Journals >Acta Photonica Sinica
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2005
Volume: 34 Issue 2
41 Article(s)
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Research Article
The Numerical Simulation on Parameters of Opto-coupler in Femtosecond Laser Micromachining
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The optical beam propagation equation is solved by finite difference iterative method. The effect of the cross angle on the ratio of field intensity in the branch is studied about the 1×2(Y type) and 2×2(X type) couplers. The simulation results show that only the cross angle was controlled in a scale,the inteThe optical beam propagation equation is solved by finite difference iterative method. The effect of the cross angle on the ratio of field intensity in the branch is studied about the 1×2(Y type) and 2×2(X type) couplers. The simulation results show that only the cross angle was controlled in a scale,the intensity ratio(1∶1) can not be effected in the branch of coupler. And the 2×2 coupler is sensitive to the cross angle and coupler width. It is a basic theoretic analysis for machining the passive fiber components with femtosecond laser..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 161 (2005)
The Resolution Simulating Measurement Setup for Range-gated Imaging System
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The range gated imaging system combines the technologies of pulsed laser illuminating and range gated ICCD. To measure and evaluate the resolution of range gated imaging system under certain atmosphere conditions, a simulating measurement setup is designed. Two light sources are used for simulating the signal and backsThe range gated imaging system combines the technologies of pulsed laser illuminating and range gated ICCD. To measure and evaluate the resolution of range gated imaging system under certain atmosphere conditions, a simulating measurement setup is designed. Two light sources are used for simulating the signal and backscatter light respectively. Based on the method of equivalent irradiance on photo cathode, the methods of power calculation and power range determination for simulating light sources are provided. In the case of image intensifier using S 20 photo cathode coupled with CCD, based on the model of optical backscatter and signal for range gated imaging system, the power of simulating light sources are calculated..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 165 (2005)
Theoretical and Experimental Study of a Laser-diode-pumped Passively Q-switched Nd: YVO4 Laser with GaAs Saturable Absorber
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By considering the Guassian distribution of the pump beam and the thermal effect in the gain medium, the coupled rate equations of a LD pumped passively Q switched Nd∶YVO4 laser at 1.06μm with GaAs are given. The theoretical average output power , pulse width,pulse repetition of the laser are obtained by the numerical By considering the Guassian distribution of the pump beam and the thermal effect in the gain medium, the coupled rate equations of a LD pumped passively Q switched Nd∶YVO4 laser at 1.06μm with GaAs are given. The theoretical average output power , pulse width,pulse repetition of the laser are obtained by the numerical solution of the rate equations. The experimental results agree with the numerical solutions of the coupled rate equations..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 169 (2005)
Dual-wavelength Fiber Laser Based on Polarisation Hole-burning Effect at Room Temperature
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A simple erbium doped fiber laser configuration for achieving stable dual wavelength oscillation at room temperature is proposed. In this configuration, a fiber Bragg grating written in a polarisation maintaining fiber as the wavelength selective component is used. Stable dual wavelength oscillation with a wave spacingA simple erbium doped fiber laser configuration for achieving stable dual wavelength oscillation at room temperature is proposed. In this configuration, a fiber Bragg grating written in a polarisation maintaining fiber as the wavelength selective component is used. Stable dual wavelength oscillation with a wave spacing of 0.52nm at room temperature can be achieved through adjusting the state of polarization controller. An amplitude variation within 16 scans time is less than 0.2dB for both wavelengths..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 173 (2005)
Effects of the Structure of HfO2 Thin Films on Its Laser-induced Damage Threshold
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HfO 2 films have been deposited with electron beam evaporation of HfO 2 and ion assisted electron beam evaporation of Hf. Optical and structural properties and laser induce damage threshold of the films have been studied; it was found that HfO 2 film deposited with electron beam evaporation of Hf with ion assisted techHfO 2 films have been deposited with electron beam evaporation of HfO 2 and ion assisted electron beam evaporation of Hf. Optical and structural properties and laser induce damage threshold of the films have been studied; it was found that HfO 2 film deposited with electron beam evaporation of Hf with ion assisted technology shows uniform structural properties and higher laser induced damage threshold. The relation between structural and damage threshold of HfO 2 films has also been studied..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 176 (2005)
The Analysis of the Non-paraxial Effects of the Ultrashort Pulsed Beam in Free Space
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Based on the spatial and temporal Fourier Transform, we developed a non paraxial correction method to the ultrashort few cycle pulsed beam, and it was illustrated with the family of pulsed Gaussian beam. The examples shows that, because of the exist of the spatiotemporal coupling, the temporal distribution of the pulseBased on the spatial and temporal Fourier Transform, we developed a non paraxial correction method to the ultrashort few cycle pulsed beam, and it was illustrated with the family of pulsed Gaussian beam. The examples shows that, because of the exist of the spatiotemporal coupling, the temporal distribution of the pulse would influence the spatial distribution of the non paraxial correction..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 180 (2005)
