Journals >Laser & Optoelectronics Progress
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2012
Volume: 49 Issue 7
28 Article(s)
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Fiber Optics and Optical Communications
Modulation Recognition of Wireless Optical Communication Using Subcarrier Modulation Over Atmosphere Weak Turbulence Channel
Chen Dan, and Ke Xizheng
Based on noise characteristics of wireless optical communication, atmospheric channel model is established. Clustering analysis in constellation is used in subcarrier M-ary phase shift keying (MPSK) modulation under different scintillation distribution. While turbulence intensity is wake, MPSK (M≤8) modulation signal cBased on noise characteristics of wireless optical communication, atmospheric channel model is established. Clustering analysis in constellation is used in subcarrier M-ary phase shift keying (MPSK) modulation under different scintillation distribution. While turbulence intensity is wake, MPSK (M≤8) modulation signal could get high recognition rate arriving 88%. With the increasing of turbulence intensity, clustering performance of constellation becomes poor, and the recognition rate of 16PSK decreases. The simulation results show that the method studied here has certain applied prospect in subcarrier modulation signal recognition over wireless optical communication..
Laser & Optoelectronics Progress
- Publication Date: May. 16, 2012
- Vol. 49, Issue 7, 70601 (2012)
Design of Interference Distributed Fiber-Optic Underwater Long Gas Pipeline Leakage Detection System
Hu Zhengsong, Yang Qihua, and Qiao Bo
A new measuring structure based on the principle of Sagnac and Mach-Zehnder mixed distributed fiber-optic interferometer is proposed. The structure can detect pipeline leakage and locate leakage point in real-time. The leakage measuring principle and leakage positioning method for the structure are described, and the wA new measuring structure based on the principle of Sagnac and Mach-Zehnder mixed distributed fiber-optic interferometer is proposed. The structure can detect pipeline leakage and locate leakage point in real-time. The leakage measuring principle and leakage positioning method for the structure are described, and the wavelet transform algorithm is used to analyze the acquisition of the leakage signals. The pipeline leakage detection experiment is carried out for the length of 3.994 km of the fiber-optic sensor, and the test experiments are repeated 10 times. The experimental results show that the system is stable and the maximum relative positioning error is 1.47%..
Laser & Optoelectronics Progress
- Publication Date: May. 16, 2012
- Vol. 49, Issue 7, 70602 (2012)
Holography
Research on Digital Synthetic Holography Based on Multi-Parallax Stereo Display
Long Tao, and Qian Keyuan
Synthetic holography takes advantage of multi-parallax images to realize stereo display, and it can produce large area image through partition exposure. We describe the theory and system of digital synthetic holography and discuss the principle of the image division and recombination for two sampling modes. After analySynthetic holography takes advantage of multi-parallax images to realize stereo display, and it can produce large area image through partition exposure. We describe the theory and system of digital synthetic holography and discuss the principle of the image division and recombination for two sampling modes. After analyzing the overlapped projection of the recombination image during the unit holograms exposure, we design an overlapped projecting lens based on nonimaging optics theory. The lens is simulated through optical design software. Finally we perform synthetic holography experiments with the lens. The results show that using the overlapped projecting lens and an appropriate image processing method, a clear-cut holographic stereogram with a strong three-dimensional sense can be obtained..
Laser & Optoelectronics Progress
- Publication Date: May. 31, 2012
- Vol. 49, Issue 7, 70901 (2012)
Image Processing
Adaptive Direction Lifting Multiwavelet Algorithm Based on D9/7 Wavelet Transform
Fang Zhijun, Gao Yongbin, Shu Lei, and Jiao Yanbin
An adaptive direction lifting multiwavelet algorithm is proposed, which combines the symmetry, orthogonality, short support set, high-order vanishing moment of multiwavelet with the directional characteristics of adaptive algorithm, therefore it improves the performance of image compression. The traditional multiwaveleAn adaptive direction lifting multiwavelet algorithm is proposed, which combines the symmetry, orthogonality, short support set, high-order vanishing moment of multiwavelet with the directional characteristics of adaptive algorithm, therefore it improves the performance of image compression. The traditional multiwavelet transform only considers the vertical and horizontal direction transform, while adaptive lifting multiwavelet algorithm utilizes more local direction features of the image to look for the correlation between the pixels, so as to reduce the prediction errors of encoding. We use two D9/7 wavelets to construct a lifting multiwavelet, in combination with rate-distortion (RD) model to adaptively choose the lifting direction of the local region of the image, which makes a balance between reducing the prediction error and coding bit rate. Experimental results show that adaptive direction lifting multiwavelet has a better performance than the traditional lifting multiwavelet in image coding..
