Journals >Laser & Optoelectronics Progress
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2011
Volume: 48 Issue 9
25 Article(s)
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Diffraction and Gratings
Intensity Distribution and Spiral Spectra of Laguerre-Gaussian Beam Passing through a Single-Slit
Gao Fuhai, Chen Baosuan, Pu Jixiong, and Zhu Jianqiang
Based on the Fresnel diffraction integral, the diffraction pattern of a Laguerre-Gaussian beam passing through a single-slit has been studied. It is found that the diffraction fringes of the Laguerre-Gaussian beam will dislocate and bend which have also been demonstrated by experiments. The spiral spectra of the LaguerBased on the Fresnel diffraction integral, the diffraction pattern of a Laguerre-Gaussian beam passing through a single-slit has been studied. It is found that the diffraction fringes of the Laguerre-Gaussian beam will dislocate and bend which have also been demonstrated by experiments. The spiral spectra of the Laguerre-Gaussian beam passing through the single-slit are also investigated. It is shown that the spiral spectra will broaden with the existence of the single-slit. In addition, the phase distribution of the Laguerre-Gaussian beam in the diffraction plane has also been investigated. The research results can be used to measure the topological charges of vortex beams..
Laser & Optoelectronics Progress
- Publication Date: Jul. 25, 2011
- Vol. 48, Issue 9, 90501 (2011)
Fiber Optics and Optical Communications
Study of Optimizing Eye Diagram of Optical Transmitter Based on Compensation Circuit
Liu Xi, Xue Yuan, and Xu Hongchun
In order to eliminate the noise and jitter of optical module in optical communication and improve communication quality, we propose a method to optimize the circuit compensation. The source and influence of laser parasitic character by establishing a laser diode module are analyzed, and the compensation theory and compIn order to eliminate the noise and jitter of optical module in optical communication and improve communication quality, we propose a method to optimize the circuit compensation. The source and influence of laser parasitic character by establishing a laser diode module are analyzed, and the compensation theory and compensation method, which have been proved in the experiment are discussed. Finally the step of compensation circuit design is introduced..
Laser & Optoelectronics Progress
- Publication Date: Jul. 07, 2011
- Vol. 48, Issue 9, 90601 (2011)
Analysis and Measurement of Stimulated Brillouin Scattering Threshold in Fiber
Wang Zhenbao, Shao Bibo, Zhang Lei, Yan Yan, Yang Pengling, and Chen Shaowu
Stimulated brillouin scattering (SBS) is one of important nonlinear effects in fiber communication system or optical fiber sensing system. SBS can be brought easily in fiber for its low threshold, inducing power loss of incident laser in fiber system which is engaged as signal carrier, damaging laser source for backwarStimulated brillouin scattering (SBS) is one of important nonlinear effects in fiber communication system or optical fiber sensing system. SBS can be brought easily in fiber for its low threshold, inducing power loss of incident laser in fiber system which is engaged as signal carrier, damaging laser source for backward scattered light caused by SBS, limiting laser power and transmitting distance of fiber system. Basing on the theory of SBS, the relation of SBS threshold with modulating frequency of laser source, linewidth of laser source, length of fiber and coefficient of loss is analyzed. The SBS threshold of 19.5 km G.653 fiber is measured by experiments, and the results accord with the theory calculation..
Laser & Optoelectronics Progress
- Publication Date: Jul. 28, 2011
- Vol. 48, Issue 9, 90603 (2011)
Microstructured Fiber with Closing-Zero Dispersion in Wide Wavelength Range
Wang Dan
A microstructured fiber (MF) with closing-zero flattened dispersion is proposed. The effect of air hole diameter and hole-pitch on dispersion of fiber is analyzed by the finite element method(FEM). By optimizing the air hole diameter and hole-pitch, closing-zero flattened dispersion and large mode area can be realized A microstructured fiber (MF) with closing-zero flattened dispersion is proposed. The effect of air hole diameter and hole-pitch on dispersion of fiber is analyzed by the finite element method(FEM). By optimizing the air hole diameter and hole-pitch, closing-zero flattened dispersion and large mode area can be realized in a very wide scope of wavelength. When the air hole diameter d=0.73 μm and the air hole-pitch Λ=2.2 μm, the wavelength is from 1.22 μm to 1.80 μm, the dispersion parameter is only within ±1 ps/(nm·km) in a 600 nm wavelength range, and three zero dispersion wavelength with 1.26, 1.51 and 1.76 μm can be achieved. When d=0.73 μm, Λ=2.3 μm, and the wavelength is from 1.20 μm to 1.65 μm, the dispersion parameter is within -2～4 ps/(nm·km) in a 400 nm wavelength range, and one zero dispersion wavelength with 1.24 μm can be achieved..