Wavelength Chirp-free Tunable Yb3+ -doped Double Cladding Fiber Laser
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Using the phase mask method ,a fiber Bragg grating is fabricated in the circle shape inner cladding Yb 3+ doped double clad fiber(CDCF).By use of this grating as the output mirror of the CDCFL,the narrow linewidthlaseroperatingwavelength1055.2nmatthereflectcenterofthegratingispresented,FWHMis0.271nmand near 40 dB signaUsing the phase mask method ,a fiber Bragg grating is fabricated in the circle shape inner cladding Yb 3+ doped double clad fiber(CDCF).By use of this grating as the output mirror of the CDCFL,the narrow linewidthlaseroperatingwavelength1055.2nmatthereflectcenterofthegratingispresented,FWHMis0.271nmand near 40 dB signal to noise ratio. There isn′t splice lose between CDCF and output mirror,and the bulk of CDCFL is reduced . Using a beam of uniform strength, which is fabricated by ourselves, bi direction chirp free tuning of center wavelengths of the fiber grating is realized, the tuning range up to 8.9 nm is obtained from 1051.1 nm to 1060.04 nm, the output laser 3 dB linewidths didn′t obviously change..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 184 (2005)
Temporal and Spectral Characteristic of a Yb-doped Double-clad Fiber Laser
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The temporal and spectral characteristic of a Yb doped double clad fiber laser has been studied. The influences of the pumped power and the cavity losses on the laser are investigated. It is found that the self pulsing and the nonlinear phenomena shch as Brillouin and Raman scatterings can be observed in a one mirror cThe temporal and spectral characteristic of a Yb doped double clad fiber laser has been studied. The influences of the pumped power and the cavity losses on the laser are investigated. It is found that the self pulsing and the nonlinear phenomena shch as Brillouin and Raman scatterings can be observed in a one mirror cavity, and the system is stabilized in a two mirrors cavity where Brillouin and Raman scatterings are efficiently suppressed. We also give a theoretical explanation about the phenomenon in our experiments..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 187 (2005)
Studies on Methods of Polarization Controlling Chaos in Dual-ring Er-doped Fiber Lasers
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Methods of chaos controlled with coupling polarization and fractional polarization are presented. The coupling polarization controlling can control the coupling interaction to control chaotic lasing, and the fractional polarization controlling can control the fractional coupling polarization effect to control chaotic lMethods of chaos controlled with coupling polarization and fractional polarization are presented. The coupling polarization controlling can control the coupling interaction to control chaotic lasing, and the fractional polarization controlling can control the fractional coupling polarization effect to control chaotic lasing. Numerically simulations illustrate that chaos laser can be controlled into stable states and periodic states by parallel adjusting the direction of the two coupling polarization, or adjusting the direction of the fractional polarization of a ring in dual ring erbium doped fiber. The methods can be real time dynamically effectively control chaotic lasing into stable states and periodic states by adjusting real time optical polarization angle..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 191 (2005)
Neural Network Model for the Noise Characteristics of Semiconductor Laser
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Through the solution of rate equation with Langevin noise of semiconductor 1aser, the noise characteristics of semiconductor 1aser are given. Its artificial neural network(ANN)model is developed. The theoretical calculation is used to provide training and testing samples for the ANN. We find that the results of simulatThrough the solution of rate equation with Langevin noise of semiconductor 1aser, the noise characteristics of semiconductor 1aser are given. Its artificial neural network(ANN)model is developed. The theoretical calculation is used to provide training and testing samples for the ANN. We find that the results of simulation are well agreed with numerical calculation results. The model has the advantages of accuracy and high efficiency..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 195 (2005)
Study on the Signal of Laser Doppler Differential Demodulation System
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The differential technology of Laser Doppler and the frequency-tracking technology of PLL are studied and a Laser Doppler differential demodulation system with high accuracyand broad dynamic range is designed. The system has the characters of tight structure, convenience on fixing and tuning and can make full use of laThe differential technology of Laser Doppler and the frequency-tracking technology of PLL are studied and a Laser Doppler differential demodulation system with high accuracyand broad dynamic range is designed. The system has the characters of tight structure, convenience on fixing and tuning and can make full use of laser energy. Furthermore, by focusing the waists of two Gauss beams on the object measured, the smallest speckle and the superposition of plane waves are obtained to enhance the resolving power, SNR and the intensity of signal. It tracks the frequency automatically to resolve the dropout of signal and to restrain all kinds of noises and disturbances. It is proved by simulation experiment that the measure accuracy of amplitude and frequency respectively are 1% and 0.6% and the resolving power is 50nm, so the technology indexes are satisfactory..
