Journals >Laser & Optoelectronics Progress
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2015
Volume: 52 Issue 6
45 Article(s)
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Detectors
Study on the Impact of Space Charge Effect to Avalanche Photodiode Gain
Wang Shen, Zeng Zhaoyang, and Zhang Fei
Avalanche photodiode (APD) is the photoelectric detector of frequency modulated continuous wave (FMCW) radar and can realize mixing functions, its self-mixing technology involved in signal receiving and processing of FMCW radar is one of the core problem restricting its performance. In the process of achieving photoeleAvalanche photodiode (APD) is the photoelectric detector of frequency modulated continuous wave (FMCW) radar and can realize mixing functions, its self-mixing technology involved in signal receiving and processing of FMCW radar is one of the core problem restricting its performance. In the process of achieving photoelectric mixing, the space charge effect have an impact on APD gain. On the basis of APD empirical gain model and theoretical analysis of space charge effect, an improvement is implemented to the original model. Experimental studies have demonstrated that the improved APD gain model is correct and the APD gain can be affected by space charge resistance, series load resistance and total current in the situation of strong light. Thereby the influencing factors of APD mixing performance as the photoelectric detector in FMCW laser radar are confirmed..
Laser & Optoelectronics Progress
- Publication Date: May. 23, 2015
- Vol. 52, Issue 6, 60401 (2015)
Fiber Optics and Optical Communications
Laser Communication/Ranging Integrated Technology and Link Characteristics in Navigation Satellite System
Zhao Xin, Niu Junpo, Liu Yunqing, Tong Shoufeng, and Wang Shifeng
Data transmission and precise distance measurement are necessary to high precision orbit determination and time synchronization in navigation satellite system. The abilities of anti-interference, confidentiality and antiinterception are improved by laser transmitting data and ranging in inter-satellite. Also the abilitData transmission and precise distance measurement are necessary to high precision orbit determination and time synchronization in navigation satellite system. The abilities of anti-interference, confidentiality and antiinterception are improved by laser transmitting data and ranging in inter-satellite. Also the ability of autonomous navigation is improved significantly. Taken the inter-satellite link characteristics, laser communication and ranging into comprehensive consideration, a kind of integration system is proposed by combination of coherent detection and data frame ranging. System principle and working process are given. According to the actual navigation satellite constellation, link characteristics such as available probability, link distance, doppler frequency shift are studied via STK software. Also link power is calculated when link distance and the parameters of optical system are given. It is used to design the laser communication and ranging integration system..
Laser & Optoelectronics Progress
- Publication Date: May. 29, 2015
- Vol. 52, Issue 6, 60601 (2015)
Design and Analysis of the High-Order-Mode Fiber Liao Suying Wu Meijun
[in Chinese], and [in Chinese]
Usually, the high-order-mode fiber is a kind of large mode area fiber with multi-cladding. In order to obtain a large mode area to suppress the fiber nonlinear effects and avoid optical damage in high power fiber lasers and amplifiers, the structural parameters of a high-order-mode fiber need to meet certain conditionsUsually, the high-order-mode fiber is a kind of large mode area fiber with multi-cladding. In order to obtain a large mode area to suppress the fiber nonlinear effects and avoid optical damage in high power fiber lasers and amplifiers, the structural parameters of a high-order-mode fiber need to meet certain conditions. The characteristic equation of high-order-mode fiber with multi-cladding and step-index distribution is derived with the theory of wave equation. According to this equation, the basis and method of choosing structural parameters for high-order-mode fiber are also described. And through numerical calculation, it analyzes the influence of the fiber cladding radius and refractive index on the core guided mode. The result shows that, under certain conditions, the cladding structure of the fiber does not affect the mode field distribution in the core and the mode field distribution in fiber cladding of certain high-order-mode can appear uniform distribution..
Laser & Optoelectronics Progress
- Publication Date: May. 13, 2015
- Vol. 52, Issue 6, 60602 (2015)
Experimental Research on Measurement Performance Evalution of a Proto-Type Optical Sampling Oscilloscope
Zhang Haiqi, Zuo Lin, Liu Chaochao, and Yang Aiying
Experimental results of a proto-type optical sampling oscilloscope based on sum frequency generation in periodically poled lithium niobate are demonstrated. The measurement performances under different conditions, like optical signal power, data rate, chromatic dispersion and wavelength, are estimated. Compared with thExperimental results of a proto-type optical sampling oscilloscope based on sum frequency generation in periodically poled lithium niobate are demonstrated. The measurement performances under different conditions, like optical signal power, data rate, chromatic dispersion and wavelength, are estimated. Compared with the measured results by an Agilent 86100A oscilloscope, the optical sampling oscilloscope has higher sensitivity and is robust to weak signal. The measured results of optical signals with different data rates show that the proto-type optical sampling oscilloscope is adaptive and transparent to different data rates. Measured results under different chromatic dispersion values show that the optical sampling oscilloscope can measure optical signals from the fiber link. Measured results of optical signals with different wavelengths indicate that, in order to make the optical sampling oscilloscope have the identical performance for measuring the wavelength division multiplexing (WDM) signal, the spectrum of mode-locked laser should be as flattened as possible. The measured results by the proto-type optical sampling oscilloscope make sense for the future design and specification..
Laser & Optoelectronics Progress
- Publication Date: May. 21, 2015
- Vol. 52, Issue 6, 60603 (2015)
Research on the Characteristic of Opened Microstructured Optical Fiber for Gas Raman Detection
Wang Guanjun, Tan Xuxiang, and Wang Zhibin
For quickening the gas sensing speed of fiber Raman detection system, a fiber Raman analyzer with sideopened configuration is proposed and explored. For exploring the relationship between Raman intensity and fiber parameters, a Raman sensing model is introduced for optimizing effective mode area and enhancing normalizeFor quickening the gas sensing speed of fiber Raman detection system, a fiber Raman analyzer with sideopened configuration is proposed and explored. For exploring the relationship between Raman intensity and fiber parameters, a Raman sensing model is introduced for optimizing effective mode area and enhancing normalized intensity overlap between Raman sensing light and analyte. Calculations predict that there is a trade-off between Raman intensity and fiber parameters, while the optimal trade-off dependes on the refractive index of the background material, core diameter and strut′s thickness. The optimized fiber core size for silica-based fiber Raman analyzer is 120~150 nm..
Laser & Optoelectronics Progress
- Publication Date: May. 22, 2015
- Vol. 52, Issue 6, 60604 (2015)
Holography
A Method of Wide-Viewing Angle Holographic Display in Color
Wang Di, Tang Wenhua, Wang Jun, and Wang Qionghua
Wide-viewing-angle color display is an important goal of holographic display. A method to achieve wide-viewing-angle color holographic display using white light illumination and a rotating mirror is proposed. By using spatial multiplexing method, each color component hologram is loaded on one third area of the spatial Wide-viewing-angle color display is an important goal of holographic display. A method to achieve wide-viewing-angle color holographic display using white light illumination and a rotating mirror is proposed. By using spatial multiplexing method, each color component hologram is loaded on one third area of the spatial light modulator (SLM). White light LED illuminates the SLM after a filter, and complete over lapping of reconstructed image can be realized by adjusting the original size of three color components. When holograms are loaded on SLM with different viewing angles, reconstructed image is reflected in different locations by rotating mirror. The switching speed of the holograms should be the same with rotation speed of mirror. When the switching speed is fast enough, the wide-viewing-angle holographic reconstruction can be seen according to the persistence of vision effect. The experimental result verifies the feasibility of the proposed theory..
