Journals >Chinese Journal of Lasers
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2014
Volume: 41 Issue 5
48 Article(s)
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Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 518001 (2014)
Biomedical Photonics and Laser Medicine
Observation of Emodin-β-CD Inclusion Complex′s Transmembrane Transport in Nasopharyngeal Carcinoma Cells and Its Distribution by the Laser Scanning Confocal Microscope
Wang Chunmiao, Hou Huaxin, Li Danrong, Chen Yunlong, Mo Chunyan, Li Jing, and Mo Yuanyuan
The transmembrane transport and distribution characteristics of emodin-β-CD inclusion complex in the nasopharyngeal carcinoma CNE-1 cells are observed using laser scanning confocal microscope. The results show that both emodin and emodin-β-CD inclusion complex are mainly distributed in the cytoplasm in granules. In theThe transmembrane transport and distribution characteristics of emodin-β-CD inclusion complex in the nasopharyngeal carcinoma CNE-1 cells are observed using laser scanning confocal microscope. The results show that both emodin and emodin-β-CD inclusion complex are mainly distributed in the cytoplasm in granules. In the concentration range of 5~40 mg·L-1, the intake of emodin-β-CD inclusion complex nonlinearly increases with the increase of concentrations. Compared with the control group, emodin-β-CD inclusion complex uptake in cells is significantly lower than that of treatment with NaN3 and mannitol. After treatment with P-glycoprotein inhibitors cyclosporin A (CsA), intake of emodin-β-CD inclusion complex at low concentrations (smaller than 5 mg·L-1) significantly increases, but at high concentrations, intake of emodin-β-CD inclusion complex significantly decreases. Emodin-β-CD inclusion complex has long time of maintaining high concentration in cell relative to emodin. The mechanism of emodin-β-CD inclusion complex uptake in cells may involve energy-dependent endocytosis and P-glycoproteins participates in the conveying process of emodin-β-CD inclusion complex in CNE-1 cells. It provides a reference to improving emodin formulations..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 504001 (2014)
Quantum Dot Conjugated RGD for Targeted in Vivo Imaging of Laryngocarcinoma Vessel
Zhu Xiaomei, Wang Xiaomei, Feng Gang, Chen Qiang, Lin Guimiao, Zhao Junting, Xu Gaixia, and Niu Hanben
The targeted imaging of quantum dot (QD) conjugated cyclo (Arg-Gly-Asp-D-Phe-Lys ) peptides [c(RGDfK), QD-RGD] for laryngeal cancer blood vessel in vivo is studied. QD is conjugated with c(RGDfK) peptides by the reaction of carboxyl and amino groups. The spectra stabilities of QD-RGD in RMPI1640 and mouse serum are meaThe targeted imaging of quantum dot (QD) conjugated cyclo (Arg-Gly-Asp-D-Phe-Lys ) peptides [c(RGDfK), QD-RGD] for laryngeal cancer blood vessel in vivo is studied. QD is conjugated with c(RGDfK) peptides by the reaction of carboxyl and amino groups. The spectra stabilities of QD-RGD in RMPI1640 and mouse serum are measured by fluorescence spectrophotometer. The targeting of QD-RGD to αvβ3 on Hep-2 and MCF-7 cells is studied by fluorescent microscope. Finally, the targeting of QD-RGD to laryngeal cancer vascular in dorsal skin fold window chamber by tail intravenous injection is investigated. The result shows that the spectra stability of QD-RGD in RPMI1640 does not obviously change in 4 hours. The fluorescence intensity of QD-RGD in mouse serum in 24 hours only decreases by 20%.The result of cells fluorescence imaging shows that QD-RGD can specifically bind to integrin αvβ3 on cells. The result of vascular imaging shows QD-RGD gathers in cancer blood vessel after injecting for 2 hours, and QD-RGD is removed from cancer blood vessel after 24 hours. The study demonstrates that QD-RGD can be used to targeted image cancer blood vessel in vivo, which offers a reference for studying targeting diagnosis and targeting therapy of laryngocarcinoma in vivo..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 504002 (2014)
Holography and Information Processing
Assessment Algorithm of Laser-Dazzling Effects Based on the Feature-Point Distributing Characteristic
[in Chinese]
Laser active imaging systems are usually used in region surveillance and target identification. However, the photoelectric imaging detector in the imaging systems is easy to be disturbed and this leads to errors of the recognition and even the missing of the target. Assessment of laser-dazzling effects in view of the iLaser active imaging systems are usually used in region surveillance and target identification. However, the photoelectric imaging detector in the imaging systems is easy to be disturbed and this leads to errors of the recognition and even the missing of the target. Assessment of laser-dazzling effects in view of the invalidation of the target feature must be better understood. A new feature-point similarity (FPSIM) assessment algorithm is proposed. The feature accelerated segmentation testing (FAST) algorithm is used to extract feature points of the original image and disturbed image. The target area is obtained via feature-point matching, and the feature-point maintenance as well as stabilization is computed in the target area. The location of the feature points in the original image is obtained, and the local luminance and contrast distortion are compared in the same place of the two images. The normalized FPSIM is obtained via product of the feature-point maintenance, stabilization, luminance distortion and contrast distortion. The luminance imaging experiment is performed for the target by utilizing the laser active imaging system. In the experiment, the disturbed images of different disturbing powers, different intense backgrounds and different spot positions are obtained. The proposed FPSIM algorithm is used to evaluate the newly obtained laser-dazzling images, and the results show that the FPSIM reflects the varieties of the feature points in target recognition objectively. Compared with normalized mean square error (NMSE) and structural simila rity (SSIM), the FPSIM gives a more reasonable evaluation result for different laser-dazzling images. The evaluation results are more suitable for the subjective visual feeling, and FPSIM can also give the guidance of the laser active imaging system defense and application..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 509001 (2014)
A Method for Moving Target Detection on a Moving Camera in the Presence of a Strong Parallax
Chen Haixin, Gu Guohua, Qian Weixian, Chen Qian, and Xu Fuyuan
Based on projective geometry, a relationship between the moving cameras in the presence of a strong parallax is analyzed, and unique constraints are proposed based on surface homography model. Generally, previous works focus on Planar + Parallax or simple geometric constraints such as fundamental matrix, but the degradBased on projective geometry, a relationship between the moving cameras in the presence of a strong parallax is analyzed, and unique constraints are proposed based on surface homography model. Generally, previous works focus on Planar + Parallax or simple geometric constraints such as fundamental matrix, but the degradation cannot be solved. A much more strong constraint is proposed to modify the surface degradation based on fundamental matrix to line degradation based on surface homography, and solves the degradation by modeling, learning and detecting. Unlike previous works, main planar is not needed and degradation is not ignored with no reason, through surface homography model and modeling-learning-detecting framework. Experiments are performed based on actual image data, and the results show that this model can learn the motion of cameras efficiently and be practical on moving target detection with a moving camera with a strong parallax..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 509002 (2014)
Laser Manufacturing
Improvement of Weld Appearance of Laser-Short Circuiting Transfer Metal-Inert Gas (MIG) Hybrid Welded Aluminum Alloys
Cai Xiaoyu, Li Huan, Yang Lijun, and Gao Ying