Acta Photonica Sinica
- Publication Date: Feb. 01, 2005
- Vol. 34, Issue 2, 199 (2005)
A New Method Called Interference Stripe Method For Measuring the Whole Thermal Focal Lens In LD End Pumped Nd:YAG Crystal
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The thermal lens effect in the end pumped DPL has been discussed in this experiment. A new method to measure the whole thermal focal lens is found in this paper which is called interference stripe method. The result based this experiment method is agree with the theory result and with the develop of the pump power ,theThe thermal lens effect in the end pumped DPL has been discussed in this experiment. A new method to measure the whole thermal focal lens is found in this paper which is called interference stripe method. The result based this experiment method is agree with the theory result and with the develop of the pump power ,they meet well deeply..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 202 (2005)
BPM-FSRM Hybrid Method for SOI Rib Waveguide-to- Fiber Coupling Analysis
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With hybrid method of BPM and FSRM , the power of transmission was calculated in the case of SOI Rib Waveguide to Fiber coupling .A simple integral formula was developed to work out the reflectivity. Based on the results acquired with the hybrid method, normal FSRM methods and Fresnel equation overlap integral method ,With hybrid method of BPM and FSRM , the power of transmission was calculated in the case of SOI Rib Waveguide to Fiber coupling .A simple integral formula was developed to work out the reflectivity. Based on the results acquired with the hybrid method, normal FSRM methods and Fresnel equation overlap integral method ,it was deduced that Fresnel equation method and overlap integral method can be used together only when the two waveguides on the each side of disconnection facet are weakly guided..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 222 (2005)
Study on Unique Saturation Properties in Fiber Optical Parametric Amplifiers
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Two very pithy and powerful analytical expressions for saturated signal gain and signal output power of fiber optical parametric amplifiers are educed with numerical analysis. Those are realized in three steps, first, a series of numerical values are worked out by numerically solving the couple NLS equations that goverTwo very pithy and powerful analytical expressions for saturated signal gain and signal output power of fiber optical parametric amplifiers are educed with numerical analysis. Those are realized in three steps, first, a series of numerical values are worked out by numerically solving the couple NLS equations that governed the fiber parameter process. Then the function form for saturated signal gain is figured out by control variates method. At last, adopting least square method, three coefficients are finely obtained with the maximum relative error (in terms of calculated saturated signal gain with numerical integration) no more than 0.46‰. At the same time, the analytical expression for saturated signal output power is worked out as well. Results of this work agree well with existing experiment results..
Acta Photonica Sinica
- Publication Date: Feb. 01, 2005
- Vol. 34, Issue 2, 226 (2005)
Double-function Optical Isolator Utilizing two Fiber Tips and Lens Twice
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Using two fiber tips and lens twice, An innovated double channel optical isolator has been advanced and fabricated, which duplicates the function in comparison with conventional optical isolator with single fiber tip. The typical insertion loss and isolation of the developed isolator are as good as that of the conventiUsing two fiber tips and lens twice, An innovated double channel optical isolator has been advanced and fabricated, which duplicates the function in comparison with conventional optical isolator with single fiber tip. The typical insertion loss and isolation of the developed isolator are as good as that of the conventional optical isolator in theory. It was experimentally confirmed that forward insertion loss of two channels at 1550 nm are lower than 0.28 dB and 0.11 dB, backward isolation of that are over 55 dB and 54 dB respectively. It′s most important that the isolator, which can be fabricated with duplicated function and high characteristics, also have a low cost and a small volume comparatively..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 230 (2005)
Study on the Technique of Brillouin Scattering Distributed Optical Fiber SensingBased on Optical Interferometric Heterodyne Detection
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The detecting mechanism and scattering optical signal′s characters of Brillouin scattering distributed sensor are analyzed first, then a novel detecting scheme is presented and demonstrated experimently, which adopts optical heterodyne detection to measure Brillouin scattering signal. In detail, a DFB LD with <1 MHzThe detecting mechanism and scattering optical signal′s characters of Brillouin scattering distributed sensor are analyzed first, then a novel detecting scheme is presented and demonstrated experimently, which adopts optical heterodyne detection to measure Brillouin scattering signal. In detail, a DFB LD with <1 MHz line width is used as light source, the source is divided into two part, one part is used as pump light which is modulated into optical pulse(100 ns); the other part acts as reference light which is modulated by microwave electric optical modulator to produce frequency adjustable light. Then Brillouin back scattering light is heterodyne detected with the reference right, the detecting photoelectric signal is first converted into digital signal by hi speed A/D, then the digital signal is stored and added, and at last the distributed sensing signal with better S/N ratio is gained. The distributed detecting of temperature and strain are gotten, and a 25 km distributed sensor is achieved with 3℃.
