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2014
Volume: 51 Issue 3
30 Article(s)
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Fiber Optics and Optical Communications
Measurement of Beat-Length for Low-Birefringence Fibers Based on Wavelength Modulation
Xu Hongjie, and Feng Yu
A measurementof beat-length in low-birefringence fibers based on wavelength modulation is shown. It measures the beat- length by wavelength modulation. Phase detection is chosen to reduce the error from environment influence. Phase compensation plate isused to ensure the testing system always sensitive to the change ofA measurementof beat-length in low-birefringence fibers based on wavelength modulation is shown. It measures the beat- length by wavelength modulation. Phase detection is chosen to reduce the error from environment influence. Phase compensation plate isused to ensure the testing system always sensitive to the change of phase.The optical path consistes of an amplified spontaneous emission (ASE) light source, a fiber Fabry-Perot tunable filter, two linear polarizes, the measured fiber and a phase compensation plate. The testing system is set up and tested in reality.The system performes well in the repeated test. It is simple and has no strict demand on these equipments. There is no limitation on the configuration and the length of the testing fiber in the measurement.It is reliable for fibers whose beat- length is up to 20 m. The beat- length precision of the measurement is less than 1%..
Laser & Optoelectronics Progress
- Publication Date: Feb. 19, 2014
- Vol. 51, Issue 3, 30601 (2014)
Displacement Mode Analysis Method for Data Processing of Photonic Doppler Velocimetry
Yuan Shuyun, Liu Shouxian, Wang Detian, Chen Guanghua, Li Tao, Li Zeren, and Peng Qixian
The short time Fourier transform (STFT) and continuous wavelet transform (CWT) cannot resolve slowly varying velocity at low velocity stage in most photonic Doppler velocimetry (PDV) data. A new analysis method based on Fourier transform is presented to overcome this shortcoming. Instead of extracting the frequency of The short time Fourier transform (STFT) and continuous wavelet transform (CWT) cannot resolve slowly varying velocity at low velocity stage in most photonic Doppler velocimetry (PDV) data. A new analysis method based on Fourier transform is presented to overcome this shortcoming. Instead of extracting the frequency of interference signal for velocity analysis, the new method uses a modified Fourier transform to analysis the phase of signal, and converts phase to displacement or velocity. The validity of the proposed method is examined in experimental data of a plate- impact experiment, which distinguishes the elastic- plastic properties of Fe sample. The method not only uses all sampling points of the raw data, but also has a higher velocity resolutions especially for low velocity stage. The method is a supplement to STFT and CWT method..
Laser & Optoelectronics Progress
- Publication Date: Feb. 19, 2014
- Vol. 51, Issue 3, 30602 (2014)
Threshold Characteristics of Forward-Pumped Fiber Raman Amplifier
Long Qingyun, Wu Tingwan, Hu Sumei, Zhang Qiujing, and Lü Xiaolan
In order to analyze the threshold characteristics of forward- pumped fiber Raman amplifier (FRA), signal power distribution along a fiber for forward- pumped FRA is provided with Runge- Kutta method based on the coupling equations. Then, the theoretical expression of forward- pumped FRA′ s threshold is obtained with coIn order to analyze the threshold characteristics of forward- pumped fiber Raman amplifier (FRA), signal power distribution along a fiber for forward- pumped FRA is provided with Runge- Kutta method based on the coupling equations. Then, the theoretical expression of forward- pumped FRA′ s threshold is obtained with considering the practical factors, and the effects of these parameters on threshold of FRA are investigated detailedly. It is found that: the threshold will decrease when the initial signal power, the effective fiber length, Raman gain coefficient or the pump and signal frequency ratio increase, and the threshold will increase when the fiber efficient area increases..
Laser & Optoelectronics Progress
- Publication Date: Mar. 01, 2014
- Vol. 51, Issue 3, 30603 (2014)
Fabrication and Polarization-Dependent-Loss Characterization of 45° Tilted Fiber Grating at 1064 nm
Fu Shenggui, Liu Xiaojuan, and Zhou Bojun
A 45° tilted fiber grating working at 1064 nm is fabricated successfully in photosensitive fiber by ultraviolet (UV) inscription technique. A phase mask with a period of 1070 nm is rotated by 32.7° to the fiber axis to produce tilted fringes of 45° in the fiber core. The length of the 45° tilted fibA 45° tilted fiber grating working at 1064 nm is fabricated successfully in photosensitive fiber by ultraviolet (UV) inscription technique. A phase mask with a period of 1070 nm is rotated by 32.7° to the fiber axis to produce tilted fringes of 45° in the fiber core. The length of the 45° tilted fiber grating is about 24 mm. The polarization dependent loss (PDL) characteristics of the tilted grating are experimentally researched. The PDL value of the 45° TFG is about 11.8 dB at 1064 nm and it keeps higher than 9 dB over a wavelength range of 50 nm from 1150 nm to 1110 nm. According to the theoretical analysis, the main causes of the relatively smaller PDL value of the tilted grating are that the period of the phase mask is not the optimum value and the length is not enough..
