Journals >Laser & Optoelectronics Progress
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2013
Volume: 50 Issue 5
29 Article(s)
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Fiber Optics and Optical Communications
Analysis of Intersatellite Microwave Photonic Link Performance under Synchronous Modulation of Two-Frequency-Band Signals
Li Xuan, Zhao Shanghong, Zhang Wei, Han Lei, and Zhao Jing
The performance of intersatellite microwave photonic link under synchronous modulation of multiple-frequency-band signals is different to the situation of single channel signal modulation. The link with synchronous modulation of four-channel signals of Ku and Ka bands is modeled. The radio-frequency signals received byThe performance of intersatellite microwave photonic link under synchronous modulation of multiple-frequency-band signals is different to the situation of single channel signal modulation. The link with synchronous modulation of four-channel signals of Ku and Ka bands is modeled. The radio-frequency signals received by satellite are optically processed such as amplification, transmission and distribution. The nonlinear components are analyzed with Bessel expansion, the signal-to-noise and distortion ratios (SNDRs) under single sideband (SSB), double-sideband (DSB) and push-pull modulation are derived. The link performances with different modulation are contrasted. The results show that, nonlinear distortion has a more serious effect on SSB modulation than DSB modulation. The optimal SNDR of SSB modulation is equal to that of DSB modulation and the corresponding modulation index of SSB is higher than that of DSB. Low bias of push-pull modulation cannot optimize the SNDR. Taking signal quality and power into consideration, the intersatellite microwave photonic link under synchronous modulation of multiple-frequency-band signals should choose the DSB modulation..
Laser & Optoelectronics Progress
- Publication Date: Apr. 28, 2013
- Vol. 50, Issue 5, 50601 (2013)
Distributed Fiber-Optic Sensing System of Brillouin Gain and Loss Effects Based on Brillouin Optical Correlation Domain Analysis
Jin Chongjiu, Zou Weiwen, Li Hao, and Chen Jianping
This paper proposes and demonstrates a novel scheme to improve the traditional Brillouin optical correlation domain analysis(BOCDA) system by combining Brillouin gain and loss effects. Thanks to the net gain measurement between the Brillouin gain and loss, the signal-to-noise ratio of the novel scheme is two-fold enhanThis paper proposes and demonstrates a novel scheme to improve the traditional Brillouin optical correlation domain analysis(BOCDA) system by combining Brillouin gain and loss effects. Thanks to the net gain measurement between the Brillouin gain and loss, the signal-to-noise ratio of the novel scheme is two-fold enhanced, but a also the scheme system needs fewer devices. We develop a prototype of the modified BOCDA system for distributed strain/temperature sensing by utilizing DMZM, two-level EDFA, polarization scrambler optimized circuit design and data acquisition technique, which has high spatial resolution of 1.6 cm, and high accuracy of 10 με (or 0.5 ℃)..
Laser & Optoelectronics Progress
- Publication Date: Apr. 12, 2013
- Vol. 50, Issue 5, 50602 (2013)
Holography
Study on Reduction of Speckle Noise in Reconstructed Image of Digital Hologram
Cai Xiaoou, and Ni Xiaojing
With the increasing application of digital hologram, how to acquire high quality of reconstructed image of digital hologram has been a very important research topic. Speckle noise has been one of the most difficult problems in the coherent imaging system because of its poor statistical regularity. Based on the statistiWith the increasing application of digital hologram, how to acquire high quality of reconstructed image of digital hologram has been a very important research topic. Speckle noise has been one of the most difficult problems in the coherent imaging system because of its poor statistical regularity. Based on the statistical characteristics and the formation cause of speckle noise in the reconstructed image of digital hologram, the way to reduce speckle noise is put forward. The frequency spectrum of reconstruction with lower energy is extracted from the reconstructed image of hologram and considered as approximate frequency spectrum of speckle noises. Then it is replaced with random data and the reconstructed image with different independent speckle noise is obtained. Lastly speckle energy is gradually reduced when the independent reproduced speckle noises are iteratively superimposed. As a result, the speckle noise can be reduced greatly and the quality of reconstructed image can be improved. The validity of this method is proved in theory and experiment. It offers a entirely new thinking and practical way to reduce the speckle noise in the reconstructed image of digital hologram..
