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2016
Volume: 53 Issue 6
38 Article(s)
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Atmospheric Optics and Oceanic Optics
Anti-Jamming Strategy for Smoke-Screen Jamming and Composite Seeker
Xu Jing, Liu Bin, Yang Junyan, Cui Yebing, and Wu Jiandong
The anti-jamming capability of seekers has been one of the most important performance indexes to appraise the missile. Anti-jamming strategies of ladar/infrared (IR) composite seeker are proposed for the common smoke-screen jamming. Based on the analysis of interference mechanism, the impact on transmittance and range The anti-jamming capability of seekers has been one of the most important performance indexes to appraise the missile. Anti-jamming strategies of ladar/infrared (IR) composite seeker are proposed for the common smoke-screen jamming. Based on the analysis of interference mechanism, the impact on transmittance and range is calculated with respect to IR channel and ladar channel, respectively. The anti-jamming strategies and available problems of IR seekers are analyzed, then the composite anti-jamming strategy with target range information is proposed..
Laser & Optoelectronics Progress
- Publication Date: May. 11, 2016
- Vol. 53, Issue 6, 60101 (2016)
Differences Between Latest V4 and V3 Products for CALIOP Clouds and Aerosols Attenuated Backscatters
Zhang Tianche, and Wu Dong
In order to study the differences of attenuated backscatter characters of global clouds and aerosols obtained from the cloud-aerosol lidar with orthogonal polarization (CALIOP) the latest version of Version 4(V4) and Version 3(V3) products separately, and the potential impacts on previous studies. The CALIOP two verticIn order to study the differences of attenuated backscatter characters of global clouds and aerosols obtained from the cloud-aerosol lidar with orthogonal polarization (CALIOP) the latest version of Version 4(V4) and Version 3(V3) products separately, and the potential impacts on previous studies. The CALIOP two vertical products in January, April, July and October of 2011 are used to gather probability distribution statistic of clouds or aerosols 532 nm total attenuated backscatters, 1064 nm attenuated backscatters and total attenuated color ratios respectively below the altitude of 20.2 km all over the world. And the relative deviation of two different versions of the corresponding data is made statistical analysis. The results show that the relative deviations of the attenuated backscatters between V4 and V3 products for clouds and aerosols tend to be positive values, and the changes from V3 to V4 data are more obvious at nighttime than those at daytime for both clouds and aerosols. The mean relative deviations from V4 and V3 of clouds daytime 532 nm total attenuated backscatters, 1064 nm attenuated backscatters and total attenuated color ratios are 3.40%, 4.66% and 1.18% separately, and those of clouds nighttime data are 2.80%,8.00% and 5.33% separately. The mean relative deviations of aerosols daytime 532 nm total attenuated backscatters, 1064 nm attenuated backscatters and total attenuated color ratios are 1.14%,6.94% and 5.62% separately, those of aerosols nighttime data are 3.33%, 10.92% and 7.64% separately..
Laser & Optoelectronics Progress
- Publication Date: May. 26, 2016
- Vol. 53, Issue 6, 60102 (2016)
Atmospheric Visibility Measurement Based on Dark Channel Prior
Zhao Rui, Hu Liaolin, and Zhao Jiangtao
Dark channel prior has a good effect on haze removing. A visibility measurement method based on dark channel prior is proposed, which can overcome the disadvantages of high cost and difficulty in building up of the meteorological visibility meter. The proper target region is selected by analyzing different regions of tDark channel prior has a good effect on haze removing. A visibility measurement method based on dark channel prior is proposed, which can overcome the disadvantages of high cost and difficulty in building up of the meteorological visibility meter. The proper target region is selected by analyzing different regions of the image so as to estimate transmittance. A more accurate transmittance is obtained by haze removal parameter optimization and guided filtering refinement, and then the atmospheric extinction coefficient and visibility are inferred. Comparing the results of dark channel prior with the data measured by forward scattering meter (CJY-1G), the error is within ±15%, which meets the application requirement of World Meteorological Orgnization..
Laser & Optoelectronics Progress
- Publication Date: May. 20, 2016
- Vol. 53, Issue 6, 60103 (2016)
Detectors
Absorption Losses of Ultrathin Crystalline Silicon Solar Cells
Lu Xiaodong, Zhang Peng, Zhao Yang, Wang Zelai, Wu Yuanqing, Zhang Yufeng, and Zhou Tao
The absorption losses of the Ag back reflector in two typical silicon solar cells have been analyzed by frequency domain finite difference method. The results show that, in flat silicon solar cell, the losses of Ag back reflector are mainly caused by intrinsic absorption and the oscillation absorption of guided modes. The absorption losses of the Ag back reflector in two typical silicon solar cells have been analyzed by frequency domain finite difference method. The results show that, in flat silicon solar cell, the losses of Ag back reflector are mainly caused by intrinsic absorption and the oscillation absorption of guided modes. The absorption peaks of TM modes caused by surface plasma oscillation are larger than those of TE modes. In the textured crystalline silicon cell, the distribution of light are complex, and strong guided modes oscillation in the active layer can be introduced by normally incident light of both TE and TM modes. Strong surface plasma oscillation in Ag back reflector can be produced by TM modes. Therefore, in the textured crystalline silicon cell, the absorption spectra show multi-peak characteristics and the values of absorption peaks are larger than those in the flat type crystalline silicon cell..
Laser & Optoelectronics Progress
- Publication Date: May. 25, 2016
- Vol. 53, Issue 6, 60402 (2016)
Fiber Optics and Optical Communications
Vibration Sensor Based on Single Mode-Multimode Optic-Fiber Cantilever Structure
Wang Hongri, Gao Renxi, Yin Yanxuan, Fu Yongpeng, Liu Yi, Li Min, Fan Guanghua, and Qu Shiliang
A kind of novel fiber cantilever vibration sensor with the structure of single mode-multimode-gap-single mode (SMGS) fiber is proposed based on the effect of multimode interference. The beam propagation method (BPM) is adopted to simulate the light propagation in the fibers. The finite element model of the cantilever iA kind of novel fiber cantilever vibration sensor with the structure of single mode-multimode-gap-single mode (SMGS) fiber is proposed based on the effect of multimode interference. The beam propagation method (BPM) is adopted to simulate the light propagation in the fibers. The finite element model of the cantilever is established in order to analyze the vibration characteristics of the optic-fiber cantilever, and the optimal design of this kind of fiber vibration sensors is conducted in theory. In the experiments, the fiber cantilevers with the length of 22 mm are fabricated by four different lengths of multimode fibers. The characteristics of cantilevers vibration with different lengths of multimode fibers are analyzed in details. The experimental results agree well with the theoretical simulation results. It shows that the proposed SMGS sensor has the maximum sensitivity of 4 mV/mPa at the frequency point of 130 kHz and the linear correlation coefficient of 0.9962. The experimental results indicate that this kind of sensor has a linear response and good repeatability within given sound pressure level. The proposed sensor maintains the advantages of easy-preparation, low-cost and high-sensitivity, which is expected to be applied to the field of the remote vibration sensing of some special resonance frequency points..