Laser & Optoelectronics Progress
- Publication Date: Apr. 10, 2015
- Vol. 52, Issue 6, 60901 (2015)
Image Processing
Study on Segmentation of Building Facade Considering Local Point Cloud Density
Wang Guo, Sha Congshu, and Wang Jian
Because of the uniformity of three-dimensional scattered point cloud, the varying of local point cloud density affects the point cloud segmentation. To solve the problem, a method considering local point cloud density for automated segmentation of building facades from point clouds is presented. Based on the introductiBecause of the uniformity of three-dimensional scattered point cloud, the varying of local point cloud density affects the point cloud segmentation. To solve the problem, a method considering local point cloud density for automated segmentation of building facades from point clouds is presented. Based on the introduction of local point cloud density, self-adaptive segmentation processes and algorithms are designed. Results of contrast experiments show that the proposed method is better than that without considering the local point cloud density..
Laser & Optoelectronics Progress
- Publication Date: May. 23, 2015
- Vol. 52, Issue 6, 61001 (2015)
Study on Fusion of Visual and Infrared Images Based on NSCT
Chen Musheng, and Cai Zhishan
A fusion method for infrared and visual images based on local energy and non-subsampled Contourlet transform (NSCT) is proposed. The two original images are decomposed into a low frequency subband image and a few high frequency subband images by NSCT. The maximum selection rule is used to fuse the low frequency subbandA fusion method for infrared and visual images based on local energy and non-subsampled Contourlet transform (NSCT) is proposed. The two original images are decomposed into a low frequency subband image and a few high frequency subband images by NSCT. The maximum selection rule is used to fuse the low frequency subband and the high frequency subbands are merged with local energy match degree. The match degree of the two corresponding local energy in high frequency subbands is computed and the match degree threshold is obtained, if the match degree is less than threshold, the maximum of local energy is used to fuse the high frequency subbands, otherwise, the weighted local energy is used to fuse high frequency subbands. The fused image using the inverse transform of NSCT is reconstructed. The experimental results show that fusion method can get better visual effect and preserve image detail information of original image. Comparing with other fusion methods based on NSCT, the entropy is increased by 0.5%~6.8% , the space frequency is increased by 1% ~13% and the standard deviation is increased by 0~24.1%, it is an effective and simple fusion method..
Laser & Optoelectronics Progress
- Publication Date: May. 15, 2015
- Vol. 52, Issue 6, 61002 (2015)
Imaging Systems
Analysis of Spark Properties of Xenon Flash Lamp Based on the Imaging Technology of Optical Speckle
Wang Lingli, Zhao Youquan, Zhai Ruiwei, Li Xia, Jiang Nan, and Liu Xiao
According to the flaming properties of xenon flash lamp, which is of small spot size, high brightness, and flash pulse, a new method based on optical imaging to capture the pulse flash is proposed to analyze the luminescence properties of xenon flash lamp. Through a neutral filter group attenuating light pulse, a lightAccording to the flaming properties of xenon flash lamp, which is of small spot size, high brightness, and flash pulse, a new method based on optical imaging to capture the pulse flash is proposed to analyze the luminescence properties of xenon flash lamp. Through a neutral filter group attenuating light pulse, a light pulse testing platform with a charge-coupled device (CCD) is established. The continuous pulsed imaging is triggered by the output signal of xenon flash lamp controller to analyse the luminous stability of xenon flash lamp. Curves of the light pulse are obtained by controlling the high-voltage pulse driver energy. The result indicates that the intensity of light pulse increases with the driver energy increasing, which is consistent with the theoretical analysis. The speckle method proposed can be better applied to the optical and electrical performance characteristics testing, quality testing and the choice of electrode material about xenon flash lamp..
Laser & Optoelectronics Progress
- Publication Date: May. 23, 2015
- Vol. 52, Issue 6, 61101 (2015)
Instrumentation, Measurement and Metrology
Analysis of Diffraction Intensity and Wavefront Error in Point Diffraction Interferometer
Zhu Wenhua, Chen Lei, Li Jinpeng, Zheng Donghui, and Zhou Binbin
In order to study the effect which the lateral and axial defocus of pinhole have on diffraction intensity and reference wavefront quality in point diffraction interferometer, a mathematical model of convergent beam diffracted by a pinhole is established based on Fresnel diffraction theory. A novel method is proposed whIn order to study the effect which the lateral and axial defocus of pinhole have on diffraction intensity and reference wavefront quality in point diffraction interferometer, a mathematical model of convergent beam diffracted by a pinhole is established based on Fresnel diffraction theory. A novel method is proposed which combines the diffraction intensity with the peak value of diffraction wavefront error to analyze the wavefront diffracted by pinhole. F number of the converging beam and diameter of the pinhole are also taken into consideration. The results show that either diffraction intensity or reference wavefront error varies in inverse proportion to the F number of converging beam. The amount of lateral defocus should be less than the difference value of the radius of Airy disk and the pinhole. The acceptable value of lateral defocus is directly proportional to the wavelength and F number while being inversely proportional to the pinhole′s diameter. With the beam F number of 10 and the lateral defocus ranging from 0 to 35 mm, the pinhole with a diameter less than 1 mm can satisfy the requirement that the peak valley (PV) value of wavefront error should be less than 0.1 λ . The reference wavefront intensity can be changed by adjusting the axis defocus. The smaller the diameter of the hole is, the more sensitive the change is. A pinhole with a diameter less than the radius of Airy disk can make sure that the peak value of diffraction wavefront error is less than 0.01 λ and the test wavefront intensity should be controlled around one tenth of the effective diffraction intensity of the pinhole. The simulation results provide a theoretical basis and data reference for the design of point diffraction interferometer and its accuracy analysis..
Laser & Optoelectronics Progress
- Publication Date: Mar. 27, 2015
- Vol. 52, Issue 6, 61201 (2015)
Theoretical and Experimental Study on Laser Self-Mixing Interference with Two Feedback External Cavity
Huan Hai, Zhang Yu, Lu Song, and Huang Lingxiao
The external cavities of laser formed by independent movement reflectors in different directions is consided, the self-mixing interference (SMI) effect with multiway feedback is investigated. The basic theory of SMI with multiway feedback external cavity (MFEC) can be obtained by the theory of interference and the theoThe external cavities of laser formed by independent movement reflectors in different directions is consided, the self-mixing interference (SMI) effect with multiway feedback is investigated. The basic theory of SMI with multiway feedback external cavity (MFEC) can be obtained by the theory of interference and the theory of laser SMI. Based on the external cavity structure with two feedback, a SMI model with two feedback external cavity structure is proposed. The expressions of the phase and output power in the MFEC are deduced and some simulations are made under different conditions. It is found that the output of the SMI system with two external cavities in different directions is sinusoidal or sawtooth waves, which is similar to the signal of SMI by low frequency sinusoidal phase modulation. The density of interference waves is uneven in one period and the shape of the interference wave is determined by the intensity of the external feedback. A SMI with two feedback external cavity experiment system is setup, and the experiment results testifies the validity of simulations..