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 233 (2005)
Simulation and Optimal Design for a Pd- coated Hydrogen Sensor Based on Integrated Optical Waevguide
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A hydrogen sensor based on integrated optical waveguide structure is one of the most promising types of the field. The sensor region of the waveguide is covered with a thin palladium layer whose optical constants are influenced by concentration of hydrogen in surrounding medium. A finite difference method (FDM) is usedA hydrogen sensor based on integrated optical waveguide structure is one of the most promising types of the field. The sensor region of the waveguide is covered with a thin palladium layer whose optical constants are influenced by concentration of hydrogen in surrounding medium. A finite difference method (FDM) is used to calculate the field distribution of the structure. The relationship between the waveguide property and the optical constants of the palladium layer is analyzed. The output power of the structure is calculated by an BPM program and an optimal thickness is obtained to achieve maximum sensitivity..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 237 (2005)
Experimental Researches on Birefringence of Fiber Bragg Grating
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The birefringence effects on uniform fiber Bragg grating (FBG) and linearly chirped FBG under lateral compression was experimentally investigated, respectively. The birefringence on uniform and linearly chirped FBG induced by pressure of piezoelectric ceramic (PZT). The induced birefringence of the FBG can be accuratelThe birefringence effects on uniform fiber Bragg grating (FBG) and linearly chirped FBG under lateral compression was experimentally investigated, respectively. The birefringence on uniform and linearly chirped FBG induced by pressure of piezoelectric ceramic (PZT). The induced birefringence of the FBG can be accurately controlled through tuning the voltage applied on PZT. Polarization mode dispersion (PMD) can be compensated using linearly chirped FBG..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 241 (2005)
A New Scheme for Integrated QoS Control in IP/WDM Networks
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A new scheme with the integration of optical and electrical QoS control for the next generation IP/WDM networks is developed. Integrating differentiated model based on generalized multi protocol label switching (GMPLS) technologies is proposed, and new service classification strategies and service mapping strategies arA new scheme with the integration of optical and electrical QoS control for the next generation IP/WDM networks is developed. Integrating differentiated model based on generalized multi protocol label switching (GMPLS) technologies is proposed, and new service classification strategies and service mapping strategies are also provided. The proposed QoS control methods in this paper have the unique features of optical electrical integrating differentiated service model, intelligent control for multi granularities multi priorities applications, and the compliance to meet carrier class service level agreement, which capture the better tradeoff between the finer QoS granularity of IP layer and the coarse QoS granularity of optical layer to support multiple levels of service performance. Furthermore, the proposed scheme provides much lower complexity, better robustness and scalability, which seems to be preferred for QoS provisioning in the future multi service IP/WDM networks..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 244 (2005)
Experiments of PMD Compensation Using Electrical Feedback Signals for a 10Gbit/s System
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Electrical power, changing with differential group delay (DGD) and detected from an optical communication link, can be used as feedback signals of compensating for PMD. Theoretical calculations and curves are given representing the change of electrical power with DGD. Experimental results confirming the theoretical calElectrical power, changing with differential group delay (DGD) and detected from an optical communication link, can be used as feedback signals of compensating for PMD. Theoretical calculations and curves are given representing the change of electrical power with DGD. Experimental results confirming the theoretical calculations are presented for voltage V changing with DGD. A setup is built for experiments of PMD compensations. Several factors affecting the feedback signals are proposed and methods are given to make the fluctuations less. Results of PMD compensation prototype for a 10 Gb/s pseudo random sequence are shown through eye patterns. These results are also shown by receiver sensitivity improvements after compensation. Receiver sensitivity under 3 different bit error rates are measured using BER measuring equipment. Comparisons of results using different fibers are made,confirming the effectiveness of compensation..