Laser & Optoelectronics Progress
- Publication Date: May. 20, 2016
- Vol. 53, Issue 6, 60601 (2016)
Analysis of Wireless Ultraviolet Communication Performance in Application of Helicopter Landing Assistance
Zhao Taifei, Liu Yijie, and Wang Xiufeng
According to characteristics of wireless ultraviolet communications and channel model of the helicopter landing process, a method of wireless ultraviolet communication to assist helicopter landing system is designed with LED array structures. Based on the ultraviolet propagation characteristics in real space, the perfoAccording to characteristics of wireless ultraviolet communications and channel model of the helicopter landing process, a method of wireless ultraviolet communication to assist helicopter landing system is designed with LED array structures. Based on the ultraviolet propagation characteristics in real space, the performance differences of wireless ultraviolet communication at various transmitting elevations and receiving elevations are explored in terms of path loss and signal-to-noise ratio. The proposed method is verified experimentally with solar blind ultraviolet LEDs and photomultiplier tubes as transmitting and receiving devices, and the path loss and the signal-to-noise ratio in the ultraviolet propagation are obtained. The results show that the performance of line-of-sight communication is the best, the communication performance with elevation lower than 30° is more applicable to actual situations, and that with the elevation higher than 30° degenerates rapidly..
Laser & Optoelectronics Progress
- Publication Date: May. 25, 2016
- Vol. 53, Issue 6, 60602 (2016)
Characteristics of the Double-Side Modulation Waveguide Bragg Grating
Zhang Ailing, Sun Qinfang, and Yan Guangtuo
A new preparation method of the double-side modulation Bragg waveguide grating by one step is proposed. In the structure, spatial modulation of the waveguide grating is achieved by periodically changing the width of the waveguide. The advantage of this structure is that waveguide and grating are achieved at the same tiA new preparation method of the double-side modulation Bragg waveguide grating by one step is proposed. In the structure, spatial modulation of the waveguide grating is achieved by periodically changing the width of the waveguide. The advantage of this structure is that waveguide and grating are achieved at the same time by using a simple waveguide fabrication technology. According to transfer matrix theory, the relationship between the reflection spectrum characteristics of this structure and the waveguide width, the difference of waveguide width, the duty cycle of gratings, the changes of the waveguide in the shape is studied. Results show that 3 dB bandwidth of grating with double-side modulation is wider than that of grating with corrugated modulation. At the same time, the maximum reflectivity is increased slightly. When the difference of waveguide width is fixed, the maximum reflectivity and bandwidth decrease while the waveguide width increases. In addition, when the waveguide width is fixed, the maximum reflectivity and bandwidth increase while the waveguide width increases. When both the waveguide width and its difference are both fixed, the maximum reflectivity and bandwidth achieve these maximums at the duty cycle of 1/2. Furthermore, the bandwidth can be controlled by changing the duty cycle when the difference of waveguide width is large enough. And the waveguide shape change has a small impact on the reflection spectrum properties of waveguide grating..
Laser & Optoelectronics Progress
- Publication Date: May. 20, 2016
- Vol. 53, Issue 6, 60603 (2016)
Fiber-Optic Toluene Gas Sensor Based on Graphene
Xiao Yi, Zheng Zhendong, Li Kunxiao, Liang Zhenrong, Ma Kezhen, and Chen Yilin
A novel fiber-optic toluene sensor is fabricated by using a side-polished fiber (SPF) and reduced graphene oxide (rGO). The sensor can work at room temperature, of which the response time and the recovery time are about 256 s, and its toluene concentration lowest detection limit is below or equal to 7.9×10-5. The A novel fiber-optic toluene sensor is fabricated by using a side-polished fiber (SPF) and reduced graphene oxide (rGO). The sensor can work at room temperature, of which the response time and the recovery time are about 256 s, and its toluene concentration lowest detection limit is below or equal to 7.9×10-5. The sensor possesses a good linearity and reversibility during the low toluene concentration detection. The estimation based on the theoretical model of sensing mechanism indicates that the doping level of graphene has an important influence on the sensitivity of the sensor, and the sensitivity has a remarkable promotion through adjusting the chemical potential of graphene. The influence of retained water molecules on the sensing process can be evaluated or even utilized by monitoring or controlling the humidity. This sensor possesses a large potential to realize low-power, low-cost, fast, sensitive and highly reversible toluene detection..
Laser & Optoelectronics Progress
- Publication Date: May. 11, 2016
- Vol. 53, Issue 6, 60604 (2016)
New Method of Indoor High Accuracy Imaging Positioning Based on LED Light Source
Hou Wenzuo, Wang Daming, and Yang Yang
A kind of visible indoor location method based on intelligent mobile terminal is put forward. The method can get the light emitting diode light source label and image information through the terminal imaging component. According to the imaging position relationships between light sources and the focal length, geometricA kind of visible indoor location method based on intelligent mobile terminal is put forward. The method can get the light emitting diode light source label and image information through the terminal imaging component. According to the imaging position relationships between light sources and the focal length, geometric optical imaging principle is used to calculate the terminal position coordinates. The nonlinear system is set up by visible light imaging positioning system model and geometric optics imaging principle. The calculation of final position is completed using unscented Kalman filter algorithm. The theoretical simulation and experimental system verify the feasibility of the proposed method. The data shows that the proposed method can realize decimeter-level precision indoor positioning..