Laser & Optoelectronics Progress
- Publication Date: May. 28, 2015
- Vol. 52, Issue 6, 61202 (2015)
Lasers and Laser Optics
Investigation of Thin Film Polarizer Nd:YAG Laser Output S-Polarized Light
Yang Xiaodong, Chen Shuhan, and Zhu Jian
It is experimentally investigated how the effect of thin film polarizer (TFP) reflecting p-polarized light in the solid state laser resonator, which outputs p-polarized light, decreases the output power. The effect of overcoming the decreasing by outputting s-polarized light laser resonator with an intracavity thin filIt is experimentally investigated how the effect of thin film polarizer (TFP) reflecting p-polarized light in the solid state laser resonator, which outputs p-polarized light, decreases the output power. The effect of overcoming the decreasing by outputting s-polarized light laser resonator with an intracavity thin film polarizer is also studied. The results show that, in a p-polarized solid state laser with an intracavity thin film polarizer, the power loss caused by thin film polarizer reflecting p-polarized light decreases with increasing output mirror transmission. When the laser diode drive current is 20 A and the output mirror transmission is 5%, the power loss caused by the effect of thin film polarizer reflecting p-polarized light can reach 7.13 W, which is 1.9 times of the output power of the resonator. When the output mirror transmission increases to 30%, the power loss decreases to 0.59 W, which is 8% of output power. The output s-polarized light laser resonator configure with an intracavity thin film polarizer can avoid the power loss caused by the thin film polarizer reflecting p-polarized light, and improve output power. The improving effect of this resonator configure is more outstanding, when output mirror transmission is small. When the drive current is 20 A and output mirror transmission is 5%, the output power of output s-polarized light resonator is 7.77 W, which is 2.05 times of that of output p-polarized light resonator. When the output mirror transmission increases to 30%, the output power of output s-polarized light is only 1.09 times of that of output p-polarizer light resonator..
Laser & Optoelectronics Progress
- Publication Date: Jun. 02, 2015
- Vol. 52, Issue 6, 61401 (2015)
Collimation of High Fill Factor Diode Laser Slow Axis Beam
Wang Yuefeng, Lei Chengqiang, Yin Zhiyong, Yin Shaoyun, and Sun Xiuhui
In order to realize the beam shaping of high-power diode laser stack by microlens array, the technique of high fill factor diode laser stack slow axis direction beam collimation is researched. The diode laser stack is accompanied with micro-cylindrical-lens of fast axis collimated. The influence of the fill factors in In order to realize the beam shaping of high-power diode laser stack by microlens array, the technique of high fill factor diode laser stack slow axis direction beam collimation is researched. The diode laser stack is accompanied with micro-cylindrical-lens of fast axis collimated. The influence of the fill factors in the slow axis direction on collimating space is analyzed. For the diode lasers with the luminescence unit size of 100 μm and the period size of 200 μm, it is difficult to collimate the slow axis direction beam by the use of micro-cylindrical-lens array, besides, there is not enough space for the fast axis beam collimation. In order to remove the influence of fill factor, bar is acted as the collimating unit in the slow axis direction for the high-power diode laser stack with the fill factor of 0.5, and simulation is carried out by the optical design software Zemax. The remaining divergence angle of slow axis direction beam after collimating is tested based on space scanning and achieve the half of the remaining divergence angle of 2.12°. The experimental results show that the collimating way of diode laser slow axis direction beam is effective. The beam collimating way proposed is simple and easy, so it is useful for high fill factor diode laser stack slow axis beam collimation..
Laser & Optoelectronics Progress
- Publication Date: May. 29, 2015
- Vol. 52, Issue 6, 61402 (2015)
Influence of Laser Shock Processing on Fatigue Properties of 6061-T6 Aluminum Alloy TIG Welded Joints
Su Chun, Zhou Jianzhong, Huang Shu, Meng Xiankai, and She Jie
The surface of 6061-T6 aluminum alloy welding line and heat-affected zone by tungsten inert gas (TIG) is processed by high power and high repetition-rate Nd∶YAG laser. The contrast test is completed through adjusting the parameters of laser energy and laser shock processing (LSP) path. The safety lives of welded joint The surface of 6061-T6 aluminum alloy welding line and heat-affected zone by tungsten inert gas (TIG) is processed by high power and high repetition-rate Nd∶YAG laser. The contrast test is completed through adjusting the parameters of laser energy and laser shock processing (LSP) path. The safety lives of welded joint specimens with and without LSP are estimated by making low cycle tensile fatigue test. The effect of LSP on fatigue properties of aluminum alloy welded joint is analyzed. The fatigue fracture mechanisms of these specimens with and without LSP are studied by fracture surface, scanning electron microscope (SEM) energy dispersive spectrometer (EDS), residual stress and hardness analysis. The result show that the safety life of 6061-T6 aluminum alloy welded joints is increased 117.1%. The welded joint specimen which has the longest fatigue life is processed by LSP with laser energy 5 J, shock area 18 mm×16 mm and double shock. Compressive residual stress is induced at the surface of welded joints by LSP. The hardness of welded joints are significantly improved after LSP..
Laser & Optoelectronics Progress
- Publication Date: May. 25, 2015
- Vol. 52, Issue 6, 61403 (2015)
Effect of Laser Peening on Mechanical Properties of 6082 Aluminum Alloy
Qiao Hongchao
In order to study the effects of laser peening on properties of 6082 aluminum alloy, 6082 aluminum alloy coupons are treated by Nd∶YAG laser system with the wavelength of 1064 nm, pulse width of 15 ns and pulse energy of 0~8 J. Surface roughness, micro- hardness, residual stress and fatigue life with different laser peIn order to study the effects of laser peening on properties of 6082 aluminum alloy, 6082 aluminum alloy coupons are treated by Nd∶YAG laser system with the wavelength of 1064 nm, pulse width of 15 ns and pulse energy of 0~8 J. Surface roughness, micro- hardness, residual stress and fatigue life with different laser peening parameters are tested by roughness tester, micro- hardness tester, X- ray diffraction machine and fatigue machine, respectively. The experimental results show that the generated pits and microstructures make the surface uneven, surface roughness increasing about 2 times, also plastic deformation and hardening layer are induced, surface micro- hardness increasing up to about 43% , max compressive residual stress increasing up to - 261 MPa , depth of hardened layer being about 700 μm, and the fatigue life increasing about 6.8 times with the laser energy of 7 J and shock impact times of 4. So laser peening can improve properties of 6082 aluminum alloy significantly..
Laser & Optoelectronics Progress
- Publication Date: May. 21, 2015
- Vol. 52, Issue 6, 61404 (2015)
Generation and Synchronization of Chaos in Single-Ring Erbium-Doped Fiber Lasers Based on Delay Polarization Feedback Control
Zhang Xu, Yao Zhihai, and Feng Yuling
The generation of chaos in single-ring erbium-doped fiber lasers (SREDFLs) is investigated by using the delay polarization feedback control. The dynamical characteristics of SREDFLs are studied by appropriately adjusting the delay time, the coupling coefficient, and the polarization angle. The routes of chaotic generatThe generation of chaos in single-ring erbium-doped fiber lasers (SREDFLs) is investigated by using the delay polarization feedback control. The dynamical characteristics of SREDFLs are studied by appropriately adjusting the delay time, the coupling coefficient, and the polarization angle. The routes of chaotic generation and the parameter ranges of the chaotic states are given. Chaotic generation is achieved in the SREDFLs. Moreover, the chaotic synchronization of two SREDFLs is investigated by using the method of chaotic signal driving. The results show that no matter the two SREDFLs are chaotic or periodic before being driven, they can realize chaotic synchronization with a suitable driving intensity. Furthermore, the influence of the driving intensity and the polarization angle on the quality of chaotic synchronization is analyzed by using the correlation coefficient..