The weld appearance of short circuiting transfer metal-inert gas (MIG) welded aluminum alloys is poor, and the penetration depth is shallow. Using high-speed camera and synchronous electrical signal acquisition system, the droplets transfer characteristics of aluminum alloys short circuiting transfer MIG welding are stThe weld appearance of short circuiting transfer metal-inert gas (MIG) welded aluminum alloys is poor, and the penetration depth is shallow. Using high-speed camera and synchronous electrical signal acquisition system, the droplets transfer characteristics of aluminum alloys short circuiting transfer MIG welding are studied, and the reasons that the weld appearance is not good are explained. In the process of aluminum alloys laser-arc paraxial hybrid welding, the results show that the droplets transfer characteristics are changed. When the laser power is below the threshold value, the droplets transfer becomes stable, and the appearance of weld are significantly improved. When the laser power exceeds the threshold value, the droplets transfer becomes instable, and there is no obvious improvement of weld appearance. By comparing the weld cross-sections of traditional MIG and laser-MIG welding when using short circuiting transfer welding, it is found that, with the addition of laser, the droplets spread better, residual height decreases, and penetration depth increases. The experiment proves that, to aluminum alloys, the assistance of laser makes the short circuiting transfer MIG welding available and valuable..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 503001 (2014)
Microstructure and High Temperature Wear Resistance Performance of Co/Mesoporous WC Laser Composite Coating
Zhang Qunli, Xu Weixian, Yao Jianhua, Chen Zhaoyang, and Ma Chunan
Diode laser is adopted to clad Co-based powder mixed with meso-porous WC with the same size range on H13 steel. High-performance coating is obtained with the help of meso-porous WC. Scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction analyzer and micro-hardness tester are used to study the mDiode laser is adopted to clad Co-based powder mixed with meso-porous WC with the same size range on H13 steel. High-performance coating is obtained with the help of meso-porous WC. Scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction analyzer and micro-hardness tester are used to study the microstructure, element distribution, phase composition and microhardness of the coating, respectively. The high-temperature wear testing machine is used to test the wear resistance of the cladded layer at room temperature and high temperature for a comparative analysis. The results show that the cladded layer is mainly composed of γ-Co and carbide hard phases WC, Cr3C2, (Cr,Co)23C6 and Cr7C3. Due to the dispersion strengthening and solid solution strengthening effects of meso-porous WC particles on the cladding layer, the hardness of laser cladding layer increases by 2 times approximately when compared to that of the matrix. Because of the effect of carbide hard phases, the wear resistance of the cladded layer at 600 ℃ increases by 3 times related to that of the matrix H13. Oxidative wear is the predominant high temperature wearing mechanism of the coating. With the temperature rising, the oxide film forms on the surface of the cladded layer to protect the coating from high temperature erosion effectively. So the wear resistance of the cladded layer improves with the increase of temperature..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 503002 (2014)
Study on Fiber Laser-Tungsten Inert Gas Hybrid Welding of Titanium Sheet
Ma Ran, Dong Bizhe, Wu Shikai, Yang Wuxiong, and Xiao Rongshi
Fiber laser-tungsten inert gas (TIG) hybrid welding is applied to TC4 sheet with the thickness of 1 mm. The influences of welding parameters such as laser power, arc current, the distance of heat sources and the shielding gas on weld bead formation are studied. The metallographic structure and mechanical properties areFiber laser-tungsten inert gas (TIG) hybrid welding is applied to TC4 sheet with the thickness of 1 mm. The influences of welding parameters such as laser power, arc current, the distance of heat sources and the shielding gas on weld bead formation are studied. The metallographic structure and mechanical properties are also analyzed. The results indicates that with the increasing of arc current and the ratio of He in main shielding gas, the welding fusion area gradually increases. With the increasing of laser power and the distance of heat sources, the welding fusion area changes in fluctuation. The tendency of undercut is related to the heat input of hybrid heat sources. With the rising of concentration and input of the energy, the undercut depth on the back side of the welding seam decreases. The efficiency of shielding is mainly determined by the heat input of arc. The more input heat is, the poorer protective effect is. The tensile strength of hybrid welding joint under optimum welding conditions is larger than the base metal, and the elongation is smaller than the base metal. This is related to the distribution of martensite in the welding seam. The fracture takes place in the base metal..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 503003 (2014)
Experimental Research on High Power Fiber Laser-TIG Hybrid Welding
Li Fei, Zou Jianglin, Kong Xiaofang, Wu Shikai, and Xiao Rongshi
Laser-induced plume affects the process of high-power fiber laser welding. The effect of Tungsten Inert gas (TIG) arc on the plume characteristics and the welding results are investigated. An IPG YLS-6000 fiber laser and a Fronius MagicWave3000job digital welding machine are used in the experiment. The profile of the pLaser-induced plume affects the process of high-power fiber laser welding. The effect of Tungsten Inert gas (TIG) arc on the plume characteristics and the welding results are investigated. An IPG YLS-6000 fiber laser and a Fronius MagicWave3000job digital welding machine are used in the experiment. The profile of the plume and the arc plasma are recorded by a high-speed camera. Furthermore, the weld depth and weld width are measured by a microscope. The fundamental law of TIG arc on plume induced in high power fiber laser welding is studied, and the main mechanism of this effect is analyzed. The results show that, the weld depth of hybrid welding significantly increases by about 20% compared with pure fiber laser welding, and almost isn′t affected by arc current. The weld width gradually improves as arc current increases. The weld depth and weld width are insensitive to the distance between laser and arc within limits. The main effect of TIG arc on plume is the gasification of the particles in plume by high temperature TIG, so the influence of plume on laser beam significantly weakened..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 503004 (2014)
Laser Physics
Accelerated Life Testing Model of Laser Diodes under Space Radiation Stress
Liu Yun, Zhao Shanghong, Yang Shengsheng, Li Yongjun, and Qiang Ruoxin
By analyzing the radiation impact mechanism in space ennironment, the irradiated performance degradation and the annealing effect during radiation are achieved. On the basis, accelerated life testing model under radiation stress is established, the expressions of failure time, accelerate factor, cumulative distributionBy analyzing the radiation impact mechanism in space ennironment, the irradiated performance degradation and the annealing effect during radiation are achieved. On the basis, accelerated life testing model under radiation stress is established, the expressions of failure time, accelerate factor, cumulative distribution function, probability density function and mean time to failure are obtained. Degradation datas under the stresses of 100, 50 and 10 Gy/s are simulated, and parameters in the accelerated life testing model are estimated. The failure time under normal radiation stress (0.03 Gy/s) is 43862 h. Basing on Weibull distribution and the simulated data under the stress of 50 Gy/s, both cumulative distribution function and mean time to failure of laser diodes are calculated, the mean time to failure is about 39755.8 h..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 502001 (2014)
Compactand Low-Noise Intracavity Frequency-Doubled Single-Frequency Nd:YAP/KTP Laser
Yang Wenhai, Wang Yajun, Li Zhixiu, and Zheng Yaohui
The intensity noise characteristics of a compact and low-noise intracavity frequency-doubled single-frequency Nd:YAP/KTP laser is analyzed theoretically and experimentally. By reducing the transmission rate at 1080 nm of the output coupling mirror, optimizing the parameters of the resonator, and so on. The intracavity The intensity noise characteristics of a compact and low-noise intracavity frequency-doubled single-frequency Nd:YAP/KTP laser is analyzed theoretically and experimentally. By reducing the transmission rate at 1080 nm of the output coupling mirror, optimizing the parameters of the resonator, and so on. The intracavity losses decrease to 0.9%. As a result, the intensity noise of the output beam, which induced from vacuum fluctuations, is reduced to a lower level. When the transmission rate at 1080 nm of the output coupling is 0.2%, an output power of 420/60 mW at 540/1080 nm dual wavelengths single-frequency laser is manufactured, and its intensity noise is reduced to shot noise limit above 1.5 MHz..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 502002 (2014)