Laser & Optoelectronics Progress
- Publication Date: May. 31, 2016
- Vol. 53, Issue 6, 60606 (2016)
Image Processing
Gesture Recognition Method of Hand over Face Occlusion in Color and Depth Images
Liu Bin, Zhao Xing, Hu Chunhai, and Wan Xin
Hand over face occlusion is a typical difficulty during depth sensor application. Aiming at this point, a gesture recognition algorithm is proposed using color and depth information comprehensively. Kernel fuzzy C-means algorithm is used to get rough segments of hand over face occlusion image and gray enhancement. The Hand over face occlusion is a typical difficulty during depth sensor application. Aiming at this point, a gesture recognition algorithm is proposed using color and depth information comprehensively. Kernel fuzzy C-means algorithm is used to get rough segments of hand over face occlusion image and gray enhancement. The hand face separation is achieved. The initial level set function is introduced to solve the clustering method of gesture area pixels missing problem. The classification of gestures is carried based on the histogram of oriented gradient (HOG) features of depth map. The sample database is established by collecting different human hand and face close covered case gesture images. Comparative result proves the feasibility and effectiveness of the proposed algorithm. The proposed method can separate hand from face efficiently and get relatively ideal result, and the HOG features can describe the spatial information more precisely and get higher recognition rate compared with traditional characteristics..
Laser & Optoelectronics Progress
- Publication Date: May. 26, 2016
- Vol. 53, Issue 6, 61001 (2016)
Instrumentation, Measurement and Metrology
Method for Measuring Slope and Cross-Fall of Highway Based on Laser Range Finders
He Li, He Ming, Cao Min, Zhang Dejin, Wang Lei, and Chen Ze
The process to measure the slop and cross-fall of highway with traditional manual methods has disadvantages of speed, low accuracy, and low efficiency, which needs imperative traffic control and shows several shortcomings in real time, flexibility and security. We design a laser detection arrays composed of four laser The process to measure the slop and cross-fall of highway with traditional manual methods has disadvantages of speed, low accuracy, and low efficiency, which needs imperative traffic control and shows several shortcomings in real time, flexibility and security. We design a laser detection arrays composed of four laser range finders (LRF), and an inertial measurement unit (IMU) is combined with global positioning system (GPS) to form a measurement plane, which realizes the measurement of slop and cross-fall of highway. Then a calibration method based on relative movement is proposed, with which we can obtain the deviation angle of laser detection arrays and correct measurement data for calibration, then we can improve the measurement accuracy. The actual road test shows that with the proposed method the accuracy is improved about 5% after calibration. The repeatability of the slope and cross-fall experimental data is more than 95%, and the correlation reaches 99.9%, which can meet the requirements of the standard of field test methods of subgrade and pavement for highway engineering..
Laser & Optoelectronics Progress
- Publication Date: May. 31, 2016
- Vol. 53, Issue 6, 61201 (2016)
Numerical Simulation of Micro-Stress Measured by Heterodyne Interference Technology Based on Total Reflection
Gao Kai
An optical method to measure micro-stress based on common-path heterodyne interference technology via multiplet total reflections is presented. A heterodyne light beam with two polarization states (s-polarization and p-polarization) is incident on a grating, the first-order diffraction light is generated. Because the gAn optical method to measure micro-stress based on common-path heterodyne interference technology via multiplet total reflections is presented. A heterodyne light beam with two polarization states (s-polarization and p-polarization) is incident on a grating, the first-order diffraction light is generated. Because the grating is stretched by stress, its period changes thus the first-order diffractive angle has offset. Then, the first-order diffraction beam enters a strip prism and total reflection occurs, which cause the variation in phase difference between the s-polarized and the p-polarized light. By substituting the phase difference into the derived grating stress equation, the stress can be calculated. The measurement accuracy can be improved by multiple total reflections inside the prism. According to the simulation results, when the incidence angle is -5°, the grating period is 10 μm, and the number of total reflections is 30, the stress sensitivity to phase is 1.500 N/(°) and the resolution is 0.015 N. This method has such advantages as simple structure, rapid measurement, high sensitivity and free from outside disturbance..
Laser & Optoelectronics Progress
- Publication Date: May. 26, 2016
- Vol. 53, Issue 6, 61202 (2016)
Phase-Extracting Method of Laser Self-Mixing Interference Signal with Two Feedback External Cavity
Huan Hai, Guo Kelun, Zhang Yu, and Zhang Jingke
Based on the analysis of the theory model of self-mixing interference (SMI) with two feedback external cavity structure, the processing method of self-mixing interference signal is analyzed and simulated. Under the weak feedback level, the reconstruction of synthetic signal phase and the shape reconstruction of two chaBased on the analysis of the theory model of self-mixing interference (SMI) with two feedback external cavity structure, the processing method of self-mixing interference signal is analyzed and simulated. Under the weak feedback level, the reconstruction of synthetic signal phase and the shape reconstruction of two channel signals of external cavity are realized by using the Hilbert transform, and the maximum error is less than 1.5 rad. The self-mixing interference signal with noise is preprocessed by the wavelet soft threshold and ensemble empirical mode decomposition (EEMD) combining algorithm, which achieves a good effect..
Laser & Optoelectronics Progress
- Publication Date: May. 31, 2016
- Vol. 53, Issue 6, 61203 (2016)
Integrated Optics
Transmission Characteristics of Long-Range Dielectric-Loaded Surface Plasmon Polariton Waveguide Based on Golden Ratio
Shao Xiaozhen, Zhang Guanmao, Wang Qiong, and Hu Nan
A novel long-range dielectric-loaded surface plasmon polariton waveguide (LR-DLSPPW) structure based on the golden ratio is proposed. Transmission characteristics, like the normalized electric field distribution, mode effective index, attenuation constant, propagation distance, mode width, figure of merit (FOM), and coA novel long-range dielectric-loaded surface plasmon polariton waveguide (LR-DLSPPW) structure based on the golden ratio is proposed. Transmission characteristics, like the normalized electric field distribution, mode effective index, attenuation constant, propagation distance, mode width, figure of merit (FOM), and coupling length of this kind of waveguide, have been analyzed and numerically calculated via the finite element method at the telecom wavelength of λ0= 1.55 μm. The results show that the LR-DLSPPW based on the golden ratio has a longer propagation distance of 1.36 mm and a smaller mode width of 1.35 μm compared to non-golden ratio waveguides. When the height-width ratio of the dielectric ridge is at the golden ratio with a fixed area of 0.9 μm2, its FOM has a maximum value larger than 6.15×105. In addition, the crosstalk can be ignored when the distance between two adjacent waveguides exceeds 3 μm. Consequently, the designed waveguide has significant potential for applications in design of high density integrated optoelectronic circuits..