Laser & Optoelectronics Progress
- Publication Date: May. 21, 2015
- Vol. 52, Issue 6, 61405 (2015)
Machine Vision
Application of Image Statistical Model in the Rice Processing-Quality
Liu Jinping, Tang Zhaohui, Zhang Jin, and Tan Zhen
Vision monitor system is far from effective in the perception of the grainy images comprised of a large number of local homogeneous particles or fragmentations without obvious foreground and background. To overcome this problem, the sequential fragmentation theory is introduced into the visual analysis of the spatial sVision monitor system is far from effective in the perception of the grainy images comprised of a large number of local homogeneous particles or fragmentations without obvious foreground and background. To overcome this problem, the sequential fragmentation theory is introduced into the visual analysis of the spatial structure of images. A kind of multi-scale and omni-directional Gaussian derivative filter is presented. The omni-directional structural features of the rice images under different observation scales are achieved by established the image Weibull distribution model. Auto- classification of the rice processing- quality is realized based on the principle of least squares-support vector machine. Abundant confirmative and comparative tests indicate the effectiveness and outperformance of the proposed method..
Laser & Optoelectronics Progress
- Publication Date: May. 15, 2015
- Vol. 52, Issue 6, 61501 (2015)
Materials
Investigation of Siliver Nanoparticle Films in Plasmonics for Use as Fluorescence Enhancement of RH6G Molecules
Gao Jun
The siliver clusters films of different coverage rates are generated with a magnetron plasma gas aggregation clusters source, the assembling of films and the space with RH6G molecules can be tuned. The effect of surface plasmon polaritions in the films for use as fluorescence enhancement of molecules is investigated. IThe siliver clusters films of different coverage rates are generated with a magnetron plasma gas aggregation clusters source, the assembling of films and the space with RH6G molecules can be tuned. The effect of surface plasmon polaritions in the films for use as fluorescence enhancement of molecules is investigated. It shows that fluorescence quenching appears when the films contact closely to the molecules, the silicon nitride spacer is thick enough to avoid fluorescence quenching. When silicon nitride thickness is 15 nm, the fluorescence intensity of molecules is enhanced by 450%. Fluorescence intensity decreases exponentially when the thickness of the silicon nitride spacer increases further..
Laser & Optoelectronics Progress
- Publication Date: May. 22, 2015
- Vol. 52, Issue 6, 61601 (2015)
Analysis of Equi-Phase Frequency Spectrum in Photonic Crystal Based on FDTD Method
Ma Luming, Hu Jinbing, Jiang Qiang, Liang Binming, Chen Jiabi, and Zhuang Songlin
A triangular photonic crystal is designed theoretically. An analysis on the transmission properties of the transverse electric mode (TE mode) in two dimensional (2D) photonic crystal with triangular lattice is presented based on the finite difference time domain technique. The frequency spectrum is extracted from the sA triangular photonic crystal is designed theoretically. An analysis on the transmission properties of the transverse electric mode (TE mode) in two dimensional (2D) photonic crystal with triangular lattice is presented based on the finite difference time domain technique. The frequency spectrum is extracted from the simulated electromagnetic field data by Fourier transform. By analyzing the phase of each spectral component, the equivalent refractive index of a photonic crystal is calculated. the results show the different relationship between the spatial frequency and phase velocity. For the frequency of positive refraction, the phase velocity and energy are in the same direction. On the contrary, For the frequency of positive refraction, the phase velocity and energy are in the opposite direction. The result might provide a solid theoretical basis in the inquisition of photonic crystal physical mechanism..
Laser & Optoelectronics Progress
- Publication Date: May. 22, 2015
- Vol. 52, Issue 6, 61602 (2015)
Research on Binary Solution Concentration Detection Method Based on Photonic Band Gap Measurement
Abuduresuli, Palihati, and Dilixiati
By using the plane-wave expansion method and fast-Fourier transform method, two dimensional photonic band structure is calculated. A two-dimensional triangular lattice photonic crystal (Si and Ge) is used as the substrate, and the air hole is filled with different molality of mixed binary solution materials under test.By using the plane-wave expansion method and fast-Fourier transform method, two dimensional photonic band structure is calculated. A two-dimensional triangular lattice photonic crystal (Si and Ge) is used as the substrate, and the air hole is filled with different molality of mixed binary solution materials under test. The photonic band gap of the photonic crystal filled with binary solution under different polarization modes is obtained. Simulation experiments show that the molality of solution has a linear relationship with photonic band gap width, and that the linear correlation degree is affected by background medium column material. When the binary solution is used as the dielectric material of the air hole, the photonic band gap (PBG) changes with different molality of the solution quality. This research has a certain guiding function in solution mass fraction detection applications..
Laser & Optoelectronics Progress
- Publication Date: Apr. 17, 2015
- Vol. 52, Issue 6, 61603 (2015)
Properties of Reflectance Phase of One Dimensional Photonic Crystal with Single-Negative Materials
Kang Yongqiang
The reflection phase properties of one dimensional photonic crystals with single-negative materials is investigated by transfer matrix method. It is demonstrated that the reflection phase in zero effective phase band gap is affected by the incident angle, polarization and the ratio of thickness，and is independent on thThe reflection phase properties of one dimensional photonic crystals with single-negative materials is investigated by transfer matrix method. It is demonstrated that the reflection phase in zero effective phase band gap is affected by the incident angle, polarization and the ratio of thickness，and is independent on the proportion of lattice. These characteristics may be useful for making photonic crystal phase or dispersion compensators..
Laser & Optoelectronics Progress
- Publication Date: May. 29, 2015
- Vol. 52, Issue 6, 61606 (2015)
Theoretical Study of Electrical and Optical Properties of Ge-Doped 6H-SiC
Zang Yuan, Cao Lin, Li Lianbi, Lin Tao, and Fei Yang
Electronic structure and optical properties of Ge- doped 6H- SiC (GexSi1- xC) are calculated by ultrasoft pseudopotential technology of total energy- plane wave based on the density functional theory. The formation energy of impurities illustrates that Ge dopants prefer to occupy the substitutional Si sites for lower eElectronic structure and optical properties of Ge- doped 6H- SiC (GexSi1- xC) are calculated by ultrasoft pseudopotential technology of total energy- plane wave based on the density functional theory. The formation energy of impurities illustrates that Ge dopants prefer to occupy the substitutional Si sites for lower energy and more stable state. Analysis band structures, density of states and optoelectronic characteristics of 6H-SiC shows that the valence band maximum is determined by C-2p states and the conduction band minimum is occupied by the Si-3p orbital. With more Ge content is incorporated within the structure, the conduction band minimum of GexSi1- xC has moved to lower energy and changes to be determined by Ge- 4p states. Dielectric function illustrates that the electronic transition in Ge0.333Si0.667C which has a maximum Ge content is more simple than in 6H- SiC, and it′ s absorption edge and peaks are red- shifted to lower energy by 0.9 eV and 3.5 eV, respectively..
