Li Yanni, and Wang Guanhua
Early dental caries is caused by demineralization of the teeth, which results in the increasing backscattered coefficient of the lesion area. In the paper, a method is proposed for detecting early caries by using optical coherence tomography (OCT). The two dimensional tomography images of the human teeth in vitro are oEarly dental caries is caused by demineralization of the teeth, which results in the increasing backscattered coefficient of the lesion area. In the paper, a method is proposed for detecting early caries by using optical coherence tomography (OCT). The two dimensional tomography images of the human teeth in vitro are obtained by using the development all fiber OCT system. Artificial caries model is made by chemical etching on the human teeth in vitro for 12, 24, 48, 72, 96 and 120 h, respectively. Using the OCT system, the level of demineralization is obtained quantitatively and the measurement data are obtained with different artificial time. The result shows that the depth of the artificial caries has the linear relationship with time. It is proved that OCT has the feasibility by detecting the level of demineralization for early caries diagnosis..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2709 (2010)
Comparison of Algorithms for Localization of Single Fluorescent Molecule in Super Resolution Imaging
Quan Tingwei, Zeng Shaoqun, and Lü Xiaohua
Super resolution imaging technique has become a key tool in imaging the structure and function of living cells. Localization of single fluorescent molecule is an integral part of super resolution imaging. From the point of view of super resolution imaging, a rigorous comparison of the performance of the different algorSuper resolution imaging technique has become a key tool in imaging the structure and function of living cells. Localization of single fluorescent molecule is an integral part of super resolution imaging. From the point of view of super resolution imaging, a rigorous comparison of the performance of the different algorithms under experimental conditions is necessary. In this paper, five commonly used localization algorithms: centroid method, generalized centroid method, Gaussian fitting, fluoroBancroft method, and maximum likelihood method are investigated, and how well these algorithms work is clarified. The results show: firstly, Gaussian fitting, generalized centroid method and maximum likelihood method are high localization precision method and have been slightly influenced by extracting sub-window. Secondly, centroid method and fluoroBancroft method could be applied in on-time imaging, however, they have low localization precision and are influenced by extracting sub-window. Thirdly, for the five algorithms, the localization precision is abruptly decreased when there are two molecules in a diffraction spot..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2714 (2010)
Upconversion Fluorescence Monitoring Near-Infrared During Tumor Photothermal Therapy
Wei Yanchun, Wu Baoyan, Yang Liyong, and Xing Da
The photothermal therapy which mainly uses near-infrared laser to heat tissue has become a new validated method for tumor treatment through direct surface irradiating or inserting light fibers in tumor. The near-infrared light transfer in tissue is limit and the thermal effect occurs only in a small volume during treatThe photothermal therapy which mainly uses near-infrared laser to heat tissue has become a new validated method for tumor treatment through direct surface irradiating or inserting light fibers in tumor. The near-infrared light transfer in tissue is limit and the thermal effect occurs only in a small volume during treatment. Thus the treating extent is difficult to control. Otherwise, it is difficult to distinguish the boundary of tumor and normal tissue in photothermal therapy. Improper heating will hurt the normal tissue. So it is important to guide the laser in time in thermal therapy. The results indicate that by using upconversion nanoparticles[Yb/Er (NaYF4Yb, Er)] to localize on tumor, the infrared light can be monitored in real time with the upconversion fluorescence. The light dosage, distribution, heating extent and the boundary of tumor can be detected to increase the effect of thermal therapy..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2719 (2010)
Approximate Wavenumber Domain Algorithm for Interferometric Synthetic Aperture Microscopy
Li Qiao, Chen Xiaodong, Lei Yong, Wang Yi, and Yu Daoyin
In the spectral optical coherence tomography(OCT) system, a high depth of field can be achieved at the expense of the poorer transverse resolution. Interferometric synthetic aperture microscopy (ISAM) is an optical computed-imaging technique, which can make transverse resolutions at the different depths identical by reIn the spectral optical coherence tomography(OCT) system, a high depth of field can be achieved at the expense of the poorer transverse resolution. Interferometric synthetic aperture microscopy (ISAM) is an optical computed-imaging technique, which can make transverse resolutions at the different depths identical by resampling the spectrum data. The procedure of ISAM and the principle of error were analyzed and a reconstruction model of multi-scatterers is established. The multiple scatterers simulation is implemented by use of ISAM compared with the standard OCT methods. The approximate wavenumber domain algorithm is applied in ISAM, which can save much rebuilding time without the Stolt interpolation and the spectral OCT experiment system was developed. The experimental results showed that it can greatly reduce computational complexity to enhance the performance of real-time, which costs 50 s to finish one 320 pixel×265 pixel image..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2725 (2010)