Laser & Optoelectronics Progress
- Publication Date: May. 25, 2016
- Vol. 53, Issue 6, 61301 (2016)
Lasers and Laser Optics
Actively Mode-Locked Lasers Based on Pulse Self-Intensity-Dependent Modulation
Wang Ruixin, Yang Meng, Zhang Qinjuan, Liu Zheng, An Xudong, and Chen Xiaochen
A novel all-polarization-maintained actively mode-locked laser with pulse self-intensity-dependent modulation is proposed. The pulse feed-forward structure and the dual-drive modulator are combined to realize the self-intensity-dependent modulation and two completely different stable mode-locking regimes. The function A novel all-polarization-maintained actively mode-locked laser with pulse self-intensity-dependent modulation is proposed. The pulse feed-forward structure and the dual-drive modulator are combined to realize the self-intensity-dependent modulation and two completely different stable mode-locking regimes. The function of the pulse feed-forward is studied theoretically. The experimental results demonstrate that the pulse feed-forward path suppresses supermode noise in the 10 GHz mode locking and makes absorption saturate in the fundamental mode-locking regime. Thanks to the multiple output property and stable operation, many applications will benefit from the novel laser..
Laser & Optoelectronics Progress
- Publication Date: May. 11, 2016
- Vol. 53, Issue 6, 61401 (2016)
Effect of Time-Frequency Disturbance on Performance of Dual-Frequency Laser Coherent Detection System
Zhang Jianhua, Yang Dezhao, Gao Jie, and Liu Ximin
The performance of laser detection system (LDS) is directly influenced by the velocity identification capability. Due to the bandwidth restriction of the receiver, the laser Doppler shift of the high speed targets can not be detected in LDS. A dual-frequency laser coherent detection (DLCD) system is introduced consequeThe performance of laser detection system (LDS) is directly influenced by the velocity identification capability. Due to the bandwidth restriction of the receiver, the laser Doppler shift of the high speed targets can not be detected in LDS. A dual-frequency laser coherent detection (DLCD) system is introduced consequently, which has successfully solved the problem and enhanced the system capabilities obviously. Based on the theory of the DLCD, the signal-noise ratio (SNR) influenced by the amplitude disturbance, the phase disturbance and the frequency disturbance are analyzed, and the characteristics different from the signal-frequency laser coherent detection (SLCD) are illuminated. The simulation results indicate that the amplitude disturbance effect on the SNR of DLCD is consistent with that of the SLCD. For various kinds of frequency and phase disturbance, the SNR of DLCD is higher than that of the SLCD. When the phase disturbance increases to 0.5π, the SNR of SLCD is 0 dB, while the DLCD is still higher than 18 dB..
Laser & Optoelectronics Progress
- Publication Date: May. 31, 2016
- Vol. 53, Issue 6, 61403 (2016)
Path Planning of Laser Cladding for Curved Surface Parts
Chen Ying, Sun Wenlei, Huang Yong, and Zhou Chaojun
In order to improve the laser cladding quality of curved surface parts, the path planning of laser cladding is carried out according to the technical characteristics of laser cladding. The laser cladding equipment is introduced, and the model of cured surface parts is established. According to the model, an orbital patIn order to improve the laser cladding quality of curved surface parts, the path planning of laser cladding is carried out according to the technical characteristics of laser cladding. The laser cladding equipment is introduced, and the model of cured surface parts is established. According to the model, an orbital path generation method based on the cutting plane method is proposed and the distance between cutting planes is determined by the cladding road overlap ratio. The effective processing defocusing amount is analyzed to calculate the processing step to obtain the interpolation point sets on the track and locate the processing control points. The offset method is used to get the position and attitude of the laser tip. The proposed method is verified by experiments with a high surface cladding quality, which proves the rationality of the path planning approach..
Laser & Optoelectronics Progress
- Publication Date: May. 19, 2016
- Vol. 53, Issue 6, 61405 (2016)
Study on Laser Cladding Process of 316L Stainless Steel Powder
Zan Shaoping, Jiao Junke, and Zhang Wenwu
In order to explore the influence of laser parameters on the cladding quality of 316L stainless steel powder on the 304# stainless steel plate and find out the optimal cladding parameters, a series of laser cladding experiments are carried out with a self-designed and assembled fiber laser cladding system. The surface In order to explore the influence of laser parameters on the cladding quality of 316L stainless steel powder on the 304# stainless steel plate and find out the optimal cladding parameters, a series of laser cladding experiments are carried out with a self-designed and assembled fiber laser cladding system. The surface morphology and cross sectional quality with different combinations of process parameters (laser power, cladding speed, laser frequency, defocusing amount, and so on) are detected and analyzed by means of laser scanning confocal microscope and Vickers hardness tester. The influence law of process parameters on the cladding quality is found and the optimum range of the cladding parameters is determined. The experimental results in this range show that the cladding surface is smooth with holonomic coating lines and without pores and cracks..
Laser & Optoelectronics Progress
- Publication Date: May. 11, 2016
- Vol. 53, Issue 6, 61406 (2016)
Rapid Measurement of Laser Linewidth Based on Fiber-Delayed AOM-Shifted Self-Heterodyne Scheme
Bai Jiandong, Wang Jieying, and Wang Junmin
The characteristics of laser power spectra under different laser linewidths are investigated experimentally based on the fiber-delayed acousto-optic modulator (AOM) shifted self-heterodyne scheme, and the relevant simulation analysis is performed. Meanwhile, a simple method is introduced that short fiber is used to meaThe characteristics of laser power spectra under different laser linewidths are investigated experimentally based on the fiber-delayed acousto-optic modulator (AOM) shifted self-heterodyne scheme, and the relevant simulation analysis is performed. Meanwhile, a simple method is introduced that short fiber is used to measure the linewidth of a narrow-linewidth laser. When the delay time of the fiber is less than the coherence time of the laser, 3 dB width of the beat signal cannot be directly used for measuring the laser linewidth. The experimental and theoretical analysis shows that the measurement result is hardly affected by the narrow peak. Therefore, it should be considered that the oscillations of the wings of the power spectrum rather than the effects of the narrow peak when dealing with the data. Using the weighted least square method, the laser linewidth can be obtained by theoretically fitting the experimental heterodyne spectrum. The scheme is not affected by the limit of the minimum resolution of the system, and it is applicable to the laser linewidth measurement, especially for narrow-linewidth lasers..