Laser & Optoelectronics Progress
- Publication Date: Jul. 25, 2011
- Vol. 48, Issue 9, 90604 (2011)
Image Processing
Mutual Information Bands Selection and Empirical Mode Decomposition Based Support Vector Machines for Hyperspectral Data High-Accuracy Classification
Shen Yi, Zhang Min, and Zhang Miao
In remote-sensing data processing research, redundant information and noise of high-dimensional hyperspectral data affect the classification accuracy of hyperspectral data seriously. To solve this problem, we propose an algorithm of hyperspectral data classification based on band selection with mutual information and eIn remote-sensing data processing research, redundant information and noise of high-dimensional hyperspectral data affect the classification accuracy of hyperspectral data seriously. To solve this problem, we propose an algorithm of hyperspectral data classification based on band selection with mutual information and empirical mode decomposition (MI-EMD-SVM). Band selection based on mutual information is used to achieve redundant information processing, and empirical mode decomposition (EMD) is used to achieve feature extraction. And the obtained hyperspectral data X″ has been processed. The support vector machines (SVM) classification of the data is classified, which has been processed. Experimental results of the AVIRIS data indicate that the proposed approach improves the classification accuracy of hyperspectral data, significantly reduces the number of support vector, and improves the speed of hyperspectral data classification..
Laser & Optoelectronics Progress
- Publication Date: Jul. 25, 2011
- Vol. 48, Issue 9, 91001 (2011)
Instrumentation, Measurement and Metrology
Design of Static Star Simulator and Proposes A Technique of Correction Method for the Position of Star
Sun Gaofei, Zhang Guoyu, Jiang Huilin, Yang Mengfei, Wang Dayi, and Hao Yuncai
In order to achieve calibration of ground testing on the high accuracy star sensor, the design of a large static viewing field star simulator is described.The star simulator system need to be established, and the requirements of the system′s measurement accuracy is less than 20″. By using star reticle as the core displIn order to achieve calibration of ground testing on the high accuracy star sensor, the design of a large static viewing field star simulator is described.The star simulator system need to be established, and the requirements of the system′s measurement accuracy is less than 20″. By using star reticle as the core display, a long-focus and large viewing field optical projection system is designed to simulate stars figure into the parallel light ejected, and star maps are produced at the pupil of the this optical system, then a technique of correction method is proposed by using the focus to modify the position of star on the star reticle. Experimental results show that the star simulator can simulate star chart after correcting the star position; the accuracy of angular distance between stars is less than 12″. It can be completely used for the calibration of high-precision star sensor..
Laser & Optoelectronics Progress
- Publication Date: Jul. 29, 2011
- Vol. 48, Issue 9, 91201 (2011)
Data Processing Methodology for Laser Measurement Point Cloud
Chen Tian
As a high-resolution, rapid, non-contact digital means, laser measurement technology is increasingly widely applied in the field of manufacturing. The data processing method of point cloud is presented on the basis of measurement of scattered laser point cloud. Based on the usual methods of data processing and analysisAs a high-resolution, rapid, non-contact digital means, laser measurement technology is increasingly widely applied in the field of manufacturing. The data processing method of point cloud is presented on the basis of measurement of scattered laser point cloud. Based on the usual methods of data processing and analysis, how to apply the virtual slicing technology and virtual projection technology of measuring point cloud is emphasized. The technologies of virtual slicing of point cloud include radial/axial slicing, cylindrical slicing, and axial slicing for the specified radius. Virtual projection technologies of point cloud mainly include feature projection and axial rotation projection technologies. Meanwhile, based on the virtual projection of point cloud, the extraction strategy of part parameter is concluded. It is validated by a part′s digital detection after its laser measurement that the proposed data processing methods and strategies are effective..