Laser & Optoelectronics Progress
- Publication Date: Feb. 11, 2014
- Vol. 51, Issue 3, 30604 (2014)
Image Processing
A New Algorithm for Color Disc Corner Detection
Gong Wenbiao, Gu Guohua, Qian Weixian, and Ren Jianle
Target disc images are widely used in camera calibration and target location for unmanned (UAV) scout task, so a method of automatically extracting feature point coordinates is proposed for the color on the two- dimensional (2D) center of the disc to solve the problems of present corner detection algorithms. The operatTarget disc images are widely used in camera calibration and target location for unmanned (UAV) scout task, so a method of automatically extracting feature point coordinates is proposed for the color on the two- dimensional (2D) center of the disc to solve the problems of present corner detection algorithms. The operation of color separation for the red and blue discs is completed with the method of hue- saturation- value (HSV) volor space in order to get a gray image which has obvious symmetry and strong contrast. According to the corner points of the candidate red and blue pixels in the neighborhood with the distance less than a threshold number, the exact value of the corner is determined, and the response value of extracted large corner point is applied as a candidate by using a new type of symmetric operator. Experiment results of Matlab simulation and hardware implementation based on the field programmable gate array (FPGA) platform show that the proposed method is easy to implement in hardware technology, real- time and has good anti- noise ability. Also it has a good robustness to image rotation, stretching and scale transformation..
Laser & Optoelectronics Progress
- Publication Date: Mar. 01, 2014
- Vol. 51, Issue 3, 31001 (2014)
Design of Experiment and Result Evaluation for Detection Range of Visible Imaging System
Fu Xingling, Lan Weihua, Wang Jianghua, Liu Yu, and Pan Xiaodong
An experiment is designed to validate the visible imaging system′ s performance through analyzing the effects of resolution, contrast and the illumination. The effective targets at a distance of about 4.5 km are tested instead of 20 km. Under conditions of 11 km visibility, the equivalent detection range is figured outAn experiment is designed to validate the visible imaging system′ s performance through analyzing the effects of resolution, contrast and the illumination. The effective targets at a distance of about 4.5 km are tested instead of 20 km. Under conditions of 11 km visibility, the equivalent detection range is figured out by means of contrast and illumination. If the target′ s illumination is not less than 300 lux, the system can identify the target with 0.253 contrast, but it is not sure when the contrast is between 0.2 and 0.253. With special image processing, the result is significantly improved. Experimental results show that the system′ s performance can meet the special requirements..
Laser & Optoelectronics Progress
- Publication Date: Feb. 19, 2014
- Vol. 51, Issue 3, 31002 (2014)
Instrumentation, Measurement and Metrology
Dynamic Light Scattering Analysis of the pH-Stability of Wolfberry Polysaccharide Nanocapsules
Lou Benzhuo
The tolerance of Lycium barbarum polysaccharide with a variety of biological activities is poor in the environment of gastric acid or intestinal canal, which leads the great weakening of to its biological activities. This defect can be modified by nano- encapsulation. Wolfberry polysaccharide nanocapsules are prepared The tolerance of Lycium barbarum polysaccharide with a variety of biological activities is poor in the environment of gastric acid or intestinal canal, which leads the great weakening of to its biological activities. This defect can be modified by nano- encapsulation. Wolfberry polysaccharide nanocapsules are prepared by microemulsion technique and compound- agglomeration method. The particle sizes and distributions of these nanocapsules in liquid phase are measured by dynamic light scattering, which can analyze the stability of wolfberry polysaccharide nanocapsules in different simulation environments of gastric acid (pH=3.5), store (pH=5.5), dodecadactylon (pH=6.8) and large intestine (pH=7.4). The results show that, the polysaccharide nanocapsules can exist steadily in the environments of gastric acid, store, dodecadactylon and large intestine without standing time and in the environments of gastric acid and store within standing time of 5 h. However, the wolfberry polysaccharide nanocapsules become unstable in dodecadactylon with standing time of 2 h or in large intestine with standing time of 1 h. The above conclusions reveal that the prepared wolfberry polysaccharide nanocapsules have the effect of pH-controlled release..