Invasion of CdSe/CdS/ZnS Quantum Dots for Oocytes in Vitro Maturation
Wang Xiaomei, Yong Ken-Tye, Xu Gaixia, Lin Xiaotan, Zhou Xiaoqing, Qu Junle, Chen Siping, and Niu Hanben
The Kunming mice immatured oocytes in vitro maturation culture system are established to investigate the reproductive toxicity of CdSe/CdS/ZnS quantum dots (QDs). QDs stock solution is added into oocyte culture medium at a final concentration of 28.90 nmol/L. Then, QDs and oocytes are co-cultured at 37 ℃, 5% CO2 for 4,The Kunming mice immatured oocytes in vitro maturation culture system are established to investigate the reproductive toxicity of CdSe/CdS/ZnS quantum dots (QDs). QDs stock solution is added into oocyte culture medium at a final concentration of 28.90 nmol/L. Then, QDs and oocytes are co-cultured at 37 ℃, 5% CO2 for 4, 8 and 20 h, respectively. The morphological information of oocytes are observed and analyzed under phase-contrast fluorescence microscope. The results demonstrate that QDs enter cumulus cells and accumulate with co-culture time. QDs can not penetrate oocytes zona pellucida, which is confirmed by laser scanning confocal microscope with high spatial resolution. After being treated for 20 h and being rejected by oocytes, QDs decrease the ratio of oocyte in vitro maturation dramatically..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2730 (2010)
Synthesis and Tumor Targeting Research of Two Near-Infrared Fluorescence Probes
Deng Dawei, Liu Fei, Cao Jie, Chen Xinyang, and Gu Yueqing
Two near infrared fluorescence probes (i.e., folate-PEG-ICG-Der-01 and LDL-ICG-Der-02) are synthesized. Here, over-expressed folate receptors and low density lipoprotein (LDL) receptors in some specific tumors are chosen as target. The residues of folic acid and LDL, as the targeted ligand, are covalently conjugated toTwo near infrared fluorescence probes (i.e., folate-PEG-ICG-Der-01 and LDL-ICG-Der-02) are synthesized. Here, over-expressed folate receptors and low density lipoprotein (LDL) receptors in some specific tumors are chosen as target. The residues of folic acid and LDL, as the targeted ligand, are covalently conjugated to organic near-infrared fluorescence dye ICG-Der-0 and ICG-Der-02 respectively, where near-infrared dyes are the output of fluorescence signal. The optical properties of the two probes are characterized by ultraviolet spectrophotometer and near-infrared fluorescence spectroscopy system. The imaging process of folate-PEG-ICG-Der-01 and LDL-ICG-Der-02 probes in tumors which over expressed folate receptors and LDL receptors is further detected by near-infrared fluorescence imaging system. The results show that as-prepared folate-PEG-ICG-Der-01 and LDL-ICG-Der-02 probes present higher fluorescence intensity and better photo stability than those corresponding near-infrared fluorescence dyes. And the results of in vivo near-infrared fluorescence imaging confirme that these two probes are highly bioactive, can efficiently target tumor sites, and finally be eliminated. Compared with LDL-ICG-Der-02, the targeting capability of folate-PEG-ICG-Der-01 probe is more effective, and has great potential in non-invasive real time early tumor diagnosis..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2735 (2010)
An Methodological and Experimental Investigation on Time-Domain Diffuse Fluorescence Tomography of Analytic Based on Two-Dimensional Circular Scheme
Li Jiao, Gao Feng, Yi Xi, Zhang Limin, and Zhao Huijuan
An image reconstruction method for time-domain fluorescence diffuse optical tomography is proposed using a two-dimensional (2D) turbid medium of circular domain. The methodology based on a linear generalized pulse spectrum technique, employs analytic expressions of the Laplace-transformed time-domain photon-diffusion mAn image reconstruction method for time-domain fluorescence diffuse optical tomography is proposed using a two-dimensional (2D) turbid medium of circular domain. The methodology based on a linear generalized pulse spectrum technique, employs analytic expressions of the Laplace-transformed time-domain photon-diffusion model to construct a Born normalized inverse model. The resultant linear inversions introducing a pair of real domain transform-factors are solved with an algebraic reconstruction technique to separate distributions of the fluorescent yield and lifetime. The effectiveness and feasibility of the proposed scheme have been validated by experiment using multi-channel time-correlated single-photon-counting system. The results show that the approach retrieves the position and shape of the targets with a reasonable accuracy..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2743 (2010)
Holography and Information Processing
Study on Accelerating Reconstruction Algorithm of Digital Holography Based on Graphic Processing Unit