Acta Photonica Sinica
- Publication Date: Feb. 01, 2005
- Vol. 34, Issue 2, 248 (2005)
A New Exact Solitary Wave Solution for the Higher Order Nonlinear Schrodinger Equation
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A new type of solitary wave solution for the higher order nonlinear Schrdinger equation(HNLSE), which governs the propagation of subpicosecond and femtosecond optical pulses in optical fibers under certain parametric conditions,is presented.The expression of this novel solution is composed of the sum of bright and darA new type of solitary wave solution for the higher order nonlinear Schrdinger equation(HNLSE), which governs the propagation of subpicosecond and femtosecond optical pulses in optical fibers under certain parametric conditions,is presented.The expression of this novel solution is composed of the sum of bright and dark solitary waves. The evolution of the solitary wave and its stability under some perturbations are investigated by using the numerical simulation methods..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 252 (2005)
Chirp Characteristics in Wavelength Converter Based on Single-Port-Coupled SOA
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A new all optical wavelength converter (AOWC) using single port coupled semiconductor optical amplifier (SOA) based on cross gain modulation (XGM) was brought forward, and a dynamic model was presented. Based on the dynamic model, factors which affect converted signal chirp, such as signal power, probe power, output exA new all optical wavelength converter (AOWC) using single port coupled semiconductor optical amplifier (SOA) based on cross gain modulation (XGM) was brought forward, and a dynamic model was presented. Based on the dynamic model, factors which affect converted signal chirp, such as signal power, probe power, output extinction ratio, input extinction ratio, were analyzed respectively. The numerical result shows that converted signal chirp decreases in some extent when using this kind of wavelength converter..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 255 (2005)
Parted Shared Restoration Scheme for WDM Networks
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The path restoration can share more capacity if the number of links of work path is 2 or 3 was found through simulation. Based on this result, a novel restoration scheme segmented shared restoration (SSR) was proposed. The end to end work path is divided into several segments and each segment is provided backup path. RThe path restoration can share more capacity if the number of links of work path is 2 or 3 was found through simulation. Based on this result, a novel restoration scheme segmented shared restoration (SSR) was proposed. The end to end work path is divided into several segments and each segment is provided backup path. Restoration time gets sharp drop at the cost of a litter increase of utilization of capacity in SSR. Partition rule and realization of SSR is explained. Through theoretical analysis and computer simulation the performance of SSR was demonstrated..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 259 (2005)
Intra-satallite Wore;essptical Network Communication Technologies and Implementation
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The intra satellite wireless optical communication links provide the foundation for the intra satellite wireless optical network communication. For guaranteeing high quality of the links, the intra satellite noise immune technology, the intra satellite multipath immune technology and so on are crucial. The parameters oThe intra satellite wireless optical communication links provide the foundation for the intra satellite wireless optical network communication. For guaranteeing high quality of the links, the intra satellite noise immune technology, the intra satellite multipath immune technology and so on are crucial. The parameters of the intra satellite optical communication instruments, especially the weight, the size and the power consumption, must fit the satellite environment for implementing. The way to do research on the intra satellite wireless optical network communication is that to fuse the wireless optical network communication technologies and implementation into the satellite technologies and implementation. To utilize the unique characteristics of carrier running in the satellite environment is highly important too. The key components of the novel intra satellite wireless optical network communication technology are the intra satellite wireless optical adaptive encoding and modulating technology wit.
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 263 (2005)
Engineering Analysis on High Resolution Space Camera
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Large CAD software SolidEdge was used to make smart models of a high resolution space camera ,and based on the model 3D FEA model has been established using MSC/Patran, and engineering analysis has been performed. The results show that the difference between analysis and examination is less than 10%. Furthermore analysLarge CAD software SolidEdge was used to make smart models of a high resolution space camera ,and based on the model 3D FEA model has been established using MSC/Patran, and engineering analysis has been performed. The results show that the difference between analysis and examination is less than 10%. Furthermore analysis results were used to verify and improve the structural design effectively..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 267 (2005)
Study on the Surface Deformation of Flat Reflector Under Gravity Load
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The static analysis for the flat reflector of interferometer in unassembled and assembled is studied by finite element method, horizontal and vertical placement under gravity load is analyzed. The calculated PV and RMS values are used to determine whether the distortion and the structure of fixation are reasonable or nThe static analysis for the flat reflector of interferometer in unassembled and assembled is studied by finite element method, horizontal and vertical placement under gravity load is analyzed. The calculated PV and RMS values are used to determine whether the distortion and the structure of fixation are reasonable or not. The datum processing is done by Zernike polynomial fittings, the aberration composition in this way is found, some corresponding approaches to improve image quality are carried out..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 272 (2005)