Laser & Optoelectronics Progress
- Publication Date: Feb. 20, 2014
- Vol. 51, Issue 3, 31201 (2014)
Design of a Temperature-Controlled Test System for Luminous Intensity Spatial Distribution Characteristics of High Power LED
Chen Guolong, Yao Qi, Zhu Lihong, Lin Siqi, Guo Ziquan, Lü Yijun, and Chen Zhong
Characteristics of the luminous intensity spatial distribution (LISD) of light emitting diodes (LEDs) are capable of determining whether these devices can be applied on specific occasions. The absolute LISD of high power LED can be accurately measured only when LED is fixed at a specific heat- sink temperature because Characteristics of the luminous intensity spatial distribution (LISD) of light emitting diodes (LEDs) are capable of determining whether these devices can be applied on specific occasions. The absolute LISD of high power LED can be accurately measured only when LED is fixed at a specific heat- sink temperature because of the LED′s large heat-generating capacity. In this study, an automatic test system based on LEDGON-100 goniophotometer and the meter′ s high- precision two- dimensional (2D) revolving platform, is designed. In addition, it comprises of a test adapter, a temperature controller, a photometer head, a Keithley 2400 source meter, and an in- house- developed software package. This assembly can both control heat- sink temperatures and measure the LISD characteristics rapidly for high- power LEDs. The software is developed using Delphi programming language. The test system is stable and reliable. The test time is greatly reduced and measurements are instantly displayed.Two general types of LEDs, Lambertian type and batwing type, are measured by the system to obtain their 2D and three- dimensional (3D) LISDs. Experimental results show that the absolute luminous intensity decreases as the heat- sink temperature increases. However, the relative LISDs are the same under different heat-sink temperatures..
Laser & Optoelectronics Progress
- Publication Date: Feb. 20, 2014
- Vol. 51, Issue 3, 31202 (2014)
Research of 3D Measurement Technology Based on Gray Code Projection
Song Qian, Chen Yue, Zhu Ronggang, and Zhu Rihong
The way of encoded fringe projection is taken through projecting six binary fringe patterns after gray coding and four sinusoidal fringe patterns with the cycle of 2N - 1 into the object to unpack phase. This method achieved a measurement of object with steep edge, and improved the accuracy of phase unwrapping at the sThe way of encoded fringe projection is taken through projecting six binary fringe patterns after gray coding and four sinusoidal fringe patterns with the cycle of 2N - 1 into the object to unpack phase. This method achieved a measurement of object with steep edge, and improved the accuracy of phase unwrapping at the same time. Compared with traditional methods, this method can measure the step characteristics of object, and the measurement accuracy can be improved when high frequency fringe is projected..
Laser & Optoelectronics Progress
- Publication Date: Feb. 11, 2014
- Vol. 51, Issue 3, 31203 (2014)
Calibration of Foci-Meter Based on Talbot-Moiré Interferometer
Zhao Qi, Jiang Zewei, Meng Qing′an, Li Yiguo, Fan Hongying, Hu Shaoyun, Li Jianxin, He Yong, and Yang Jie
It developed a method to calibrate the foci- meter based on Talbot- Moiré interferometer, the calibration range of focal length up to 100 meters. Moreover, it introduced a foci-meter based on Talbot-Moiré interferometer. It includes a lens group and a laser source to generate laser beams with steady focal lenIt developed a method to calibrate the foci- meter based on Talbot- Moiré interferometer, the calibration range of focal length up to 100 meters. Moreover, it introduced a foci-meter based on Talbot-Moiré interferometer. It includes a lens group and a laser source to generate laser beams with steady focal length and wavefronts which used to calibrate the foci- meter. The focal length of the lens group is measured by experiments taking advantage of a traceable lens.The following conclusions can be derived from experimental results: the uncertainty of this calibration method is acceptable..
Laser & Optoelectronics Progress
- Publication Date: Feb. 19, 2014
- Vol. 51, Issue 3, 31204 (2014)
Integrated Optics
Computation of the Field Patterns in Dielectric-Loaded Double Ridge Waveguides of Ridge on the Short Side
Sun Hai, Wang Tianfei, and Li Hongheng
The edge- based vector finite element method is introduced to calculate the field patterns in four types of dielectric- loaded double- ridge waveguides of the ridge on theshort side, including double- rectangleridge waveguide, double- V- ridge waveguide, double- elliptical- ridge waveguideand double- trapezoidal- ridgeThe edge- based vector finite element method is introduced to calculate the field patterns in four types of dielectric- loaded double- ridge waveguides of the ridge on theshort side, including double- rectangleridge waveguide, double- V- ridge waveguide, double- elliptical- ridge waveguideand double- trapezoidal- ridge waveguide. The changes of the field patterns of various modes by changing ridge dimensions are analyzed. The figures are considered to be helpful in the design of many microwave components..