Ding Heping, Zhu Zhuqing, Sun Min, Wang Xiaolei, and Zhou Yanhuai
A speed-up reconstruction algorithm of digital holography is studied based on graphic processing unit(GPU) hardware, which can effectively shorten the reconstruction time of digital hologram with powerful parallel computation capacity of GPU. The reconstruction time of two different size digital holograms are compared A speed-up reconstruction algorithm of digital holography is studied based on graphic processing unit(GPU) hardware, which can effectively shorten the reconstruction time of digital hologram with powerful parallel computation capacity of GPU. The reconstruction time of two different size digital holograms are compared under GPU acceleration calculation mode and single CPU calculation mode. The result shows that the reconstruction time is shorten to be about 1/15 for a hologram size of 2048 pixel× 2048 pixel with GPU mode. The speed-up reconstruction algorithm of digital holography is designed to be exercisable and universal software, which can satisfy the real-time demand of digital holography system such as display and microscopy and also can instruct rapid setup of digital holography experimental system..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2901 (2010)
Experimental Study on the Quantitative Phase-Contrast Imaging of the Biological Samples by Digital Holographic Microscopy
Zhao Jie, Wang Dayong, Li Yan, Wang Yunxin, and Zhang Yizhuo
A setup of the lensless Fourier transform digital holography is built to get the quantitative high-fidelity phase-contrast images of the biological samples. The basic advantage of such system is that the numerical reconstruction is directly applying only once fast Fourier transform to the intensity distribution of the A setup of the lensless Fourier transform digital holography is built to get the quantitative high-fidelity phase-contrast images of the biological samples. The basic advantage of such system is that the numerical reconstruction is directly applying only once fast Fourier transform to the intensity distribution of the hologram. However, the aberration appears in the phase image obtained by this kind of reconstruction algorithm and degrades the quality of the phase image seriously. Then, two-step subtraction method is applied to correct the phase aberration. In the experiments, at first two biological sample-plates for teaching are used as the objects, which are the mouse of the skeeter and the epidermal cells of the onion respectively. Then the living free-of-marker cervical carvinoma cells are presented as the object. Not only the clear morphologies of the static biological samples, but also the dynamic variations of the living cells are observed. The experimental results verify the validity of the digital holographic microscopy for the quantitative phase-contrast imaging of the biological samples..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2906 (2010)
Laser Manufacturing
Research on Laser Shock Strengthening and Stress Corrosion Cracking Resistance of AZ31B Magnesium Alloy
Ge Maozhong, Zhang Yongkang, and Xiang Jianyun
In order to study the effect of laser shock processing (LSP) on the properties of magnesium alloy, according to the laser technology parameters after optimization, Rolled AZ31B magnesium alloy sheets surface were processed with Ndglass laser. Test results showed that grain is refined obviously , grain size changes fromIn order to study the effect of laser shock processing (LSP) on the properties of magnesium alloy, according to the laser technology parameters after optimization, Rolled AZ31B magnesium alloy sheets surface were processed with Ndglass laser. Test results showed that grain is refined obviously , grain size changes from about 20 μm to 10 μm. Residual compressive stress induced by LSP reached up to -126 MPa. At room temperature, through three points loading method, samples performed by LSP, local regional LSP and without LSP were immersed in deionized water to carry out stress corrosion experiment. Macroscopical and microcosmical analysis was applied to its fracture surface.It shows that LSP completely prevents stress corrosion cracking (SCC) initiation for AZ31B in deionized water, and it indicats that LSP inhibits the propagation of the SCC crack..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2925 (2010)
Influence of Glass Forming Ability of Alloy on Crystallization in Heat-Affected Zone by Laser Remelting Zr Based Bulk Metallic Glasses
Liu Weiwei, Lin Xin, Yang Gaolin, Yang Haiou, Huang Weidong, and Li Jinfu
