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2013
Volume: 40 Issue 10
42 Article(s)
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Holography and Information Processing
An Improved Algorithm for Multi-Plane Reconstruction with Gerchberg-Saxton Phase Retrieval Algorithm
Li Fang, Bi Yong, Kong Xinxin, Wang Hao, Sun Minyuan, and Li Tuo
Gerchberg-Saxton (GS) phase retrieval iteration algorithm is widely used in multi-plane reconstruction despite of the low correlation coefficient C values of most planes. Method of compensation, which we call strong compensation, was proposed by the researchers but it has little function. In this paper, an improved algGerchberg-Saxton (GS) phase retrieval iteration algorithm is widely used in multi-plane reconstruction despite of the low correlation coefficient C values of most planes. Method of compensation, which we call strong compensation, was proposed by the researchers but it has little function. In this paper, an improved algorithm based on the concept of weak compensation is proposed. Introduction of weight factors to adjust the balance of the multi-plane reconstruction and to realize the weak compensation is the core concept in this proposal. The simulation results show that with this method the average and variation of C values can be improved by at least 59.82% and 97.03% compared with original GS iterative algorithm, respectively..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1009001 (2013)
Recording, Reconstruction and Realization of White-Light Fresnel Incoherent Digital Holography
Liu Yingchen, Fan Jinping, Zeng Fanchuang, Lü Xiaoxu, and Zhong Liyun
Based on the analysis of the fundamental principle of the recording and reconstruction of white-light fresnel incoherent digital holography, the relationship between the reconstructed image resolution and recording parameters is discussed in detail. With two different types of phases loaded on the spatial light modulatBased on the analysis of the fundamental principle of the recording and reconstruction of white-light fresnel incoherent digital holography, the relationship between the reconstructed image resolution and recording parameters is discussed in detail. With two different types of phases loaded on the spatial light modulator (SLM), numerical simulation and experimental research of white-light fresnel incoherent digital holography are implemented respectively to analyse the relationship between image quality and recording parameters quantitatively. Results show that white-light fresnel incoherent digital holography based on SLM can realize the recording and reconstruction of three-dimensional object rapidly in a single channel and motionless way. Theoretically, a high quality reconstructed image with the same maximum resolution can be obtained, whichever phase loaded on SLM it is, a plane wave and a spherical wave or two spherical waves. However, due to the different requirements of the bandwidth of the light source and CCD size in the experimental study, the recording condition of loaded phase of two spherical waves is greatly reduced than that of loaded phase of a plane wave and a spherical wave. Under the same experimental conditions, the former reconstructed image resolution is much higher than the latter..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1009002 (2013)
Laser Manufacturing
Performance of Narrow Gap Laser Welding with Filling Wire for SUS304 Stainless Steel
Xu Guojian, Zhong Liming, Hang Zhengxiang, Li Ting, Xing Fei, Shi Lei, and Chang Lili
The narrow-gap solid fiber laser welding with filling hot wire replaces the previous narrow gap tungsten inert gas (TIG) welding. The thickness of the welding is 20 mm and the material is SUS304 austenitic stainless steel. Preliminary study shows that the groove form and the welding process parameters are suitable for The narrow-gap solid fiber laser welding with filling hot wire replaces the previous narrow gap tungsten inert gas (TIG) welding. The thickness of the welding is 20 mm and the material is SUS304 austenitic stainless steel. Preliminary study shows that the groove form and the welding process parameters are suitable for narrow gap laser welding with filling hot wire. The causes of blowhole and crystallization crack in the weld metal are analyzed through experiments and the process parameters are adjusted. Under the optimum process parameters, smaller heat affected zone, better surface formability are obtained, and there is no welding defects in the welded joints. The weld metal is fine austenite columnar crystals, which forms a good connection with the base material. Welding deformation is small enough to satisfy the requirement. The weld metal is slightly micro harder than the base metal. The tensile and bending properties meet the test requirements, obtaining good mechanical properties of the welded joints..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1003001 (2013)
Influence of Spot Arrangements on Laser Spot Weld Bonded Joint Fracture Process
Ma Yinan, Tao Wang, Chen Yanbin, and Wang Mingmao
The CO2 pulse laser is used in laser spot weld bonding test using Q195 mild steel and adhesive J-11. The fracture process of laser spot weld bonded (LWSB) joints with different spot arrangements is studied. The results show that the adhesive bonded area in LWSB joint firstly fractures, and then the spot fractures, whenThe CO2 pulse laser is used in laser spot weld bonding test using Q195 mild steel and adhesive J-11. The fracture process of laser spot weld bonded (LWSB) joints with different spot arrangements is studied. The results show that the adhesive bonded area in LWSB joint firstly fractures, and then the spot fractures, when there is only one spot in LSWB joint. When the spot arrangement in LSWB joint is parallel to the load direction, the fracture sequence is the adhesive bonded area outside of the spot, and the adhesive bonded area inside of the spot. When the spot arrangement in LSWB joint is vertical to the load direction, the adhesive bonded area of the LWSB first fractures, then the adhesive bonded area and the spot fracture together. Besides, the finite element modeling is used to analyze the influence of spot arrangement in LSWB joint on stress distribution under some tensile-shear condition. The calculated results are in good agreement with the experimental results..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1003002 (2013)
Research on Double-Station Processing System in Laser Processing
Zhang Jian, Wu Ruihuan, Li Zexi, Chen Guo, Zhang Qingmao, and Liu Songhao
In order to meet the need of multi-station or multi-craft laser processing, with the Nd:YAG pulse laser as the optical source, a double-station processing system is developed. A double-station processing implementing scheme is proposed, and then a light-splitting device that can change the laser path in real time is deIn order to meet the need of multi-station or multi-craft laser processing, with the Nd:YAG pulse laser as the optical source, a double-station processing system is developed. A double-station processing implementing scheme is proposed, and then a light-splitting device that can change the laser path in real time is designed. As well as a control circuit of the whole system, and the workflow, work time sequence of the system is worked out. Finally, a double-station system is realized, and it can provide the same output power as which of the single-station one. To test the processing result of the system, the cladding and welding experiments are respectively carried out on AZ91D magnesium alloy and 3003 aluminum alloy. With the help of scanning electron microscope(SEM) and the measuring system of electrochemistry, the features and corrosion resistance of the interface between the coating of cladding sample and the substrate are tested respectively. Besides, the microhardness and tensile property of the welding sample are tested. The results show that after cladding, the clad layer integrates well with the substrate and is compact in texture without cracks or holes. The self-corrosion potential is higher than the substrate by 1.18V and corrosion current is lower by 5 orders of magnitude. It also shows that the processing results are quite good after welding, with the hardness of aluminum alloy varying from HV4.927 to 54 and the tensile strength reaching 82.3% of that of the parent metal. And the process efficiency is improved by 24.6% compared with the single station processing system..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1003003 (2013)