Laser & Optoelectronics Progress
- Publication Date: Jul. 25, 2011
- Vol. 48, Issue 9, 91202 (2011)
Lasers and Laser Optics
Application of Spectrum Measurements in Working Status Diagnosis of Chemical Lasers
Zou Qianjin, Yuan Shengfu, Luo Wei, and Fan Hongjie
Working conditions of chemical lasers are discussed. The particle number concentration changing with the J values is shown. There are quantum number J0 of cutoff wavelength and quantum number Jm of maximum spectral transition. The method of working status diagnosis of chemical lasers is proposed by combination of spectWorking conditions of chemical lasers are discussed. The particle number concentration changing with the J values is shown. There are quantum number J0 of cutoff wavelength and quantum number Jm of maximum spectral transition. The method of working status diagnosis of chemical lasers is proposed by combination of spectrum measuring, the relationships between J0, Jm, cavity static temperature T, and the mass fraction ratio of lower level and upper level Nx. The cavity static temperature T and mass fraction ratio of lower level and upper level Nx according with the actual spectrum measurements of HF chemical laser are given..
Laser & Optoelectronics Progress
- Publication Date: Jul. 25, 2011
- Vol. 48, Issue 9, 91401 (2011)
Microstructures and Corrosion Resistance Properties of Ni-Based WC/Cr3C2 Coating Prepared by Laser Cladding
Xue Minpeng, Han Bin, Wang Yong, and Liu Xingguang
Ni-based WC/Cr3C2 composite coating is produced on 1045 steel substrates by high-power CO2 laser. The chemical composition, phase composition, microstructures and corrosion resistance of the cladding layer are analyzed respectively by electron probe microanalyzer (EPMA), X-ray diffractometer (XRD), scanning electron miNi-based WC/Cr3C2 composite coating is produced on 1045 steel substrates by high-power CO2 laser. The chemical composition, phase composition, microstructures and corrosion resistance of the cladding layer are analyzed respectively by electron probe microanalyzer (EPMA), X-ray diffractometer (XRD), scanning electron microscope (SEM) and M352 electrochemical measurement system. The results show that the surface of the Ni-based WC/Cr3C2 cladding layer is bright and crack free, and the wettability and slag detachability are excellent. The cladding layer is mainly composed of Cr2Ni3, γ-(Fe, Ni), Ni17W3, Fe0.64Ni0.36, WC, Cr7C3 and CrSi2. Dentrite is highly developed on the bottom of the cladding layer, with abundant Fe elements distributed in the dendritic and interdendritic grains. The central zone are plenty of long strip shape Cr7C3 and some chrysanthemum-like CrSi2 distributed on the γ-(Fe, Ni) base. The microstructures of the top zone are similar to the central zone′s, but the grains are finer and denser. The corrosion potential and corrosion current density of Ni-based WC/Cr3C2 cladding layer are respectively -359.9 mV and 2.75 μA/cm2, which indicates that the corrosion resistance of the cladding layer is improved obviously compared with Ni-based WC cladding layer..