Laser & Optoelectronics Progress
- Publication Date: Apr. 06, 2015
- Vol. 52, Issue 6, 61607 (2015)
Effect of Double-Layer SiNx Film on Mono-Crystalline Silicon Solar Cells and XPS Characterization
Ma Xinjian, and Lin Tao
Chemical bond in single-layer and double-layer SiNx film, N/Si ratio and atomic percentage of Si、N、C、O are analyzed by X-ray photoelectron spectroscopy (XPS) in this paper. The impact of single-layer and double-layer SiNx film deposited by plasma enhanced chemical vapor deposition (PECVD) on mono-crystalline silicon soChemical bond in single-layer and double-layer SiNx film, N/Si ratio and atomic percentage of Si、N、C、O are analyzed by X-ray photoelectron spectroscopy (XPS) in this paper. The impact of single-layer and double-layer SiNx film deposited by plasma enhanced chemical vapor deposition (PECVD) on mono-crystalline silicon solar cells electrical characteristic is verified. Analyses of XPS、reflectivity and minority carrier lifetime show that the film of SiNx with H atoms is generated on the mono-crystalline surface through NH3 and SiH4. The N/Si ratio of outer film of double-layer SiNx is slightly higher than that of single-layer SiNx, which play the better effect on anti-reflection. And the internal film had a better passivition effect than single-layer film because of richer Si. The electrical characteristic test shows that, comparing with single-layer SiNx film solar cell, open circuit voltage, short circuit current and photoelectric conversion efficiency of double-layer SiNx film solar cell improve by 2 mV, 47 mA and 0.17% respectively..
Laser & Optoelectronics Progress
- Publication Date: May. 06, 2015
- Vol. 52, Issue 6, 61608 (2015)
Medical Optics and Biotechnology
Characteristics of Shift-Multiplexing Complex Spectral Domain Optical Coherence Tomography
Hu Yujie, Jiang Zhuqing, Zhao Ye, Huang Haochong, and Wang Zhe
The shift-multiplexing complex spectral domain optical coherence tomography (CSD-OCT) is presented according to the occurrence of high-resolution tomographic image near the virtual image of reference mirror. The method of shift-multiplexing CSD-OCT is experimentally demonstrated by using p/2 phase-shifting algorithm toThe shift-multiplexing complex spectral domain optical coherence tomography (CSD-OCT) is presented according to the occurrence of high-resolution tomographic image near the virtual image of reference mirror. The method of shift-multiplexing CSD-OCT is experimentally demonstrated by using p/2 phase-shifting algorithm to remove complex conjugate image and by shifting detection position to improve the quality of tomographic image, detection depth and bandwidth utilization. The tomographic imaging for a target sample of five-layer cover slips is performed in different depth regions with this method. The tomographic imaging of the sample made of eight-layer cover slips is further carried out combining with lateral scanning. The tomographic images of the target object are clear and legible. The results show that the higher quality tomographic image of a target sample within its desired depth can be achieved by moving the virtual image of reference mirror to the specified depth of the sample. The CSDOCT system with shifting detection can effectively extend the detection range inside sample, perform tomographic imaging at the specified location and make full use of optical coherence tomography system′ s bandwidth. The tomographic image of an object in its depth-target area can be improved..
Laser & Optoelectronics Progress
- Publication Date: May. 23, 2015
- Vol. 52, Issue 6, 61701 (2015)
Nonlinear Optics
Study of Synthesis and Optical Properties of Ferrocene Derivative Doped Polyimide Film
Song Qiuyan, Chen Genxiang, Zhao Minggen, and Li Tong
In view of the applications of ferrocene derivatives in photoelectric functional material, a new type ferrocene derivative，1-ferrocenyl-3-(4-dimethylamino phenyl)-c-2-alkene-1-ketone,with a big π -conjugate system is made of acetylferrocene and p-dimethylaminobenzaldehyde by condensation reaction. The compound is contaIn view of the applications of ferrocene derivatives in photoelectric functional material, a new type ferrocene derivative，1-ferrocenyl-3-(4-dimethylamino phenyl)-c-2-alkene-1-ketone,with a big π -conjugate system is made of acetylferrocene and p-dimethylaminobenzaldehyde by condensation reaction. The compound is containing ferrocene ketone as an acceptor and dimethylamino phenyl as a donor. The structure of the compound is characterized by 1H-nudear magnetic resonance (NMR) spectra. Combining doctor blading and gradient temperature-elevating, the compound-doped polyimide thin film with mass fraction of 4% is prepared. The ultraviolet visible (UV-VIS) absorption spectra and optical constant of the thin film are determined by UV-VIS spectrophotometer and the transmission spectrum method, respectively. The nonlinear optical property of the thin film is studied using Z-scan technique with 30 ps pulses at 1064 nm. The value of the third-order nonlinear susceptibility of the thin film is 1.0375×10－11 esu. It is better than optical fiber by three orders of magnitude, so it can be used in the production of optoelectronic devices..
Laser & Optoelectronics Progress
- Publication Date: May. 23, 2015
- Vol. 52, Issue 6, 61901 (2015)
Theoretical Investigation of Terahertz Generation in GaP via Difference Frequency Pumped by Dual-wavelength Ceramic Laser
Lü Jiantao, Wang Kejia, and Chen Guojie
Based on the plane wave approximate theory for terahertz generation via difference frequencies, the characteristics of terahertz wave generated in GaP pumped by dual- wavelength ceramic laser is investigated, including the phase matching, output power and temperature behavior. Results show that the coherent length is lBased on the plane wave approximate theory for terahertz generation via difference frequencies, the characteristics of terahertz wave generated in GaP pumped by dual- wavelength ceramic laser is investigated, including the phase matching, output power and temperature behavior. Results show that the coherent length is large enough via collinear matching method by use of the pumping light near 1060 nm. The output power of the terahertz emission relates to the crystal length and there is an optimal value for specific terahertz wavelength. The phase matching effect can be adjusted via changing the temperature of the GaP crystal, so different phase matching wavelength ranges can be obtained. The simulation result can provide some guidance for terahertz generation in GaP via difference frequency pumped by dual-wavelength ceramic laser..
Laser & Optoelectronics Progress
- Publication Date: Jun. 02, 2015
- Vol. 52, Issue 6, 61902 (2015)
Optical Design and Fabrication
Optical Simulation Research on Damage Testing System of Extreme Ultraviolet Radiation
Chen Jinxin, Wu Xiaobin, and Wang Yu
Damage testing system of extreme ultraviolet radiation, which is set to filter reasonably the materials and manufacturing processes for extreme ultraviolet lithography, consists of extreme ultraviolet source, collector chamber and sample chamber. Simulations of the damage testing system is provided when image plane is Damage testing system of extreme ultraviolet radiation, which is set to filter reasonably the materials and manufacturing processes for extreme ultraviolet lithography, consists of extreme ultraviolet source, collector chamber and sample chamber. Simulations of the damage testing system is provided when image plane is at focus and out of focus, and when the ellipsoidal collector is moving and rotating. The simulation results show that depth of focus in this system is ±3 mm. When there is no typical change of average image size in image plane, the maximum moving distance of collector is ±1.2 mm and the maximum rotation angle is ±0.08°. When the collector rotates by a small angle, the image moves along a certain orientation and image moving distance is directly proportional to collector rotation angle. The results are instructive to build the damage testing system of extreme ultraviolet radiation and implement the testing..