Laser & Optoelectronics Progress
- Publication Date: May. 16, 2012
- Vol. 49, Issue 7, 71001 (2012)
Research on Speckle Range Measurement Based on Virtual Sports
Ruan Chuanyang, Deng Feiqi, Jiang Jun, and Cheng Jun
Virtual sports is a vivid human-computer interaction system. Search speed of the traditional speckle correlation algorithm is a little lower and it cannot meet the actual requirement of virtual sports. By studying the methods of digital speckle correlation measurement, a kind of an effective fast search method based onVirtual sports is a vivid human-computer interaction system. Search speed of the traditional speckle correlation algorithm is a little lower and it cannot meet the actual requirement of virtual sports. By studying the methods of digital speckle correlation measurement, a kind of an effective fast search method based on the relevant information of the neighborhood is proposed which can greatly reduce the computational complexity of the corresponding point matching and increase the speed of depth measurement. According to the error characteristics, a new interpolation method based on distance weighting is presented, which can greatly improve the accuracy of depth measurement. Experiments are demonstrated to support the effectiveness of this method..
Laser & Optoelectronics Progress
- Publication Date: May. 21, 2012
- Vol. 49, Issue 7, 71002 (2012)
Instrumentation, Measurement and Metrology
Measurement and Analysis on the Modulation Transfer Function of CCD Camera
Zhao Man, Jiang Bo, Fan Xiuying, and Guo Fei
Modulation transfer function (MTF) plays an important role in the CCD camera imaging system. It indicates the relation between spatial frequency and image contrast. In the MTF measurement experiment, the choosing of the test board is the key. The measurement accuracy of the system and the complexity of operating procedModulation transfer function (MTF) plays an important role in the CCD camera imaging system. It indicates the relation between spatial frequency and image contrast. In the MTF measurement experiment, the choosing of the test board is the key. The measurement accuracy of the system and the complexity of operating procedure strongly depend on it. Although the ideal function of the test board is sine function, it is difficult to make up the sine test board. In order to solve this problem, the testing method of MTF is introduced, in which the sine test board is replaced by the resolving power test target consisting of parallel dark and bright stripes alternately. The MTF of CCD camera is examined at the Nyquist frequency and the results are analyzed and evaluated in detail..
Laser & Optoelectronics Progress
- Publication Date: May. 22, 2012
- Vol. 49, Issue 7, 71201 (2012)
Research on Improving Accuracy of Large Radius of Curvature Measurement Using Surface Profiler
Liang Xu, Wang Junhua, and Xu Min
The disadvantages of large radius of curvature measurement using surface profiler according to ultra-precision optical manufacturing are discussed. An improved method is proposed to achieve higher accuracy, in which the NIKON Autocollimator 6D is used to assist the measurement of the Form Talysurf PGI 1250 A surface prThe disadvantages of large radius of curvature measurement using surface profiler according to ultra-precision optical manufacturing are discussed. An improved method is proposed to achieve higher accuracy, in which the NIKON Autocollimator 6D is used to assist the measurement of the Form Talysurf PGI 1250 A surface profiler. When the optical axis of autocollimator and the normal direction of vertex of sample are coaxial, rotating the sample, the normal direction of vertex of it will not change, and then the position of reflected image received by autocollimator will not change too. Meanwhile, autocollimator can be used to find the vertex of sample because of its high accuracy. Theoretical calculation and Zemax simulation based on relevant parameters are given. Experimental equipment is set up for measuring samples with different radii of curvature, and comparison with previous experimental results is illustrated. Measurement accuracy of surface profiler is increased to 2～4 times, showing that this method is suitable for large radius of curvature measurement. Rationality and effectiveness of the method are validated..