Laser & Optoelectronics Progress
- Publication Date: Mar. 01, 2014
- Vol. 51, Issue 3, 31301 (2014)
Lasers and Laser Optics
Influences of Compton Scattering on Transverse Dispersion of Relativistic Electron-Positronplasma
Feng Guanghui, and Hao Dongshan
By using the model of multi- photon nonlinear Compton scattering and the transverse dielectric constant formula of electron- positron plasma，the transverse dielectric in the un- magnetized, non- collision, isotropic and ultra- relativistic electron- positron plasma is studied by using the analytic and numerical computiBy using the model of multi- photon nonlinear Compton scattering and the transverse dielectric constant formula of electron- positron plasma，the transverse dielectric in the un- magnetized, non- collision, isotropic and ultra- relativistic electron- positron plasma is studied by using the analytic and numerical computing methods. The relativistic Fermi′s distribution under the Compton scattering，the expression of linear dispersion, and the numerical analytic and numerical of the transverse dispersion are given. The results show that the curve length of the short wave in the analytic transverse dispersion is increased in comparison with that before scattering, the curve length of the long wave is decreased, and their positions move to left and upward. The key causesare that frequency of the electron-positron plasma is increased by the scattering, the short wave and long wave components are increased and decreased, respectively. The two discontinuous analytic curves areabsolutely connected by the numerical transverse dispersion curve, so that a smooth curve is formed. The key causes are that the ultra- relativistic probabilities resulting from Compton scattering in the electronpositron plasma are greatly increased, the coupling density and temperature are increased，the high frequency component is decreased，and the whole dispersion composition is increased..
Laser & Optoelectronics Progress
- Publication Date: Feb. 11, 2014
- Vol. 51, Issue 3, 31401 (2014)
Spectrum Characteristics of Laser-Induced Single Bubble Collapse Noise
Zhang Tingting, Cao Guoxiang, Wang Yanjiao, Xia Tingting, Cai qiang, Wang Panda, Li Beibei, and Liu Xiumei
The laser-induced cavitation bubble collapse noise spectrum in the liquid are studied experimentally by using a piezoelectric transducer (PTZ) hydrophone. Experimental methods and a cavitation detection system are designed to investigate bubble collapse noise. The wavelet transformation, fast Fourier transform (FFT) anThe laser-induced cavitation bubble collapse noise spectrum in the liquid are studied experimentally by using a piezoelectric transducer (PTZ) hydrophone. Experimental methods and a cavitation detection system are designed to investigate bubble collapse noise. The wavelet transformation, fast Fourier transform (FFT) and other signal analysis methods are used to monitor the cavitation noise and reduce wavelet noise, analyze power spectrum. The result shows that application of wavelet denoising in cavitation bubble collapse noise spectrum analysis is an effective method. In addition, the designed software can quickly analyze the spectral characteristics of bubble noise signal, and it can detect and monitor cavitation on-line. The results have certain significance on the warning and researching of turbine cavitation, propeller cavitation and other water conservancy machineries..
Laser & Optoelectronics Progress
- Publication Date: Feb. 20, 2014
- Vol. 51, Issue 3, 31402 (2014)
Laser Welding of High Strength Steel Using Fiber Laser and CO2 Laser
Xu Guojian, Li Xiang, Hang Zhengxiang, Pu Xiongying, Zhang Chaoyi, and Kutsuna Muneharu
In order to compare the welding characteristics of fiber laser and CO2 laser, a 2 kW fiber laser and a 2.4 kW CO2 laser are used to weld 590 MPa high strength steel plates. By changing the defocusing distance and the welding speed, the penetration depth is investigated. The results show that with the same welding speedIn order to compare the welding characteristics of fiber laser and CO2 laser, a 2 kW fiber laser and a 2.4 kW CO2 laser are used to weld 590 MPa high strength steel plates. By changing the defocusing distance and the welding speed, the penetration depth is investigated. The results show that with the same welding speed and the same output power, the fiber laser welding gets more penetration depth compared with CO2 laser welding. With a negative defocusing distance, the penetration depth becomes greater when the defocusing distance is within the range of focal depth; the penetration depth increases with the decrease of welding speed when the power is constant, and the penetration depth using the CO2 laser welding decreases faster with the increase of welding speed than fiber laser welding..