Laser & Optoelectronics Progress
- Publication Date: May. 28, 2015
- Vol. 52, Issue 6, 62201 (2015)
Study on Alignment Technology of Scanning Pentaprism System for Testing Large Flat Mirrors
Qi Erhui, Luo Xiao, Liu Quan, Zheng Ligong, and Zhang Xuejun
The scanning pentaprism system (PPS) is an effective method for guiding large flat optical processing, due to its advantages such as simple structure, high testing efficiency and precise measurement of low order aberrations. This paper established PPS′s mathematical model according to vectorial ray tracing theory, the The scanning pentaprism system (PPS) is an effective method for guiding large flat optical processing, due to its advantages such as simple structure, high testing efficiency and precise measurement of low order aberrations. This paper established PPS′s mathematical model according to vectorial ray tracing theory, the analytical relationship between PPS′s performance and its components′ angular motion is obtained by least square fitting, which is useful for analyzing PPS′s sensitivity to components′ alignment errors. Afterward a fine alignment procedure is proposed. Experimental results show that PPS′s measurement error caused by alignment is better than 40 nrad after fine alignment. The result shows that PPS is practical for large flat testing..
Laser & Optoelectronics Progress
- Publication Date: Mar. 31, 2015
- Vol. 52, Issue 6, 62202 (2015)
Design of Support Structure for K Mirror
Zhang Yan, Zhang Jingxu, Chen Baogang, Wang Fuguo, and Xu Wei
Aiming at the problem of support structure for K mirror in Alt- az telescope, the union support structure which includes three- point bottom support and side support is designed, and the experimental study about support structure is completed. According to the relation of radius-thickness ratio and shape change, the thAiming at the problem of support structure for K mirror in Alt- az telescope, the union support structure which includes three- point bottom support and side support is designed, and the experimental study about support structure is completed. According to the relation of radius-thickness ratio and shape change, the thickness of mirror is determined. Based on kinematics mount principle of mirror, the bottom and side support structure is designed, and the structure includes flexibility hinge which ensure that the support stress is not interference. Then, the parameter model of K mirror is established by Ansys software, the points of support position are optimized, and root mean square (RMS) of mirror surface diguer is obtained. Finally, the splice experiment is promoted, and platform of detection experiment is constructed. Experimental results indicate that the RMS of mirror is 12 nm, the peak valley (PV) of mirror is 76 nm, the experimental results are close to the simulation results. It can certify that the support structure of K mirror is validity and feasibility, and it accords with the design requirements of K mirror system..
Laser & Optoelectronics Progress
- Publication Date: Apr. 04, 2015
- Vol. 52, Issue 6, 62203 (2015)
Study of Anterior Corneal Surface Design Based on Reverse Ray-Tracing Method
Chen Zhijie, Li Dahai, Zhang Chen, Song Yuwei, Xu Wenfeng, and Huang Yi
To achieve customized corneal ablation of myopic eyes, the anterior surface of human cornea is fitted by using the even aspheric surface shape fitting method based on the theoretical precision human eye model of Gullstrand. With the known degree of refractive error of a patient, the axial length increase of the patientTo achieve customized corneal ablation of myopic eyes, the anterior surface of human cornea is fitted by using the even aspheric surface shape fitting method based on the theoretical precision human eye model of Gullstrand. With the known degree of refractive error of a patient, the axial length increase of the patient eyeball is calculated by using paraxial optical theory. Then a reverse ray- tracing method is used to redesign the shape of anterior surface of the patient′ s cornea by choosing eight points along axis of the Gullstrand eye to obtain eight coefficients of even aspheric surface. These coefficients are imported to Zemax optical design software, and the wavefront aberration, spot diagram and modulation transfer function (MTF) of the redesigned patient eye are analyzed. Compared with the image quality of the ideal human eye model, it shows that the reverse ray- tracing design method can achieve good image quality. The proposal may provide a new method for the ideal refractive correction of individual myopic refractive surgery in the clinical application..
Laser & Optoelectronics Progress
- Publication Date: May. 28, 2015
- Vol. 52, Issue 6, 62204 (2015)
Optical Devices
Research of Diffusion Tube for Double-Capped Cast LED Daylight Lamp
Zhuang Linling, Zhuang Qiren, Wang Jufeng, Hu Yibin, and Liu Shiwei
In order to overcome the defects such as low light emitting efficiency of double-capped cast light emitting diode (LED) daylight lamp using a general diffusion tube, a new diffusion tube with triangular microstructure as inner surface and with concave micro-lens microstructure as outer surface is studied. The principleIn order to overcome the defects such as low light emitting efficiency of double-capped cast light emitting diode (LED) daylight lamp using a general diffusion tube, a new diffusion tube with triangular microstructure as inner surface and with concave micro-lens microstructure as outer surface is studied. The principles of such a diffusion tube used for double-capped cast LED daylight lamp is introduced. A formula to calculate triangle microstructure′s base angles is derived. The influences of the parameters of the diffusion microstructure on the efficiency of the transmitted light are analyzed by simulations using TracePro software. The results show that, when triangle microstructure′s base angles are certain, triangular bottom width D has no effect on the light transmittance. Diameter d of the outer micro-lens surface has a greater impact on the transmittance, and the transmittance is the lowest when d=D/2. The shape of the outer micro-lens surface determines the divergence angle of light beam from this diffuser, and the divergence angle for a concave micro-lenses with cross-section being spline curve is greater than that with cross-section being perfect circular or elliptic curve. However，their transmittances are similar. The transmittance of this diffuser after optimization is about 0.92, the axial beam divergence angle is about 180°, and the radial beam divergence angle is 360°. The axial illumination uniformity of the daylight tube is better than 90% when using the improved double triangle inner surface microstructure..
Laser & Optoelectronics Progress
- Publication Date: May. 28, 2015
- Vol. 52, Issue 6, 62301 (2015)
Optics at Surfaces
Research of Mutiple Fano Resonances in Plasmonic Octamer Clusters
Huang Yunhuan, and Xue Baoping
The extinction spectra and distribution of electric near field of the octamer clusters composed of nanorings and split nanorings are calculated by using the finite-difference time-domain method (FDTD). The results show that the Fano resonances are generated in the plasmonic octamer clusters composed of nanorings and spThe extinction spectra and distribution of electric near field of the octamer clusters composed of nanorings and split nanorings are calculated by using the finite-difference time-domain method (FDTD). The results show that the Fano resonances are generated in the plasmonic octamer clusters composed of nanorings and split nanorings with different incident light polarizations. In addition, multiple Fano resonances can be generated and the modulation depth and resonance wavelength of Fano resonances can be tuned by adjusting the angle of the external ring of the plasmonic octamer clusters. These results can be used in Raman scattering, biological and chemical molecule detection..
Laser & Optoelectronics Progress
- Publication Date: May. 23, 2015
- Vol. 52, Issue 6, 62401 (2015)
Physical Optics
Coulomb′s Law in the Presence of Anisotropic Medium-Applications of Length Standards
Li Jin
Based on the scales theory of electromagnetic filed, the anisotropic medium is changed to beisotropic. The electric field intensity of a point charge and Coulomb′s law are obtained. Coulomb′s law states that the direction of the force between two point charges in the presence of anisotropic medium is not along the lineBased on the scales theory of electromagnetic filed, the anisotropic medium is changed to beisotropic. The electric field intensity of a point charge and Coulomb′s law are obtained. Coulomb′s law states that the direction of the force between two point charges in the presence of anisotropic medium is not along the line connecting the charges. When the relative permittivity tensor increases, the off connection of the force increases. The motion of a charged particle in the presence of anisotropic medium is researched..