Laser & Optoelectronics Progress
- Publication Date: May. 16, 2012
- Vol. 49, Issue 7, 71202 (2012)
An Ultra-Precision on-Machine Measurement Method of Aspheric Surface
Chen Fengjun, Yin Shaohui, Yu Jianwu, Wang Yu, and Zhu Yongjian
High quality ultra-precise machining of aspheric surface includes machining, test, and compensation machining. In order to remove repeating installation error and decrease on-machine time of the aspheric surface, a contact on-machine measurement method is proposed in combination with a laser interferometer. Shape errorHigh quality ultra-precise machining of aspheric surface includes machining, test, and compensation machining. In order to remove repeating installation error and decrease on-machine time of the aspheric surface, a contact on-machine measurement method is proposed in combination with a laser interferometer. Shape error of the ground surface is measured directly on the machine. The on-machine measuring principle and aspheric measuring process are studied. The measurement errors caused by positional deviation and inclination angle error are corrected in ultra-precise contact on-machine measurement process. A small aspheric surface after grinding is measured by the on-machine contact measurement method and the off-line measurement system, and the measuring results are compared to confirm the validity of the proposed method..
Laser & Optoelectronics Progress
- Publication Date: May. 16, 2012
- Vol. 49, Issue 7, 71203 (2012)
Lasers and Laser Optics
Variable Beam Divergence Design Method for High Power Diode Laser
Fei Bing, Wang Youzi, Liu Tao, Sun Jian, Wang Wei, Du Yan, Duan Yong, and Cui Qingfeng
On the basis of studying the beam characteristics of high power diode laser (HPLD), variable beam divergence design method for high power diode laser is presented. A variable beam divergence shaping system with two plane-convex cylindrical lenses perpendicular to each other for extended astigmatic source is designed. TOn the basis of studying the beam characteristics of high power diode laser (HPLD), variable beam divergence design method for high power diode laser is presented. A variable beam divergence shaping system with two plane-convex cylindrical lenses perpendicular to each other for extended astigmatic source is designed. This system can obtain the required beam divergence and change it in a certain range by defocusing. A mathematical model between motion quantity and beam divergence is set up. The results simulated by commercial optical design software show that this system can reduce the beam divergence and change it continually in a certain range. The transformed beam can illuminate different area objects..
Laser & Optoelectronics Progress
- Publication Date: Apr. 24, 2012
- Vol. 49, Issue 7, 71401 (2012)
Particle-in-Cell of Self-Generated Magnetic Fields and Thermal Transport in Laser Inertial Fusion
P. Tuniyazi, A. Abudurexiti, and P. Mejid
Stimulated self-generated magnetic field and electron thermal transport properties in ultraintense laser-plasma interactions are studied by using electromagnetic relativistic particle-in-cell simulation program. The generation mechanism of spontaneons magnetic and nonlinear saturation process are discussed. Functional Stimulated self-generated magnetic field and electron thermal transport properties in ultraintense laser-plasma interactions are studied by using electromagnetic relativistic particle-in-cell simulation program. The generation mechanism of spontaneons magnetic and nonlinear saturation process are discussed. Functional relation between linear growth rate of spontaneons magnetic and anisotropic parameters is provided. The state of transport of energy in the heat exchange with electron is analyzed by the Spitzer-Harm theory, and electron′s vertical pyrogenation phenomenon resulting from anisotropic heating of laser is observed. The results may be important for understanding the spontaneous magnetic field generation and fast electron propagation in fast iginition physics..
Laser & Optoelectronics Progress
- Publication Date: May. 16, 2012
- Vol. 49, Issue 7, 71402 (2012)
Experimental Study on Intra-Cavity Frequency-Doubling at 532 nm in an Yb-Doped Fiber Laser
An Hongbo, Niu Lihong, Su Binghua, Xue Junwen, and Tan Yu
A structure of intra-cavity frequency doubling in a continuous-wave (CW) Yb-doped double-clad fiber laser is proposed. High conversion efficiency green laser can be obtained in theory due to the high pump power density in the cavity. Advances in compact structure of double-clad fiber laser also allow for the availabiliA structure of intra-cavity frequency doubling in a continuous-wave (CW) Yb-doped double-clad fiber laser is proposed. High conversion efficiency green laser can be obtained in theory due to the high pump power density in the cavity. Advances in compact structure of double-clad fiber laser also allow for the availability of laser integration. In this work, the optimized efficiency is achieved when the waist is located at the edge of MgO∶PPLN and the Rayleigh length is equal to twice the length of the crystal, and the lens′ location in the system was calculated. 10.5 mW green laser is obtained, and the second harmonic generation (SHG) efficiency of the system is 0.35%. Laser oscillation in the cavity is verified and it is indicated that the structure can achieve effective CW green output..