Low Noise Continuous-Wave Single Frequency 780 nm Laser High-Efficiently Generated by Extra-Cavity-Enhanced Frequency Doubling
Li Hong, Feng Jinxia, Wan Zhenju, and Zhang Kuanshou
Low noise continuous-wave single frequency 780 nm laser is generated high-efficiently by an extra-cavity-enhanced frequency doubler constructed from a periodically poled lithium niobate crystal and a linear cavity that is pumped by a continuous-wave single frequency fiber laser at 1.56 μm. Based on the design of the trLow noise continuous-wave single frequency 780 nm laser is generated high-efficiently by an extra-cavity-enhanced frequency doubler constructed from a periodically poled lithium niobate crystal and a linear cavity that is pumped by a continuous-wave single frequency fiber laser at 1.56 μm. Based on the design of the transmission of input coupler and the waist of cavity to optimize the mode and impedance matching of the frequency doubler, a second-harmonic laser at 780 nm is obtained experimentally with the output power of 1 W and conversion efficiency of 84.8%. Using a high fineness mode cleaner to reduce the laser intensity noise, a low noise 780 nm laser with the output power of 700 mW is achieved and intensity noise reaches the shot-noise-limit at analysis frequency of 4 MHz. The center wavelengths of the laser system at 1.56 μm and 780 nm are in the wave bands of quantum states transmission and quantum storage, respectively, so this kind of system can be employed for researches of practical quantum information processing..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 502003 (2014)
Influence of Phase Distortion on Near Field Beam Quality in Final Target System
Jiao Zhaoyang, Zhang Yanli, Zhang Junyong, and Zhu Jianqiang
There are inevitable defects in optical elements of the final target system, which bring in wavefront distortion. According to the intense light beam propagation characteristics of the final target focusing system of high power laser, a model of localized phase distortion brought by optical elements is established. In There are inevitable defects in optical elements of the final target system, which bring in wavefront distortion. According to the intense light beam propagation characteristics of the final target focusing system of high power laser, a model of localized phase distortion brought by optical elements is established. In final target system, a plane beam with Gaussian phase distortion is focused by the lens and then passes through fused silica, such as the subsequent splash-proof panels, in which nonlinear growth is experienced. The influences of Gaussian phase distortion, thickness of fused silica and focal length on the near field beam quality of the final target focusing system are investigated in detail. Results demonstrate that when the wavefront distortion is more serious, the thickness of fused silica is longer, and the focal length is shorter, the near field beam quality is worse and the growth of middle-high frequency component is bigger..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 502004 (2014)
Ultrafast Thermal Relaxation Characteristics in Gold Film Excited by Shaped Femtosecond Laser Pulses
Yang Qing, Du Guangqing, Chen Feng, Wu Yanmin, Si Jinhai, and Hou Xun
The temporally sequential thermal relaxation model is proposed, in which the Fourier thermal diffusion mechanism is coupled into the two-temperature model for investigation of the full temperature evolution (fs～ns) in Au films under shaped femtosecond laser pulses excitation. The termperature field relaxations in Au fiThe temporally sequential thermal relaxation model is proposed, in which the Fourier thermal diffusion mechanism is coupled into the two-temperature model for investigation of the full temperature evolution (fs～ns) in Au films under shaped femtosecond laser pulses excitation. The termperature field relaxations in Au films are obtained by solving the model. The studies clarify the roles of different thermal relaxation mechnisms in femtosecond laser heating of metal, which have the significance for optimizing ultrafast heating processes during femtosecond laser micro-and nanofabrication..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 502005 (2014)
Two Types of Particle Trapping Using a Partially Coherent Elegant Hermite-Gaussian Beam
Luo Hui, Wang Bing, Yuan Yangsheng, Cui Zhifeng, and Qu Jun
Based on the cross-spectral density function and the Rayleigh scattering theory, analytical expressions of the radiation force on Rayleigh dielectric sphere and beam intensity distribution of a focused partially coherent elegant Hermite-Gaussian beam are theoretically derived and corresponding numerical calculations arBased on the cross-spectral density function and the Rayleigh scattering theory, analytical expressions of the radiation force on Rayleigh dielectric sphere and beam intensity distribution of a focused partially coherent elegant Hermite-Gaussian beam are theoretically derived and corresponding numerical calculations are done. The results denote that when the transverse coherence length degree is large, the focused partially coherent elegant Hermite-Gaussian beam gets a hollow beam profile. Furthermore, the hollow size increases as the beam orders increase. With the decrease of the coherence degree, the focused partially coherent elegant Hermite-Gaussian beam gradually transforms into a Gaussian beam. The light intensity peak decreases as the beam orders increase. Two types of particles with different refractive indexes can be stably trapped in a larger range by changing the degree of spatial coherence and selecting appropriate beam orders, beam waists and focus lengths. The acquired results will have some certain theoretical reference value to optical trapping..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 502006 (2014)
1027 nm Large-Mode-Area Double-Cladding Photonic Crystal Fiber Mode-Locked Laser Based On SESAM
Li Pingxue, Yang Chun, Zhao Ziqiang, Chi Junjie, Yao Yifei, Zhang Guangju, and Hu Haowei
A large-mode-area double-cladding Yb-doped photonic crystal fiber (PCF) mode-locked laser based on semiconductor saturable absorber mirror (SESAM) is reported. Without any pulse compression mechanism, a pulse with duration of 3.3 ps and repetition frequency of 93.33 MHz is generated in a ring cavity when the power coupA large-mode-area double-cladding Yb-doped photonic crystal fiber (PCF) mode-locked laser based on semiconductor saturable absorber mirror (SESAM) is reported. Without any pulse compression mechanism, a pulse with duration of 3.3 ps and repetition frequency of 93.33 MHz is generated in a ring cavity when the power coupling into the fiber reaches 12.2 W. The central wavelength and the spectrum bandwidth are 1027 nm and 1 nm, respectively. When the power coupling into the fiber reaches 14 W, a maximam output power of 150 mW can be achieved. The laser can work stably for 2 h. Q-switched and pulse splitting are observed and analyzed..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 502007 (2014)
Research on Quasi-Coaxial Beams Collimation Technique of Multi-Wavelength Infrared Laser Diode
Xue Mingxi, Chen Zhibin, Wang Weiming, and Wang Xiaoyan
We present a packaging structure of multi-wavelength infrared laser diode and study the beams collimation techniques under this structure for improving beams parallelism of wavelengths at 860 nm, 905 nm and 1064 nm (pulse/single). By the imaging analysis of Gaussian beam in both paraxial and off-axial conditions, we suWe present a packaging structure of multi-wavelength infrared laser diode and study the beams collimation techniques under this structure for improving beams parallelism of wavelengths at 860 nm, 905 nm and 1064 nm (pulse/single). By the imaging analysis of Gaussian beam in both paraxial and off-axial conditions, we summarize and present an imaging theory of “quasi-coaxial” laser beams. The collimating optical system is designed by this imaging theory, and corresponding optical paths are modeling by the optical-design software. A prototype of multi-wavelength laser source is prepared under the guidance of optical paths model, and the parallelisms of “quasi-coaxial” beams are tested by a verification experiment. The experimental results show that the “quasi-coaxial” beams of 860 nm, 905 nm and 1064 nm (pulse/single) have well parallelisms..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 502008 (2014)
Research on Near-Field Angular Power Spectrum Characteristics of High Frequent Light in High Energy Chemical Oxygen Iodine Laser
Wei Jifeng, An Jianzhu, Su Yi, Chen Xingwu, Wan Min, Zhang Wei, and Fan Guobin