Laser & Optoelectronics Progress
- Publication Date: Apr. 12, 2013
- Vol. 50, Issue 5, 50901 (2013)
Image Processing
Varying-Parameter Tikhonov Regularization Image Restoration
Yan Xuefei, Xu Tingfa, and Bai Tingzhu
Regularization is popular in image restoration recent years. We analyze the preconditioning conjugate gradient method with Tikhonov regularization under the periodic boundary conditions, and propose a new preconditioning matrix and the varying regularization parameter method. At first, we choose a larger regularizationRegularization is popular in image restoration recent years. We analyze the preconditioning conjugate gradient method with Tikhonov regularization under the periodic boundary conditions, and propose a new preconditioning matrix and the varying regularization parameter method. At first, we choose a larger regularization parameter to restrain the noise in the restored image, get a convergent result to modify the initial gradient. After that, we choose a smaller one to increase the details. Experiments on a set of image restoration and reconstruction benchmark problems show that the proposed algorithm performs favorably in comparison with several state-of-the-art regularization image restoration algorithms..
Laser & Optoelectronics Progress
- Publication Date: Apr. 12, 2012
- Vol. 50, Issue 5, 51001 (2013)
Imaging Systems
Design of Mobile Phone Camera Lens Based on CODE V
Yang Zhou, and Ding Guilin
Combining the aspherical lens principle, a fixed-focus lens with compact structure and low cost is designed with the optical system design software CODE V to meet the requirement of the mobile communication on miniaturization and simplification of camera lenses. For the designed lens, the F number is 2.05, the angle ofCombining the aspherical lens principle, a fixed-focus lens with compact structure and low cost is designed with the optical system design software CODE V to meet the requirement of the mobile communication on miniaturization and simplification of camera lenses. For the designed lens, the F number is 2.05, the angle of vision is 62°, the half image height is 2.4 mm, and the total length of the system is 5.59 mm. The aspherical lens made of plastic is used to reduce the size and save production cost in the structural design. The design result shows that the pixel size of the lens is 1.1 μm×1.1 μm, the corresponding Nyquist frequency is 454 lp/mm, the modulation transfer function (MTF) values of most FOV at half Nyquist frequency are more than 0.4, transverse aberration of all FOV is less than 9.26 μm, the root-mean-square (RMS) radii are less than Airy disk, and the distortion is less than 1%. The designed lens has an excellent imaging performance..
Laser & Optoelectronics Progress
- Publication Date: Apr. 12, 2013
- Vol. 50, Issue 5, 51101 (2013)
Instrumentation, Measurement and Metrology
Wind Tunnel Measurements Based on Digital Image Correlation Method
He Neng, Liao Haili, Ma Cunming, Wang Kai, Zeng Yaozheng, and Zeng Li
Based on mark points on the surface of bridge pneumatic model adopting the digital image correlation (DIC) method to handle the pictures captured by CCD video camera in the high frequency, the displacement values of the mark points in the time series are gotten and thus the vibration responses of the bridge are obtaineBased on mark points on the surface of bridge pneumatic model adopting the digital image correlation (DIC) method to handle the pictures captured by CCD video camera in the high frequency, the displacement values of the mark points in the time series are gotten and thus the vibration responses of the bridge are obtained. The fundamental principles of the DIC method and its application are introduced. The reliability, stability and advantages of the method are testified by the comparison of the results with those measured by the laser displacement sensor..
Laser & Optoelectronics Progress
- Publication Date: Apr. 08, 2013
- Vol. 50, Issue 5, 51201 (2013)
Testing Large SiC Mirror by Subaperture Stitching Interferometry
Wang Xiaokun
In order to overcome the difficulty of testing the surface shape of large mirror, the subaperture stitching interferometry (SSI) is introduced. The basic principle and flow chart of SSI are analyzed, the synthetical optimization stitching model and effective stitching algorithm are established based on triangulation alIn order to overcome the difficulty of testing the surface shape of large mirror, the subaperture stitching interferometry (SSI) is introduced. The basic principle and flow chart of SSI are analyzed, the synthetical optimization stitching model and effective stitching algorithm are established based on triangulation algorithm, least-squares fitting and homogeneous coordinates transformation etc. With engineering examples, a large sic mirror with the aperture of 800 mm is tested by SSI with 7 subapertures. The coordinate transformation between digital controlled fine processing the mirror surface and pixel coordinate is fulfiled by bench mark and iterative algorithm, so it provide the basis for the subsequent the physical coordinate of the large mirror..
Laser & Optoelectronics Progress
- Publication Date: Apr. 08, 2013
- Vol. 50, Issue 5, 51202 (2013)
Integrated Design of Multifunction TRFIA and Phenylketonuria Fluorometer
Guo Long
Fluorescence analysis and time-resolved fluorescence immunoassay (TRFIA) are often used in screening of new born babies′ desease, while there is no domestic instrument having a collection of two measurements. A multi-function time-resolved instrument is developed to integrate two measurements, which is a lens-optical fFluorescence analysis and time-resolved fluorescence immunoassay (TRFIA) are often used in screening of new born babies′ desease, while there is no domestic instrument having a collection of two measurements. A multi-function time-resolved instrument is developed to integrate two measurements, which is a lens-optical fiber combined instrument. According to the US. Committee for Clinical Laboratory Standards (NCCLS) documents and related literatures, the instrument is tested. It is compared with THERMO Varioskan Flash and PekinElmer Wallac 1420, which are used widely by major hospitals in China. The results show that the specification of the instrument are in line with requirements, and it could be put into practical production..