Laser & Optoelectronics Progress
- Publication Date: May. 22, 2012
- Vol. 49, Issue 7, 71403 (2012)
Study on Corrosion Resistance Property of Welding HAZ Treated by Laser Surface Quenching
Li Yanli, Li Ling, Liu Xin, and Liu Jie
Welding is a main joint way of the alloy constructional steel. The welding heat affected zone (HAZ) is more sensitive to corrosion in comparison with other areas. In order to increase the corrosion resistance of the welding HAZ, laser surface quenching is used to treat the welding HAZ. According to the results of the oWelding is a main joint way of the alloy constructional steel. The welding heat affected zone (HAZ) is more sensitive to corrosion in comparison with other areas. In order to increase the corrosion resistance of the welding HAZ, laser surface quenching is used to treat the welding HAZ. According to the results of the orthogonal test, the optimized processing parameters are obtained. Based on the electrochemical analysis, it is found that the corrosion current of 30CrMnSi welding HAZ can be decreased obviously by laser quenching technology. So the corrosion resistance of the HAZ can be improved effectively with this method..
Laser & Optoelectronics Progress
- Publication Date: May. 22, 2012
- Vol. 49, Issue 7, 71404 (2012)
Materials
Transmission Characteristic of 2-D Regular Triangular Lattice Metallic Photonic Crystal in THz Range
Tan Yi, and Yuan Zongheng
Transmission characteristic of terahertz wave in two-dimensional regular triangular lattice metallic photonic crystal is analyzed and studied through frequency-domain finite element algorithm. Copper is chosen for dielectric cylinder, and the background material is air. By changing the incident direction of terahertz, Transmission characteristic of terahertz wave in two-dimensional regular triangular lattice metallic photonic crystal is analyzed and studied through frequency-domain finite element algorithm. Copper is chosen for dielectric cylinder, and the background material is air. By changing the incident direction of terahertz, lattice constant and the ratio of filling material, and combining with a thoroughly systematic analysis of the transmission properties of both the TM mode and TE mode, the transmission patterns of terahertz in metallic photonic crystal with regular triangular lattice are acquired.The research results indicate that the characteristics of transmission are related to the ratio of filling material, lattice constant and incident direction of terahertz, and the band gap ranges of TE mode and TM mode are also very different. These have provided theoretic foundation for the development and production of photonic crystal filter, reflector and E/H polarization in terahertz region..
Laser & Optoelectronics Progress
- Publication Date: May. 16, 2012
- Vol. 49, Issue 7, 71601 (2012)
Research on Technics of TiC Hardened Coating Prepared by Hybrid Process of Laser and Sol-Gel
Zeng Qi, Zhang Qunli, Xu Ning, and Yao Jianhua
Laser hardening experiments are performed by Nd:YAG laser on the surface of 45 steel with TiO2/C compound powder prepared by sol-gel to get TiC enhanced coating. The influence of laser parameters and ratio of the powder materials on phases of hardened coating are investigated to explore the optimum technics. The phasesLaser hardening experiments are performed by Nd:YAG laser on the surface of 45 steel with TiO2/C compound powder prepared by sol-gel to get TiC enhanced coating. The influence of laser parameters and ratio of the powder materials on phases of hardened coating are investigated to explore the optimum technics. The phases, microstructures and elemental analysis are tested by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS), respectively. The results show that the optimum processing parameters should be laser current of 250 A, pulse frequency of 18 Hz, pulse width of 2.5 ms, laser velocity of 50 mm/min, and the mole ratio of TiO2 and C should be 15. Under the above condition, TiC reinforcing phase can be in-situ synthesized on the surface of 45# steel and the hardened coating with TiC particles uniformly distributed can be obtained..