Investigation on the Characteristics of Polarized Optical Field of Solid Immersion Lens
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In near field optical storage system of solid immersion lens, the polarization of the incident light affects the near field optical image greatly. In this paper 3 component optical fields intensity of focused linear polarized Gauss beam in the focal plane and the intensity patterns in the sections of various distance fIn near field optical storage system of solid immersion lens, the polarization of the incident light affects the near field optical image greatly. In this paper 3 component optical fields intensity of focused linear polarized Gauss beam in the focal plane and the intensity patterns in the sections of various distance from the focal plane are simulated using 3 dimensional finite difference time domain (FDTD) method. The results show that the image pattern in the focal plane or the sections near the focal takes on approximate ellipse, while the patterns in the planes of far region displays asymmetrical round..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 276 (2005)
Design and Application of Volume Holographic Grating Lenses
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New volume holographic grating lenses for laterally focusing an optical wave or collimating an optical wave emitted from an optical dot in an optical plate (volume holographic material), has been designed. Grating pitch and grating vector of the grating lenses are derived from intensity distribution of wavefront interfNew volume holographic grating lenses for laterally focusing an optical wave or collimating an optical wave emitted from an optical dot in an optical plate (volume holographic material), has been designed. Grating pitch and grating vector of the grating lenses are derived from intensity distribution of wavefront interfering field of a plane wave and a spherical wave. And basis is provided to design and fabricate volume holographic grating lenses devices. On the basis of two beams coupled wave theory, coupled wave differential equations and the boundary conditions are derived. Numerical results of the diffraction efficiency and the best size with high efficiency of the grating lenses are also given. And the practical applications in integrated optics or other fields are discussed..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 280 (2005)
Spectral Features Extraction in Hyperspectral RS Data and Its Application to Information Processing
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Oriented to the demands of hyperspectral RS information processing and applications, spectral features in hyperspectral RS image can be categorized into three scales: point scale, block scale and volume scale. Based on the properties and algorithms of different features, it is proposed that point scale features can be Oriented to the demands of hyperspectral RS information processing and applications, spectral features in hyperspectral RS image can be categorized into three scales: point scale, block scale and volume scale. Based on the properties and algorithms of different features, it is proposed that point scale features can be divided into three levels: spectral curve features, spectral transformation features and spectral similarity measure features. Spectral curve features include direct spectra encoding, reflection and absorption features. Spectral transformation features include Normalized Difference of Vegetation Index (NDVI), derivate spectra and other spectral computation features. Spectral similarity measure features include spectral angle (SA), Spectral Information Divergence (SID), spectral distance,correlation coefficient and so on. Based on analysis to those algorithms, several problems about feature extraction, matching and application are discussed further, and it proved that quaternary encoding,spectral angle and SID can be used to information processing effectively..
Acta Photonica Sinica
- Publication Date: Feb. 01, 2005
- Vol. 34, Issue 2, 293 (2005)
Self-adaptive Contrast Enhancement Algorithm for Infrared Images Based on Plateau Histogram
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In this paper, a new self adaptive contrast enhancement algorithm for infrared images is presented based on plateau histogram equalization. By self adaptively selecting threshold value, this algorithm can enhance objects efficiently , and constrain the background and noises greatly in infrared images. With the proposedIn this paper, a new self adaptive contrast enhancement algorithm for infrared images is presented based on plateau histogram equalization. By self adaptively selecting threshold value, this algorithm can enhance objects efficiently , and constrain the background and noises greatly in infrared images. With the proposed method, the disadvantages of histogram equalization are overcome, and large computational amount decreased greatly compared to other plateau histogram equalization algorithm while achieving high contrast. Theory analysis and experiments show that it is an effective enhancement algorithm for infared images..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 299 (2005)
Digital Radiography Image Adaptive Enhancement Based on Wavelet Transform
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The equivalence equation in wavelet domain is deduced from the basic theory of adaptive image contrast enhancement in time domain.Based on the principle of visually receptive psychology, the gain should be determined by the background of the image.At the same time, the gain should be adjusted when taking the trait of tThe equivalence equation in wavelet domain is deduced from the basic theory of adaptive image contrast enhancement in time domain.Based on the principle of visually receptive psychology, the gain should be determined by the background of the image.At the same time, the gain should be adjusted when taking the trait of the digital radiography with important details lie in medium spatial frequency into account.The experiment results show that wavelet adaptive enhancement with adjusted gain is effective for the enhancement.