Laser & Optoelectronics Progress
- Publication Date: Feb. 20, 2014
- Vol. 51, Issue 3, 31403 (2014)
Cavity Mirrors Influence on Thulium-Doped Fiber Lasers Output Performance
Liu Zhengtao, and Zheng Yi
As 2 mm laser is in eye-safe areas and weak atmospheric absorption band, thulium-doped fiber laser attracts a lot of attentions. The lasers output power characteristics of thulium- doped double- clad fiber under laser diode (LD) backward pumping using a plane mirror and concave mirror are compared. Experiments and theoAs 2 mm laser is in eye-safe areas and weak atmospheric absorption band, thulium-doped fiber laser attracts a lot of attentions. The lasers output power characteristics of thulium- doped double- clad fiber under laser diode (LD) backward pumping using a plane mirror and concave mirror are compared. Experiments and theories suggest that the laser cavity losses increase because the gap, tilt, and fiber end face defects between the fiber end face and the plane mirror and mirror thermal damage and other factors, and the laser output performance is severely affected. The cavity insertion loss properties are analyzed after using a plane mirror and concave mirror respectively at the end of the fiber based on the wave theory, which suggests that using a concave mirror cavity the loss is smaller than that using a plane mirror. When using the concave mirror cavity structure after fiber end, the maximum output power of 22 W is obtained, corresponding to the center wavelength of 1998.6 nm and the slope efficiency of 43% relative to the incident pump power. Comparing to the use of plane mirror cavity the laser slope efficiency increases of 10% , and the thermal damage of mirror is alleviated obviously..
Laser & Optoelectronics Progress
- Publication Date: Mar. 01, 2014
- Vol. 51, Issue 3, 31404 (2014)
Nonlinear Optics
Theoretical Analysis of the Influence of Multi-Photon Absorptionon Terahertz Generation via ptical-Difference Frequency Generation
Zhang Yuping, Wu Zhixin, Shen Duanlong, Liu Meng, Yin Yiheng, Zhang Huiyun, Zhong Kai, and Yao Jianquan
A general analysis of the influence of two- photon or three- photon absorption on terahertz (THz) generation via optical- difference frequency generation from the nonlinear optical material is presented. We calculate the best length of crystal and the corresponding THz quantum conversion efficiency for different valuesA general analysis of the influence of two- photon or three- photon absorption on terahertz (THz) generation via optical- difference frequency generation from the nonlinear optical material is presented. We calculate the best length of crystal and the corresponding THz quantum conversion efficiency for different values of the pump peak power under phase-mismatched condition and compare the results with that in phasematched condition. From the results we know that multi- photon absorption influence difference frequency generation slightly at low pump power and the impact will be strong with the increase of pump power. Because of the effect of two- photon or three- photon absorption, difference frequency generation at high pump power requires longer crystal to achieve the maximum photon conversion efficiency for both phase- matched and phase-mismatched situations. The maximum photon conversion decreases when pump power increases.We also present approaches to reduce this adverse effect..
Laser & Optoelectronics Progress
- Publication Date: Feb. 25, 2014
- Vol. 51, Issue 3, 31901 (2014)
Experimental Study of Multiple Rotational Symmetry Photonic Lattices
Wu Yijie, Yang Lisen, Wang Longfei, Li Qiang, and Shi Huiyuan
Utilizing the method of light- induced photonic lattices，we fabricate multiple rotational symmetry two- dimensional photonic lattices in LiNbO3:Fe crystal by masks with 3, 4, 5, 8 and 12 holes. Based on the interference principle, the multiple- beam interference pattern is obtained by numerical simulation. We observe tUtilizing the method of light- induced photonic lattices，we fabricate multiple rotational symmetry two- dimensional photonic lattices in LiNbO3:Fe crystal by masks with 3, 4, 5, 8 and 12 holes. Based on the interference principle, the multiple- beam interference pattern is obtained by numerical simulation. We observe the 3, 4, 5, 8 and 12 holes Brillouin- zone spectra and far- field diffraction patterns, and analyze the relationship between them. Experimental results are quite consistent with the simulation results. Traditional methods of observing Brillouin-zone spectra need rotating diffuser, using different optical paths to induce superlattices and observe Brillouin zone. We use attenuator only, so that the proposed method is simpler, more stable, and easier to adjust..
Laser & Optoelectronics Progress
- Publication Date: Mar. 01, 2014
- Vol. 51, Issue 3, 31902 (2014)
Optical Devices
Research on Efficiency Improvement of InGaN Light-Emitting Diodes with InGaN/GaN Superlattice Barrier
Yang Guofeng, Zhu Huaxin, Guo Ying, Li Guohua, and Gao Shumei
InGaN/GaN superlattice (SL) barrier near p- GaN and n- GaN are designed to replace the conventional GaN barrier of InGaN/GaN multiple quantum well (MQW) light-emitting diodes (LEDs). The lightvoltage performance curves, electroluminescence (EL) characteristics, energy band diagrams, electron concentration and radiativeInGaN/GaN superlattice (SL) barrier near p- GaN and n- GaN are designed to replace the conventional GaN barrier of InGaN/GaN multiple quantum well (MQW) light-emitting diodes (LEDs). The lightvoltage performance curves, electroluminescence (EL) characteristics, energy band diagrams, electron concentration and radiative recombination rate of LEDs with SL barrier near p- GaN and n- GaN have been studied numerically. The results indicate that the InGaN/GaN LED with SL barrier near n- GaN improves light output performance mane than that near p- GaN. The improved performance is due to the enhanced injection efficiency of electrons and radiative recombination rate..