Much high frequent light exist in the near-field of the high energy chemical oxygen iodine laser (COIL), which cause serious harm to beam quality and system near the high power beam tune. So it is necessary to study the propagation laws of the high frequency light. The generating mechanism and characteristics of differMuch high frequent light exist in the near-field of the high energy chemical oxygen iodine laser (COIL), which cause serious harm to beam quality and system near the high power beam tune. So it is necessary to study the propagation laws of the high frequency light. The generating mechanism and characteristics of different high frequent light are analyzed. Since the diffraction of cavity mirror and higher-order modes contribute to most of the high frequent light, they are main objects of the study. The energies of different positions are measured by the measurement diaphragm set in the beam tune. The angular power spectra of the high frequent light are calculated according to the corresponding space angles on the diaphragm. The angular power spectrum curves changing with the duration are analyzed by three different methods, and the accordant results are got. The research results show that the angular power spectrum in the front is bigger than that in the back, and the angular power spectrum increases with the deterioration of beam quality, and in the same time, the energy loss may enhance, too. The power and energy on each defending diaphragm can be calculated with the angular power spectra, which lays a good foundation of heat control technology for the high energy COIL..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 502009 (2014)
1064 nm Nd:YVO4 Laser Pumped by Wave-Locked 878.6 nm Laser Diode
Li Bin, Ding Xin, Zhang Wei, Sheng Quan, Fan Chen, Zhang Haiyong, Jiang Pengbo, Liu Jian, Yao Jianquan, Sun Bing, and Wang Peng
A Nd:YVO4 laser at 1064 nm pumped by a wave-locked 878.6 nm laser diode is achieved. An output power of 5.75 W at 1064 nm for an absorbed pump power of 7.41 W, corresponding to an optical efficiency of 80.2%, optical to optical efficiency of 77.6%. The temperature characteristics of wave-locked 878.6 nm, wave-unlocked A Nd:YVO4 laser at 1064 nm pumped by a wave-locked 878.6 nm laser diode is achieved. An output power of 5.75 W at 1064 nm for an absorbed pump power of 7.41 W, corresponding to an optical efficiency of 80.2%, optical to optical efficiency of 77.6%. The temperature characteristics of wave-locked 878.6 nm, wave-unlocked 808 nm and 878.6 nm pump laser are also researched. The result shows that wave-locked 878.6 nm pumped Nd:YVO4 laser has excellent output stability when the temperature varies from 10 ℃ to 40 ℃..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 502010 (2014)
A PbWO4 Solid-State Raman Amplifier Excited by 1064 nm Nanosecond Pulses
Zhang Wenhui, Ding Shuanghong, Ding Ze, Jia Haixu, and Liu Jiajia
The output properties of an extracavity PbWO4 Raman laser are investigated. A PbWO4 solid Raman amplifier is also presented. The extracavity PbWO4 Raman laser and PbWO4 solid Raman amplifier are both pumped by an electro-optically Q-switched Nd:YAG laser. For the extra cavity PbWO4 Raman laser, with incident pulse enerThe output properties of an extracavity PbWO4 Raman laser are investigated. A PbWO4 solid Raman amplifier is also presented. The extracavity PbWO4 Raman laser and PbWO4 solid Raman amplifier are both pumped by an electro-optically Q-switched Nd:YAG laser. For the extra cavity PbWO4 Raman laser, with incident pulse energy of 40 mJ, the obtained maximum conversion efficiency of the first Stokes is 13%. When the pump energy is 48 mJ, the obtained maximum pulse energy and conversion efficiency of the second Stokes are 11 mJ and 23%, and the conversion efficiency of the full scattering laser is 34%. For the PbWO4 solid Raman amplifier, the maximum output energy of the amplifying first Stokes pulse and the amplification factor are 11 mJ and 3.3..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 502011 (2014)
Materials and Thin Films
Growth Method, Optical and Laser Properties of Titanium-Doped Sapphire Crystals
Zhang Xiaocui, Si Jiliang, Xu Min, Liang Xiaoyan, and Chu Yuxi
Large-sized titanium doped sapphire (TiAl2O3) crystal with high quality is grown by the temperature gradient technique (TGT). The as-grown crystal has an excellent absorption features in 300~900 nm. The doping uniformity of titanium is demonstrated by measuring the absorption fluctuation in cross-section of the crystalLarge-sized titanium doped sapphire (TiAl2O3) crystal with high quality is grown by the temperature gradient technique (TGT). The as-grown crystal has an excellent absorption features in 300~900 nm. The doping uniformity of titanium is demonstrated by measuring the absorption fluctuation in cross-section of the crystal. The transmittance of TiAl2O3 is measured in 200~1100 nm, and a figure of merit (FOM) is evaluated above 240. The laser quality of TiAl2O3 in both static and single pulsed amplifier system are outstanding without distortion, and the amplified output energy achieves international level..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 506001 (2014)
Optical Characteristics of GaAsP/GaInP Quantum Well Grown by Metal-Organic Chemical Vapor Deposition
Yuan Huibo, Li Lin, Qiao Zhongliang, Kong Lingyi, Gu Lei, Liu Yang, Dai Yin, Li Te, Zhang Jing, and Qu Yi
GaAsP/GaInP quantum wells are grown on different misoriented substrates by low pressure_metal-organic chemical vapor deposition (LP_MOCVD) technique. The samples are characterized via photo luminescence (PL) spectroscopy at room temperature. The effect of the growing temperature of barrier layer、 Ⅴ/Ⅲ ratio of quantum wGaAsP/GaInP quantum wells are grown on different misoriented substrates by low pressure_metal-organic chemical vapor deposition (LP_MOCVD) technique. The samples are characterized via photo luminescence (PL) spectroscopy at room temperature. The effect of the growing temperature of barrier layer、 Ⅴ/Ⅲ ratio of quantum well layer and offcut substrate to emitting wavelength、 PL intensity and full-width at half-maximum (FWHM) is discussed. Samples with lower barrier growing temperature shows higher PL intensity. The PL intensity will increase when the Ⅴ/Ⅲ ratio of quantum well layer decreases, and the PL peak exhibits a red shift at the same time. Samples grown on substrate (100) oriented 15° off towards <111> exhibit the highest PL intensity and narrowest FWHM..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 506002 (2014)
Deposition of Nano-Diamond Film by Double Beam Pulse Laser Irradiation of Graphite Suspension
Yang Huimin, Ren Xudong, Zheng Lamei, Ren Naifei, and Tang Shaoxiong
High-quality and large area nano-diamond film is prepared via double beam pulse laser irradiation of graphite suspension. The inhomogeneity of diamond films and influence of substrate temperature are improved. The microstructure and composition of the diamond films are detected by the visible Raman spectroscopy and higHigh-quality and large area nano-diamond film is prepared via double beam pulse laser irradiation of graphite suspension. The inhomogeneity of diamond films and influence of substrate temperature are improved. The microstructure and composition of the diamond films are detected by the visible Raman spectroscopy and higher solution transmission electron microscopy. The experimental result demonstrates that the Raman spectroscopy reveals that disorder peak is at 1334 cm-1 and graphite peak is at 1571 cm-1, the diamond film is compact and homogeneous, its average crystalline grains are around 5 nm. The composite beam provides moderate temperature for the growth of diamond films, and the continuous synthesis of homogeneous nano-diamond films is realized at normal temperatures and pressures..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 507001 (2014)
Measurement and Metrology
Calibration of Camera with Rational Function Lens Distortion Model
Huang Junhui, Wang Zhao, Xue Qi, and Gao Jianmin
Camera imaging model is a key factor to determine the accuracy of vision measurement. With the increasingly demand for accuracy in visual measurement, improvement of the accuracy of camera model and calibration are primary means to solve the accuracy problem. A new model of the rational function lens distortion model iCamera imaging model is a key factor to determine the accuracy of vision measurement. With the increasingly demand for accuracy in visual measurement, improvement of the accuracy of camera model and calibration are primary means to solve the accuracy problem. A new model of the rational function lens distortion model is introduced into the camera imaging model, which can better correct the errors caused by lens distortion, and thereby, it can improve the accuracy of the camera imaging model. Moreover, a two-step and step-iterative optimization method is proposed to precisely obtain the parameters of camera imaging model and to solve the problem that the parameters of the rational function lens distortion model cannot be solved directly. The experimental results demonstrate that the accuracy of the camera imaging model with the new distortion correction model is better than the conventional model and the new model can also effectively reduce the large errors. Therefore, the new camera imaging model and calibration method can improve the accuracy of visual measurement comprehensively..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 508001 (2014)