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 302 (2005)
Noisy Image Estimation With Translation Invariant Wavelet Thresholding
The simple thresholding algorithm in a wavelet basis is almost optimum nonlinear estimation. For piecewise smooth signal, the risk with wavelet thresholding is nearly the best value. The PSNR of Estimation with standard wavelet thresholding is enhanced, but edges of the picture are influenced by Gibbs′s surge, so the vThe simple thresholding algorithm in a wavelet basis is almost optimum nonlinear estimation. For piecewise smooth signal, the risk with wavelet thresholding is nearly the best value. The PSNR of Estimation with standard wavelet thresholding is enhanced, but edges of the picture are influenced by Gibbs′s surge, so the visual quality is lower. With a advanced translation invariant wavelet thresholding algorithm, the higher PSNR of Estimation is obtained, and it is more important to improve the visual quality of Estimation..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 306 (2005)
The Multi-Stopband Characteristic of Quasi-Fractal Photonic Crystal and its Application
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The photonic band of kinds of quasi fractal photonic crystal is calculated by finite difference time domain method. The results show that there are multi stopband characteristics with the quasi fractal photonic crystal.As we treat these photonic band gaps as one photonic band gap with several conduction bands in it, thThe photonic band of kinds of quasi fractal photonic crystal is calculated by finite difference time domain method. The results show that there are multi stopband characteristics with the quasi fractal photonic crystal.As we treat these photonic band gaps as one photonic band gap with several conduction bands in it, the width and center frequency of the photonic band gap, and also the center frequency of the conduction bands in the photonic band gap vary with changing the structure of the unit cell of the quasi fractal photonic crystal..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 310 (2005)
Development of Plasma Leakage Detecting System Based on Ultraviolet Absorption Spectrum
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Blood circle treatment is a new remedy developed for reducing low density lipoprotein and endotoxin of patients′ plasma, consequently, curing or alleviating cardiovascular and cerebrovascular diseases, hypertension and inflammation. However, for there is possibility of plasma leakage before the treated blood is transmiBlood circle treatment is a new remedy developed for reducing low density lipoprotein and endotoxin of patients′ plasma, consequently, curing or alleviating cardiovascular and cerebrovascular diseases, hypertension and inflammation. However, for there is possibility of plasma leakage before the treated blood is transmitted back to patient and some monitoring procedure is to be maintained. The approach to monitor plasma leakage was presented after a brief introducing of the working principle of the blood circle treatment apparatus. Experiments on ultraviolet absorption spectrum of waste solution of the blood circle treatment apparatus mixed with plasma of different concentration were carried out and, the conclusion that such a solution has an absorption peak at about 278 nm was made. A set of detecting system of plasma leakage suited for the blood circle treatment apparatus was developed with the base of ultraviolet absorption spectrum experiments. In the set double beam scheme was utilized for the optical des.
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 315 (2005)
[in Chinese]
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Acta Photonica Sinica
- Publication Date: Jun. 12, 2006
- Vol. 34, Issue 2, 315 (2005)
Optoelectronics
Photoelectric Characteristics of SiC1-xGex/SiC Heterojunction Diode
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Abstract Photoelectric characteristics of SiC1-xGex/SiC heterojunction diode were simulated using MEDICI tools, and the simulation results are presented and discussed in this letter. The abrupt heterojunction diode is composed of a 1 μm thick heavily doped n-type SiC layer and a 0.4 μm thick lightly doped p-type SiC1-xAbstract Photoelectric characteristics of SiC1-xGex/SiC heterojunction diode were simulated using MEDICI tools, and the simulation results are presented and discussed in this letter. The abrupt heterojunction diode is composed of a 1 μm thick heavily doped n-type SiC layer and a 0.4 μm thick lightly doped p-type SiC1-xGex layer with varied composition ratios. It has been shown that photocurrent of the p- n+ SiC1-xGex/SiC diode is not decreased apparently by change the composition ratio from 0.2 to 0.3 for the applied reverse-bias voltage of 3 V and the incident light intensity of 0. 23 W/cm2.Corresponding photocurrents of the diodes are 7. 765 × 10 -7 A/μm and 7. 438 × 10-7 A/ μm, and the longest wavelength limits are 0.64 μm and 0.70 μm, respectively. It has also been shown by the simulation results that p-i-n structure composed by adding a p + -SiC1-xGex thin layer on top of the lightly doped p-type SiC1-xGex layer is much better for obtaining a higher photocurrent. Under the same conditions, photocurrents of 1. 6734 10-6 A/μm and 1. 844 × 10-6 A/μm can be obtained in the p-i-n SiC1-xGex/SiC diodes with x = 0.2 and 0.3, respectively..