Mechanics of Removing Residual Stress of Fe314 Cladding Layers with Laser Shock Processing
Yan Shixing, Dong Shiyun, Xu Binshi, Wang Yujiang, Xiao Aimin, and Lu Jinzhong
Due to the thermal deformation and crack of laser cladding layers induced by residual stress, a treatment of laser shock processing (LSP) is performed to remove the residual stress of Fe314 alloy cladding layer, its mechanics and residual stress distribution are investigated as well. Results show that residual stress cDue to the thermal deformation and crack of laser cladding layers induced by residual stress, a treatment of laser shock processing (LSP) is performed to remove the residual stress of Fe314 alloy cladding layer, its mechanics and residual stress distribution are investigated as well. Results show that residual stress can be removed significantly when a high specific energy of laser cladding comprised of slow scanning speed, small spot size and low powder feed rate is adsorbed by melt pool. Furthermore, LSP decreases the residual stress, and with the number of LSP increasing, the residual stress of cladding layer descends gradually while the removing capability attenuates. The mechanics of variation show that a micro-plastic deformation appears on the Fe314 cladding layer surface, which is induced with a huge strain rate of shock wave. A compression stress field is formed and removes the tensile stress of cladding layer. It is observed that mass dislocation lines emerge in the γ-Fe grain due to LSP. Then a dislocation wall is formed and separates one grain into several subgrains. Eventually, the effect of grain refinement is occurred in the Fe314 alloy cladding layer..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1003004 (2013)
Microstructure and frictional wear Properties of Laser Clad in Situ CrxSy/Ni Composite Coating
Sun Ronglu, Niu Wei, Lei Yiwen, and Tang Ying
CrxSy/Ni coating is prepared on H13 steel by laser cladding using powder mixture of NiCrBSi+33%Ni/MoS2 (mass fraction). The microstructure of the coating is examined using optical microscope (OM), scanning electronic microscope (SEM), energy dispersive spectrometer (EDS), and X-ray diffractor (XRD). The frictional wearCrxSy/Ni coating is prepared on H13 steel by laser cladding using powder mixture of NiCrBSi+33%Ni/MoS2 (mass fraction). The microstructure of the coating is examined using optical microscope (OM), scanning electronic microscope (SEM), energy dispersive spectrometer (EDS), and X-ray diffractor (XRD). The frictional wear properties of the coating are tested. The results show that the coating consists of CrxSy particles distribute in γ-Ni dentrites and γ-Ni+MoNi4 eutectics matrix. The in situ formed CrxSy particles appear quasi-spherical shape, with size of 5～20 μm. The relatively larger particles are mainly distributed in the upper layer of the coating and the smaller particles are mainly distributed in the middle and bottom layer of the coating. Due to the lubrication of CrxSy, the friction coefficient of the situ formed CrxSy/Ni self-lubricating coating is significantly lower than that of laser clad NiCrBSi coating. However, its wear resistance slightly decreases..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1003005 (2013)
Off-Line Automatic Programming Research of Laser Remanufacturing Robot Based on Machine Vision
Dong Ling, Yang Xichen, and Lei Jianbo
Off-line automatic programming system of laser remanufacturing robot based on 3D vision is developed in order to repair the complex parts accurately and efficiently. The system mainly consists of six functional modules: machine vision measurement, 3D modeling, remanufacturing planning, automatic programming, simulationOff-line automatic programming system of laser remanufacturing robot based on 3D vision is developed in order to repair the complex parts accurately and efficiently. The system mainly consists of six functional modules: machine vision measurement, 3D modeling, remanufacturing planning, automatic programming, simulation and optimization, and communication module. It applies standard calibration plate to carry out calibration based on HALCON software, and uses gradient gravity method to extract laser stripe center precisely, and carries on feature matching fastly on the basis of limit geometric theory. Parts′ point cloud data is obtained according to the triangulation principle. Then reconstructing parts and extracting the 3D model of the repair area are done, remanufacturing path planning and robot control program generation are executed automatically in the light of the parameters of process planning. Linkage between multiple devices and timing control are implemented with robot master mode. Tests show that robot action is coherent, and repair pathway is consistent with the design by using this method, which can improve efficiency and accuracy of robot programming and meet parts′ repair requirements..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1003006 (2013)
Laser Physics
Hundreds Watts Nd:YAG Slab Laser Amplifier with High Beam Quality
Wang Dan, Zhou Tangjian, Wang Juntao, Tong Lixin, Hu Hao, and Li Mi
An end pumped Nd:YAG slab laser amplifier is presented. Low doped and composited Nd:YAG slab is used to obtain continuous wave output power of 330 W and beam qualities of M2x=1.23, M2y=1.73 under the 3 passes amplification stucture. Taking advantage of 4f image system, the loss from light cutoff is reduced and the unifAn end pumped Nd:YAG slab laser amplifier is presented. Low doped and composited Nd:YAG slab is used to obtain continuous wave output power of 330 W and beam qualities of M2x=1.23, M2y=1.73 under the 3 passes amplification stucture. Taking advantage of 4f image system, the loss from light cutoff is reduced and the uniformed energy extraction is realized. In addition, gain coefficients are calculated by the output power of single and multiple pass amplifications. It is also investigated that the multiple amplification structure is good to restrain the amplified spontaneous emission..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1002001 (2013)
Pulsed Laser Diode Dual-End Pumped Tm:YAG Rod Transient Thermal Effect Analysis
Jin Guangyong, Wu Jing, Wu Chunting, Fan Erhe, Wang Chao, Chen Xinyu, Yu Yongji, and Tan Xuechun
Based on transient heat conduction equation, pulse Gaussian beam dual-end pumped Tm:YAG rod time-varying temperature field analytical expression and the time-varying thermal focal length are obtained by the integral transform method. The effects of pumping power, repetition frequency and duty ratio on pulse laser diodeBased on transient heat conduction equation, pulse Gaussian beam dual-end pumped Tm:YAG rod time-varying temperature field analytical expression and the time-varying thermal focal length are obtained by the integral transform method. The effects of pumping power, repetition frequency and duty ratio on pulse laser diode dual-end pumped Tm:YAG rod axial transient temperature distribution and the time-varying thermal focal length are quantitatively analysed. Simulation results show that with the increase of pulse number, the temperature distribution and the thermal focal length of Tm:YAG crystal rod appear jagged and eventually get to the periodic distributions. As the increase of pumping power, repetition rate and duty ratio, the whole temperature of Tm:YAG crystal rod increases and the temperature difference between the Tm:YAG rod on both ends of the center and the axis center of rod becomes larger, while the time-varying thermal focal length gradually becomes shorter and the fluctuation range is smaller. The results provide theoretical basis for the further study of heating compensation and cavity design..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1002002 (2013)