A Binocular Matching Algorithm Based on Similar Image Geometric Features
Xie Zexiao, and Lu Wenjuan
Concerning the high probability of mismatching and matching-loss that exists in traditional epipolar constraint matching algorithm, an algorithm based on similar image geometric features is proposed for binocular matching. The initial matching points which locate in the same or different epipolar lines are identified rConcerning the high probability of mismatching and matching-loss that exists in traditional epipolar constraint matching algorithm, an algorithm based on similar image geometric features is proposed for binocular matching. The initial matching points which locate in the same or different epipolar lines are identified respectively using epipolar geometric constraint algorithm. According to the position similarity of matching points, maximum vector angle criterion and maximum angle difference criterion are derived. In order to match the points locat in different epipolar lines, utilizing disparity gradient limited constraint as well as maximum vector angle criterion, a mismatching elimination algorithm based on updating strategy is proposed, which can reduce the rate of mismatching and erroneous elimination. For the initial matching points locating in the same epipolar line, maximum angle difference and maximum vector angle criterion are used to extract candidate matching points. These candidate matching points are further examined, thus decreases the rate of matching-loss. Experimental results indicate that the algorithm has high matching accuracy and versatility. The incidence rate of mismatching and matching-loss can be controlled within 0.1% and 7%, respectively, and the algorithm is appropriate for objects with different structural complexity..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 508002 (2014)
A Thirteen-Step Phase Restoration Algorithm in Lateral Shearing Interferometry
Fang Chao, and Xiang Yang
Lateral shearing interferometer can achieve ultra-high-precision measurement of the optical system aberration. It is currently an important component content of the projection lens development. Two main factors affecting lateral shearing interferometry measurement accuracy are 0th order effect and phase shift error. ThLateral shearing interferometer can achieve ultra-high-precision measurement of the optical system aberration. It is currently an important component content of the projection lens development. Two main factors affecting lateral shearing interferometry measurement accuracy are 0th order effect and phase shift error. Therefore, a thirteen-step phase restoration algorithm in phase shearing interferometry is proposed. It can 0th zeroth order effect and greatly reduce the phase shifting error demanding. Analysis shows that when the phase shift error is not more than 25° the phase restoration error is less than 0.01° (2.8×10-5λ). For λ=193.386 nm, wavefront restoration error is less than 0.005 nm. Thus, by system error correction wavefront measurement of projection lens of phase shearing interferometer can achieve sub-nanometer accuracy..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 508003 (2014)
Application Laser Ultrasound Imaging Technology for Detecting Defect Based on Hilbert Transform
Zeng Wei, Wang Haitao, Tian Guiyun, Fang Lin, and Wang Wen
This paper describes a method of laser ultrasonic propagation imaging based on Hilbert transform. The ultrasonic signals are excited by pulsed laser on the measured material surface. Then ultrasonic signal is transformed by Hilbert transfrom. and time-domain waveforms of analyzed measured ultrasonic signal propagation.This paper describes a method of laser ultrasonic propagation imaging based on Hilbert transform. The ultrasonic signals are excited by pulsed laser on the measured material surface. Then ultrasonic signal is transformed by Hilbert transfrom. and time-domain waveforms of analyzed measured ultrasonic signal propagation. Finally, ultrasonic signal propagation in the material is displayed by ultrasound imaging technology. The experimental results show that taking the ultrasonic signal Hilbert transform method can not only effectively extract the ultrasonic signal propagation at the defect, but also the shape, size and distribution of surface defects can be intuitive, efficiently detected by ultrasonic propagation imaging. Hence, the Hilbert-transform ultrasonic propagation imaging technology provides a method for quantitative detection of defects in manufacturing..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 508004 (2014)
Study of Improved Phase Unwrapping Algorithm Based on Least Squares
Guo Yuan, and Chen Xiaotian
Among all the present phase unwrapping algorithms, the main idea is to get the real phase directly. However, the meaning of phase unwrapping coefficient k is rarely taken into account. A new algorithm to gain directly the value of k based on least-square (LS) phase unwrapping algorithm is proposed. It can unwrap the phAmong all the present phase unwrapping algorithms, the main idea is to get the real phase directly. However, the meaning of phase unwrapping coefficient k is rarely taken into account. A new algorithm to gain directly the value of k based on least-square (LS) phase unwrapping algorithm is proposed. It can unwrap the phase more rapidly and accurately. On this basis, a new phase unwrapping method is put forward. It not only improves the accuracy of phase unwrapping, but also reduces the time of phase unwrapping and accelerates the running speed of the program. Experiments show that the algorithm is feasible. It provides a new way for large amount of calculation in phase unwrapping with high speed and precision..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 508005 (2014)
System Errors Analysis of Grating Lateral Shearing Interferometer
Li Jie, Tang Feng, Wang Xiangzhao, Dai Fengzhao, and Feng Peng
Based on analysis of the typical structure and system configuration parameters of grating lateral shearing interferometer, we systematically study the most significant errors of the interferometer system: geometric optical path difference and detector tilt error. We give the analytical expression of systematic errors bBased on analysis of the typical structure and system configuration parameters of grating lateral shearing interferometer, we systematically study the most significant errors of the interferometer system: geometric optical path difference and detector tilt error. We give the analytical expression of systematic errors before and after wavefront reconstruction in the form of Zernike polynomials. The relationship between the system errors and the measured numerical aperture (NA), the distance of diffracted light converging point d, the shear ratio s are quantitatively analyzed. The most important errors for differential wavefront of shearing interferometer are the coma and astigmatism of geometric optical path difference, the astigmatism and defocus of detector tilt. These error terms will cause the errors of spherical aberration and coma of geometric optical path difference, the coma and astigmatism of detector tilt through wavefront reconstruction. The error of reconstructed wavefront increases rapidly with the increasing of NA、d, but increases with the decreasing of s. Especially, the wavefront reconstruction has gained effect on system errors with small shear ratio (s≤0.05), and the system errors of wavefront reconstruction is much larger than the differential wavefront. The root-mean-square (RMS) of reconstructed wavefront error is much greater than 1nm under small shear ratio when d>2 μm, NA>0.1..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 508006 (2014)
Measurement of Steel Ball Surface Flaw Based on Dual Wavelength Interferometry and Digital Phase Detection
Pan Weiqing, and Zhao Xiaobo