Laser & Optoelectronics Progress
- Publication Date: Apr. 12, 2012
- Vol. 50, Issue 5, 51203 (2013)
Measurement of Dynamically Changing Pupil in Optical System
Sun Zheng, and Shen Feng
The measurement of pupil-positoin change in real-time precise automatic alignment of optical system is investigated. The translation data of the pupil is obtained by processing reference of phase-correlation algorithm and experimentally measured image; the measurement relative error is less than 0.4 pixel. In accordancThe measurement of pupil-positoin change in real-time precise automatic alignment of optical system is investigated. The translation data of the pupil is obtained by processing reference of phase-correlation algorithm and experimentally measured image; the measurement relative error is less than 0.4 pixel. In accordance with the various influencing factors such as the grey level change, noise, rotation and scaling, theoretical analysis and simulation test of the algorithm is performed. The results show that algorithm can overcome effect of inhomo-geneous distrbution of light intensity and severe noise, so that high measurement result can be obtained. After correction of the rotation and scaling corrected, the measurement precision remains in 1 pixel. The measurement method that superposed multi-image sum is taken as the reference image is proposed, the phase correlation SNR is enhanced by 88.6%, robutness is obviously increased..
Laser & Optoelectronics Progress
- Publication Date: Apr. 12, 2012
- Vol. 50, Issue 5, 51204 (2013)
Highlight Removal Based on Frequency-Domain Filtering
Chai Yuting, Wang Zhao, Gao Jianmin, and Huang Junhui
Three-dimensional (3D) measurement technique of structured light is widely used in objects′ outline measurement. However, when it is applied to measure mechanical components and parts, some parts of intense reflection (highlight or specular light) on the surface of metal components would form highlight area. The intensThree-dimensional (3D) measurement technique of structured light is widely used in objects′ outline measurement. However, when it is applied to measure mechanical components and parts, some parts of intense reflection (highlight or specular light) on the surface of metal components would form highlight area. The intense reflected light can make CCD saturate and cause the extraction of center of light stripe inaccurate, and then errors would appear in the measurement results. Thus, it is a matter of great urgency to find a way to avoid highlight. We try to use the characteristic of structured light measurement system to propose a new method of highlight removal——frequency-domain filtering. Highlight is defined as a kind of noise, and this method compares the difference between highlight frequency spectrum and diffuse light frequency spectrum to make frequency filtering, and then to remove the influence of highlight. Simulating highlight in 3dsmax software, the proposed method can get 0.8 pixel improvement in the accuracy of light stripe extraction. Results of real blade test are also provided and prove that it is a better solution in actual blade test. Both simulation and experiment confirm that the proposed method could improve the accuracy in extraction of light stripe center..
Laser & Optoelectronics Progress
- Publication Date: Apr. 28, 2013
- Vol. 50, Issue 5, 51205 (2013)
Integrated Optics
Research on the Slow Light Characteristics of a Novel Low-Dispersion Photonic-Crystal Coupled-Cavity Waveguide
Zhang Changxin, Xu Xingsheng, Xi Wei, Li Tianle, Lu Ji, and Wang Xiaofang
We design a two-dimensional photonic crystal coupled-cavity waveguide. Transmission spectra of the waveguide are calculated by using finite-difference time-domain (FDTD) method, and slow light with an average group velocity vg=c/725.93, group refractive index ng=725.93 at the central wavelength of 1.54538 μm is obtaineWe design a two-dimensional photonic crystal coupled-cavity waveguide. Transmission spectra of the waveguide are calculated by using finite-difference time-domain (FDTD) method, and slow light with an average group velocity vg=c/725.93, group refractive index ng=725.93 at the central wavelength of 1.54538 μm is obtained. This coupled-cavity waveguide can produce “U” type group index-frequency curves with low-dispersion slow-light area at the bottom of the “U” type curves, and the central wavelength of the area of 1.54720 μm, average group index g=142.6, bandwidth Δλ=2.16 nm and flat ratio σ=3.20% are obtained by calculation. We shift the location of the first row of air hole in the coupled-cavity waveguide to investigate the change of low-dispersion slow light. The results show that the central wavelength of low-dispersion slow light at the bottom of the “U” type area varies from 1.54720 μm to 1.60549 μm, the average group index g varies from 142.6 to 26.7 and the bandwidth Δλ increases from 2.16 nm to 15.21 nm by shifting the location of the first row of air hole in the coupled-cavity waveguide..