Laser & Optoelectronics Progress
- Publication Date: May. 22, 2012
- Vol. 49, Issue 7, 71602 (2012)
Medical Optics and Biotechnology
Experiment Study of Selective Abortion Surgery with 1064 nm Pulsed Laser
Ge Jianhong, Wang Yixin, Pan Sunqiang, and Xiang Zhen
Due to the increase of multiple pregnancy rate and the shortcomings of the selective abortion surgery used now, a new method that uses 1064 nm pulsed laser to operate on the embryo and results in abortion selective is presented. Such method is more safe, reliable, convenient and quick. In the experiment, cattle muscle Due to the increase of multiple pregnancy rate and the shortcomings of the selective abortion surgery used now, a new method that uses 1064 nm pulsed laser to operate on the embryo and results in abortion selective is presented. Such method is more safe, reliable, convenient and quick. In the experiment, cattle muscle tissue and mouse are used as samples and operated by laser pulse with pulse width of 8 ns, pulse energy of 60~100 mJ and pulse repetition rate of 1~10 Hz adjustable, which cause the sample has a foraminal damage of 1 mm in diameter and 4 mm in depth. From the results, a point that pulsed laser can be used in selective abortion surgery can be confimed..
Laser & Optoelectronics Progress
- Publication Date: May. 21, 2012
- Vol. 49, Issue 7, 71701 (2012)
Redundant Photonics in Function Networks
Liu Chengyi, Zhu Ling, Li Fanghui, Liu Yanying, and Zhang Jie
A function performance of a biosystem is maintained by its negative feedback and redundant pathways. The negative feedback response has been defined as a function-specific homeostasis (FSH) in the laboratory. A FSH non-essential subfunction (FNS) may be in its FNS-specific homeostasis (FNSH). A FSH-specific stress (FSSA function performance of a biosystem is maintained by its negative feedback and redundant pathways. The negative feedback response has been defined as a function-specific homeostasis (FSH) in the laboratory. A FSH non-essential subfunction (FNS) may be in its FNS-specific homeostasis (FNSH). A FSH-specific stress (FSS) disrupting the FSH may also be in its FSS-specific homeostasis (FSSH). A FSS in its FSSH is called successful stress, but a FSS far from its FSSH is just chronic stress. A stress disrupting a FNSH is called an ordinary stress. It was supposed that redundant genes/pathways may be activated partially in a chronic ordinary stress but completely in a successful ordinary stress after studying the deeper networks controlling function networks. Low level laser irradiation or monochromatic light has no direct effects on completely activated redundant genes/pathways, but can modulate partially activated redundant genes/pathways. The redundant hypothesis on redundant pathways is primarily supported by experimental studies, but the one on redundant genes should be further verified..
Laser & Optoelectronics Progress
- Publication Date: May. 16, 2012
- Vol. 49, Issue 7, 71702 (2012)
Optical Design and Fabrication
Measurement and Evaluation for the Optical System in Laser Large-Area Scanning Projection Imaging Lithography
Mei Longhua, Zhou Jinyun, Lei Liang, Lin Qinghua, Wang Xinxing, and Shi Ying
Based on the system of a large-area laser projection imaging lithography using 351 nm XeF excimer laser, some optical properties of the system including illumination system and folded projection system are measured. According to the variation of energy and beam quality of the beam passing through two cylindrical squareBased on the system of a large-area laser projection imaging lithography using 351 nm XeF excimer laser, some optical properties of the system including illumination system and folded projection system are measured. According to the variation of energy and beam quality of the beam passing through two cylindrical square lenses and two microlens arrays and projection folded system, some evaluating norm about excimer laser beam uniformity is partly adopted to evaluate this optical system. The energy distribution on different crucial areas of the optical system and the top-hat factor can be obtained. The results show that the microlens array maintains the beam uniformity, whereas the energy utilization rate is suppressed due to the diffraction. Meanwhile, through the printed circuit board (PCB) and ITO lithographic experiment, it shows that the designed double-telecentric confocal projection lithographic system can meet the required resolution, provided the uniform-output energy is controlled to be in accord with the exposure dose..
Laser & Optoelectronics Progress
- Publication Date: May. 21, 2012
- Vol. 49, Issue 7, 72201 (2012)
Structural Design of Large-Frame Continuous Rotating Mirror Framing Camera
Li Jian, Wang Wei, and Shang Changshui
A large-frame continuous rotating mirror framing camera is developed by using the coaxial imaging theory and controlling defocusing range. It has the frame size of 30 mm×18 mm, dynamic visual resolution of 35 lp/mm, relative aperture of 1/15 in spatial direction and 1/35 in scanning direction, frame number of 80, A large-frame continuous rotating mirror framing camera is developed by using the coaxial imaging theory and controlling defocusing range. It has the frame size of 30 mm×18 mm, dynamic visual resolution of 35 lp/mm, relative aperture of 1/15 in spatial direction and 1/35 in scanning direction, frame number of 80, and framing rate from 1×104 to 5×105 frame/s. The camera runs conveniently under a new control system. High-resolution images about a detonation experiment are obtained with this camera under the framing rate of 2×105 frame/s. It is proved that this camera can be used for imaging in such experiments as shock wave, detonation and gesture of bowb..