Laser & Optoelectronics Progress
- Publication Date: Mar. 01, 2014
- Vol. 51, Issue 3, 32301 (2014)
Optimization of Freeform Surface Lens for Collimating Illumination of LED
Hao Jian, Liu Hua, Sun Qiang, Wang Yao, and Jing Lei
An optimization design method of collimating lens is proposed. The quadratic B-spline theory, Scheme language and optimization engine are used in combination to achieve the optimization of freeform surface lens. The Lambert emission of 1 mm × 1 mm LED is used as light source, and the lens material is polymethyl meAn optimization design method of collimating lens is proposed. The quadratic B-spline theory, Scheme language and optimization engine are used in combination to achieve the optimization of freeform surface lens. The Lambert emission of 1 mm × 1 mm LED is used as light source, and the lens material is polymethyl methacrylate (PMMA). The collimating lenses of different structures are optimized by this way. The energy efficiency can be up to 90% . Compared with the current methods, it has the advantages of less dependence on the initial model, simple design process and high versatility..
Laser & Optoelectronics Progress
- Publication Date: Feb. 20, 2014
- Vol. 51, Issue 3, 32302 (2014)
Physical Optics
Propagation Properties of Hollow Gaussian Beams in Gradient-Index Medium
Huang Yongchao, Li Changjin, and Zhang Xinlong
Using the Collins formula, we deduce the analytical expression of hollow Gaussian beams propagating in a gradient-index medium and analyze the corresponding propagation properties of hollow Gaussian beams. The influence of the gradient-index medium on the propagation properties of hollow Gaussian beams is also discusseUsing the Collins formula, we deduce the analytical expression of hollow Gaussian beams propagating in a gradient-index medium and analyze the corresponding propagation properties of hollow Gaussian beams. The influence of the gradient-index medium on the propagation properties of hollow Gaussian beams is also discussed. The results show that propagation properties of hollow Gaussian beams are largely influenced by the medium′s gradient-index..
Laser & Optoelectronics Progress
- Publication Date: Feb. 11, 2014
- Vol. 51, Issue 3, 32601 (2014)
Reviews
Solid-State Laser Distortion Wavefront Adaptive Correction Technology and Its Research Progress
Guo Guangyan, Fan Zhongwei, Yu Jin, Ge Wenqi, Kang Zhijun, Tang Xiongxin, Mo Zeqiang, Wang Haocheng, and Wang Zhihao
As an active optical compensation technology, adaptive optics (AO) is used to correct wavefront distortion extensively because of its advantages such as simplicity, instantaneity and validity. In recent years, AO technology is increasingly used in high- energy laser system. We review the basic principles of the AO systAs an active optical compensation technology, adaptive optics (AO) is used to correct wavefront distortion extensively because of its advantages such as simplicity, instantaneity and validity. In recent years, AO technology is increasingly used in high- energy laser system. We review the basic principles of the AO system, and discuss the research progress of solid- state AO correction technology at home and aboard. Introduction to two categories is presented according to if there is a wavefront sensor in an AO system to correct the wavefront distortion in solid state lasers, and the key technologies are introduced. Finally, theexisting technical difficulties are summarized, and the application prospect is presented..
Laser & Optoelectronics Progress
- Publication Date: Mar. 01, 2014
- Vol. 51, Issue 3, 30001 (2014)
Development of Lidar Detection Technology for Chemical/Biological Agents
Zhang Yan, Yang Zehou, Li Xiaofeng, Chen Yong, Zhou Dingfu, and Hou Tianjin
The principle and main characteristics of lidar detection technologies for biological/chemical warfare agents are described. The foreign developments of the primary lidar detection technologies such as differential laser radar technology, Raman spectroscopy and laser- induced fluorescence technique are analyzed. Some nThe principle and main characteristics of lidar detection technologies for biological/chemical warfare agents are described. The foreign developments of the primary lidar detection technologies such as differential laser radar technology, Raman spectroscopy and laser- induced fluorescence technique are analyzed. Some newest technologies are introduced such as photo- acoustic spectroscopy, Raman fluorescence detection, quantum cascade lasers and infrared focal planar array to detect biological/chemical warfare agents. Finally, the review points out the development trend of lidar detection technology for biological/chemical warfare agents..