Laser & Optoelectronics Progress
- Publication Date: May. 11, 2016
- Vol. 53, Issue 6, 61407 (2016)
Effect of Airflow on Metal Plate Melted Through by Laser
Peng Guoliang, Wei Chenghua, Du Taijiao, and Zhang Xianghua
A numerical model of laser irradiating metal under airflow is established. The flame ablations irradiated by laser under different airflow velocity and thickness of tin plates are simulated by the CFD software and contrasted with experimental results. Laser irradiation on metal plates with different thickness affected A numerical model of laser irradiating metal under airflow is established. The flame ablations irradiated by laser under different airflow velocity and thickness of tin plates are simulated by the CFD software and contrasted with experimental results. Laser irradiation on metal plates with different thickness affected by airflow velocity is analyzed based on the research on liquid metal removal and heat convection mechanisms. The results indicate that the melting-through time of thicker metal plate decreases with the increasing airflow velocity as deeper craters are formed in the irradiation process and the melted liquid metal is more difficult to remove at the same airflow velocity; however, the melting-through time of thinner metal plate increases with the increasing airflow velocity as the craters are shallower, the liquid metal is easier to remove, and the heat convection is enhanced by mixing of the removed metal drop with air..
Laser & Optoelectronics Progress
- Publication Date: May. 21, 2016
- Vol. 53, Issue 6, 61408 (2016)
Optimization of an End-Pumped Yb3+:KGd(WO4)2 Laser with Different Parametrical Conditions
Gao Ming, Wang You, Wang Hongyuan, Jiang Zhigang, Zhang Wei, An Guofei, Han Juhong, Cai He, Xue Liangping, Zhou Jie, and Wang Shunyan
Yb3+:KGd(WO4)2 laser is a new solid-state laser source which has been paid much attention in the recent years. It is characterized with the high absorption and emission cross-section, broad fluorescent linewidth and low laser threshold. The microcosmic kinetic of three energy-level laser system is theoretically analyzeYb3+:KGd(WO4)2 laser is a new solid-state laser source which has been paid much attention in the recent years. It is characterized with the high absorption and emission cross-section, broad fluorescent linewidth and low laser threshold. The microcosmic kinetic of three energy-level laser system is theoretically analyzed. After investigating the absorptive and emission features with the different crystal cuttings, pump and laser polarization directions, the relationship between the output characteristics of a Yb3+:KGd(WO4)2 laser and the crystal length as well as the reflectance of the output coupler is analyzed. Finally, the optimum conditions for a real Yb3+:KGd(WO4)2 laser have been obtained as: crystal cut-direction parallel to g axis, pump polarization direction parallel to m axis and laser polarization direction parallel to p axis..
Laser & Optoelectronics Progress
- Publication Date: May. 31, 2016
- Vol. 53, Issue 6, 61409 (2016)
Tuning Characteristics of Periodically Poled Crystals in Optical Parameter Process
Xue Junwen, An Yulei, Xie Haijun, and Su Binghua
The temperature-tuning characteristic of periodically poled crystal, taking MgOsPPLT as an example, in the optical parameter process in the near infrared range with 532 nm pumping laser is studied by considering Sellmeier equation for the change of crystal refractive index with wavelength and temperature, the thermal eThe temperature-tuning characteristic of periodically poled crystal, taking MgOsPPLT as an example, in the optical parameter process in the near infrared range with 532 nm pumping laser is studied by considering Sellmeier equation for the change of crystal refractive index with wavelength and temperature, the thermal expansion of poled period with temperature, and the energy conservation condition during frequency conversion process. By increasing the poled period, the non-temperature-sensitive characteristic at the mid-infrared range with 1064 nm pumping laser is also obtained. Just by adjusting or ignoring the poled period term, and replacing the crystal dispersion equation, the method can be easily extended to other quasi-phase matched or phase-matched nonlinear crystals..
Laser & Optoelectronics Progress
- Publication Date: May. 31, 2015
- Vol. 53, Issue 6, 61410 (2016)
Stable All-Solid-State Single-Longitudinal-Mode Pulse Laser
Li Yuanji, Zhao Xin, Feng Jinxia, and Zhang Kuanshou
A stable all-solid-state single-longitudinal-mode acoustic-optic Q switched laser was developed based on a Nd:YVO4 crystal quasi-continuously pumped by an 880 nm laser diode and unidirectional travelling wave laser operation achieved by a 6-mirror ring cavity . The stable single-longitudinal-mode pulsed laser operationA stable all-solid-state single-longitudinal-mode acoustic-optic Q switched laser was developed based on a Nd:YVO4 crystal quasi-continuously pumped by an 880 nm laser diode and unidirectional travelling wave laser operation achieved by a 6-mirror ring cavity . The stable single-longitudinal-mode pulsed laser operation was realized by inserting an acoustic-optic Q-switch and combined etalons in the cavity. With the optimization to the transmissivity of the output coupler, laser pulse width can be narrowed and the single pulse energy can be increased. Laser output with repetition rate of 1 kHz, pulse width of 23.5 ns and single pulse energy of 1.64 mJ was achieved at the peak pump power of 29.1 W. This single pulse energy possesses a long-term stability better than ±1.3% within 2.5 h..