Design of High Power Laser Beam Automatic Alignment System
Li Hong, Wang Dongfang, Zou Wei, Lin Qiang, Zhang Yanli, Jiang Zhuochai, Liu Daizhong, Zhu Baoqiang, Zhu Jianqiang, and Gong Lei
High power laser device beam is detected and aligned with TMCM 351E device control board and a self-made automatic alignment procedures, and a set of novel optical monitoring alignment system is desigred. With the use of variable structure control algorithm, automatic extraction of the near and far field reference centHigh power laser device beam is detected and aligned with TMCM 351E device control board and a self-made automatic alignment procedures, and a set of novel optical monitoring alignment system is desigred. With the use of variable structure control algorithm, automatic extraction of the near and far field reference center and the spot center are achieved, and automatic alignment procedures are realized with high stability, high precision and high efficiency. Experiments are conducted on platform to verify the performance of the alignment system. Experimental results show that, compared to traditional method, the adjusted average error of spatial filter pinhole diameter is 0.9% in the monitoring collimation system, which can meet the precision requirement of far field adjusting collimation system (less than 5% of small hole diameter) and near field adjusting collimation system (less than 1% of small diameter). Stability test of 10 h shows that the control system has good stability with angle jitter of ±12.6 μrad. The system is verified in the high power laser device. The alignment time of eight pre-light road is less than 3 min and the alignment time of the main light path is less than 7 min..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1002003 (2013)
20 MHz Compact High Power Passively Mode-Locked Nd:YVO4 Laser
Mao Xiaojie, Bi Guojiang, Pang Qingsheng, and Zou Yue
A compact passively mode-locked laser with 7.5-m cavity length is reported. The laser is 55 cm in length and 15 cm in width by the resonator folding design. The Nd:YVO4 crystal is end-pumped by the diode laser. The output laser with double-pass of the gain crystal after passively mode locked by semiconductor saturable A compact passively mode-locked laser with 7.5-m cavity length is reported. The laser is 55 cm in length and 15 cm in width by the resonator folding design. The Nd:YVO4 crystal is end-pumped by the diode laser. The output laser with double-pass of the gain crystal after passively mode locked by semiconductor saturable absorber is obtained. The repetition rate is 20 MHz and the pulse width is 14.2 ps, the average power is 6.14 W and the output laser is TEM00 at 1064 nm. The pulse energy is 0.3 μJ. The quality of laser beam M2 is 1.17 in X direction and 1.06 in Y direction. The power unstability is 0.5%..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1002004 (2013)
Research of Picosecond Raman Amplifier in YVO4 Crystal
Xu Yang, Chen Meng, Li Zhengwei, Chen Liyuan, Yang Chao, Gao Xiaoqiang, and Li Gang
The performance of YVO4 crystal as Raman amplifier is reported. The beam quality of Raman Stokes light is improved due to Raman “cleanup” in the amplification stage. Then, by changing the pump pulse width, the experiment is carried out in three different pulse width conditions. The experimental results show that the wiThe performance of YVO4 crystal as Raman amplifier is reported. The beam quality of Raman Stokes light is improved due to Raman “cleanup” in the amplification stage. Then, by changing the pump pulse width, the experiment is carried out in three different pulse width conditions. The experimental results show that the wider the pump pulse is, the more easily the pump-seed delay is adjusted. By changing the incident angle between seed and pump light, its influence on the performance of Raman amplifier is also studied. Raman amplifier based on four wave mixing (FWM) is very sensitive to the change of the incident angle. Third order Stokes and third order anti-Stokes Raman lights are obtained at different incident angles, and the spectral composition of all the Raman Stokes is identified to the calculated Raman Stokes spectral composition..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1002005 (2013)
Precise Thermal Simulation Module for DFB Laser Sub-Assembly with Transistor Outline Package
Hou Xiaoke, Zhang Liqing, Zhang Shengli, Wang Lei, and Yao Yong
A precise thermal simulation model for distributed feedback Bragg (DFB) laser transmitter optical swb-assembly (TOSA) with uncooled transistor outline package is established based on the finite element method (FEM). The thermal gradient and junction temperature are simulated and analyzed. The self-consistency of this mA precise thermal simulation model for distributed feedback Bragg (DFB) laser transmitter optical swb-assembly (TOSA) with uncooled transistor outline package is established based on the finite element method (FEM). The thermal gradient and junction temperature are simulated and analyzed. The self-consistency of this model is verified by comparing with experiments. The change of lasing peak wavelength as a function of case temperature is measured by pulse injection and the relationship is calculated. The relationships between laser junction temperature, case temperature of transistor outline (TO) case and thermal power are obtained by measurements. The laser junction temperature and TO case temperature are also simulated at different thermal powers. The simulated results are agree well with the measured results. The thermoresistance of the laser subassembly is calculated based on the measured temperature gradient at different environmental temperatures. The thermal model reported by this paper is very precise and can be used for thermal design of TOSA and transceiver..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1002006 (2013)
Research on Energy Distribution after Laser-Induced Optical Breakdown Underwater
Wang Xiaoyu, Wang Jiang′an, Zong Siguang, and Liu Tao
The distribution of laser energy after laser-induced optical breakdown in water is theoretically analyzed. The calculation methods for energy are given. Experimental platform is built to research energy distribution after laser-induced optical breakdown underwater. A high speed camera is used to record the procession oThe distribution of laser energy after laser-induced optical breakdown in water is theoretically analyzed. The calculation methods for energy are given. Experimental platform is built to research energy distribution after laser-induced optical breakdown underwater. A high speed camera is used to record the procession of laser-induced optical breakdown underwater, from which the speed of shockwaves and maximum radius of bubble are got. A hydrophone is used to measure the acoustic signals in far field. The results show that 60%~90% of laser energy is converted into shock wave energy and bubble energy. The laser energy has no influence on experimental results. With the increase of laser focusing angle, the energies of shock wave and bubble both increase, and that of transmitted laser decreases..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1002007 (2013)