Laser & Optoelectronics Progress
- Publication Date: Sep. 25, 2011
- Vol. 48, Issue 9, 91403 (2011)
Analysis of Thermal Characteristic in Optically Pumped Semiconductor Vertical-External-Cavity Surface-Emitting Laser with Double Heatspreaders
Liu Xiangnan, Wang Xiaohua, Wang Fei, Wang Jinyan, Zhou Huang, Liu Pengfei, and Jin Guangyong
By using ANSYS finite element software, the internal distribution of heat fields and heat flow vector in an optically pumped semiconductor vertical-external-cavity surface-emitting laser (OPS-VECSEL) was simulated. The heat performance of OPS-VECSEL with two different configurations of heat dissipation was compared. BeBy using ANSYS finite element software, the internal distribution of heat fields and heat flow vector in an optically pumped semiconductor vertical-external-cavity surface-emitting laser (OPS-VECSEL) was simulated. The heat performance of OPS-VECSEL with two different configurations of heat dissipation was compared. Besides, the effects of parameters of pump spot and thickness of heatspreader on temperature rise of VECSEL were discussed. Simulation and analysis show that the temperature rise of OPS-VECSEL with double diamond heatspreaders is much lower as well as the resonate wavelength difference at larger pump power density, and meanwhile it is beneficial for heat dissipation because the heat transports to the top and bottom side of OPS-VECSEL chip. With pump power density increasing, the superiority of heat dissipation becomes more notable. It is also showed that better heat dissipation will be achieved when the top diamond thickness is 500 μm and the bottom diamond thickness is 300～500 μm..
Laser & Optoelectronics Progress
- Publication Date: Jul. 25, 2011
- Vol. 48, Issue 9, 91404 (2011)
Analysis and Control of Self-Excitation Oscillation in TIL of the SG-Ⅲ Facility
Lu Zhenhua, Hao Xin, Tang Jun, Deng Qinghua, Luo Yiming, Gao Song, and Ding Lei
In the pre-amplifier of high power laser facilities, more than 106 gain is produced by the high gain amplifier, in which self-excitation oscillation would be easily formed. Based on the theory of self-excitation oscillation, the gain and loss in the system are analyzed, and the self-excitation problems in the high gainIn the pre-amplifier of high power laser facilities, more than 106 gain is produced by the high gain amplifier, in which self-excitation oscillation would be easily formed. Based on the theory of self-excitation oscillation, the gain and loss in the system are analyzed, and the self-excitation problems in the high gain amplifiers of TIL of the SG-Ⅲ facility are studied. There self-excitation cavities would possibly exist in the system. Using the methods including tilting the ends of Ndglasses, adjusting the beam, utilizing isolations and electro-optical switches, the self-excitation oscillation is controlled. These suppression methods are validated in experiments..
Laser & Optoelectronics Progress
- Publication Date: Jul. 25, 2011
- Vol. 48, Issue 9, 91405 (2011)
Applied Research on Medium and Low Power Level Dual-CO2-Laser Cutting Machine
Gan Jialiang, Sun Hong′an, and Tang Haichang
Cutting principles of high-power single-CO2-laser cutting and low-power dual-CO2-laser cutting are discussed. Non-metallic materials such as wood die-boards are cut by using these two laser cutting techniques. The dependences of cutting depth and seam shape on laser power and cutting speed are analyzed. The results shoCutting principles of high-power single-CO2-laser cutting and low-power dual-CO2-laser cutting are discussed. Non-metallic materials such as wood die-boards are cut by using these two laser cutting techniques. The dependences of cutting depth and seam shape on laser power and cutting speed are analyzed. The results show that cutting wood die-boards with low-power dual-CO2-laser cutting has many advantages over high-power single-laser-head cutting in the manufacturing costs, operating costs, cutting precision and seam shape..
Laser & Optoelectronics Progress
- Publication Date: Jun. 30, 2011
- Vol. 48, Issue 9, 91406 (2011)
Microscopy
Two-Channel Frequency Division Multiplexed Fluorescence Confocal Microscopy
Tang Pingyu, Zheng Jihong, Cao Jianwei, Zhang Yunbo, Jiang Yanmeng, Huang Aiqin, Zhou Zengjun, and Zhuang Songlin
We present a setup of confocal fluorescence microscopy system combined with frequency division multiplexing so that the detection ability of the system is enhanced. In the proposed frequency division multiplexed confocal fluorescence microscopy (FDMCFM) system, fluorescence is excited on the sample (rat neural cell) byWe present a setup of confocal fluorescence microscopy system combined with frequency division multiplexing so that the detection ability of the system is enhanced. In the proposed frequency division multiplexed confocal fluorescence microscopy (FDMCFM) system, fluorescence is excited on the sample (rat neural cell) by two beams of light modulated individually in two arms of the system. Fourier transform, filtration and demodulation are then carried out to restore the fluorescence intensity signal. The FDMCFM system is experimentally conducted, through which the target cells are detected successfully. The experimental results show that the FDMCFM system is convenient for multiple-channels and real-time detection of biological cells′ fluorescence signal. Moreover, it maintains the high spatial and temporal resolution of confocal microscopy..