Laser & Optoelectronics Progress
- Publication Date: May. 16, 2016
- Vol. 53, Issue 6, 61411 (2016)
Materials
Study on First-Principle of Ce/S Co-Doped Anatase TiO2
Zeng Fanju, Tan Yongqian, Liang Dongmei, Yue Li, Zhang Song, Han Weichao, and Yang Yongliang
The energy band structure, density of electronic state and optical properties of Ce-doped anatase titanium dioxide（TiO2）, S-doped anatase TiO2 and Ce/S co-doped anatase TiO2 are investigated with first-principles based on density functional theory（DFT）. The results show that the lattice constant is enlarged due to dopiThe energy band structure, density of electronic state and optical properties of Ce-doped anatase titanium dioxide（TiO2）, S-doped anatase TiO2 and Ce/S co-doped anatase TiO2 are investigated with first-principles based on density functional theory（DFT）. The results show that the lattice constant is enlarged due to doping and the forbidden band is also decreased. For the Ce/S co-doped anatase TiO2, its forbidden bandgap is the smallest of all because of the synergy of S-3p and Ce-4f electronic orbits, which leads to the red shifts of the absorption spectra. Furthermore, Ce atom has two kinds of variable valence (Ce4+ and Ce3+), which can prevent the recombination of electrons and holes. The photocatalytic properties of TiO2 can be improved by Ce/S co-doping..
Laser & Optoelectronics Progress
- Publication Date: May. 20, 2016
- Vol. 53, Issue 6, 61601 (2016)
Optical Design and Fabrication
Fresnel Lens of Freeform Surface for Realizing Uniform Light Distribution on General LED Light Sources
Wan Yunjia, Liu Jie, Lin Haobo, and Xiong Hui
A general design method of Fresnel lens is proposed, which can be applied to LED light sources of general Lambert distribution, and the focusing and uniform light illuminance are realized simultaneously. The proposed method overcomes the imperfect focusing and uniform light illuminance optical effects of traditional leA general design method of Fresnel lens is proposed, which can be applied to LED light sources of general Lambert distribution, and the focusing and uniform light illuminance are realized simultaneously. The proposed method overcomes the imperfect focusing and uniform light illuminance optical effects of traditional lens. And the obtained Fresnel lens has the advantages of high focusing rate, thin thickness, large numerical aperture, and high efficiency of light extraction, which is beneficial to improving the lighting quality of LED sources. The lens is especially suitable for LED sources of large emission angle. Based on the theoretical design, 3D modeling of the lens and simulation are carried out by professional software, and the results verifies the validity and reliability of the proposed method..
Laser & Optoelectronics Progress
- Publication Date: May. 10, 2016
- Vol. 53, Issue 6, 62201 (2016)
Research for Magnetic Compound Fluid Slurry of Optical Glass
Li Wenmei, Jiang Chen, Xu Jipeng, and Wang Chunhua
According to the requirement of ultra-fine finishing of optical glass, composition and preparation of magnetic compound fluid (MCF) slurry are analyzed, and the polishing quality of BK7 optical glass is investigated with the different polishing parameters based on the prepared MCF slurry. Firstly, the physical performaAccording to the requirement of ultra-fine finishing of optical glass, composition and preparation of magnetic compound fluid (MCF) slurry are analyzed, and the polishing quality of BK7 optical glass is investigated with the different polishing parameters based on the prepared MCF slurry. Firstly, the physical performances of MCF polishing head in different mass fractions are investigated. A good shaped and stable MCF polishing head composed by iron powder 55%( mass fraction), H2O 30%, cerium oxide 12% and α-cellulose 3% is obtained. Then, the prepared MCF slurry has been used to spot polish experiment on BK7 optical glass by using a self-designed MCF polishing machine. The normal pressures of MCF polishing head and polished surface roughness have been experimentally investigated. The experimental results show that normal pressure of MCF polishing increases with the increase of spindle speed, and decreases with the increase of magnet eccentricity. And the surface roughness of workpiece has been improved from 10.2 nm to 6.7 nm after 50 min spot-polishing. It indicates that the MCF slurry meets the demand of ultra-fine finishing of optical glass..
Laser & Optoelectronics Progress
- Publication Date: May. 26, 2016
- Vol. 53, Issue 6, 62202 (2016)
Physical Optics
Triple-Momentum-Correlation of Orbital Electrons: Ab Initio Experiment on Ne Atom
Hu Tian, Ding Xin, Wang Yuye, Zhang Guizhong, and Yao Jianquan
By deploying the time-dependent Kohn-Sham (TDKS) scheme of the density functional theory, numerical simulations are performed on the photoionization of Ne atom and a triple-momentum-correlation (TMC) affected by intense extreme ultra-violet (XUV) laser pulses is found. The simulation results show the different characteBy deploying the time-dependent Kohn-Sham (TDKS) scheme of the density functional theory, numerical simulations are performed on the photoionization of Ne atom and a triple-momentum-correlation (TMC) affected by intense extreme ultra-violet (XUV) laser pulses is found. The simulation results show the different characteristics of ionization from different orbital electrons. For strong XUV laser intensity, ionization undergoes mainly along the orbital direction (longitudinal direction) for the p-type orbits in Ne atom. By simulating the momenta components of different orbital electrons, it is unveiled that the parallel momenta of the orbital electrons are mutually correlated, and the perpendicular momenta are also mutually correlated, but not between them. These correlation relations are deciphered in the interplay between the orbital geometry, orbital orientation and laser polarization. The simulation results also show a profound ionization of the inner orbital electrons..
Laser & Optoelectronics Progress
- Publication Date: May. 31, 2016
- Vol. 53, Issue 6, 62601 (2016)
Remote Sensing and Sensors
Application and Improvement of Phase Gradient Autofocus Algorithm in Synthetic Aperture Lidar
Zhang Jie, Wang Ran, and Zhang Keshu
Phase gradient autofocus (PGA) algorithm can be used to estimate and correct phase errors effectively in echo signals of synthetic aperture lidar. The wavelength of laser is three to four magnitudes shorter than that of the microwave, so the vibration of experimental platform can bring great phase errors during the proPhase gradient autofocus (PGA) algorithm can be used to estimate and correct phase errors effectively in echo signals of synthetic aperture lidar. The wavelength of laser is three to four magnitudes shorter than that of the microwave, so the vibration of experimental platform can bring great phase errors during the process of synthetic aperture lidar (SAL) imaging, which results in the reduction of imaging quality. To improve the image quality, a PGA algorithm with an improved method of windowing compared to the conventional PGA method is applied in SAL and is experimentally verified by an SAL demonstrator on a 64 m-distance-target to not only realize the accuate compensation to the phase errors in the defocusing data, but also have fewer iteration times and the same compensation effect..