A measurement method of steel ball surface flaw based on dual wavelength interferometry and digital phase detection is presented. An illumination optical path is designed based on a wavefront matching method. With this optical path the steel ball is illuminated with the max solid angle when the radius of curvature of tA measurement method of steel ball surface flaw based on dual wavelength interferometry and digital phase detection is presented. An illumination optical path is designed based on a wavefront matching method. With this optical path the steel ball is illuminated with the max solid angle when the radius of curvature of the incident optical wave is equal to that of the steel ball. And the max solid angle of illumination is dependent on the numerical aperture of the objective lens. Dual wavelength interferometry and digital phase procession are applied to gain the wrapped phase at an equivalent wavelength. The phase ambiguities in the single wavelength phase data are removed to extend the axial measurement range using the equivalent wavelength results. The phase distortion of inclination and spherical aberration is adjusted with application of a phase mask calibrated beforehand. After that high precision three-dimensional data of the steel ball surface can be acquired and applied for surface flaw measurement. Experiments using this technique are shown for the measurement of steel surface flaw and roughness. The results demonstrate the effectiveness of the proposed method..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 508007 (2014)
Development of a Laser-Based Geometric Measurement System for Large-Scale Conical
Zhou Sen, Guo Yongcai, and Gao Chao
According to the characters of large-scale conical workpieces, a novel rapid on-machine geometric measurement system integrating three-dimensional (3D) laser scanning and virtual environments is proposed. In the system, key parts of upper surface of two ends of workpiece are fast captured by two static laser scanners. According to the characters of large-scale conical workpieces, a novel rapid on-machine geometric measurement system integrating three-dimensional (3D) laser scanning and virtual environments is proposed. In the system, key parts of upper surface of two ends of workpiece are fast captured by two static laser scanners. Vertical and horizontal virtual datum planes are respectively established based on the characters of end planes in order to construct 3D virtual measurement space. The positions of end points are then identified and located by the respect of their height features. Thus, both the center and the diameter of end planes can be obtained by the use of space projection theory and least square method. The height and the taper half-angle can be calculated by the geometric relationship of the center of end planes in 3D measurement space, respectively. The experiments on several typical large-scale conical workpieces are performed. Results indicate that the system can offer the resolution less than 10 μm, measuring precision over 100 μm to the height and the diameter, and it can offer the resolution less than 0.001°, measuring precision over 0.010° to the taper half-angle. According to the actual operation results, this proposed measuring system based on human-computer interaction can be well acceptable for application as on-line geometric detection for large-scale conical workpieces in industrial production..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 508008 (2014)
Micro and Nano Optics
Unidirectional Excitation of Surface Plasmon Based on Metallic Slit-Groove Structure
Chen Quansheng, Tong Yuying, Zhuang Yuan, Jiang Xiaoyue, Gu Lei, Wang Jicheng, and Wang Yueke
Unidirectional excitation of surface plasmon polaritons has been applied widely in optical communication, integrated optics, lithography and so on. A subwavelength structure of metallic slit-groove in theory is proposed. This structure achieves unidirectional excitation of surface plasmon polaritons along the metallic Unidirectional excitation of surface plasmon polaritons has been applied widely in optical communication, integrated optics, lithography and so on. A subwavelength structure of metallic slit-groove in theory is proposed. This structure achieves unidirectional excitation of surface plasmon polaritons along the metallic film under back illumination. During our design, finite-difference time-domain method (FDTD) is adopted for numerical simulation. At first, the electric field intensity of surface plasmon polaritons which transmits through the groove can reach minimum by changing the depth and width of the groove, and the physical mechanism can be explained with the scattering matrix theory very well. Then based on surface plasmons′ interference principle, the interference of surface plasmon polaritons, which propagate along the side deviating from the groove, can be strengthened by changing the distance between the slit and groove. Thereby, the metallic slit-groove structure realizes unidirectional excitation of surface plasmon polaritons. The maximum splitting ratio can reach up to 8..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 510001 (2014)
Optical Communication
Research of Twin-Core Optical Fiber Polarization Beam Splitter with Input and Output Waveguides
Mao Yanping, Ji Minning, Xie Qingming, and Liu Zhen
Based on modes interference, twin-core optical fiber polarization beam splitter can spatially separate different polarized incident lights according to the coupling length difference of the two orthogonal polarization states. Making the dual-core optical fiber as a directional coupler, the power and polarization selectBased on modes interference, twin-core optical fiber polarization beam splitter can spatially separate different polarized incident lights according to the coupling length difference of the two orthogonal polarization states. Making the dual-core optical fiber as a directional coupler, the power and polarization selectivity of the twin-core optical fiber polarization beam splitter are affected by the shape and size of the input and output waveguides when the light goes through the twin-core coupling area. Based on an elliptical twin-core optical fiber beam splitter and the RSOFT-Beamprop numerical calculation, the effects of the shape and size on the polarization selectivity, the bandwidth and fabrication tolerance are researched under the required extinction ratio (≥20 dB). The results show that the shape of twin-core optical fiber beam splitter is S-Bend, the input and output waveguide size is 40 μm and 4000 μm in the transversal X and longitudinal Z direction, respectively. Bandwidth of input light can greater than 7.5 nm and its coupled length is as comparatively short as about 209.87 mm..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 505001 (2014)
Influences of Compton Scattering to Temporal Evolution of Plasma Density in Femto-Second Light Filaments
Hao Dongshan
The influences of Compton scattering to temporal evolution of plasma density in femto-second light filaments are studied by using Compton scattering model, plasma time-section model and number computing means. A new mechanism that the electron crest density in the plasma is changed by Compton scattering is proposed. ThThe influences of Compton scattering to temporal evolution of plasma density in femto-second light filaments are studied by using Compton scattering model, plasma time-section model and number computing means. A new mechanism that the electron crest density in the plasma is changed by Compton scattering is proposed. The amended dynamic equations of charged particles are given out, and the equations are computed by numerical method. The results show that the time the plasma need to be conductive is reduced by Compton scattering, the increasing of electron density in the ionization area is in quasi-saturated state, the electron densities in the ionization decreased area is almost constant, and the differences of the ionization contribution rates of different pulses are very little. The O2 ionization contribution rate decreases along with the increase of the light intensity of the pulse section and the O2 ionization contribution rate is finally overstepped by the N2 contribution rate. The electron crest density increases in plasma channel and the channel lifetime is extended as well. Under the same crest density, the increases of the electron crest density produced by the long or short pulses are almost the same, and the increases are rather smaller after scattering..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 505002 (2014)
Numerical Simulation and Analysis of Photonic Crystal Fibers with High Nonlinearity and Flattened Chromatic Dispersion
Li Xuyou, Xu Zhenlong, Ling Weiwei, Guo Hui, and Wang Suier