Laser & Optoelectronics Progress
- Publication Date: Jun. 20, 2011
- Vol. 48, Issue 9, 91801 (2011)
Optical Design and Fabrication
Analysis on Influence of Vacuum Chuck on Machined Surface of KDP Crystal Using Power Spectral Density
Chen Shanshan, and Xu Min
Because KDP crystal is a soft material, when it is machined by single point diamond turning, vacuum chuck will result in surface waviness on crystal′s surface. Surface waviness will seriously affect the quality of high power laser beam, or even destroy optical elements, due to the nonlinear effect of high power laser. Because KDP crystal is a soft material, when it is machined by single point diamond turning, vacuum chuck will result in surface waviness on crystal′s surface. Surface waviness will seriously affect the quality of high power laser beam, or even destroy optical elements, due to the nonlinear effect of high power laser. In order to improve the ultra-precision machining of KDP crystal, power spectral density is used to detect the machined surface of KDP crystal, and to analyze error sources. It is discovered that processing methods should be chosen according to the shape of vacuum chuck, and the use of vacuum chuck should be avoid in the vertical direction..
Laser & Optoelectronics Progress
- Publication Date: Jul. 29, 2011
- Vol. 48, Issue 9, 92201 (2011)
Design of Optical System of Very High Precision Star Sensor with Small F-Number
Yan Peipei, and Fan Xuewu
The very high precision star sensor is the most accurate attitude sensor at present. According to the star sensor system detection requirements, the optical system parameters are figured out. A kind of optical structures of star sensor with small F-number and good imaging quality is realized on the stage of Code V softThe very high precision star sensor is the most accurate attitude sensor at present. According to the star sensor system detection requirements, the optical system parameters are figured out. A kind of optical structures of star sensor with small F-number and good imaging quality is realized on the stage of Code V software. The system has an effective focal length of 90 mm, an F-number of 1.5, a field of view of 7°, and a working wavelength range of 0.45～0.85 μm. The imaging quality is enhanced and special requirements of the spot, energy concentration, distortion, lateral color etc., are all satisfied. The total system length is only 90.36 mm, which meets the demand of miniaturization and light weight in engineering. Meanwhile, it works steadily with high optical quality in the required temperature range and has good athermal and anti-defocus performances..
Laser & Optoelectronics Progress
- Publication Date: Jul. 25, 2011
- Vol. 48, Issue 9, 92202 (2011)
Optical Devices
Signal Flow Graph for Analyzing Characteristics of Multiple-Ring Microring Resonator Filters
Yang Pengbo, Liang Jinlong, Qu Yang, Chen Chen, Wang Jiawei, and Gao Shaohong
Microring resonator has become a hotspot due to its functionality, compactness, and dense integration. The microring resonators provide passband characteristics of steeper roll-off, flatter top and greater stopband rejection than single ring resonators. Both the transfer functions of series-coupled and parallel-coupledMicroring resonator has become a hotspot due to its functionality, compactness, and dense integration. The microring resonators provide passband characteristics of steeper roll-off, flatter top and greater stopband rejection than single ring resonators. Both the transfer functions of series-coupled and parallel-coupled multi-ring microring resonator filters are derived by the signal flow graph method. For the series-coupled structure, the filtering response of filter is determined by the coupling coefficients between rings and the optical loss. For the parallel-coupled structure, the good shape of spectral response is achieved by optimizing the ring distance..