Laser & Optoelectronics Progress
- Publication Date: May. 13, 2016
- Vol. 53, Issue 6, 62801 (2016)
Reviews
Application of Robust Control to Adaptive Optics Systems: A Summary and Review
Song Ding′an, Li Xinyang, and Peng Zhenming
In virtue of its excellent capability of managing uncertainty systems, robust control is applied to the adaptive optics system controller design, marking a new stage of development. While researchers overseas have done a lot of work, researchers in China are still at the threshold of this field. Existed theses are reviIn virtue of its excellent capability of managing uncertainty systems, robust control is applied to the adaptive optics system controller design, marking a new stage of development. While researchers overseas have done a lot of work, researchers in China are still at the threshold of this field. Existed theses are reviewed to promote research in this regard. It firstly introduces the concept and essence of robust control and sketches the outlines of robust control research at home and abroad in adaptive optics system. It then summarizes the previous research results and discusses several robust control methods in adaptive optics as well as major problems encountered. At last, future perspectives of the robust control used in adaptive optics system are discussed..
Laser & Optoelectronics Progress
- Publication Date: May. 16, 2016
- Vol. 53, Issue 6, 60001 (2016)
Research Progress Toward Flat Supercontinuum Generation in Fibers
Liang Tian, and Feng Xiaomei
With the advent of photonic crystal fiber in 1990s, researchers extend the research on the broadband high-brightness coherent supercontinuum light source. A lot of new technologies and new methods are emerging. In practical applications, the broadband high-brightness flat supercontinuum light source can not only satisfWith the advent of photonic crystal fiber in 1990s, researchers extend the research on the broadband high-brightness coherent supercontinuum light source. A lot of new technologies and new methods are emerging. In practical applications, the broadband high-brightness flat supercontinuum light source can not only satisfy system requirements on spectral bandwidth, but also improve detection accuracy and decrease difficulty to equalize the optical power. The supercontinuum light source has become an important research direction. The latest supercontinuum projects are introduced, then the research progress in supercontinuum generation in fibers with ultrashort pulses and continuous waves and the status of spectral manipulation are reviewed, and the prospect and applications of supercontinuum development are presented..
Laser & Optoelectronics Progress
- Publication Date: May. 24, 2016
- Vol. 53, Issue 6, 60002 (2016)
Review on RGB-D Image Classification
Tu Shuqin, Xue Yueju, Liang Yun, Huang Ning, and Zhang Xiao
The color and depth information of multi-scenario, multi-vision and multiple target in the RGB-D images are conveniently obtained using a new 3D sensor at the same time. The RGB-D image classification accuracy is effectively improved using the depth information invariant characteristics of color and brightness, when thThe color and depth information of multi-scenario, multi-vision and multiple target in the RGB-D images are conveniently obtained using a new 3D sensor at the same time. The RGB-D image classification accuracy is effectively improved using the depth information invariant characteristics of color and brightness, when the objects overlap and occlusion occurs. The development and theory of Microsoft Kinect are introduced in detail, and the existing RGB-D datasets are described. Then the feature extraction and classification methods are summarized, analyzed and compared. The development trend of RGB-D image classification is discussed..
Laser & Optoelectronics Progress
- Publication Date: Jun. 01, 2016
- Vol. 53, Issue 6, 60003 (2016)
Research Status and Developing Tread for Waveguide-Based Board-Level Optical Interconnects Technology
Yang Wei, Mao Jiubing, and Feng Xiaojuan
Compared to the conventional electrical interconnects, the optical interconnects has the advantages of higher speed, higher bandwidth, lower power, lower propagation loss and anti-electromagnetic interference. This make the optical interconnects have the potential application prospects in many fields, such as high perfCompared to the conventional electrical interconnects, the optical interconnects has the advantages of higher speed, higher bandwidth, lower power, lower propagation loss and anti-electromagnetic interference. This make the optical interconnects have the potential application prospects in many fields, such as high performance computer, high speed switching system, wavelength division multiplex (WDM) terminal and so on. The board-level circuits play a leading role in the electronic systems. Hence, the state of the art of waveguide-based board-level optical interconnects is introduced and analyzed. Moreover, through comparing the development status of the optical-electrical printed circuit board (EOPCB) in domestic and abroad, a reference of the main research direction and focus is provided for our country. Finally, the future development of the board-level optical interconnect technology is prospected..
Laser & Optoelectronics Progress
- Publication Date: May. 20, 2016
- Vol. 53, Issue 6, 60004 (2016)
All-Solid Chalcogenide Microstructured Optical Fiber with Two Zero-Dispersion Mid-Infrared Wavelengths
Chen Yali, and Yang Weibing
Based on As2Se3 and As2S5 glasses, an all-solid microstructured optical fiber with simple and easily drawing structure, and two zero-dispersion wavelengths in the mid-infrared is designed. Its effective refractive index, effective mode area, nonlinear coefficient, dispersion and group velocity are numerically simulatedBased on As2Se3 and As2S5 glasses, an all-solid microstructured optical fiber with simple and easily drawing structure, and two zero-dispersion wavelengths in the mid-infrared is designed. Its effective refractive index, effective mode area, nonlinear coefficient, dispersion and group velocity are numerically simulated by the finite-difference time-domain method. The result shows that dynamic adjustment of the two zero-dispersion wavelengths can be realized in the mid-infrared, and the second zero-dispersion wavelength can shift to the maximum wavelength of 7388 nm. The space between the two zero-dispersion wavelengths can continually be changed from 2706 nm to 3773 nm. This work provides a theoretical guidance for the application of nonlinear fiber optics..