Modelling Laser Phase Screen Induced by Turbulence in Channel Flow
Su Hua, Wang Xiaojun, Yu Zhen, and Tang Chun
Inspired by the technique development of solid-state lasers cooled by liquid directly, the phase aberrations at laser wavefront induced by the turbulence in channel flow is investigated theoretically. By means of the statistic characteristic of the channel-flow turbulence, a method to model the laser phase-screen inducInspired by the technique development of solid-state lasers cooled by liquid directly, the phase aberrations at laser wavefront induced by the turbulence in channel flow is investigated theoretically. By means of the statistic characteristic of the channel-flow turbulence, a method to model the laser phase-screen induced by turbulence in channel flow is proposed. Within the assumption of incompressible fluid, there are two kinds of turbulence thermal mechanics, which are heat transfer of transport and heat generation of dissipation, that generate temperature fluctuations in both temporal and spatial regions, and further generate the phase screen induced by the channel-flow turbulence. The numerical result shows that the degeneration of beam quality is mainly caused by heat transfer of transport instead of heat generation of dissipation. The phase aberration induced by the density fluctuations is discussed as well..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1002008 (2013)
A Novel Multi-Wavelength Mid-Infrared Difference Frequency Generation Laser Source Based on PPLN
Chang Jianhua, Yang Zhenbo, Lu Zhou, and Dong Shichao
A novel difference frequency generation (DFG) scheme for simultaneously achieving multi-wavelength mid-infrared (mid-IR) emissions based on a bulk PPLN crystal is proposed. For the combination of 1060 nm and 1550 nm wavelength band fundamental light sources, multiple pump quasi-phase-matching (QPM) peaks can be obtaineA novel difference frequency generation (DFG) scheme for simultaneously achieving multi-wavelength mid-infrared (mid-IR) emissions based on a bulk PPLN crystal is proposed. For the combination of 1060 nm and 1550 nm wavelength band fundamental light sources, multiple pump quasi-phase-matching (QPM) peaks can be obtained by using the segmented temperature controlling techniques on a PPLN chip. Moreover, the multiple pump QPM peaks can be widely tuned by adjusting the segmented crystal temperatures and thus the tunability for the generated multiple mid-IR wavelengths is realized. Our simulated results show that when the PPLN crystal are evenly divided into two sections for temperature controlling, four pump QPM peaks are simultaneously reached, corresponding to the mid-IR idler QPM peaks at 2.95, 3.03, 3.75, 3.83 μm, as the signal wavelength setting at 1.58 μm and the segmented crystal temperatures setting at 20 ℃ and 60 ℃, respectively. When the segmented crystal temperatures are adjusted to 50 ℃ and 90 ℃, the idler QPM peak positions in the mid-IR DFG output spectrum are changed to 3.01, 3.11, 3.67, 3.77 μm. Such results may provide reference and guidance for design and development of widely tunable multi-wavelength DFG light sources..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1002009 (2013)
Research on Microsphere Array Laser in Circulating State Pumped by LDA
Ding Jianyong, Gui Luo, Zhao Pengfei, Peng Bo, and Wei Wei
A novel laser gain medium, microsphere array cooled by refractive index-matched coolant, is presented in response to the thermal management of high-power solid-state lasers in this paper. Experiments on microsphere array lasers in circulating state are carried out. The emission spectra and flourescence decay curves areA novel laser gain medium, microsphere array cooled by refractive index-matched coolant, is presented in response to the thermal management of high-power solid-state lasers in this paper. Experiments on microsphere array lasers in circulating state are carried out. The emission spectra and flourescence decay curves are measured. Besides, the stable pulse output energy is achieved and its laser characteristics are studied. The maximum pulse energy of microsphere array laser with diameters of 2 mm and 4 mm are 30.2 mJ and 115.4 mJ, respectively at a repetition rate of 1 Hz, and the corresponding slope efficiencies are 4.6% and 16.2%, respectively. Output energy decreases as pumping frequency increases. Experimental results show that the microsphere array laser has relatively good thermal performance and thermal stability, and can be used in high-power laser systems..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1002010 (2013)
420 nm Alkali Blue Laser Based on Two-Photon Absorption
Tan Yannan, Li Yimin, Gong Faquan, Liu Tong, and Liu Wanfa
Based on two-photon absorption and pumped by a 778.1 nm dye laser, a 420 nm blue laser is achieved by using alkali Rb vapor as gain medium. Utilizing the energy level structure of Rb atom, blue laser mechanism and two-photon absorption process are analysed. By absorbing two 778.1 nm photons, Rb atoms are transitted froBased on two-photon absorption and pumped by a 778.1 nm dye laser, a 420 nm blue laser is achieved by using alkali Rb vapor as gain medium. Utilizing the energy level structure of Rb atom, blue laser mechanism and two-photon absorption process are analysed. By absorbing two 778.1 nm photons, Rb atoms are transitted from ground state 52S1/2 to excited state 52D5/2, then to laser up state 62P3/2 and ground state 52S1/2 populating inversion is fromed through radiating mid-infrared photon. The 420 nm blue laser is achieved through 62P3/2 to 52S1/2. The development prospect of laser diode pumped alkali vapor blue laser is expected..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1002011 (2013)
Effects of Phase Perturbation of KDP Crystal in Middle and High Spatial Frequency on SGⅡ Updated Laser Facility
Liu Dong, Ji Lailin, Wang Li, Zhu Haidong, Guo Ailin, Ma Weixin, and Zhu Jian
The perturbation of middle and high spatial frequency caused by the polish process of the large aperture KDP crystal in high-power laser system has a certain impact on the performance of the facility. To study the effects of this kind of phase perturbation on the near-field uniformities and far-field focusing abilitiesThe perturbation of middle and high spatial frequency caused by the polish process of the large aperture KDP crystal in high-power laser system has a certain impact on the performance of the facility. To study the effects of this kind of phase perturbation on the near-field uniformities and far-field focusing abilities, a calculation model which is based on fast Fourier transform (FFT) theory and optics wavefront data of SG-Ⅱ is established. The potential dangerousness which derives from the laser propagation to the facility is discussed..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1002012 (2013)
Speckle Suppression Method with Vibrating Light Pipe
Sun Mingjie, Yu Kanglong, and Meng Zhaokui
Speckle effect severely affects the laser projection image quality, therefore it needs to be suppressed. A speckle suppression method with a vibrating light pipe is proposed. It is theoretically analyzed, and the effectiveness is verified by simulations and experiments. Experiments are performed with two typical laser Speckle effect severely affects the laser projection image quality, therefore it needs to be suppressed. A speckle suppression method with a vibrating light pipe is proposed. It is theoretically analyzed, and the effectiveness is verified by simulations and experiments. Experiments are performed with two typical laser sources. The results show that, with the proposed method, no additional reforming lens is necessary for efficient rectangular illumination, which reduces the system size; the vibrating light pipe method can effectively reduce the speckle contrast to less than 6%, which is not recognizable to human eyes; the illumination efficiency of the speckle suppression system is above 90%..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1002013 (2013)