A novel structure of photonic crystal fiber (PCF) is proposed ,and the dispersion and nonlinear properties of the PCF are analyzed numerically based on full vector finite element method. Three PCFs with high linearity and nearly-zero flattened dispersion or broadband flattened even ultra-flattened dispersion in differeA novel structure of photonic crystal fiber (PCF) is proposed ,and the dispersion and nonlinear properties of the PCF are analyzed numerically based on full vector finite element method. Three PCFs with high linearity and nearly-zero flattened dispersion or broadband flattened even ultra-flattened dispersion in different wave bands are obtained by optimizing the structure parameters, and the method is presented to fabricate the microstructured fiber preform as well. These novel PCFs proposed have bright prospects of applications in all-optical format conversion, super-continuum generation and optical wavelength conversion，and other fields..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 505003 (2014)
Modified Optical-Signal-Noise-Ratio Monitoring Method Based on High Order Statistical Moment in PM-QPSK Coherent Optical System
Zhang Lei, Zhang Xiaoguang, Xi Lixia, Zhao Donghe, Tang Xianfeng, and Zhang Xia
For polarization multiplexed quadrature phase shift keying (PM-QPSK) coherent receiver system, a modified optical-signal-noise-ratio (OSNR) monitoring method based on high order statistical moment is presented. The calibration value of different modulation formats and the tolerance of residual chromatic dispersion (CD)For polarization multiplexed quadrature phase shift keying (PM-QPSK) coherent receiver system, a modified optical-signal-noise-ratio (OSNR) monitoring method based on high order statistical moment is presented. The calibration value of different modulation formats and the tolerance of residual chromatic dispersion (CD) and polarization mode dispersion (PMD) for the modified method are investigated. The proposed method is verified in numerical simulations in 112 Gb/s PM-QPSK coherent receiver system, and the OSNR measurement error is within 0.5 dB for all modulation formats with a wide range from 8 dB to 26 dB. The method also has a CD tolerance of 2800 ps/nm and a first-order PMD tolerance of 65 ps if the acceptable error is set to 0.5 dB when real OSNR is around 14 dB, and it is available in real time and in-band OSNR measurement of PM-QPSK coherent receiver system with lower computation complexity and without the requirement of extra monitoring device..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 505004 (2014)
A High-Efficiency Tunable Polarization-Insensitive Wavelength Convertor Based on Degenerate Four-Wave Mixing in a Highly Nonlinear Photonic Crystal Fiber
Huang Xinning, Xie Xiaoping, Zhao Wei, Han Biao, and Feng Huan
A high-efficiency tunable polarization-insensitive all-optical wavelength convertor for 10 Gb/s return-to-zero on-off keying (RZ-OOK) signals using degenerate four-wave mixing (FWM) in a highly nonlinear photonic crystal fiber (PCF) is demonstrated. The residual birefringence in the 50 m dispersion-flattened PCF with 1A high-efficiency tunable polarization-insensitive all-optical wavelength convertor for 10 Gb/s return-to-zero on-off keying (RZ-OOK) signals using degenerate four-wave mixing (FWM) in a highly nonlinear photonic crystal fiber (PCF) is demonstrated. The residual birefringence in the 50 m dispersion-flattened PCF with 11 W-1·km-1 nonlinear coefficient guarantees the FWM-based wavelength conversion to be polarization-insensitive when the pump polarization is exactly at 45°to the birefringent axes of the PCF. Experimental results show that with 45°pump launch, the polarization dependence of FWM in the PCF can be decreased to less than 0.6 dB over the entire 25 nm conversion bandwidth. The optical signal-to-noise ratios (OSNR) of the converted signals are better than 40 dB and the conversion efficiencies are better than -15 dB over the conversion range with 10 Gb/s signal polarization-scrambled..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 505005 (2014)
High Sensitive Fiber Bragg Grating Vibration Sensor Based on Averaged Periodogram Method
Chen Xi, and Dong Xiaopeng
Fiber Bragg grating (FBG) sensor monitor the micro-vibration in harsh environment is adopted. The micro-vibration cannot be detected when FBG sensor signal has low signal noise ratio (SNR) (less than 1). The averaged periodogram method is used to improve the sensitive. It divides the signal into N segments，fast FourierFiber Bragg grating (FBG) sensor monitor the micro-vibration in harsh environment is adopted. The micro-vibration cannot be detected when FBG sensor signal has low signal noise ratio (SNR) (less than 1). The averaged periodogram method is used to improve the sensitive. It divides the signal into N segments，fast Fourier transform (FFT) is performed on each data segments, then averaging the N power spectrum to get the new power evaluation. The primary results show, SNR is improved by 15.6 dB in frequency domain after the treatment with averaged periodogram method, and the FBG detection sensitivity is up to 1.5 fm. This high-accuracy sensor can be used in sustained vibration detection in structural health monitoring. It is important to increase the detection accuracy of the micro-vibration..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 505006 (2014)
Defective Pixel Correction of Spot-Detecting Camera in Satellite-to-Ground Laser Communication ATP System
Qian Feng, Jia Jianjun, Zhang Liang, and Wang Jianyu
The function of spot-detecting camera in satellite-to-ground laser communication acquisition, tracking, pointing (ATP) system is expounded. When defective pixels exist on the detector, the false alarm rate and positioning accuracy of spot-detecting camera will be affected. The kinds and sources of defective pixels on mThe function of spot-detecting camera in satellite-to-ground laser communication acquisition, tracking, pointing (ATP) system is expounded. When defective pixels exist on the detector, the false alarm rate and positioning accuracy of spot-detecting camera will be affected. The kinds and sources of defective pixels on matrix detector are analyzed. The characteristics of spot-detecting camera in satellite-to-ground laser communication ATP system are also analyzed. According to these characteristics of camera, the real time method of defective pixel check and correction is explained. A spot-detecting camera based on STAR-1000 sensor is designed, which also uses the correction method. Some tests are carried out to verify the correction method. The results show that the real time correction method can restrain defective pixels effectively and the gray value of defective pixels will be corrected. Because this method has short delay and it can reduce the positioning error when the camera has defective pixels, it cna well apply to the satellite-to-ground laser communication ATP system..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 505007 (2014)
Refractive Index Sensing Characteristics of a Mach-Zehnder Interferometer Based on Directly Photonic Crystal Fiber
Bi Weihong, Shen Yuan, Liu Qiang, Fu Guangwei, Fu Xinghu, and Ji Yushen
Based on a directly melting-collapsed tapered photonic crystal fiber (PCF), a novel Mach-Zehnder interferometer (MZI) sensor is proposed. The taper region is formed directly by arc discharge. By controlling the parameters and times of arc discharge, the taper geometry can be flexibly controlled. The output spectra undeBased on a directly melting-collapsed tapered photonic crystal fiber (PCF), a novel Mach-Zehnder interferometer (MZI) sensor is proposed. The taper region is formed directly by arc discharge. By controlling the parameters and times of arc discharge, the taper geometry can be flexibly controlled. The output spectra under different taper lengths are discussed, and the relationship between the wavelength shifts and the refractive index(RI) is investigated. Experimental results show that with the increase of taper length, the free spectral range of MZI output spectrum decreases in the whole wavelength range, and decreases from 33.38 nm to 7.86 nm nearby 1554.34 nm. When the RI ranges from 1.3414 to 1.3862, the refractive index sensitivity of the sensor reaches 276.38 nm/RIU (RIU is refractive index unit)..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 505008 (2014)
Line-of-Sight Initial Alignment Model and Test in Dynamic Space Laser Communication
Zhao Xin, Liu Yunqing, and Tong Shoufeng
A cquisition, pointing, and tracking is an important component in space laser communication. It is the premise and guarantee to normal work. Line-of-sight initial alignment is researched in detail and initial alignment model is proposed. Coordinate conversion method is used to solve alignment affect to azimuth and pitcA cquisition, pointing, and tracking is an important component in space laser communication. It is the premise and guarantee to normal work. Line-of-sight initial alignment is researched in detail and initial alignment model is proposed. Coordinate conversion method is used to solve alignment affect to azimuth and pitch angle, by compensating position change, attitude varying, difference to installation datum, initial zero inconsistent. Calibration method on initial alignment line-of-sight is proposed. Acquisition uncertain area and alignment accuracy are determined according to error theory. In dynamic aircraft to aircraft, the initial alignment performance is tested by using the parameters of position, attitude provided by double antenna global position system/inertial narigation system (GPS/INS). Area of uncertainty measured by observation camera is 10 mrad and it is consistent with theoretical analysis results..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 505009 (2014)