Laser & Optoelectronics Progress
- Publication Date: Jun. 02, 2015
- Vol. 52, Issue 6, 62601 (2015)
Quantum Optics
Distillability Sudden Death in Qutrit-Qutrit Systems
Huang Jiang
Recently the distillability entanglement in qutrit-qutrit systems with Horodecki states under various decoherence is studied widely. The regulation of distillability evolution with convex linear combination states is investigated. The result shows that the convex linear combination states which are initially in the freRecently the distillability entanglement in qutrit-qutrit systems with Horodecki states under various decoherence is studied widely. The regulation of distillability evolution with convex linear combination states is investigated. The result shows that the convex linear combination states which are initially in the free-entangled states become bound-entangled in a finite time, the phenomenon of distillability sudden death appears in the qutrits systems..
Laser & Optoelectronics Progress
- Publication Date: May. 06, 2015
- Vol. 52, Issue 6, 62701 (2015)
Reviews
Study of Optical Feedback and Its Application Progress
Fu Yangying, Xiao Guangzong, and Zhang Bin
The concept of optical feedback and a theoretical analysis of two models are introduced, inclubing Fabry-Perot cavity and the injection model. Compared with traditional two-beams interferometer, self-mixing interferometer not only has similar phase sensitivity, but also has inherent simplicity, compactness and robustneThe concept of optical feedback and a theoretical analysis of two models are introduced, inclubing Fabry-Perot cavity and the injection model. Compared with traditional two-beams interferometer, self-mixing interferometer not only has similar phase sensitivity, but also has inherent simplicity, compactness and robustness, as well as the self-aligning capability. Applications in interferometry are presented, such as displacement sensor, velocimeter sensor, as well as biomedical sensor. Speckle effect occurs when a coherent light is back-reflected from a rough surface, the self-mixing signal can be affected. The amplitude fading as well as the speckle phase error of the self-mixing signal due to the speckle effect are analyzed. The methods to alleviate the amplitude fading of the self-mixing signal are reviewed, yet the applications of speckle self-mixing interferometer are summarized..
Laser & Optoelectronics Progress
- Publication Date: Mar. 29, 2015
- Vol. 52, Issue 6, 60001 (2015)
Research Progress of Airy Beam′s Propagation Trajectory Control
Cheng Zhen, Chu Xingchun, Zhao Shanghong, Deng Boyu, and Zhang Xiwen
Airy beam gains a widespread concern owing to its particular properties, such as approximate nondiffraction, self-accelerating in the transverse and self-recovery as a member of nondiffraction light families. Airy beam has a broad application prospect in optoelectronics, particle manipulation, atmospheric communicationAiry beam gains a widespread concern owing to its particular properties, such as approximate nondiffraction, self-accelerating in the transverse and self-recovery as a member of nondiffraction light families. Airy beam has a broad application prospect in optoelectronics, particle manipulation, atmospheric communication and so on. The main methods of Airy beam′s propagation trajectory control are summarized. Each control principle of propagation trajectory in acceleration direction, self-bending degree, peak intensity position is analyzed. The advantages and disadvantages for each method is concluded. The research result shows that the method of controlling the peak intensity position and self-bending degree of the propagation trajectory of Airy beam by changing system parameters is simple and the system is easy to be implemented. The method based on refractive-index gradient and the special medium-nonlinear photonic crystals can reverse the direction of acceleration, but it is difficult to make it come true. The acceleration direction and intensity distribution of Airy beam′s propagation trajectory can be controlled by the special transform and it is easy to be realized..
Laser & Optoelectronics Progress
- Publication Date: Jun. 02, 2015
- Vol. 52, Issue 6, 60002 (2015)
Research on Magneto-Optic Modulation Technology and Application
Cai Wei, Wu Fancheng, Yang Zhiyong, and Huang Kunyang
Faraday effect is a magneto-optic effect which closely linkes physical quantities such as light, electricity and magnetic. Magneto-optic modulation technique based on Faraday effect is widely used because of strong antijamming, high precision, small volume, light weight, etc. On the basis of a summary of magneto-optic Faraday effect is a magneto-optic effect which closely linkes physical quantities such as light, electricity and magnetic. Magneto-optic modulation technique based on Faraday effect is widely used because of strong antijamming, high precision, small volume, light weight, etc. On the basis of a summary of magneto-optic modulation technology literature, the basic principle of magneto-optic modulation technology is introduced. The applications of magneto-optic modulation technology in the fields of azimuth benchmark transfer, precision angle measurement, material performance research, industrial parameter measurement, biochemistry, etc are introduced at home and abroad in detail. Key technologies of precision optimization and reliability improvement in magneto-optic modulation are emphatically analyzed. Finally, the future research hot spot in this technology is discussed..
Laser & Optoelectronics Progress
- Publication Date: May. 21, 2015
- Vol. 52, Issue 6, 60003 (2015)
Research Status and Progress of Measurement Uncertainty in Interferometric Testing of Surface Figure
Quan Haiyang, Hou Xi, and Wu Fan
Estimating uncertainty of measurement is an effective route to improve quality of surface figure testing in laboratories. To promote the popularization and application of measurement uncertainty in the field of interferometric surface figure testing, the latest progress of uncertainty evaluation in figure measurements Estimating uncertainty of measurement is an effective route to improve quality of surface figure testing in laboratories. To promote the popularization and application of measurement uncertainty in the field of interferometric surface figure testing, the latest progress of uncertainty evaluation in figure measurements is reviewed. The associated international standards of metrological traceability and uncertainty are introduced. Evaluating measurement uncertainty with the bottom-up approach (i.e. modelling approach) and top-down approach is mainly introduced. The progress and development of uncertainty evaluation are focused on in interferometric surface figure measurements. The development direction and further development of uncertainty evaluation method in interferometric surface figure measurements are prospected..
Laser & Optoelectronics Progress
- Publication Date: May. 07, 2015
- Vol. 52, Issue 6, 60004 (2015)
Research Progress in Applications of Chaotic Laser
Wu Yuan, Wang Bingjie, and Wang Yuncai
Chaotic laser, viewed as a special form of laser outputs, has noise-like timeseries and wide frequency spectrum bandwidth. In recent years, the application of chaotic laser has attracted the wide attentions as the characteristics of chaos laser are being understood and controlled. Combined with the research situation，tChaotic laser, viewed as a special form of laser outputs, has noise-like timeseries and wide frequency spectrum bandwidth. In recent years, the application of chaotic laser has attracted the wide attentions as the characteristics of chaos laser are being understood and controlled. Combined with the research situation，the current hot spots and the research progresses of the chaotic laser applications are riviewed in the fields of high-speed random bit sequence generation, chaos secure communication and chaos key distribution,chaotic laser ladar and chaotic optical time domain reflectometer, ultrawideband pulse signal generator, laser source with tunable coherence length and chaos computing. Furthermore, some possible development orientations in the future are pointed out..