High Stability Laser Diode Side-Pumped Nd:YAG 300 Hz Regenerative Amplifier
Zhang Ruofan, Wei Hui, Wang Jiangfeng, Fan Wei, and Li Xuechun
A new method is proposed to measure the thermal focal length of laser crystal. Based on the experimental results, a laser diode (LD) side-pumped, flat-flat cavity regenerative amplifier is developed. By injecting a small signal seed light with wavelength of 1064 nm, pulse width of 2 ns, repetition rate of 300 Hz and puA new method is proposed to measure the thermal focal length of laser crystal. Based on the experimental results, a laser diode (LD) side-pumped, flat-flat cavity regenerative amplifier is developed. By injecting a small signal seed light with wavelength of 1064 nm, pulse width of 2 ns, repetition rate of 300 Hz and pulse energy of 300 pJ, the output TEM00 laser with maximum pulse energy of 1.5 mJ, pulse width of 2 ns is obtained. The corresponding amplification ratio is 5×106, and the output energy stability is 1.08% [root-mean-square (RMS)] with the square-pulse distortion of 1.10..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1002014 (2013)
Materials and Thin Films
Filter with One-Dimensional Photonic Crystal Quantum Well Possessing High-Quality Filtering Functions
Su An, Meng Chengju, and Gao Yingjun
The qualities of the filters with one-dimensional photonic crystal quantum well of single and double barriers are studied by transmission matrix method. The results show that the quality of experimented filter has a delicate response to the refractive index of barrier layer medium. The larger the refractive index of baThe qualities of the filters with one-dimensional photonic crystal quantum well of single and double barriers are studied by transmission matrix method. The results show that the quality of experimented filter has a delicate response to the refractive index of barrier layer medium. The larger the refractive index of barrier layer medium, or the larger the ratio between the refractive index sum of barrier layer medium and well layer medium, the higher the quality of the filter with photonic crystal quantum well of single barrier is. The quality of the filter with photonic crystal quantum well of double barrier is higher when the ratio between the refractive index sum of inner barrier medium and well layer medium, or the ratio between the refractive index sum of outer barrier medium and well layer medium, especially the ratio of the summed refractive index of inner and outer barrier mediums to the summed refractive index of well layer medium, become larger. As the ratio between the refractive index sum of barrier layer and well layer is increasing, the quality of filter with photonic crystal quantum well of double barrier improves more quickly than the one of single barrier. These characteristics provide definite reference to theoretical study of photonic crystal quantum well and the practical design of new quantum optical filter of high quality..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1006001 (2013)
Analysis on Transmission Properties of Electromagnetic Wave in One-Dimensional Multilayer Structure
Liu Mingyang, and Dong Yunxia
Recently two kinds of artificial structures, namely photonic crystal and left-handed material, have potential applications in the control of light. One of the artificial structures is photonic crystal which has periodic structure array of dielectric material. The photonic crystal shows band gap structure for the wave aRecently two kinds of artificial structures, namely photonic crystal and left-handed material, have potential applications in the control of light. One of the artificial structures is photonic crystal which has periodic structure array of dielectric material. The photonic crystal shows band gap structure for the wave and it can be used as potential optical devices. Another structure is the left-handed material. The left-handed materials with simultaneous negative permittivity and negative permeability possess a number of unusual electromagnetic effects. Transfer matrix method is used to analyze the transmission spectra of one-dimensional photonic crystals with negative refractive index material and positive refractive index material alternant structure. The bang gaps and dispersive relation of one-dimensional photonic crystals are analyzed. The general Bragg gaps and the resonant gap of low frequency exist in the photonic crystal. Not only the nonlocalized modes are found in such a disordered system, but also the localization states with short localization length can be easily realized due to the existence of the low frequency resonant gap..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1006002 (2013)
Optical Properties of Third-Order Nonlinearities of CdSeS Quantum Dots/Polystyrene Composite Film
He Zhicong, and Li Fang
The off-resonant nonlinear optical properties of the composite film of CdSeS quantum dots (QDs) stabilized in polystyrene (PS) nanosphere are investigated by Z-scan technique with femtosecond laser (800 nm, 50 fs, 1 kHz). It is observed that the signs of the nonlinear absorption coefficients and refractive indices chanThe off-resonant nonlinear optical properties of the composite film of CdSeS quantum dots (QDs) stabilized in polystyrene (PS) nanosphere are investigated by Z-scan technique with femtosecond laser (800 nm, 50 fs, 1 kHz). It is observed that the signs of the nonlinear absorption coefficients and refractive indices changes from negative to positive with laser intensity increasing, which is due to the transition from saturable absorption to two-photon absorption (TPA). With laser intensity of 4.2 GW/cm2 and 16.8 GW/cm2, the two-photon absorption coefficient (β) are 1.6×10-8 cm/W and 2.8×10-8 cm/W, respectively, and the third-order nonlinear refractive indices (n2) are -6.2×10-11 cm2/W and 2.7×10-12 cm2/W, respectively, which shows an increase of about one magnitude for β and two magnitudes for n2 compared with previous reports. The results indicate that CdSe QDs doped PS has high potential application value for all-optical switching devices..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1007001 (2013)
Measurement and Metrology
New Method of Restraining the Saturated Error in Phase Measuring Profilometry
Zhao Jing, Wang Yongchang, and Liu Kai
In three-dimensional (3D) scanning via phase measuring profilometry, if there exists saturation in captured patterned images, the accuracy of reconstructed 3D point clouds will be ruined. The phase error caused by saturated pixel values is studied, and a mathematical model for the error is derived. With such a model, aIn three-dimensional (3D) scanning via phase measuring profilometry, if there exists saturation in captured patterned images, the accuracy of reconstructed 3D point clouds will be ruined. The phase error caused by saturated pixel values is studied, and a mathematical model for the error is derived. With such a model, a novel algorithm is proposed to minimize the phase error by employing unsaturated pixel values. The proposed method is proved by both simulation and experiment, i.e., analysis of the root mean square error of the corrected phase will show a 92.5% reduction in phase error in simulation, and an 82.8% reduction in phase error in the experiment..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1008001 (2013)
Three-Dimensional Refractive Index Quantitative Measurement for Optical Fiber by Digital Holographic Tomography