Laser & Optoelectronics Progress
- Publication Date: May. 24, 2012
- Vol. 49, Issue 7, 72202 (2012)
OPTOELECTRONICS
Performance of Heterojunction Organic Photovoltaic Device with the Mixed CuPcC60 Layer
Li Weimin, Guo Jinchuan, and Zhou Bin
CuPcC60 mixed-layer heterojunction organic photovoltaic devices (OPV) and the different performance with the double-layer device is investigated. The results suggest that OPV with the mixed layer has the enhanced device performance, and the open circuit voltage, short circuit current density, the power conversion efficCuPcC60 mixed-layer heterojunction organic photovoltaic devices (OPV) and the different performance with the double-layer device is investigated. The results suggest that OPV with the mixed layer has the enhanced device performance, and the open circuit voltage, short circuit current density, the power conversion efficiency and fill factor have been improved, respectively, from CuPc-C60 double-layer structure devices 0.39 V, 1.92 mA/cm2 and 0.36%, 0.48 to CuPcC60 mixed layer devices 0.48 V, 2.21 mA/cm2 and 0.54%, 0.51. The properties of donor-acceptor (D/A) and organic/metal interfaces are studied according to the integer charge transfer model, the open-circuit voltage enhancement of mixed-layer device is due to the increment of HOMO(D)-LUMO(A) offset. The short-circuit current density increase is attributed to the enhancement of the mixed layer heterojunction organic photovoltaic devices D/A interfaces and the increment of HOMO(D)-LUMO(A) offset, leading to the higher photo generated exciton dissociation..
Laser & Optoelectronics Progress
- Publication Date: Apr. 24, 2012
- Vol. 49, Issue 7, 72501 (2012)
Linear Electro-Optic Effect of Near-Infrared Femtosecond Laser Pulses with High Intensity in MgO:LiNbO3 Crystal
Zhong Dongzhou, and She Weilong
The linear electro-optic (EO) effect of near-infrared femtosecond laser pulses with high intensity in MgOLiNbO3 crystal is numerically investigated. It is found that, if an external electric field is applied along the direction perpendicular to the optical axis of crystal and is set at the optimization value of EO effeThe linear electro-optic (EO) effect of near-infrared femtosecond laser pulses with high intensity in MgOLiNbO3 crystal is numerically investigated. It is found that, if an external electric field is applied along the direction perpendicular to the optical axis of crystal and is set at the optimization value of EO effect, a high input intensity will result in the broadening of output pulses in normal dispersion region. And in abnormal dispersion region, the output durations become narrower when the input light intensity becomes higher. For the light pulse with central wavelength at λ0=1.6335 μm, the output durations can be compressed by this EO effect. For example, with the input pulse duration T0=5 fs and intensity I0=20 GW/cm2 fixed, the minimum output duration is 0.76 T0. And for T0>5 fs, the minimum output duration is less than 0.76 T0. If another external electric field is applied along the direction of optical axis of crystal to modulate the phase of light pulse，the central wavelength corresponding to the minimum pulse duration will make a blue or red shift and the shift becomes large with the increase of applied electric field..
Laser & Optoelectronics Progress
- Publication Date: May. 21, 2012
- Vol. 49, Issue 7, 72502 (2012)
Reviews
Recent Research Progress in Green IP over WDM Network
Guo Aihuang, and Xue Lin
In recent years, optical network is developing towards high rate and wide bandwidth. As the number of network equipments in optical network increases, the network power consumption has a sharp rising. In order to decrease the energy consumption and improve the energy efficiency, the concept of green IP over WDM networkIn recent years, optical network is developing towards high rate and wide bandwidth. As the number of network equipments in optical network increases, the network power consumption has a sharp rising. In order to decrease the energy consumption and improve the energy efficiency, the concept of green IP over WDM network has been proposed and it has become a hotspot for research in the area of optical network. The existing research status for energy-saving approaches in optical network is reviewed. Specifically, starting with network equipment, the relationship between traffic load and energy consumption of network equipments is discussed and two power consumption models are established. Then a mathematical expression of minimized energy consumption for IP over WDM network is introduced based on the network structure. Subsequently, the methods to reduce the energy consumption at network level are divided into different categories, whose fundamental principles and energy saving effects are summarized, and several typical energy-saving approaches are compared as well. Finally, the limitations of existing approaches are analyzed and some suggestions are provided for the further research directions..