Laser & Optoelectronics Progress
- Publication Date: Jul. 29, 2011
- Vol. 48, Issue 9, 92301 (2011)
OPTOELECTRONICS
Noninvasive Detection of Latent Fingerprints Using Ultraviolet Laser
Li Hongxia, Niu Jieqing, Huang Yungang, Mao Linjie, and Chen Jingrong
Detection of latent fingerprints is one of the key problems in the forensic science area, and ultraviolet (UV) photography technology is an important method of latent fingerprints noninvasive detection. The 266 nm UV solid state laser is used as the excitation light source. According to the special absorption, reflectiDetection of latent fingerprints is one of the key problems in the forensic science area, and ultraviolet (UV) photography technology is an important method of latent fingerprints noninvasive detection. The 266 nm UV solid state laser is used as the excitation light source. According to the special absorption, reflection, scattering and fluorescence characteristics of fingerprint ridge residuals to UV light, and by using reflection photography and fluorescence photography technologies, fresh and old latent fingerprints on the surface of four types of non-absorbent objects (magazine cover, glass, back of cellular phone, wood desktop paintwork), and two types of absorbing objects (manila envelope and notebook paper) are noninvasively detected and revealed. The results have identification value..
Laser & Optoelectronics Progress
- Publication Date: Jun. 30, 2011
- Vol. 48, Issue 9, 92501 (2011)
Reviews
Research Progress of Chalcogenide Glass Photonic Crystal Fibers
Dai Shixun, Yu Xingyan, Zhang Wei, Lin Changgui, Song Bao′an, Wang Xunsi, Liu Yongxing, Xu Tiefeng, and Nie Qiuhua
Compared with silica glass, chalcogenide glasses possess some unique advantages, such as high refractive indices (2.0～3.5), low photon energies (lower than 350 cm-1), tailorable compositions, and large infrared transmission window (from 1.0 to 20 mm). As a novel mid-infrared photonic crystal fiber (PCF), chalcogenide gCompared with silica glass, chalcogenide glasses possess some unique advantages, such as high refractive indices (2.0～3.5), low photon energies (lower than 350 cm-1), tailorable compositions, and large infrared transmission window (from 1.0 to 20 mm). As a novel mid-infrared photonic crystal fiber (PCF), chalcogenide glass PCFs have attracted many attention recently. We review the research progress of chalcogenide glass PCFs, in terms of the glass composition design, structure simulation, fiber fabrication, reduction of transmission loss and their special properties, e.g., dispersion properties and high optical nonlinearity. Their potential applications and development prospects are also discussed..
Laser & Optoelectronics Progress
- Publication Date: Jul. 28, 2011
- Vol. 48, Issue 9, 90602 (2011)
Research Progress of Tandem-Pumped Fiber Lasers
Wu Wuming, Xiao Hu, Xu Jiangming, Leng Jinyong, Zhou Pu, and Guo Shaofeng
High-brightness in-band pumping sources are used in tandem-pumping. It makes it possible to pump close to the emission wavelength, so the quantum defect heating can be low. This allows for the use of a shorter fiber. Therefore, it is easier to avoid thermal and nonlinear limits simultaneously. In view of the important High-brightness in-band pumping sources are used in tandem-pumping. It makes it possible to pump close to the emission wavelength, so the quantum defect heating can be low. This allows for the use of a shorter fiber. Therefore, it is easier to avoid thermal and nonlinear limits simultaneously. In view of the important of tandem-pumping in high power fiber laser, the experimental researches of tandem-pumped over seas are introduced firstly, including Yb-doped, Er-doped, Tm-doped, Ho-doped fiber lasers. Then the advantages such as restraining unwanted excess gain for higher order modes in cladding-pumped large-core Yb-doped fiber amplifiers are presented. And the potential benefits of reducing fiber photodarkening are also analyzed. At last, the problem and techniques of the tandem-pumping in high power fiber lasers are discussed..