Su Linglong, Ma Lihong, Wang Hui, and Li Yong
A new method to measure the three-dimensional refractive index distribution of optical fiber is proposed. A set of experiment system based on microscopic tomography with sample rotation is set up, which can quantitatively reconstruct the three-dimensional refractive index distribution inside optical fiber. The digital A new method to measure the three-dimensional refractive index distribution of optical fiber is proposed. A set of experiment system based on microscopic tomography with sample rotation is set up, which can quantitatively reconstruct the three-dimensional refractive index distribution inside optical fiber. The digital holograms are acquired at regularly-spaced angular positions within 180° viewing angle by the rotating sample in the digital holographic microscopy system of pre-amplification transmission type. Then, the refractive index integral projections for each degree′s optical fiber sample is calculated from the holograms. The three-dimensional refractive index distribution of the internal optical fiber is rebuilt by filtered back-projection algorithm. The experimental results of single-mode optical fiber and single-mode polarization maintaining optical fiber with the panda type demonstrate that the established system is feasible and effective in measuring the three-dimensional refractive index distribution of optical fiber..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1008002 (2013)
Analysis of Random Errors in High Precision Wavelength Phase Shifting Interferometers by Numerical Simulation
Wen Gang, Su Dongqi, Su Zhide, Sui Yongxinm, and Yang Huaijiang
To choose proper laser and CCD for studying of wavelength phase-shifting interferometry, the main random errors are numerically simulated in the system based on direct algorithm and Monte-Carlo method. The basic structure of Fizeau wavelength phase-shifting interferometer and theory of measurement are introduced, the eTo choose proper laser and CCD for studying of wavelength phase-shifting interferometry, the main random errors are numerically simulated in the system based on direct algorithm and Monte-Carlo method. The basic structure of Fizeau wavelength phase-shifting interferometer and theory of measurement are introduced, the errors by vibrating, air turbulence and instability of laser frequence are analysed and the model is set up. Then, combined with the results of numerical simulation, the correspondence between each error and its measuring result is abtained, and proper laser and CCD are determined, simultaneously the error distribution is given. By setting up the interferometer and measuring, the results show that repeatability root-mean-square (RMS) error is better than 0.07 nm, which reaches the requirement..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1008003 (2013)
Dynamic Three-Dimensional Shape Measurement Based on Regional Binary Encoding Method
Huang Huaquan, Wu Qingyang, and He Wei
A regional binary encoding method that applied in the structured light projection three-dimensional (3D) shape measurement is proposed. This method determines the region encoding range and binary encoding patters according to the maximum depth of the surface of measured object. Then the continuous phase distribution ofA regional binary encoding method that applied in the structured light projection three-dimensional (3D) shape measurement is proposed. This method determines the region encoding range and binary encoding patters according to the maximum depth of the surface of measured object. Then the continuous phase distribution of the deformed fringe can be acquired directly by using the basic regional order. On the premise of guaranteeing the reliability and accuracy, this technique can effectively reduce the number of encoded patterns and improve the measurement speed. Meanwhile, hardware module used in the dynamic three-dimensional shape measurement system is designed, which can achieve high-speed fringe projection and synchronized image capture at 240 frame/s and meet the requirements of dynamic 3D shape acquisition. Experimental measurement uses six patterns to accomplish the 3D shape acquisition at a speed of 40 frame/s, which realizes the dynamic 3D shape measurement. The experimental results are presented to demonstrate the feasibility of this technique..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1008004 (2013)
Method of Measuring Dispersion and Refractive Index of Transparent Object Based on Spectral Fiber Low Coherence Interferometry
Chen Chaoliang, and Gao Wanrong
A method of measuring dispersion and refractive index of transparent object based on spectral fiber low coherence interferometry is proposed, in which the path length of the reference arm is changed by a step motor and the interferometric signals are measured by a CCD detector. The difference between the signals from tA method of measuring dispersion and refractive index of transparent object based on spectral fiber low coherence interferometry is proposed, in which the path length of the reference arm is changed by a step motor and the interferometric signals are measured by a CCD detector. The difference between the signals from the upper and lower surfaces of a transparent plate is found and a polynominal fitting-based method is used to find the group delay dispersion. One advantage of the method is that the value of the measured dispersion is not affected by the dispersion introduced due to the mismatch between dispersions of the sample and reference arms of the system. The accuracy of the dispersion measurement is ±0.2747×10-14fs2/mm. By placing a reflective mirror in the sample arm of the interferometer, the values of dispersion mismatch can be measured and can be employed to quantitatively compensate the system dispersion. Compared with traditional methods of measuring variation of the full width at half maximum (FWHM), the proposed method can improve the accuracy and efficiency of the dispersion compensation. The dispersion compensation accuracy achieved is ±0.019×10-12fs2..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1008005 (2013)
Multi-Sensor Synchronous Calibration Method for Line Laser Human-Body 3D Scanner
Li Yunpeng, Tian Qingguo, Zhang Xiangyu, Wei Yaolin, and Ge Baozhen
In order to calibrate line laser human-body 3D scanner quickly and accurately, a multi-sensor synchronous calibration method which uses ceramic gauge block is proposed. V-shaped laser stripe which is made by line laser projection on ceramic gauge block is used as calibration point. 8 CCDs are distributed on 4 uprights,In order to calibrate line laser human-body 3D scanner quickly and accurately, a multi-sensor synchronous calibration method which uses ceramic gauge block is proposed. V-shaped laser stripe which is made by line laser projection on ceramic gauge block is used as calibration point. 8 CCDs are distributed on 4 uprights, and capture V-shaped light stripe simultaneously to record V-shaped laser stripe pattern. Use gray centroid algorithm and dual fitting line intersection method to extract the light band′s sub-pixel-precision center grid. In order to obtain precision calibration point grid pairs, the grids are paired with 2D translation stage′s world grids. Based on pinhole camera model and using Levenberg-Marquardt (LM) nonlinear optimization algorithm, all sensors′ calibration matrices are obtained. The calibration results are tested by feature points which are different from calibration points, and the result shows that all sensors′ average projection errors are less than 0.3480 mm, standard deviations are less than 0.2524 mm..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1008006 (2013)
Principal and Error Analysis on Measurement of Multiple-Surface Interference with Wavelength-Tuning Phase-Shifting