Laser & Optoelectronics Progress
- Publication Date: Apr. 08, 2013
- Vol. 50, Issue 5, 51301 (2013)
Lasers and Laser Optics
Experimental Study on Laser Transmission Welding of PMMA
Jiao Junke, Jiang Huarui, Zhou Guangbing, and Bai Xiaobo
To investigate the physical principle of laser transmission welding of plastics, comprehend the effect of welding parameters on the welding quality, find out the optimum welding parameters and improve the quality of plastic transmission welding, an experimental investigation of transmission welding of polymethyl methacTo investigate the physical principle of laser transmission welding of plastics, comprehend the effect of welding parameters on the welding quality, find out the optimum welding parameters and improve the quality of plastic transmission welding, an experimental investigation of transmission welding of polymethyl methacrylate (PMMA) with 1064 nm fiber laser is carried out on the fiber laser material processing system. The physical phenomena in the welding process are analyzed, the welding quality for different welding parameters such as laser power, laser diameter and welding speed is compared. The influencing law of welding parameters on the welding quality and the optimum welding parameters under special condition are found out. The welding piece is tested by a pull testing unit. The result shows that the strength of the welding seam is higher than that of base material..
Laser & Optoelectronics Progress
- Publication Date: Apr. 08, 2013
- Vol. 50, Issue 5, 51401 (2013)
Investigation and Application of Coaxial Output Three-Wavelength Picosecond Laser Micro-Machining System
Liu Yang, Yu Jin, Zhang Xue, Mo Zeqiang, Nie Shuzhen, Huang Yutao, Fan Zhongwei, and Chen Bo
In order to satisfy micro-machining requirements of different materials, a coaxial output three-wavelength picosecond laser micro-machining system is designed with three-wavelength picosecond laser, self-designed optics system and control system. This system can use any one, two or three of the laser wavelengths to proIn order to satisfy micro-machining requirements of different materials, a coaxial output three-wavelength picosecond laser micro-machining system is designed with three-wavelength picosecond laser, self-designed optics system and control system. This system can use any one, two or three of the laser wavelengths to process at the same working distance. Through the axial chromatic aberration compensation design, the maximum distance of axial focus compensation is 0.4 mm, and the diameter of the minimum focal spot is 3 μm. With this system，the experiments of cutting copper electrode plates and mobile phone screen and fabricating graphics for position-sensitive anode detector have been carried out. Experiments show that the system can satisfy the micro-machining requirements of many materials..
Laser & Optoelectronics Progress
- Publication Date: Apr. 08, 2013
- Vol. 50, Issue 5, 51402 (2013)
Effects of Laser Shock Peening and Ultrasonic Shot Peening on Fatigue Property of 1Cr11Ni2W2MoV Stainless Steel
Lai Zhilin, Wang Cheng, Li Yinghong, Zhou Liucheng, He Weifeng, Nie Xiangfan, and Sun Dong
In order to compare the effects of laser shock peening (LSP) and ultrasonic shot peening (USP) on fatigue property in 1Cr11Ni2W2MoV stainless steel, vibration fatigue tests of three different samples are conducted at 20 ℃, X-ray diffractometry (XRD), scanning electron microscopy (SEM) and transmission electron microscoIn order to compare the effects of laser shock peening (LSP) and ultrasonic shot peening (USP) on fatigue property in 1Cr11Ni2W2MoV stainless steel, vibration fatigue tests of three different samples are conducted at 20 ℃, X-ray diffractometry (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are used to investigate the mechanism of fatigue property improvement. Experimentally, the fatigue lives of 1Cr11Ni2W2MoV stainless steel after USP and LSP are increased by 88.2% and 280.1%, respectively. The surface residual stress after LSP is -810 MPa and the one after USP is -545 MPa, and the compressive residual stress depth after LSP and USP is 1.8 mm, 0.4 mm, respectively. The surface microhardness after LSP and USP increases from 392 HV to 434 HV and 405 HV, respectively. The microstructure studies demonstrate that USP has an advantage in microstructure refinement and surface nanocystallines. We come to the conclusion that the residual stress and the small influence to the roughness make great contributions to the superiority of LSP in the improvement in fatigue property of 1Cr11Ni2W2MoV stainless steel over USP at 20 ℃..