Crystallization in the heat-affected zone with nominal composition of Zr55All 0Ni5Cu30 and Zr65Al7.5Ni10Cu17.5, which has different glass forimg abilities, is investigated during pulsed Nd:YAG laser remelting processing. It is found that the crystallization in the heat-affected zone for Zr65Al7.5Ni10Cu17.5 alloy with lCrystallization in the heat-affected zone with nominal composition of Zr55All 0Ni5Cu30 and Zr65Al7.5Ni10Cu17.5, which has different glass forimg abilities, is investigated during pulsed Nd:YAG laser remelting processing. It is found that the crystallization in the heat-affected zone for Zr65Al7.5Ni10Cu17.5 alloy with low glass forming ability is more severe than that for Zr55All 0Ni5Cu30 alloy. There are only small number of micron-scale spherical grains sparsely formed in heat-affected zone, even Zr55All0Ni5Cu30 alloy is laser remelted repeatedly by four times. However, the heat-affected zone is almost fully covered with the spherical grains when Zr65Al7.5Ni10Cu17.5 alloy is laser remelted once. When Zr65Al7.5Ni10Cu17.5 alloy is laser remelted by four times, the size of spherical grains increase obviously, and there exhibits a radial dendritic growth in the spherical grain.Crystallization in the heat-affected zone for bulk metallic glasses during pulsed Nd:YAG laser remelting mainly depends on the glass forming ability of the alloy, and the high glass-forming ability is in favor of keeping the heat-affected zone under amorphous state..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2931 (2010)
3D Reconstruction of Parts to be Processed by Laser Remanufacturing Robot
Zhang Haiming, Yang Xichen, and Gao Gui
An intelligent laser processing robot with active vision composed of binocular stereo camera and structure light is developed in this paper. It can measure a variety of complex surface and reconstruct its 3D shape. The system consists of a robot with six degrees of freedom, binocular cameras and structure light. CameraAn intelligent laser processing robot with active vision composed of binocular stereo camera and structure light is developed in this paper. It can measure a variety of complex surface and reconstruct its 3D shape. The system consists of a robot with six degrees of freedom, binocular cameras and structure light. Cameras and structure light emitter are fixed on the robot and follow the robot movement, which accomplishes multi-angle measurement to eliminate “dead space”, as well as transforms point cloud data to the robot coordinate. In this paper, measurement principle and mathematical model are described. Inside and outside parameters of single-camera calibration, the relative relationship between binocular camera calibration, binocular camera and robot hand-eye relationship calibration are carried out to obtain the parameters of camera matrix, hand-eye matrix, robot-world matrix. The target is extract by big step segmentation, and the image is smoothed to reduce noise. Sub-pixel center of structure light is extracted by gravity algorithm, and the left and right image is registrated according to the epipolar constraint. Point coordinate calculated by 3D algorithm, can be easily converted to the world coordinate to achieve the unity of the global coordinates..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2937 (2010)
Measurement and Metrology
Natural Gas Pipeline Leak Detection System for Laser Remote Sensing and Calibration
Wang Lei, Tan Tu, Wang Guishi, and Gao Xiaoming
Based on principle of the bidirectional reflectance distribution function(BROF) and theory of harmonic detection about remote sensing system, we design and build a gas pipeline leak detection system of laser remote sensing. This platform detect distance is 120 m. The concentration of 0.308％ on the natural gas simulatioBased on principle of the bidirectional reflectance distribution function(BROF) and theory of harmonic detection about remote sensing system, we design and build a gas pipeline leak detection system of laser remote sensing. This platform detect distance is 120 m. The concentration of 0.308％ on the natural gas simulation of remote sensing can realized the air trace gas detection of methance. The minimum detection sensitivity of the system is about 29.75 ×10-6 m. At the same time we studied the efficiency ρtotof various reflection scattering effect on the experiment. The feasibility of the new calibration method for the concentration is proposed and experimentally verificated. The experimental results can using in the real detection..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2912 (2010)
A New Color Structured Light Coding Method for Three-Dimensional Measurement of Isolated Objects
Ma Ke, and Zhang Qican
A new coding method based on color Gray-code is proposed for measuring the three-dimensional (3D) shape of the isolated objects in space. This coded fringe appears to be a color coded sinusoidal fringe, which is used to record the information of object′s 3D shape. Firstly, a digital color coded sinusoidal fringe is proA new coding method based on color Gray-code is proposed for measuring the three-dimensional (3D) shape of the isolated objects in space. This coded fringe appears to be a color coded sinusoidal fringe, which is used to record the information of object′s 3D shape. Firstly, a digital color coded sinusoidal fringe is projected onto the tested object′s surface to modulate the height information of the measured object into its phase distribution, then the color Gray coding is used to obtain the fringe order and the sinusoidal fringe is used to get the wrapped phase. With only one image, 3D shape of the isolated objects can be exactly reconstructed. An actual measurement is done, the results of the reconstructed shapes prove its correctness and feasibility..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2918 (2010)
Optical Communication
Research of the Transmittance of Atmospheric Turbulent Channels
Yang Shiji, He Zhiping, Jia Jianjun, Wu Jincai, and Wang Jianyu