Liu Yong, Liu Xu, Ren Huan, Jiang Hongzhen, Yang Yi, and Ma Hua
To solve the multiple-surface interference fringe pattern admixture problem in measuring parallel plate with phase-shifting interfermetry (PSI), the basic principle of multiple-surface interference fringe analysis method with wavelength-tuning phase-shifting is introduced. As the three surfaces interference for exampleTo solve the multiple-surface interference fringe pattern admixture problem in measuring parallel plate with phase-shifting interfermetry (PSI), the basic principle of multiple-surface interference fringe analysis method with wavelength-tuning phase-shifting is introduced. As the three surfaces interference for example, the front and back surfaces can be got by analyzing the interferograms by Fourier transform and getting the phase of the corresponding spectrum. The maximum error and variance distributions with different sampling buckets and light spectral ranges are compared. In ideal case, the error of this method is lower than 10-4λ. Experiments on an optical element by this method and Zygo′s interferometer, the result shows that the relative errors of surface peak-to-valley (PV) and root mean square (RMS) is lower than 1%..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1008007 (2013)
Optical Communication
Slot Processing Based on Large Dynamic Delay Range All-Optical Buffer
Wang Yongjun, Zhang Xiaolei, Wu Chongqing, Wang Zhi, Shang Chao, Yang Zhaoyi, and Xin Xiangjun
Based on a cascaded double-loop all-optical buffer (DLOB) structure, a new all-optical slot processing scheme is proposed. The all-optical slot processing functions which include slot compressing, slot expanding and slot interchanging or re-aligning, are proved by experiments. The results demonstrate that the interval Based on a cascaded double-loop all-optical buffer (DLOB) structure, a new all-optical slot processing scheme is proposed. The all-optical slot processing functions which include slot compressing, slot expanding and slot interchanging or re-aligning, are proved by experiments. The results demonstrate that the interval between two 2.448 Gb/s optical packets can be compressed from 24.3 μs to 110 ns, or expanded from 100 ns to 26.11 μs by two-level DLOB, and the output optical packets have no bit error. The all-optical slot processing scheme proposed in this paper can provide as a reference for all-optical buffer..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1005001 (2013)
Performance Analysis of High Altitude Platform Multi-Hop Optical Communication with Variable Gain Relay
Wang Xiang, Zhao Shanghong, Shi Lei, Li Yongjun, Chu Xingchun, Zhao Guhao, and Zhu Zihang
Based on variable gain relays, the expression of outage probability lower bound for high altitude platform multi-hop optical communication is given. The effect of the factors, including atmospheric turbulence, tracking error and relay node position, on the performance of multi-hop optical links is analyzed. The simulatBased on variable gain relays, the expression of outage probability lower bound for high altitude platform multi-hop optical communication is given. The effect of the factors, including atmospheric turbulence, tracking error and relay node position, on the performance of multi-hop optical links is analyzed. The simulation results show that the influence of atmospheric turbulence on optical links is lower than pointing error. The influence of relay node position on multi-hop optical links is related with tracking error. The bigger tracking error is, the stronger is the dependence of the position of relay node on optical links. The influence of relay node position on inter-high altitude platform (HAP) optical link will worsen and the performance of multi-hop optical links can be improved by the improvement of signal noise ration (SNR). Taking relay number of 2 and tracking error of 20 m as an example, outage probability of links reduces approximately by 2.2 dB while the average SNR per hop increases by 1 dB..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1005002 (2013)
Dual-Fiber Fabry-Perot Displacement Sensor Based on Ratio Method Fringe Counting Demodulation
Shu Zhuo, Tong Bin, Xu Chunhui, Chen Fengxiang, and Li Min
Conventional fringe counting method has difficulty in direction judgment, especially at the peak or valley of cosine signal. In order to overcome this problem, we present a double Fabry-Perot (F-P) interferometer using a ratio fringe counting approach. Since the value of tangent signal jumps at which phase is an integeConventional fringe counting method has difficulty in direction judgment, especially at the peak or valley of cosine signal. In order to overcome this problem, we present a double Fabry-Perot (F-P) interferometer using a ratio fringe counting approach. Since the value of tangent signal jumps at which phase is an integer multiple of π/2, we use two orthogonal cosine interference signal ratio to get the tangent signal. Meantime, by counting the number of pulse, we can not only measure the phase difference but also judge the direction change. This approach has no strict requirement for initial phase difference of two optic paths. It′s very feasible for manufacturing, and experimental results demonstrate the linearly dependent coefficient up to 0.9999, a good linearity to 0.306% and a displacement resolution to ±3 μm within a dynamic range from 0 to 1mm of the sensor system..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1005003 (2013)
Analysis of Optical Aberration Impact on Acquisition Performance
Wu Congjun, Yan Changxiang, and Liu Wei
Acquisition is essential to laser communication link′s establishing. In order to study the impact of optical aberrations on acquisition performances, based on the transmission process of beacon beam and image quality evaluation of laser communication system, the impact of monochromatic aberrations on acquisition centroAcquisition is essential to laser communication link′s establishing. In order to study the impact of optical aberrations on acquisition performances, based on the transmission process of beacon beam and image quality evaluation of laser communication system, the impact of monochromatic aberrations on acquisition centroid intensity and acquisition errors caused by tilt and coma with centroid and weighted centroid algorithm is analyzed as the root mean square (RMS) of monochromatic aberrations is less than 0.2λ. Besides, compensations between aberrations to the centroid intensity and acquisition errors are also discussed. The analysis reveales that acquisition errors caused by tilt (distortion) and coma can completely compensate for each other, and defocus can greatly compensate the centroid intensity decrease caused by sphere and astigmatism. The Cassegrain and three-mirror anastignat (TMA) antenna systems are designed by Zemax optical software, and by using the method, the combined effect of aberration on centroid intensity and acquisition errors within 0.3° circle field is calculated. The result can sufficiently support the above view. These conclusions can give some guides to antenna type selection and image quality optimization strategy in laser communication optical system design..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1005004 (2013)
Scheduling Algorithm for Data Relay Satellite with Microwave and Laser Hybrid Links
Zhao Jing, Zhao Weihu, Li Yongjun, Zhao Shanghong, Han Lei, and Li Xuan