Rapid Communications
[in Chinese]
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 502004 (2014)
[in Chinese]
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 505007 (2014)
Remote Sensing and Sensors
High-Sensitivity Gas Sensor Based on Suspended Core Subwavelength Fiber
Luan Nannan, Wang Ran, Hao Congjing, Yuan Cai, Lu Ying, and Yao Jianquan
A suspended-core fiber (SCF) with subwavelength core diameter is numerically analyzed for gas sensing application. The dependence of the relative sensitivity, effective mode area, and confinement loss on the fiber parameters as well as the refractive index of fiber material is investigated with finite element method. TA suspended-core fiber (SCF) with subwavelength core diameter is numerically analyzed for gas sensing application. The dependence of the relative sensitivity, effective mode area, and confinement loss on the fiber parameters as well as the refractive index of fiber material is investigated with finite element method. The simulation results show that the relative sensitivity and confinement loss will increase with the decrease of the core diameter and the fiber refractive index. The effective mode area decreases at first, and then increases when the fiber core decreases to a certain value. The confinement loss decreases dramatically with the increase of the air hole diameter, while the relative sensitivity and effective mode area remain unchanged. These results prove that the proposed SCF with subwavelength core diameter is very promising for developing a high-sensitivity gas sensor with large effective mode area and low confinement loss..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 514001 (2014)
New Absolute Spectral Irradiance Source with Wide Band and Monochromatic Light Outputing
Zhang Zihui, Wang Shurong, and Huang Yu
With the development of optical remote sensing technology, spectral radiometric calibration got more and more attention. Currently, the integrating sphere is the main tool to make radiometric calibration in ultraviolet and visible band. However, the integrating sphere cannot output the monochromatic light, and the stabWith the development of optical remote sensing technology, spectral radiometric calibration got more and more attention. Currently, the integrating sphere is the main tool to make radiometric calibration in ultraviolet and visible band. However, the integrating sphere cannot output the monochromatic light, and the stability of the output is not enough. In order to solve these problems, we propose a new method of absolute spectral irradiance source based on double Féry subtraction structure. With the design and simulation of Zemax, the spectral range of the new spectral irradiance source is 240~2400 nm; and the spectral bandwidth at 350, 600, 1000 nm are less than 3, 9, 29 nm respectively; the uniformity of the output is less than 1.9% within Ф50 mm or 1.4% within Ф30 mm; the degree of the polarization is less than 0.7% in full aperture. The new irradiance source can be used to measure the spectral response and geometric calibration of the detector or remote sensing instrument in a wide range of spectra. The new radiation source used with polarizers can be used to measure the polarization response of instruments. Which has a wide range of applications..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 514002 (2014)
Spectroscopy
Measurement of Alkali Concentration in Dioded Pumped Alkali Vapor Lasers by 100 GHz Spectral Scanning
Que Yiqin, Wang Hongyan, Yang Zining, Hua Weihong, and Xu Xiaojun
Diode-pumped alkali vapor laser (DPAL) has great potential in high power scaling due to its high quantum efficiencies, convenient thermal management by flowing the gaseous medium, all-electric operation, light weight and compact configuration, etc. The measurement of alkali concentration inside the gain medium is necesDiode-pumped alkali vapor laser (DPAL) has great potential in high power scaling due to its high quantum efficiencies, convenient thermal management by flowing the gaseous medium, all-electric operation, light weight and compact configuration, etc. The measurement of alkali concentration inside the gain medium is necessary and important to analyze the laser performance. By scanning the wavelength of the single-frequency distributed Bragg reflector (DBR) laser, the absorption spectrum of rubidium vapor is measured. By using the spectral matching method which is realized by integrated adjustment of the DBR′s driven current and operation temperature, the mode-hop free tuning range of DBR laser is extended from 23 GHz to 100 GHz. And the full absorption spectrum of rubidium D1 line is well scanned with buffer gas at an atmospheric pressure. By compared with the theoretical result, the concentration of alkali atom is obtained. This method can be applied for the measurement of alkali concentration under conditions of high power pumping with a flowing medium..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 515001 (2014)
Study on Plasma Characteristics of Fly Ash in Different Gas Environments
Shen Yueliang, Li Xu, Liu Yaming, Fan Ju, Chen Qianming, Lu Jidong, and Yao Shunchun
Using laser-induced breakdown spectroscopy (LIBS), the main elements in fly ash, including C, Si, Al, Mg and Fe, are measured. KBr is employed as binder to press the fly ash powder to pellets. The differences of fly ash plasma characteristics in different gas environments (CO2, air, N2, Ar ) are analyzed, and their effUsing laser-induced breakdown spectroscopy (LIBS), the main elements in fly ash, including C, Si, Al, Mg and Fe, are measured. KBr is employed as binder to press the fly ash powder to pellets. The differences of fly ash plasma characteristics in different gas environments (CO2, air, N2, Ar ) are analyzed, and their effects to unburned carbon measurements are studied. The results show that the spectral intensities obtained in argon are the highest among the four environments, and intensities in nitrogen take the second place. The intensities in air atmosphere are just a little less than those in nitrogen, while those in carbon dioxide are the least. Furthermore, carbon element in CO2 disturbs the unburned carbon analysis extremely. Comparing the plasma temperatures in different environments, plasma in CO2 atmosphere get the lowest temperature, implying it is the hardest to induce in CO2..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 515002 (2014)
Quantitative Measurement and Analysis of Potassium in Soil Using Laser-Induced Breakdown Spectroscopy
Meng Deshuo, Zhao Nanjing, Liu Wenqing, Ma Mingjun, Wang Yin, Yu Yang, Fang Li, Hu Li, Zhang Dahai, Yang Ruifang, Wang Jiuyue, and Liu Jianguo
It has great significance to achieve the fast, in-situ measurement of potassium content in soil to the fertilization in farmland and agricultural production management. The spectroscopy emission characteristics of potassium in soil are studied based on laser-induced breakdown spectroscoy techinque with a 1064 nm waveleIt has great significance to achieve the fast, in-situ measurement of potassium content in soil to the fertilization in farmland and agricultural production management. The spectroscopy emission characteristics of potassium in soil are studied based on laser-induced breakdown spectroscoy techinque with a 1064 nm wavelength NdYAG laser as the excitation source, the echelle spectroscopy with high resolution and wide spectral range as the spectral separation device and the intensified charge coupled device (ICCD) as the spectral detection device. With the spectral line of 769.90 nm as the analytical line, the best detection delay time is 1 μs, gate time is 5.2 μs, and the limit of detection is 0.006858%. The calibration curve of soil samples is obtained. While the relative error between the predicted value and true value is within 5%. 12 different types of soil with different matrix effects are measured. The result shows that, for the actual quantitative measurement of soil samples with different matrix types, they need to be calibrated respectively. The research result provides a reference for the fast, in-situ quantitative measurement of potassium in soil..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 515003 (2014)
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