Laser & Optoelectronics Progress
- Publication Date: Apr. 08, 2013
- Vol. 50, Issue 5, 51403 (2013)
Analysis and Computation of Band Offset of Strained Quantum Wells
Hua Lingling, and Yang Yang
We calculate the band offset ratio of InGaAs quantum wells with different barrier materials using Model-solid theory and Harrison model. The Model-solid theory, which is more suitable for the studied materials, is selected to calculate the band offset ratio. Then we discuss the influence of the strain, quantum well matWe calculate the band offset ratio of InGaAs quantum wells with different barrier materials using Model-solid theory and Harrison model. The Model-solid theory, which is more suitable for the studied materials, is selected to calculate the band offset ratio. Then we discuss the influence of the strain, quantum well material composition, barrier material composition and band gap, on the band offset. The results show that the compressive strain will increase the band gap and reduce the band offset. With increase of the trap material composition and barrier material composition, the band offset will gradually increase. However, the band offset ratio is not always increased with the increase of barrier material composition. In InxGa1-xAs/AlyGa1-yAs quantum wells, the Al content (y) of about 0.1 is the preferred value, and the In content (x) less than 0.2 is the preferred value..
Laser & Optoelectronics Progress
- Publication Date: Apr. 28, 2013
- Vol. 50, Issue 5, 51404 (2013)
Optical Devices
Radiative Recombination Coefficient of the Streamer in GaAs Photoconductive Semiconductor Switches
Liu Hong, Zheng Li, Yang Hongjun, Yang Wei, Zheng Yonglin, and Zhu Xiaolin
The radiative recombination coefficient is introduced in spontaneous emission phenomena of GaAs samples. For the spontaneous emission phenomena of streamer in high gain GaAs photoconductive semiconductor switch (PCSS), the average radiative recombination coefficient, (883)≈0.1125, is approximately determined by the simThe radiative recombination coefficient is introduced in spontaneous emission phenomena of GaAs samples. For the spontaneous emission phenomena of streamer in high gain GaAs photoconductive semiconductor switch (PCSS), the average radiative recombination coefficient, (883)≈0.1125, is approximately determined by the simple average method and the normalization conditions. The relationship between radiative recombination coefficients of different radiation wavelengths and the average radiative recombination coefficient is derived. The radiative recombination coefficient of 890 nm radiation, η(890)=0.1182, is calculated. The maximum optical output energy calculated by substituting the value of η(890) coincides with the result of experimental observations. This demonstrates that the approximation method and the results are reasonable..
Laser & Optoelectronics Progress
- Publication Date: Apr. 08, 2013
- Vol. 50, Issue 5, 52301 (2013)
Precise Analysis of Formation and Suppression of Intensity Transmittance Fluctuations of Glan-Taylor Prisms
Zhu Huafeng, Li Dailin, Song Lianke, Wang Xiumin, Zhan Kaiyun, Wang Ning, and Yun Maojin
The light intensity transmittance of Glan-Taylor polarizing prism suffers from fluctuations in spatial incident angle. By using three-axis model and multibeam interference theory, we develop the expression of light transmittance of the prism in spatial incident angle. Based on Malus law, the light intensity transmittanThe light intensity transmittance of Glan-Taylor polarizing prism suffers from fluctuations in spatial incident angle. By using three-axis model and multibeam interference theory, we develop the expression of light transmittance of the prism in spatial incident angle. Based on Malus law, the light intensity transmittance of the analyzer in optical system is simulated, which shows that the fluctuations on intensity transmittance curve result from the multibeam interference in the parallel air gap, and the magnitude and position of the fluctuations lie on the parallelism of the air gap and the spatial position of the prism in the optical system. The intensity fluctuations can be completely suppressed with the angle between the rotation axis of the prism and the optical axis β=0°. For β≠0°, by giving the air gap a glued error angle, the transmittance fluctuations are well suppressed. The critical glued error angle for suppressing fluctuaitons decreases with the increase of the incident spot size..
Laser & Optoelectronics Progress
- Publication Date: Apr. 12, 2013
- Vol. 50, Issue 5, 52302 (2013)
A Control Scheme of Polarization Generator Based on Three LiNbO3 Wave Plates
Huang Chunhui, and Rong Weibo
Based on Pockels effect of LiNbO3 crystal, a retardation-control-type polarization controller (PC) of three wave plates is designed. Creatively using the polarization controller as polarization generator for continuous variable quantum key distribution (CVQKD), the rapid conversion of polarized states is achieved. The Based on Pockels effect of LiNbO3 crystal, a retardation-control-type polarization controller (PC) of three wave plates is designed. Creatively using the polarization controller as polarization generator for continuous variable quantum key distribution (CVQKD), the rapid conversion of polarized states is achieved. The proposed communication system uses a single-channel optical signal as a carrier, and the two orthogonal Stokes components as a physical quantity can be observed and encoding controlled. The implementation principle of the proposal is analyzed and verified. An improved simulated annealing algorithm (SAA) is constructed to complete the search of the optimal path for the rapid conversion of polarizated states. The voltage value of the search step is set below 2.5 V, which not only guarantees the applied control voltage gradient and benefits the actual hardware circuit design, but also eliminates the influence of the device structure defects. Control process simulation is carried out to verify the feasibility of the scheme implementation. The actual circuit is suggested to be designed using a digital signal processor (DSP) to complete the entire control process, and further a high-speed information encoding..