Laser & Optoelectronics Progress
- Publication Date: Feb. 20, 2013
- Vol. 51, Issue 3, 30002 (2014)
Application of Surface-Enhanced Raman Spectrum Technology in Detecting Environment Pollutants
Yang Pan, Ding Shuaijun, Chen Fansheng, Shi Jinle, and Hu Jianming
Surface- enhanced Raman Scattering (SERS), with high sensitivity and selectivity , has been used in many areas of scientific research and production practice. The developme- nt of SERS technology in detecting environmental pollutants of heavy metal ions, polycyclic aromatic hydrocarbons, pathogenic microorganisms and pSurface- enhanced Raman Scattering (SERS), with high sensitivity and selectivity , has been used in many areas of scientific research and production practice. The developme- nt of SERS technology in detecting environmental pollutants of heavy metal ions, polycyclic aromatic hydrocarbons, pathogenic microorganisms and pesticide in recent years is presented in this paper .And the advantages and disadvantages of SERS in these applications was analyzed. The development tendency of SERS was predicted in the end..
Laser & Optoelectronics Progress
- Publication Date: Mar. 01, 2014
- Vol. 51, Issue 3, 30003 (2014)
Research Progress in Materials and Preparation Techniques of Thermal Barrier Coatings
Zhang Tianyou, Wu Chao, Xiong Zheng, and Zhou Shengfeng
To increase the operation temperature and service life of superalloy, thermal barrier coatings are widely employed in the surface protective field of high- temperature components of aircraft engine. In this paper, the research progress on materials and preparation techniques of thermal barrier coatings is reviewed. TheTo increase the operation temperature and service life of superalloy, thermal barrier coatings are widely employed in the surface protective field of high- temperature components of aircraft engine. In this paper, the research progress on materials and preparation techniques of thermal barrier coatings is reviewed. The main issues are analyzed and the method of the functionally graded thermal barrier coatings by laserinduction hybrid cladding (LIHC) is put forward. Namely, the substrate is preheated meanwhile laser cladding is carried out to form LIHC heat source, which is combined with the design of functionally graded structure. As a result, the crack- free and high- property thermal barrier coatings can be obtained under the condition of high efficiency..
Laser & Optoelectronics Progress
- Publication Date: Feb. 19, 2014
- Vol. 51, Issue 3, 30004 (2014)
Survey on Methods and Systems of Color Holographic Display
Shen Chuan, Wei Sui, Liu Kaifeng, Zhang Fen, Li Hao, and Wang Yue
Color holographic display is an important aim of holographic video display technology. In this paper， an overview of the issues about the methods and system design of color holographic display based on spatial light modulator (SLM) is presented. Firstly, the basic principles that three monochromatic holographic images Color holographic display is an important aim of holographic video display technology. In this paper， an overview of the issues about the methods and system design of color holographic display based on spatial light modulator (SLM) is presented. Firstly, the basic principles that three monochromatic holographic images are combined into a color image are introduced. The methods of generating holograms are analyzed and the comparison of three kinds of holograms including optical holograms, digital holograms, and computergenerated holograms (CGHs) is achieved. Secondly, the choice of SLM to design a color holographic display system and the phase modulation characteristics for multi- wavelength illumination are discussed. It is feasible to employ either red, green, and blue (RGB) lasers or light- emitting diodes (LEDs) as illumination source in practice system. Then, the configurations of color holographic display system by use of different methods including time division multiplexing, space division multiplexing, spatial division, and spatial multiplexing are described, and it is pointed out that the color holographic reconstructions are corrupted by effects arising from the discrete nature of SLM and the chromatics. Finally, the prospective development of color holographic display technology is given..
Laser & Optoelectronics Progress
- Publication Date: Mar. 01, 2014
- Vol. 51, Issue 3, 30005 (2014)
Developing Bottlenecks of Quasi-Zero-Dimensional Quantum Dot Lasers
Li Shiguo, Wang Xinzhong, Zhou Zhiwen, and Zhang Weifeng
In recent years, the developments of semiconductor materials follow two directions. One is socalled the material engineering, which is focusing on continuously pursuing new semiconductor material systems. The other one is the band engineering which is used to change the band energy of known semiconductor material systeIn recent years, the developments of semiconductor materials follow two directions. One is socalled the material engineering, which is focusing on continuously pursuing new semiconductor material systems. The other one is the band engineering which is used to change the band energy of known semiconductor material system by adjusting their dimensions. Quasi-zero-dimensional semiconductor quantum dot is a typical representative of band engineering by changing the size of dot. In this paper, we are mainly concentrated on introducing the bottlenecks of quasi-zero-dimensional semiconductor quantum dot lasers..