According to the developing trend for the combination of microwave and laser links in the future data relay satellite system, the scheduling problem for data relay satellite with microwave/laser hybrid links is studied. Microwave and laser hybrid links are analyzed in data rate, links establishment and power consumptioAccording to the developing trend for the combination of microwave and laser links in the future data relay satellite system, the scheduling problem for data relay satellite with microwave/laser hybrid links is studied. Microwave and laser hybrid links are analyzed in data rate, links establishment and power consumption. With the multi-window, multi-antenna and mission priority as parameters, and the gross weight of un-scheduling missions, the gross power consumption and the scheduling-time as object functions, the multi-objective scheduling model is formulated. The model is decomposed into a task assignment sub-problem and a scheduling optimizing sub-problem. In the task assignment phase, the mission is scheduled with time window update, and in the scheduling optimizing phase, the scheduling project is optimized by genetic algorithm. The simulation result shows that the mission compeletion rate is 93.75% and the sum of mission weights is 96.96%. the simulation result reveals that the model and algorithm are suitable in multi-mission and multi-antenna microwave/laser hybrid links data relay satellite scheduling problem..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1005005 (2013)
Transient Process of Dissipative Soliton Generation in Normal Dispersion Fiber Lasers
Ge Yanqi, Luo Jiaolin, Zhang Shumin, Tang Dingyuan, Shen Deyuan, and Zhao Luming
The transient process of dissipative soliton (DS) generation is numerically revealed in normal dispersion fiber lasers. It is shown that the gain dispersion is critical for the DS generation. The steep spectral edges of DSs are the consequence of the interaction among the normal dispersion, fiber nonlinearity, gain andThe transient process of dissipative soliton (DS) generation is numerically revealed in normal dispersion fiber lasers. It is shown that the gain dispersion is critical for the DS generation. The steep spectral edges of DSs are the consequence of the interaction among the normal dispersion, fiber nonlinearity, gain and loss, and gain dispersion effect. Narrow gain bandwidth could result in multiple DSs while broad gain bandwidth (up to 100 nm) could support DS generation provided that enough pump power is available. Consequently, DSs could be generated in fiber lasers even when the gain bandwidth is broad and there is no requirement for other spectral filtering in cavity..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1005006 (2013)
Analysis of Optical Fiber Acoustic Transducer with a MEMS Membrane
Li Xiaolong, Wang Jiang′an, and Zong Siguang
To be used in sound sensor field, a new intensity modulated optic microphone theory is introduced. Here single-mode optical fiber and single fiber C-lens are used to realize light intensity modulation; the system also contains micro-electro-mechanical system (MEMS) membrane to be compatible with vibration displacement.To be used in sound sensor field, a new intensity modulated optic microphone theory is introduced. Here single-mode optical fiber and single fiber C-lens are used to realize light intensity modulation; the system also contains micro-electro-mechanical system (MEMS) membrane to be compatible with vibration displacement. Simulation results show that the proper choice of parameters like membrane size can make the sensitivity of sensor improve in orders of magnitude than traditional light intensity modulation methods, and the experimental results also show that the theoretical simulation is persuasive..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1005007 (2013)
Optical Design and Fabrication
Design and Optimization of Two-Dimensional Laser Source Used for Projection
Zhang Yunfang, Li Hui, Dong Hui, Kong Qingshan, Shi Ancun, Duan Jingyuan, Fang Qing, and Liu Yuliang
A two-dimensional laser source with high power, small size and the ability to suppress speckle noise is designed for projection. This laser source module is composed of an array of laser diodes and a lens array which can realize uniform rectangular beam without other optical elements. The source module is built in ZemaA two-dimensional laser source with high power, small size and the ability to suppress speckle noise is designed for projection. This laser source module is composed of an array of laser diodes and a lens array which can realize uniform rectangular beam without other optical elements. The source module is built in Zemax software. The influences of the factors including the divergence angle, the number, the interval of laser diode (LD), and the beam divergence angle after the micro lens on the light efficiency, the beam size, the illumination distance and the beam uniformity are studied. A two-dimensional laser source module for liquid crystal display (LCD) projection is built based on theoreical analysis..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1016001 (2013)
Remote Sensing and Sensors
Influences of the Probe Beam Convergence on the Performance of Surface Plasmon Resonance Sensor
Chen Xinlin, Xiao Guangzong, Zhang Bin, and Fu Yangying
In the surface plasmon resonance (SPR) sensor system with Kretschmann configuration based on wavelength modulation technology, the theoretical model of the influence of beam reshaped system and the beam diameter on the convergence angle is built. The influence of convergence angle of probe beam on resonance wavelength,In the surface plasmon resonance (SPR) sensor system with Kretschmann configuration based on wavelength modulation technology, the theoretical model of the influence of beam reshaped system and the beam diameter on the convergence angle is built. The influence of convergence angle of probe beam on resonance wavelength, the full width at half maximum (FWHM) and the depth of resonance peak is analyzed. As the convergence angle decreases, the resonance wavelength is enhanced, the FWHM is reduced, and the depth of resonance peak is enhanced. As a result, the capacity of resisting disturbance is enhanced, and the system resolution is enhanced. It is confirmed by experiment, and the experimental result fit well with the simulated one when considering the influence of convergence angle. When the convergence angle varies from 0.8° to 0°, the resonance wavelength varies from 662 nm to 623 nm, the FWHM is reduced from 157 nm to 117 nm, and the depth of resonance peak is enhanced from 70.5% to 93.3%..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1014001 (2013)
Spectroscopy
Temperature Characteristics of Near-Infrared Luminescence of Yb-Doped Bismuth-Based Glasses
Cheng Jimeng, Li Weiwei, Zhao Guoying, Li Shunguang, Chen Wei, Hu Lili, and Georges Boulon
The temperature dependence of near-infrared around 1 μm emission properties of Yb-doped 55Bi2O3-25B2O3-10SiO2-(10-x)Ga2O3-xYb2O3（x=0.5, 2.0, 5.0) glasses is investigated. Emission spectra, covering a major 975 nm fluorescence peak with a minor 1003 nm weaker peak, are determined within the temperature range of 9 K~350 The temperature dependence of near-infrared around 1 μm emission properties of Yb-doped 55Bi2O3-25B2O3-10SiO2-(10-x)Ga2O3-xYb2O3（x=0.5, 2.0, 5.0) glasses is investigated. Emission spectra, covering a major 975 nm fluorescence peak with a minor 1003 nm weaker peak, are determined within the temperature range of 9 K~350 K. The full width at half-maximum of them does not change a lot. An important cause for the width of fluorescence line is inhomogeneous broadening from this bismuth-based glass host. On the other hand, the electron-phonon coupling will have some influence on the emission spectrum and emission lifetime. For the temperature dependence of lifetime, a longer emission lifetime of Yb at higher temperature region indicates a more significant influence of radiation trapping effect..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 10, 1015001 (2013)
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