Acta Photonica Sinica
- Publication Date: Jun. 12, 2006
- Vol. 34, Issue 2, 205 (2005)
Parameters Affecting the Characteristic of X-ray Source
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The characteristic of X ray source is one of the most important parameters on the image quality of radiography. The X ray source is composed of bremsstrahlung photons produced by the high energy electron beam impinging on the heavy metal target. The effects of parameters (include radius and emittance of the e beam and The characteristic of X ray source is one of the most important parameters on the image quality of radiography. The X ray source is composed of bremsstrahlung photons produced by the high energy electron beam impinging on the heavy metal target. The effects of parameters (include radius and emittance of the e beam and the target thickness) on the characteristic of X ray source are detailed by means of Monte Carlo method. It is shown that (1) giving a e beam radius, the exposure at 1m from the converting target increases and the uniformity of exposure distribution becomes bad, when the normalized emittance of e beam decreases; (2) for a given normalized emittance, the exposure uniformity becomes bad, when the e beam radius increases, but there exists an e beam radius under which the exposure at 1m is the largest; (3) in the case of zero emittance, enlarging the e beam radius can slightly improve the uniformity; and (4) given an e beam, there exists a target thickness which causes the exposure at 1m.
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 209 (2005)
Improved Carrier-Wave Electric Speckle Interferometry
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A new carrier wave electronic speckle method for deformation measurement was proposed. In this method, the deformation was measured by comparing the straight parallel fringes to the carrier wave interferometric fringes in the spatial frequency domain. The calculation of the carrier wave frequency and its induced measurA new carrier wave electronic speckle method for deformation measurement was proposed. In this method, the deformation was measured by comparing the straight parallel fringes to the carrier wave interferometric fringes in the spatial frequency domain. The calculation of the carrier wave frequency and its induced measurement error are avoided, thus obtaining a higher accuracy. Both the theory and the verifying experiment were presented in this paper..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 214 (2005)
Effect of Typical Control Parameters on Ferroelectric Liquid Crystal Opto-electronic Velocity
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In order to analyze different performances of a ferroelectric liquid crystal (FLC) layer when it works in different conditions, an electronic model in Pspice is presented. Using this equivalent circuit, it is easy to simulate and analyze how a FLC layer behaves in different temperatures, different wavelengths of incideIn order to analyze different performances of a ferroelectric liquid crystal (FLC) layer when it works in different conditions, an electronic model in Pspice is presented. Using this equivalent circuit, it is easy to simulate and analyze how a FLC layer behaves in different temperatures, different wavelengths of incident lights and different frequencies of drive voltage. According to the simulation, when wavelength changes within the range of visible lights, the response velocity drops as wavelength increases. As to the parameter of temperature, the velocity reaches its lowest when temperature gets to a certain degree. Meanwhile, the response velocity is greatly influenced by the frequency of drive voltage only when it is beyond its critical value. The result corresponds well with the reports of previous articles..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 218 (2005)
Physical Optics
Numerical Analysis of Coupled-wave Equation Derived from Multiple Scattering Theory Using Rouge-Kutta Method
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Fourth order Runge Kutta method was proposed to solve the acousto optic couple wave equation derived from the multiple scattering theory. Bragg diffraction efficiency varying with the key parameters was numerical simulated. The relation between the Bragg diffraction efficiency and the incidence light which was deflecteFourth order Runge Kutta method was proposed to solve the acousto optic couple wave equation derived from the multiple scattering theory. Bragg diffraction efficiency varying with the key parameters was numerical simulated. The relation between the Bragg diffraction efficiency and the incidence light which was deflected from the exact Bragg incidence angle was analyzed. The optimal parameters selected according to the Bragg diffraction efficiency was discussed too. The numerical simulation result showed that, when Q=4π, the Bragg diffraction efficiency was 97%, this was coincident with the traditional characteristic length..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 284 (2005)
Sers Effect on Cpp
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The SERS quality of cobalt and palladium and platinum (CPP) is calculated and analyzed using Antenna Resonance Model. The result from calculation of enhancing factor is 1 and about 4 and 2～4 for CPP respectively. The experimental result is about 5 and 105 and 140 accordingly. Results from the theory and tests are consiThe SERS quality of cobalt and palladium and platinum (CPP) is calculated and analyzed using Antenna Resonance Model. The result from calculation of enhancing factor is 1 and about 4 and 2～4 for CPP respectively. The experimental result is about 5 and 105 and 140 accordingly. Results from the theory and tests are consistent. When the chemical effect is brought in consideration. SERS spectrums of cytosine are obtained from pieces of CPP treated by ORC. Strength of the spectrum is not coincident and the largest is for platinum smallest for cobalt. Moreover, Enhancing abilities of vibrating models of cytosine on three pads are basically homology..
Acta Photonica Sinica
- Publication Date: Feb. 25, 2005
- Vol. 34, Issue 2, 288 (2005)
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