Laser & Optoelectronics Progress
- Publication Date: Feb. 11, 2014
- Vol. 51, Issue 3, 30006 (2014)
Progress and Study of Measurement of Surface Oxide Layer on Single Crystal Silicon Sphere
Liu Wende, Chen Chi, Luo Zhiyong, Fan Qiming, and Liu Yulong
Single crystal silicon (Si) sphere method is an important scheme for precise measurement of Avogadro constant and redefinition of kilogram. The surface oxide layer thickness is related to the correction of the measured mass and diameter of the single crystal sphere, and contributes a large proportion of the relative unSingle crystal silicon (Si) sphere method is an important scheme for precise measurement of Avogadro constant and redefinition of kilogram. The surface oxide layer thickness is related to the correction of the measured mass and diameter of the single crystal sphere, and contributes a large proportion of the relative uncertainty of the Avogadro constant. We discuss several basic problems in measuring the sphere surface by ellipsometer, i.e., the influence of the crystal- orientation- dependent optical constants and surface curvature induced ellipsometric light beam scattering. And the uncertainty components for the adopted indirect method are analyzed. The study provides both experimental and theoretical bases for the measurement research in surface layer on Si sphere..
Laser & Optoelectronics Progress
- Publication Date: Mar. 01, 2014
- Vol. 51, Issue 3, 30007 (2014)
Research Progress on Laser-Arc Hybrid Welding of Steel
Wang Xiaonan, Chen Changjun, Zhu Guangjiang, Zhang Min, and Zhang Shunhu
Laser-arc hybrid welding technology is one of the research focuses in the high-energy beam welding areas, and also the optimal welding method for heavy- gauge steel (thickness not less than 5 mm). This paper systematically introduces the research progress of domestic and foreign researchers and companies in the laserarLaser-arc hybrid welding technology is one of the research focuses in the high-energy beam welding areas, and also the optimal welding method for heavy- gauge steel (thickness not less than 5 mm). This paper systematically introduces the research progress of domestic and foreign researchers and companies in the laserarc hybrid welding of steel, and our latest research work on fiber laser- arc hybrid welding ofnew nano- scale strengthened steel (yield strength of 600~700 MPa) steel is briefly described. Finally, the heavy- gauge steel laser-arc hybrid welding technology research directions are analyzed and discussed..
Laser & Optoelectronics Progress
- Publication Date: Feb. 20, 2014
- Vol. 51, Issue 3, 30008 (2014)
Spectroscopy
Measurement and Analysis on Elemental Composition of Mosquito Coil by Laser-Induced Breakdown Spectroscopy
Wang Pengzhan, Sun Duixiong, Su Maogen, Zhang Qianqian, and Dong Chenzhong
Laser-induced breakdown spectroscopy(LIBS) has been used as a promising element analysis technique with the advantages of in-situ detection and remote monitoring etc. It is a relatively new task to apply LIBS to mosquito coil sample. In order to apply LIBS technique in the field related to environmental monitoring, we Laser-induced breakdown spectroscopy(LIBS) has been used as a promising element analysis technique with the advantages of in-situ detection and remote monitoring etc. It is a relatively new task to apply LIBS to mosquito coil sample. In order to apply LIBS technique in the field related to environmental monitoring, we use time-resolved LIBS to measure and analyze mosquito coil sample. Eleven kinds of elemental composition of mosquito coil, which are Al, Mn, Mg, Sr, Zn, Ba, Na, Ca, Fe, Si and H, are identified. Based on local thermodynamic equilibrium (LTE) assumption, the plasma temperature is obtained. The relative concentrations of these elements are estimated by calibration-free method. The experimental result prove that LIBS can be applied to the rapid and effective detection on the harmful elements..
Laser & Optoelectronics Progress
- Publication Date: Feb. 20, 2014
- Vol. 51, Issue 3, 33001 (2014)
Thin Films
Numerical Study on Transmission Enhancement of Metallic Nanohole Array
Yang Wenxu, Song Hongfei, and Lei Jianguo
Transmission enhancement of nanohole array has very important applications and prospects in many fields. Numerical simulation on transmission enhancement of metallic nanohole array is performed with finitedifference time-domain (FDTD) method. The factors such as round hole radius, film thickness, array cycle, and diffeTransmission enhancement of nanohole array has very important applications and prospects in many fields. Numerical simulation on transmission enhancement of metallic nanohole array is performed with finitedifference time-domain (FDTD) method. The factors such as round hole radius, film thickness, array cycle, and different materials are analyzed, and changing trend of transmission enhancement spectrum is discussed under the conditions of different parameters. Studies show that large round hole radius and thin film are helpful to the improvement of transmission enhancement, and larger hole array cycle is not conducive to transmission enhancement. The effect of different shape of nanohole on transmission enhancement is discussed, and rectangular hole array is used for comparison. Finally by changing thin film material the corresponding transmission performance is calculated..
Laser & Optoelectronics Progress
- Publication Date: Feb. 20, 2014
- Vol. 51, Issue 3, 33101 (2014)
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