Laser & Optoelectronics Progress
- Publication Date: May. 21, 2012
- Vol. 49, Issue 7, 70001 (2012)
Developments of X-Ray Grating Imaging Based on Talbot Interferometry
Han Yueping, Chen Zhiqiang, Zhang Li, Huang Zhifeng, Zhang Ran, and Jiang Xiaolei
We present a review of X-ray grating-based imaging based on interferometry, including the recent developments in instrumentation and methodology. The classic X-ray grating-based imaging based on Talbot-Lau interferometry is introduced in terms of its general principles and system configuration, as well as the multiple We present a review of X-ray grating-based imaging based on interferometry, including the recent developments in instrumentation and methodology. The classic X-ray grating-based imaging based on Talbot-Lau interferometry is introduced in terms of its general principles and system configuration, as well as the multiple information (i.e., attenuation, refraction and small-angle scattering information) retrieval algorithms. Up-to-date analyses and optimizations of this method are presented, including approaches to relax the high positioning resolution requirement in phase stepping process and attempts on large-field-of-view imaging with high-resolution gratings. Secondly, we introduce the latest developments in two-dimensional grating-based imaging and time-resolved four-dimensional grating-based imaging. An outlook of X-ray grating-based imaging is given..
Laser & Optoelectronics Progress
- Publication Date: Apr. 24, 2012
- Vol. 49, Issue 7, 70002 (2012)
New Development of Solar Simulator
Su Shi, Zhang Guoyu, Fu Yun, and Wang Lingyun
Solar simulator as an important test equipment is widely used in the fields of aerospace and solar energy. This paper briefly introduces the structural composition and working principle of traditional solar simulators, and then discusses the advantages, disadvantages and existing value. It also analyzes the new typicalSolar simulator as an important test equipment is widely used in the fields of aerospace and solar energy. This paper briefly introduces the structural composition and working principle of traditional solar simulators, and then discusses the advantages, disadvantages and existing value. It also analyzes the new typical solar simulator systems and operation forms, such as LED solar simulator, multiple-source solar simulator, uniform light bar solar simulator, integral sphere solar simulator, optical fiber transmission solar simulator and moving solar simulator and so on. Finally, the characteristics of the solar simulators mentioned above and the development in future are summarized..
Laser & Optoelectronics Progress
- Publication Date: Apr. 01, 2012
- Vol. 49, Issue 7, 70003 (2012)
Research Progress on Supercontinuum Generation in Fiber Tapers
Chen Haihuan, Chen Zilun, Zhou Xuanfeng, and Hou Jing
With the development of tapering theory and technology, supercontinuum (SC) generation in conventional fiber tapers or tapered photonic crystal fibers continues to attract significant interests. Tapers are efficient in SC generation at both short and long wavelength due to their special dispersion properties and nonlinWith the development of tapering theory and technology, supercontinuum (SC) generation in conventional fiber tapers or tapered photonic crystal fibers continues to attract significant interests. Tapers are efficient in SC generation at both short and long wavelength due to their special dispersion properties and nonlinearities. This paper introduces the tapering technology first, and then the research progresses of SC generation in both conventional fiber tapers and tapered photonic crystal fibers are reviewed. Finally the prospects and applications SC generated in tapered fiber are presented..
Laser & Optoelectronics Progress
- Publication Date: Apr. 01, 2012
- Vol. 49, Issue 7, 70004 (2012)
Development of the Polarization Beam Combining Technique of Lasers
Ma Pengfei, Zhou Pu, Ma Yanxing, Wang Xiaolin, and Liu Zejin
The coherent polarization beam combining technique is the highlight in the field of beam combination, which attracts extensive attention recently. Tracing the typical coherent polarization beam combining techniques, some typical schemes are analyzed and evaluated. It is evident that coherent polarization beam combiningThe coherent polarization beam combining technique is the highlight in the field of beam combination, which attracts extensive attention recently. Tracing the typical coherent polarization beam combining techniques, some typical schemes are analyzed and evaluated. It is evident that coherent polarization beam combining based on master oscillator power-amplifier (MOPA) structure has the possibility of achieving high power with excellent beam quality and can be extended easily..