Laser & Optoelectronics Progress
- Publication Date: May. 05, 2016
- Vol. 53, Issue 6, 60605 (2016)
Transmission Characteristics of the Double-Layer Semi-Circular Dielectric-Loaded Surface Plasmon Polariton Waveguides
Wang Qiong, Shao Xiaozhen, Zhang Guanmao, and Hu Nan
A new structure of double-layer semi-circular dielectric-loaded surface plasmon polariton (SPP) waveguide is proposed. By using the finite element method (FEM) on the waveguide structure at the telecom wavelength of λ=1550 nm, the transmission characteristics are simulated and analyzed to get the fundamental parametersA new structure of double-layer semi-circular dielectric-loaded surface plasmon polariton (SPP) waveguide is proposed. By using the finite element method (FEM) on the waveguide structure at the telecom wavelength of λ=1550 nm, the transmission characteristics are simulated and analyzed to get the fundamental parameters of this kind of waveguide. The results show that the optimal transmission characteristics of the waveguide propagation can be achieved with the same total area for the waveguide and the refractive index of n1=1.4 and n2=1.473 for the double semi-circular dielectric layers. When the ratio of the inner and outer semi-circular dielectric radii is r1/r2 = 0.5, the maximum propagation length, minimum attenuation coefficient, ideal waveguide mode area and figure of merit can be achieved with the same refractive index parameters, so the optimal transmission results can be obtained..
Laser & Optoelectronics Progress
- Publication Date: May. 05, 2016
- Vol. 53, Issue 6, 61302 (2016)
Effect of Refractive Index Inhomogeneity on Backscattering of Laser Gyros
Jiang Junbiao, Ma Jiajun, and Liu Jianning
Backscattering characteristics of mirror laser gyros and total reflection prism laser gyros are studied based on their structure features. The functional relationship between the refractive index inhomogeneity and backscattering is analyzed theoretically. The methods and formulas to calculate backscattering coefficientBackscattering characteristics of mirror laser gyros and total reflection prism laser gyros are studied based on their structure features. The functional relationship between the refractive index inhomogeneity and backscattering is analyzed theoretically. The methods and formulas to calculate backscattering coefficients of the two kinds of laser gyros are deduced according to the multi-layer high reflection film structure of the mirror laser gyro and the total reflection characteristic of the total reflection prism laser gyro. The correctness of the proposed method is verified by the comparison of numerical simulation and experimental results. The result shows that the non-uniform loss is the primary factor to influence the locking area of laser gyros and the refractive index inhomogeneity is the secondary factor..
Laser & Optoelectronics Progress
- Publication Date: Apr. 26, 2016
- Vol. 53, Issue 6, 61402 (2016)
Simulation and Analysis of Smith-Purcell Free Electron Laser Based on Sheet-Beam
Meng Xianzhu, Wang Minghong, and Ren Zhongmin
The radiation output characteristics of the Smith-Purcell free electron laser (S-P FEL) based on different sheet-beams are studied by the three-dimensional numerical simulation. As a sheet-beam flies closely to the rectangular gratings, it emits incoherent Smith-Purcell (S-P) radiation. The full feedback resonator reflThe radiation output characteristics of the Smith-Purcell free electron laser (S-P FEL) based on different sheet-beams are studied by the three-dimensional numerical simulation. As a sheet-beam flies closely to the rectangular gratings, it emits incoherent Smith-Purcell (S-P) radiation. The full feedback resonator reflects the radiation with a random azimuth angle back onto the sheet-beam and causes the electrons to be modulated, which leads to electron bunching and coherent S-P radiation. The numerical simulation results show that the power and power spectrum density of S-P FEL can be increased by the sheet-beams. The modulation of sheet-beam, the bunching state of sheet-beam, and the power and power spectrum density of S-P FEL, all increase with the increasing aspect ratio of sheet-beam..
Laser & Optoelectronics Progress
- Publication Date: May. 11, 2016
- Vol. 53, Issue 6, 61404 (2016)
Super-Resolution Remote Sensing Technology Based on Line-Array Detector Dislocation Imaging
Wu Zepeng, Cheng Fei, Qu Yaobin, and Huang Yeping
In order to improve the spatial resolution of optical remote sensing systems, a super-resolution remote sensing technique based on line-array detectors dislocation imaging is proposed. The dislocation arrangement of line-array detectors is presented and the super-resolution reconstruction algorithm is introduced to posIn order to improve the spatial resolution of optical remote sensing systems, a super-resolution remote sensing technique based on line-array detectors dislocation imaging is proposed. The dislocation arrangement of line-array detectors is presented and the super-resolution reconstruction algorithm is introduced to post-process the dislocated low-resolution images. A cost function is built based on the optical camera imaging theory. In the case of super-resolution factor is 2, the simulation experiments are conducted and the reconstruction methods are applied. Experimental results show that when four dislocated line-array detectors are deployed, the modulation transfer function(MTF) value at the equivalent Nyquist frequency of the reconstructed image is only 0.01 using the traditional interpolation, and the projection method while the MTF value at the same frequency is 0.28 using the proposed regularized reconstruction method. Besides, compared to the single line-array case with the MTF of 0.13 at the real Nyquist frequency, the proposed method also has a great promotion. Both image visual effect and statistical results of MTF validate the effectiveness of the proposed technique. This technology has great application value in the field of remote sensing imaging..
Laser & Optoelectronics Progress
- Publication Date: May. 18, 2016
- Vol. 53, Issue 6, 62802 (2016)
Spectroscopy
Overall Design of Miniature Spectrometer Based on Android
Zhou Haibin, Lei Xinzhuo, Zhou Wang, and Xu Feng
A spectrometer based on the Android processing system instead of the traditional personal computer system is developed in order to overcome the inconvenience in outdoor using and satisfy the needs of miniaturization and portability. The design of the optical system, mechanical structure, electronics and application proA spectrometer based on the Android processing system instead of the traditional personal computer system is developed in order to overcome the inconvenience in outdoor using and satisfy the needs of miniaturization and portability. The design of the optical system, mechanical structure, electronics and application program (APP) is introduced. To simplify the structure of the optical system, a plane holographic concave grating is used in the system, and the 3D printing technology is used to shape the mechanical structure. With a linear CCD array (TCD1304DG) as the photoelectric detector and an STC15 microcontroller unit (MCU) as the core, a high resolution spectrum data acquisition system based on the Android system is designed with Android USB (universal serial bus) communication. APP is developed for real-time processing of spectral data. The electronic shutter technology is utilized to realize the real-time adjustment of CCD integral time and satisfy the requirement on the portable spectrometer working in different environmental conditions. The design scheme uses the Android system as the data processing platform instead of the traditional personal computer system, exhibiting portability advantage..
Laser & Optoelectronics Progress
- Publication Date: May. 16, 2016
- Vol. 53, Issue 6, 63001 (2016)
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