Laser & Optoelectronics Progress
- Publication Date: Apr. 12, 2013
- Vol. 50, Issue 5, 52303 (2013)
Reviews
Recent Progress of Semiconductor Mode-Locked Lasers
Wang Huolei, Kong Liang, Pan Jiaoqing, Xu Tianhong, Ji Wei, Ni Haiqiao, Cui Bifeng, and Ding Ying
Ultrashort-pulse lasers are attractive sources for a number of applications including optical fiber communication and biomedical imaging etc. Semiconductor mode-locked lasers are excellent candidates for ultrashort pulse generation due to their advantages in compactness, weight, energy efficiency and cost. We give a coUltrashort-pulse lasers are attractive sources for a number of applications including optical fiber communication and biomedical imaging etc. Semiconductor mode-locked lasers are excellent candidates for ultrashort pulse generation due to their advantages in compactness, weight, energy efficiency and cost. We give a comprehensive introduction to the latest progress of semiconductor mode-locked lasers based on an overall review of recent research reports for the semiconductor mode-locked lasers operating at the wavelength range from 400 nm to 2 μm..
Laser & Optoelectronics Progress
- Publication Date: May. 06, 2013
- Vol. 50, Issue 5, 50001 (2013)
Techniques on Long-Range and High-Resolution Imaging Lidar
Jin Xiaofeng, Zhang Peng, Liu Chunhua, Sun Jianfeng, and Liu Liren
Techniques of spaceborne and airborne high-resolution imaging for long-range target are always the goals of researchers. To break through the diffraction limitation of optical aperture system, several imaging lidar techniques are developed at home and abroad. Four types of imaging lidar principle based on “point emittiTechniques of spaceborne and airborne high-resolution imaging for long-range target are always the goals of researchers. To break through the diffraction limitation of optical aperture system, several imaging lidar techniques are developed at home and abroad. Four types of imaging lidar principle based on “point emitting, area irradiating, point receiving” are given. The corresponding experimental and engineering achievements are introduced and compared..
Laser & Optoelectronics Progress
- Publication Date: May. 06, 2013
- Vol. 50, Issue 5, 50002 (2013)
Research of Key Enabling Technologies for High-Speed Visible-Light Communication
Li Rongling, Shang Huiliang, Lei Yu, Wang Yiguang, Wang Yuanquan, Lu Xiaoyuan, and Chi Nan
LED replacing fluorescent and incandescent lamps for lighting has become an obvious trend. The feature that LED can be used for both illumination and communications makes visible-light communication (VLC) become a hot point in recent years. With the rapid popularization of computers and smart devices, the bandwidth andLED replacing fluorescent and incandescent lamps for lighting has become an obvious trend. The feature that LED can be used for both illumination and communications makes visible-light communication (VLC) become a hot point in recent years. With the rapid popularization of computers and smart devices, the bandwidth and coverage of access networks need further improvement. VLC technology is a promising communication technology for high speed data transmission to break through the bottlenecks. A main challenge of this technology is the limited modulation bandwidth of white LED. Researchers have proposed a variety of techniques, such as equalization technology, blue filtering, high-order modulation formats, discrete multi-tone (DMT) modulation, wavelength division multiplexing (WDM) technology, and multiple-input multiple-output (MIMO) technology, to extend bandwidth and increase transmission speed. The principles and performances of those techniques are analyzed and discussed to provide a reference for future researches..
Laser & Optoelectronics Progress
- Publication Date: May. 06, 2013
- Vol. 50, Issue 5, 50003 (2013)
Research Progress on Laser Surface Modification by High-Power Diode Laser
Guo Shirui, Chen Zhijun, Zhang Qunli, and Yao Jianhua
High-power diode laser (HPDL) is widely used in the field of industry. This paper summarizes the characteristics of HPDL, mainly introducing the research progress on laser surface modification by HPDL both at home and abroad. The application statuses of HPDL in laser surface modification are reviewed. At the end, futurHigh-power diode laser (HPDL) is widely used in the field of industry. This paper summarizes the characteristics of HPDL, mainly introducing the research progress on laser surface modification by HPDL both at home and abroad. The application statuses of HPDL in laser surface modification are reviewed. At the end, future development and trend about this field are looked forward to..