Laser & Optoelectronics Progress
- Publication Date: May. 25, 2015
- Vol. 52, Issue 6, 60005 (2015)
Research Advances in Wavelength-Division-Multiplexing Passive Optical Network Monitoring with Tunable Optical Time-Domain Reflectometry
Sun Fei, Xie Liang, Qi Xiaoqiong, and Gong Ping
The wavelength-division-multiplexing passive optical network (WDM-PON) is considered as a promising technology for passive optical network (PON). With the increase of complexity and the expansion of scale, to ensure access network with the reliability and maintaining, the search for the physical-layer WDM-PON monitorinThe wavelength-division-multiplexing passive optical network (WDM-PON) is considered as a promising technology for passive optical network (PON). With the increase of complexity and the expansion of scale, to ensure access network with the reliability and maintaining, the search for the physical-layer WDM-PON monitoring is therefore becoming crucial to the high quality and reliable system. The tunable optical time-domain reflectometry (OTDR) is an effective way, however, due to the complexity of WDM-PON fiber link, tunable OTDR also faces many challenges. By addressing the features of WDM-PON structure and major requirements of WDM-PON monitoring techniques, the research advances of tunable OTDR and the application of other technologies which are used for tunable OTDR are reviewed..
Laser & Optoelectronics Progress
- Publication Date: May. 21, 2015
- Vol. 52, Issue 6, 60006 (2015)
Progress and Thinking for the Application of Laser Array Directed Energy in Planetary Defense
Zhang Heyong
An orbital planetary defense system which is capable of heating the surface of potentially hazardous objects to the vaporization point as a feasible approach to impact risk mitigation is proposed. The system is called DE-STAR for directed energy system for targeting of asteroids and exploration. DE-STAR is a modular phAn orbital planetary defense system which is capable of heating the surface of potentially hazardous objects to the vaporization point as a feasible approach to impact risk mitigation is proposed. The system is called DE-STAR for directed energy system for targeting of asteroids and exploration. DE-STAR is a modular phased array of kilowatt class lasers powered by photovoltaic′s. Modular design allows for incremental development, lowering cost, minimizing risk, and technological co-development. The main objective of DE-STAR is to use the focused directed energy to raise the surface spot temperature to 3000 K, allowing direct vaporization of all known substances. In the process of heating the surface ejecting evaporated material a large reaction force alters the asteroid′s orbit, so the collision risk is decreased. The previous results can be used in the space debris removal and cleaning..
Laser & Optoelectronics Progress
- Publication Date: May. 23, 2015
- Vol. 52, Issue 6, 60007 (2015)
Dispersion Analysis of Pulse Compression System Based on Prism-Grating
Su Juan, Liu Zhonghua, Wei Tao, and Li Jüfen
Dispersion controllment is an important step in ultrafast optics. A reflection grism is introduced, which is composed of the prism and grating. The dispersion of the grism is analyzed with ray-tracing method, and the impact of grism structural parameters on the dispersion is discussed. As seen from the results, the secDispersion controllment is an important step in ultrafast optics. A reflection grism is introduced, which is composed of the prism and grating. The dispersion of the grism is analyzed with ray-tracing method, and the impact of grism structural parameters on the dispersion is discussed. As seen from the results, the second-order dispersion increases with the separation of the prism and grating, however, the third-order dispersion decreases. The separation of two grisms can be asymmetric in order to adjust the dispersion value of grism pair. The second-order dispersion of grism decreases with the incidence angle, and the third-order dispersion increases with the angle. When the grating constant is changed, grism dispersion corresponding changes. The separation of the grism-pair has little effect on the dispersion of grism. The results show that the dispersion of grism is heavily influenced by the separation of the prism and grating, incidence angle, and the grating constant. By adjusting the above parameters to change the dispersion of grism, it can meet the needs of ultrafast optics..
Laser & Optoelectronics Progress
- Publication Date: May. 06, 2015
- Vol. 52, Issue 6, 60501 (2015)
Investigation and Discussion on High Average-Power Fiber Stimulated Brillouin Scattering Phase-Conjugation Mirror
Ge Chuanwen, and Xiao Shuang
Fiber stimulated Brillouin scattering (SBS) phase-conjugation mirrors (PCM) are used for improving higher average-power solid-state laser′s beam quality, due to their advantages in all solid-state, low power threshold, high fidelity and no toxicity. On the other hand, these fiber SBS-PCMs have the disadvantage of low lFiber stimulated Brillouin scattering (SBS) phase-conjugation mirrors (PCM) are used for improving higher average-power solid-state laser′s beam quality, due to their advantages in all solid-state, low power threshold, high fidelity and no toxicity. On the other hand, these fiber SBS-PCMs have the disadvantage of low laser damageresistant threshold, which limits their applications in high power laser systems. The research progress of various fiber SBS-PCMs is introduced, including single-core diameter fiber, fused silica rod-fiber combination, tapered fiber. The influence of laser-induced damage, laser thermal effects, acoustic wave field distribution of high repetition rate and high average power laser, on the characteristics of fiber SBS-PCMs is discussed..
Laser & Optoelectronics Progress
- Publication Date: May. 29, 2015
- Vol. 52, Issue 6, 70002 (2015)
Spectroscopy
WT-SVD Feature of Three Dimensional Fluorescence Spectra of Mineral Oil
Tian Guangjun, and Yang Zichen
Singular value decomposition (SVD) has a shortcoming in feature extraction of mineral oil′ s 3D fluorescence spectrum, as it easily discards small eigen values that may be important for identification. A new method that combines wavelet transform (WT) and SVD in feature extraction is presented. Wavelet approximation coSingular value decomposition (SVD) has a shortcoming in feature extraction of mineral oil′ s 3D fluorescence spectrum, as it easily discards small eigen values that may be important for identification. A new method that combines wavelet transform (WT) and SVD in feature extraction is presented. Wavelet approximation components of mineral oil′s 3D fluorescence data and detail components in different directions are obtained, and their singular value feature is extracted. The fuzzy clustering method (FCM) is used to classify or discriminate mineral oils, and a further test is carried out with random noise introduced. The result shows that WT-SVD feature vector is superior to SVD in mineral oil classification or oil identification, with higher accuracy and robustness than SVD in anti-jamming performance..
Laser & Optoelectronics Progress
- Publication Date: May. 28, 2015
- Vol. 52, Issue 6, 63001 (2015)
Vision, Color, and Visual Optics
Chromaticity Changes of Instrument Measurement for Color Patches with Different Gloss Levels
Dong Shuwen, Liao Ningfang, Lü Hang, Lin Kai, and Cao Bin
Chromaticity changes of two instrument measurement for color patches with different gloss levels are investigated. The tristimulus values are predicted based on Dalal-Natale-Hoffman1999 reflection model for thirtyfive color patches printed in five kinds of paper with different gloss levels for three geometrical measureChromaticity changes of two instrument measurement for color patches with different gloss levels are investigated. The tristimulus values are predicted based on Dalal-Natale-Hoffman1999 reflection model for thirtyfive color patches printed in five kinds of paper with different gloss levels for three geometrical measurement. For yellow samples and blue samples, a nonlinear fitting algorithm by exponential function is applied to develop the model between gloss and predicted lightness, chroma and hue among three geometrical measurement. The results show that for specular light included (di∶8°) geometries, predicted lightness, predicted chroma and predicted hue are constant. For specular light excluded (de∶8°) and 45°a∶0°geometries, predicted lightness decreased with increasing gloss for all color patches, predicted chroma correspondingly increased and predicted hue was constant. Meanwhile, measured lightness, chroma and hue are used to characterize accuracy of predicting model. The results also illustrate that for yellow samples it is available to predict chromaticity changes of instrument measurement for a wide range of gloss values for the model between gloss and predicted lightness, chroma and hue. However, for blue samples it is unavailable and need to improve..
Laser & Optoelectronics Progress
- Publication Date: May. 28, 2015
- Vol. 52, Issue 6, 63301 (2015)
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