Laser & Optoelectronics Progress
- Publication Date: Jul. 28, 2011
- Vol. 48, Issue 9, 91402 (2011)
Progress of Encapsulation Technology for OLED
Liang Ning, and Li Junjian
Organic light emitting diode (OLED) device will have a bright future in the display field, because of its advantages. The most important advantage is the ability to achieve flexible display and be made into flexible organic light emitting diode (FOLED). OLED materials are extremely sensitive to vapor and oxygen. The vaOrganic light emitting diode (OLED) device will have a bright future in the display field, because of its advantages. The most important advantage is the ability to achieve flexible display and be made into flexible organic light emitting diode (FOLED). OLED materials are extremely sensitive to vapor and oxygen. The vapor and oxygen penetrating into the interior of the device are the main factor that affects the lifetime of OLED. Thus, encapsulation technology is important to OLED device. The substrate material and encapsulation technology used in FOLED are reviewed and meanwhile, their advantages and disadvantages are fully discussed, and the progress of the recent research on novel substrate material and encapsulation method are described..
Laser & Optoelectronics Progress
- Publication Date: Jul. 25, 2011
- Vol. 48, Issue 9, 92302 (2011)
Present Status and Developing Trends of Satellite Laser Communication
Zhao Shanghong, Wu Jili, Li Yongjun, Wang Xiang, Ma Lihua, and Han Zhongxiang
Status of space optical communication over the past decade has been summarized. The successful in-orbits experiments are depicted with the developing trends of future space optical communications. According to the analysis on the state-of-the-art technologies, the inter-satellite laser communication is maturing on its Status of space optical communication over the past decade has been summarized. The successful in-orbits experiments are depicted with the developing trends of future space optical communications. According to the analysis on the state-of-the-art technologies, the inter-satellite laser communication is maturing on its second generation, which will transfer from scientific test into extended applications. The different impact of atmosphere turbulence on the down-links and the up-links is analyzed respectively, which demands for the adaptive optics and multi-beam transmitting to cope with the scintillations in the ground-to-satellite links. The outlooks were provided on the architectures of satellite optical networks from the research in recent years. It is pointed out that after the 10 years′ downturn, satellite optical networks will meet a booming period with the maturing of the second generation of inter-satellites laser communication. The hardware and experimental foundations are shaped up. A method on the double layered satellite optical networking is presented, which will be a designation reference on the constructing of future space optical networks..
Laser & Optoelectronics Progress
- Publication Date: Jul. 25, 2011
- Vol. 48, Issue 9, 92801 (2011)
Spectroscopy
Rapid and Nondestructive Detection of Quality of Panax Quinquefolium Effected by Humidity
Cui Daijun, Pang Qichang, Ma Ji, Zhao Jing, Hu Cuiying, Li Qizhan, and Li Zilei
In order to detect the quality change of Panax quinquefolium in different humidity environments, the spectral imaging technology is applied to detect active constituent of Panax quinquefolium, based on the principle that variation of molecular structure causes variation of fluorescence spectrum. Ultraviolet ray source In order to detect the quality change of Panax quinquefolium in different humidity environments, the spectral imaging technology is applied to detect active constituent of Panax quinquefolium, based on the principle that variation of molecular structure causes variation of fluorescence spectrum. Ultraviolet ray source that with a central wavelength of 254 nm is used to stimulate the Panax quinquefolium sample to emit fluorescence. The continuous fluorescent spectrum image within the range 420～680 nm is got by adjustable liquid crystal light filter based spectrum imaging device. The frame differential method is used to extract the effective area of the spectrum cube and draw the characteristic spectrum image. Three Panax quinquefolius samples that are kept in different humidity conditions are detected, and the normalized characteristic spectrum diagram is drew. The characteristic spectrum shows that the change trend of relative intensity of fluorescence of Panax quinquefolium in different humidity environments are similar. Weighted Euclidean distance between comparison products and samples is utilized to show regularity of the change of Panax quinquefolium. The higher the humidity is, the faster the variation of weighted Euclidean distance is. The result shows that in different humidity environments, the active constituent of Panax quinquefolium will change with time, and this kind of change is irreversible..