Laser & Optoelectronics Progress
- Publication Date: Apr. 01, 2012
- Vol. 49, Issue 7, 70005 (2012)
Progress of Optical Maskless Lithography Based on Spatial Light Modulator
Ma Yanqin, and Du Jinglei
As device feature size continues to decrease, the resolution of conventional lithography which is restricted by diffraction limit, have been approaching to the theoretical limit and the cost is very high. Maskless lithography is a potential program to solve the high cost caused by the rising price of the mask. MasklessAs device feature size continues to decrease, the resolution of conventional lithography which is restricted by diffraction limit, have been approaching to the theoretical limit and the cost is very high. Maskless lithography is a potential program to solve the high cost caused by the rising price of the mask. Maskless lithography has been widely used in nanofabrication, mask direct writing and low-volume integrate circult (IC) production because of its low cost, high flexibility and short production cycle. Currently, spatial light modulator (SLM)-based maskless lithography made some progress in improving the resolution and throughput. Both the theory and experiment of SLM-based maskless lithography achieved good results. A review on the principle, feature and progress of maskless lithography based on SLM is presented..
Laser & Optoelectronics Progress
- Publication Date: May. 16, 2012
- Vol. 49, Issue 7, 70006 (2012)
Research Progress of HB-LED Based on Patterned Sapphire Substrate
Huang Chengqiang, Chen Bo, Li Chaobo, Xia Yang, Wang Minggang, and Rao Zhipeng
In order to make high-brightness LED, patterned sapphire substrate (PSS) is adopted. To make PSS, the first step is to make patterned mask on the planar sapphire substrate, and the second step is to copy the pattern of mask onto the sapphire substrate through etching. To make GaN grow on PSS by epitaxial lateral overgrIn order to make high-brightness LED, patterned sapphire substrate (PSS) is adopted. To make PSS, the first step is to make patterned mask on the planar sapphire substrate, and the second step is to copy the pattern of mask onto the sapphire substrate through etching. To make GaN grow on PSS by epitaxial lateral overgrowth and do subsequent processing, HB-LED based on PSS can be fabricated. The dislocation density of GaN on PSS is decreased from 1010 cm-2 to 107 cm-2, compared with the density of GaN on the planar sapphire substrate. The decrease of dislocation density of GaN decreases the number of carrier which vanish through the nonradiative recombination. Therefore, more photons are emitted from the multi-quantum well (MQW), and the internal quantum efficiency of LED is increased. Furthermore, PSS can effectively scatter the beam of light from the MQW, which increases the probability of light in escaping area, so the extraction rate of LED is enhanced. The combination of the enhancement of internal quantum efficiency and extraction rate greatly improves the photoelectrical characteristic of LED..
Laser & Optoelectronics Progress
- Publication Date: May. 08, 2012
- Vol. 49, Issue 7, 70007 (2012)
Research Progress of Scintillations for Laser Array Beams in Atmospheric Turbulence
Wu Wuming, Ni Yu, Ren Yajie, Wu Yi, and Shu Baihong
Compared with single beam, arrays beams which are composed of spatially separated beamlets are suggested to be used for scintillation reduction. Incoherent combined array laser can distinctly reduce intensity fluctuations and signal fades in active illumination and optical communications. Research progress of scintillaCompared with single beam, arrays beams which are composed of spatially separated beamlets are suggested to be used for scintillation reduction. Incoherent combined array laser can distinctly reduce intensity fluctuations and signal fades in active illumination and optical communications. Research progress of scintillations for kinds of laser array beams in atmospheric turbulence is depicted, including coherent and Incoherent combined array laser. In view of the advantage of incoherent combined array laser, the experiments of laser illumination and satellite laser communication have been summarized simply. And the means and results of kinds of beam arrays are described, including different wavelengths beam, fundamental Gaussian beam, partially coherent Gaussian beam and Airy beam. Problems that should be further studied are presented..
Laser & Optoelectronics Progress
- Publication Date: May. 31, 2012
- Vol. 49, Issue 7, 70008 (2012)
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