Laser & Optoelectronics Progress
- Publication Date: Apr. 28, 2013
- Vol. 50, Issue 5, 50004 (2013)
Status and Development of Tertiary Mirror Technology in Large Aperture Telescope
Yang Fei, Wang Fuguo, Chen Baogang, and Zhang Limin
In order to comprehend the functions of tertiary mirror applied in large aperture telescopes and meet the requirements for developing large aperture telescope, the technologies of tertiary mirror systems are summarized from the development of optics system configuration, variation of aperture and variation of functionaIn order to comprehend the functions of tertiary mirror applied in large aperture telescopes and meet the requirements for developing large aperture telescope, the technologies of tertiary mirror systems are summarized from the development of optics system configuration, variation of aperture and variation of functionality. A more detailed description about the tertiary mirror technology is given with the conceptual design of Thirty-Meter Telescope (TMT) tertiary mirror system. The tertiary mirrors play a more and more important role in telescopes, especially in large aperture telescopes. With the development of telescope technology, the requirements for tertiary mirrors also become more and more strict, and the functions of tertiary mirrors become more and more variable..
Laser & Optoelectronics Progress
- Publication Date: Apr. 28, 2013
- Vol. 50, Issue 5, 50005 (2013)
Confinement and Trapping of Light in Organic Solar Cells
Xiao Xiao, Xie Shiwei, Zhang Zhiyou, Li Shuhong, Hou Yidong, Liu Yu, Hu Dejiao, Gao Fuhua, and Du Jinglei
The mismatch between electrical transmission properties and light absorption properties is one of the main reasons that limit the power conversion efficiency of organic solar cells. This contradiction could be efficiently resolved by light trapping structures which manipulate incident light and enhance light absorptionThe mismatch between electrical transmission properties and light absorption properties is one of the main reasons that limit the power conversion efficiency of organic solar cells. This contradiction could be efficiently resolved by light trapping structures which manipulate incident light and enhance light absorption. These structures essentially extend the photoactive layer thickness, therefore achieve light absorption equivalent to that of a much thicker layer, and nevertheless retain good charge transport properties of a thin layer. The characteristics and principles of these architectures such as plasmonics and photonic crystal are discussed in detail. The prospect of light trapping architectures is also presented. It may be helpful to expand the design ideas of organic solar cells and understand the advanced light management of the next-generation solar cells..
Laser & Optoelectronics Progress
- Publication Date: Apr. 28, 2013
- Vol. 50, Issue 5, 50006 (2013)
Spectroscopy
Synchronous Fluorescence Spectra Study on Changes in Metmyoglobin under Ultraviolet Irradiation
Wu Mingcao, Jin Bangquan, Chen Xuming, Feng Yuying, and Huang Heyong
The changes in porcine myocardial metmyoglobin (pMetMb) and horse myocardial metmyoglobin (hMetMb) under ultraviolet irradiation are studied comparatively by synchronous fluorescence spectra. The ultraviolet irradiation is designed for the six gradients of 0, 5, 10, 20, 30, 60 min. With the irradiation of ultraviolet lThe changes in porcine myocardial metmyoglobin (pMetMb) and horse myocardial metmyoglobin (hMetMb) under ultraviolet irradiation are studied comparatively by synchronous fluorescence spectra. The ultraviolet irradiation is designed for the six gradients of 0, 5, 10, 20, 30, 60 min. With the irradiation of ultraviolet light, disintegration happens in the senior structure of MetMb. Synchronous fluorescence spectra can identify the influences of ultraviolet induction on tyrosine (Tyr) and tryptophan (Trp). The amino acid absorption value decreases for 0~5min, increases for 5~30 min, and decreases again for 30~60 min. It is identified that the ratio of Trp in the protein peptide chain is higher than the proportion of Tyr and two kinds of fluorescence spectra in pMetMb and hMetMb have similar changes. Synchronous fluorescence spectra further identify the heme-Fe3+ fluorescence spectra sign change in MetMb. The heme-Fe3+ fluorescence intensity is reduced when MetMb has been exposured for 5 min, and fluorescence intensity becomes higher for 10 min. After 20 min, the senior structure of heme-Fe3+ may be degraded or destroyed obviously, that may be fluorescence spectra variation characteristics in MetMb caused by the loss of biological activity..
Laser & Optoelectronics Progress
- Publication Date: May. 06, 2013
- Vol. 50, Issue 5, 53001 (2013)
Detection of Cu and Cr in the Soil of Navel Orange Plantation in Gannan by LIBS
Lin Yongzeng, Yao Mingyin, Chen Tianbing, Li Wenbing, Zheng Meilan, and Liu Muhua
In order to detect the heavy metal in the soil of navel orange plantation land in Gannan based on laser induced breakdown spectroscopy (LIBS), LIBS and atomic absorption experiments are performed on the samples collected from 16 different areas in Xinfeng an Anxi county of Gannan to detect the Cu and Cr elements. From In order to detect the heavy metal in the soil of navel orange plantation land in Gannan based on laser induced breakdown spectroscopy (LIBS), LIBS and atomic absorption experiments are performed on the samples collected from 16 different areas in Xinfeng an Anxi county of Gannan to detect the Cu and Cr elements. From the information of spectral intensity, signal to background ratio and real concentrations of Cu and Cr in different areas, the lowest concentration of Cu and Cr in the soil gained in atomic absorption experiment are 3.179 μg/g and 6.524 μg/g, respectively, while their spectral intensities in elements are both very obvious. And the relative standard deviation (RSD) in LIBS are all around 10%. However, in-depth experimental study to eliminate matrix effects and new methods for data processing should be done for quantitative analysis..