Laser & Optoelectronics Progress
- Publication Date: Jul. 25, 2011
- Vol. 48, Issue 9, 93001 (2011)
Spectroscopical Characteristics and Color-Causing Mechanism of Light Pink-Red Jadetite
Liu Xueliang, Fan Jianliang, and Guo Shouguo
X-ray fluorescence (XRF) spectrum, Raman spectrum and ultraviolet-visible (UV-VIS) absorption spectrum are used for analyzing the samples of light pink-red jadeites with white banded struture. It shows that this type of jadeite is assigned to jadeite jade, and it also has diagnostic Raman shifts located at 377, 700 andX-ray fluorescence (XRF) spectrum, Raman spectrum and ultraviolet-visible (UV-VIS) absorption spectrum are used for analyzing the samples of light pink-red jadeites with white banded struture. It shows that this type of jadeite is assigned to jadeite jade, and it also has diagnostic Raman shifts located at 377, 700 and 1039 cm-1, which are respectively attributed to unsymmetrical bending, symmetrical bending and symmetrical strecthing of Si-O band; Light pink-red color of jadeite is attributed to Mn3+ located at the center of ［MO6］ octahedral in crystal structure, and d-d transitions of Mn3+ bring one wide absorption band centered at 520 nm. Additionally, there are many types of minor color-causing ions being in light pink-red jadeite, such as Fe3+, Mn2+ and Cr3+, and also their absorption bands are assigned..
Laser & Optoelectronics Progress
- Publication Date: Jul. 07, 2011
- Vol. 48, Issue 9, 93002 (2011)
Thin Films
Luminescence of GaN Thick Film Grown by HVPE
Zhu Youzhang, Fu Guanxin, Wang Hongxia, Sun Zhen, and Yuan Jinshe
Unintentionally doped GaN thick film grown on (0001) oriented Al2O3 substrate by hydride vapor phase epitaxy (HVPE) is studied in experiments, by absorption spectra and photoluminescence (PL) spectrum. The blue and yellow luminescence at room temperature are observed. The results indicate that when the frequency is lowUnintentionally doped GaN thick film grown on (0001) oriented Al2O3 substrate by hydride vapor phase epitaxy (HVPE) is studied in experiments, by absorption spectra and photoluminescence (PL) spectrum. The blue and yellow luminescence at room temperature are observed. The results indicate that when the frequency is low, the PL spectrum is contained by only band-side emission; however, when the frequency becomes high, there are three emission bands (band-side emission, blue emission and yellow emission). Meanwhile, the higher of the frequency, the larger of I1(intensity of band-side emission) /I2 (intensity of blue emission) and I1/I3 (intensity of yellow emission). After calculation and analysis, it can be considered that the blue luminescence is related with the impurity C of the sample, and the yellow luminescence is related with the structure defects like as dislocations..
Laser & Optoelectronics Progress
- Publication Date: Jul. 07, 2011
- Vol. 48, Issue 9, 93101 (2011)
Analyses of Structure Parameters of Amorphous Silicon Film Photovoltaic Cells
Wu Dingyun, Peng Yufeng, Zhao Jichang, Bi Xiaoqun, and Zhang Yi
Taking into account the film layer thickness and silicon impurities of amorphous silicon solar cells with the nip-type[ITO/a-Si (n)/a-Si (i)/ a-Si (p)/Al] structure, the conversion efficiency, fill factor, and open circuit voltage of the nip-type amorphous silicon solar cell are numerically analyzed and discussed. The Taking into account the film layer thickness and silicon impurities of amorphous silicon solar cells with the nip-type[ITO/a-Si (n)/a-Si (i)/ a-Si (p)/Al] structure, the conversion efficiency, fill factor, and open circuit voltage of the nip-type amorphous silicon solar cell are numerically analyzed and discussed. The results show that the short circuit voltage, conversion efficiency, and open circuit voltage increase as the thickness of p-type layer increases. With the increase in the thickness of intrinsic layer, the spectrum characteristics for the short wavelength range becomes worse and the quantum efficiency degrades. When the thickness of n-type, intrinsic, and p-type layers are 5 nm, 5 nm, 10 μm, respectively, the conversion efficiency gets to 9.728% for the donor impurity concentration of 1.5×1016 cm-3 and the acceptor impurities of 2.5×1019 cm-3..
Laser & Optoelectronics Progress
- Publication Date: Jul. 07, 2011
- Vol. 48, Issue 9, 93102 (2011)
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