The atmospheric transmittance is valuable in designing and applying free space optical communication system. The precision of classical method can not meet actual needs. In this paper, by ameliorating classical method of measuring atmospheric transmittance, and combining the Gauss distribution of the energy of the laseThe atmospheric transmittance is valuable in designing and applying free space optical communication system. The precision of classical method can not meet actual needs. In this paper, by ameliorating classical method of measuring atmospheric transmittance, and combining the Gauss distribution of the energy of the laser beam and the turbulent influence existing in the atmospheric channel, the experiment scheme of accurately measuring atmospheric transmittance is designed. Actual atmospheric transmittance of several free space channels in Shanghai and Qinghai are measured. The results of classical method and the method which we mention above are different. The results show that, in Qinghai, the transmittance is high, but turbulence is bad; in Shanghai, the situation is opposite. The analytic and experimental results also indicate that the distant turbulent channels influence facular spread strongly..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2860 (2010)
Theoretical Investigation of Nearly Degenerate Four-Wave Mixing in Semiconductor Optical Amplifier
Li Peili, Shi Weihua, Huang Dexiu, and Zhang Xinliang
A comprehensive broad-band dynamic model of nearly degenerate four-wave mixing (FWM) in semiconductor optical amplifier (SOA), in case of the polarization states of two input lights being not parallel, is presented. By numerical simulation, take the all-optical wavelength conversion based on nearly degenerate FWM in anA comprehensive broad-band dynamic model of nearly degenerate four-wave mixing (FWM) in semiconductor optical amplifier (SOA), in case of the polarization states of two input lights being not parallel, is presented. By numerical simulation, take the all-optical wavelength conversion based on nearly degenerate FWM in an SOA for an example, the effects of two input light powers, frequency detuning and polarization angle of two input lights on the nearly degenerate FWM and the performances of wavelength conversion are theoretically investigated. The results indicate that there exist the optimal powers of two input lights. As the frequency detuning between the two input signals and the polarization angle of two input lights increase, the conversion efficiencies are decreased. The polarization state of C13 becomes larger as the polarization angle of two input lights increases..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2864 (2010)
A Novel Scheme for Optical Inverse Return-to-Zero-Differetial Quadrature Phase-Shift-Keying Modulation
Wen Aijun, Lü Liang, Yang Lei, Shang Lei, and Li Xiaojun
A novel scheme to generate inverse return-to-zero-differetial quadrature phase-shift-keying (IRZ-DQPSK) modulation format is introduced. The IRZ signal generated in this scheme does not contain any original phase information, so it is convenient to combine IRZ modulation with the phase modulation, and both the duty cycA novel scheme to generate inverse return-to-zero-differetial quadrature phase-shift-keying (IRZ-DQPSK) modulation format is introduced. The IRZ signal generated in this scheme does not contain any original phase information, so it is convenient to combine IRZ modulation with the phase modulation, and both the duty cycle and the extinction ratio of the IRZ-DQPSK signal are tunable. The influence of self phase modulation (SPM) is compared between IRZ-DQPSK and amplitude shift keying-differetial quadrature phase-shift-keying (ASK-DQPSK) in a 40Gb/s single channel long distance transmission by simulation. Results show that IRZ-DQPSK signal offers much better performance against SPM..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2872 (2010)
Reviews
Distributed Optical Fiber Raman Photon Sensor Research Review
Zhang Zaixuan, Jin Shangzhong, Wang Jianfeng, Liu Honglin, Sun Zhongzhou, Gong Huaping, Yu Xiangdong, and Zhang Wensheng
Temperature measurement methods and principles of the distributed optical fiber sensors (DOFS ) are studied and discussed. The research profile and current research trends are introduced in this paper. New generation of optical fiber sensing mechanism based on optical fiber nonlinear effect is explored. The fusion prinTemperature measurement methods and principles of the distributed optical fiber sensors (DOFS ) are studied and discussed. The research profile and current research trends are introduced in this paper. New generation of optical fiber sensing mechanism based on optical fiber nonlinear effect is explored. The fusion principle of optical fiber nonlinear scattering effect is put forward to research and design a new generation of series distributed optical fiber sensors based on Raman and Brillouin scattering. The reliability, spatial resolution and temperature measurement accuracy of the system are improved using optical fiber dispersion and loss spectra of auto-correction method. Using pulse code modulation source, the signal to noise ratio of DOFS is improved..
Chinese Journal of Lasers
- Publication Date: Mar. 30, 2020
- Vol. 37, Issue 11, 2749 (2010)
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