Laser & Optoelectronics Progress
- Publication Date: Apr. 12, 2013
- Vol. 50, Issue 5, 53002 (2013)
Visible-Near-Infrared Transmission Spectra for Rapid Analysis of the Freshness of Eggs
Zhao Jiewen, Bi Xiakun, Lin Hao, Sun Li, and Guan Binbin
The Haugh unit, yolk index and weight loss rate are important indicators to evaluate the freshness of eggs. Near-infrared (550~985 nm) transmission spectra expressing the egg internal quality are collected to make non-destructive quantitative analysis. Pretreatment of spectrum is based on Savitzky-Golay spectrum smoothThe Haugh unit, yolk index and weight loss rate are important indicators to evaluate the freshness of eggs. Near-infrared (550~985 nm) transmission spectra expressing the egg internal quality are collected to make non-destructive quantitative analysis. Pretreatment of spectrum is based on Savitzky-Golay spectrum smoothness method and first-order differential. A model is established using synergic-interval partial least square (SI-PLS) method for an appropriate spectral or wavelength range. Effective information of the spectrum, obtained from the principal component analysis of characteristic variables, is input into the back propagation artificial neural network (BP-ANN) to set a nonlinear model. The comparison of the two models shows that the SI-PLS model is better than the BP-ANN model. The results prove that the application of near-infrared transmission spectrum to evaluate egg freshness is feasible..
Laser & Optoelectronics Progress
- Publication Date: May. 06, 2013
- Vol. 50, Issue 5, 53003 (2013)
Thin Films
Enhanced Optical Transmission through the Periodic Arrays of Fish-Shaped Metallic Nano Structure
Yi Chenlin, Liu Jun, Liu Hui, Chen Zhiyong, Guo Wei, Zhu Weihua, and Wang Xinlin
We numerically studied the enhancement of optical transmission through the periodic arrays of fish-shaped nano structure metallic arrays by using the three-dimensional finite-difference time-domain (3D-FDTD) method, and investigate the influence of lattice constant and hole shape on the optical filtering properties，whiWe numerically studied the enhancement of optical transmission through the periodic arrays of fish-shaped nano structure metallic arrays by using the three-dimensional finite-difference time-domain (3D-FDTD) method, and investigate the influence of lattice constant and hole shape on the optical filtering properties，which is based on transmission. Results show that fish-shaped metallic nano structure has the properties of high transmission efficiency and high filtering quality factor. It is revealed by analyzing the maps of electric-field distribution that optical transmission originates from two different physical mechanisms: localized waveguide resonance mode and surface plasmon resonance mode. Two resonance modes arise in different places in fish-shaped hole region at different time with different forms..
Laser & Optoelectronics Progress
- Publication Date: Apr. 28, 2013
- Vol. 50, Issue 5, 53101 (2013)
Effect of Annealing with CdCl2/ZnCl2 on Properties of Cd1-xZnxTe Polycrystalline Thin Films
Jin Shuo, Wang Wenwu, Wu Lili, Zeng Guanggen, Li Wei, Zhang Jingquan, Li Bing, and Feng Lianghuan
Cd1-xZnxTe (CZT) polycrystalline thin films are deposited by vacuum co-evaporation and then annealed either with 50%CdCl2+50%ZnCl2 complex source or with ZnCl2 source. The optical, morphological and electrical properties of films annealed at different temperatures and in different time are studied by X-ray fluorescenceCd1-xZnxTe (CZT) polycrystalline thin films are deposited by vacuum co-evaporation and then annealed either with 50%CdCl2+50%ZnCl2 complex source or with ZnCl2 source. The optical, morphological and electrical properties of films annealed at different temperatures and in different time are studied by X-ray fluorescence, scanning electron microscopy, transmission spectra and conduction type tests. The results show that the band gaps of CZT thin films annealed with 50%CdCl2+50%ZnCl2 complex source decrease apparently. CZT thin films annealed with ZnCl2 source show smooth morphology and larger grain size and the band gaps remain steady. Both annealing temperature and the amount of ZnCl2 source have influence on film morphology and electrical properties..
Laser & Optoelectronics Progress
- Publication Date: Apr. 28, 2013
- Vol. 50, Issue 5, 53102 (2013)
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