Contents
2008
Volume: 28 Issue 6
36 Article(s)
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Diffraction and Gratings
Phase Gratings Formed in Photoinduced Azo-Polymer in Liquid Crystal
Dong Yufang, Li Haiyan, and Xu Zeda
A new composite system of azo polymer doped liquid crystal is reported. In this system, phase grating is formed after photoinduced trans-cis isomerization occurs on azo polymer and it separates with the liquid crystal. Through the establishment of a multi-exponential model the refractive index changes of phase grating A new composite system of azo polymer doped liquid crystal is reported. In this system, phase grating is formed after photoinduced trans-cis isomerization occurs on azo polymer and it separates with the liquid crystal. Through the establishment of a multi-exponential model the refractive index changes of phase grating in the He-Ne laser irradiation are studied. And through adding continuously variable voltage to polymer-doped liquid crystal sample, its response to the electric field is studied. At the same time, the evolution of monomer doped liquid crystal with light and electric fields is studied. The results have shown that the refractive index change in sample of photoinduced polymer doped liquid crystal is saturated after 45 s and the relaxation time is 10 min.The saturation and relaxation time are respectively 0.17 s and 0.9 s when the sample is monomer-doped liquid crystal. The grating diffraction efficiency will suddenly drop down when the electric field reaches 1.0 V, 1.4 V and 2.6 V and 4.0 V, while that of monomer presents no significant changes..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1021 (2008)
Fabrication of 3333 lp/mm Soft X-Ray Transmission Gratings
Zhu Xiaoli, Ma Jie, Xie Changqing, Ye Tianchun, Liu Ming, Cao Leifeng, Yang Jiamin, and Zhang Wenhai
The manufacture of high-line-density X-ray transmission gratings for X-ray spectroscopy by using electron beam lithography and X-ray lithography was reported. Firstly, a master mask was fabricated on polyimide membrane by electron beam lithography and micro-electroplation. Secondly, X-ray transmission gratings were effThe manufacture of high-line-density X-ray transmission gratings for X-ray spectroscopy by using electron beam lithography and X-ray lithography was reported. Firstly, a master mask was fabricated on polyimide membrane by electron beam lithography and micro-electroplation. Secondly, X-ray transmission gratings were efficiently replicated by X-ray lithography and micro-electroplating. With the combined technology, 3333 lp/mm X-ray transmission gratings with 300 nm period, 150 nm width of grating bar, and 500 nm thickness of gold absorber, were successfully fabricated in China for the first time. The calibration results of diffraction efficiency show that the fabricated gratings with rectangle cross-section profile and reasonable dispersion and line-and-space ratio, can meet the requirement of X-ray transmission spectroscopy in many fields such as astrophysics, synchrotron radiation facilities and plasma diagnostics, etc..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1026 (2008)
Non-Contact Cascaded Dual-Layer Sub-Wavelength Gratings
Chen Yongli, Zhao Dazun, Zhang Jingfang, Zhu Jun, and Wang Xiaoli
A non-contact cascaded dual-layer sub-wavelength grating is presented. It can broaden the spectral peak linewidth, modify the spectral lineshape and improve the optical variable effect of basic sub-wavelength gratings. It is a kind of security grating configuration with potential for achieving application in industry. A non-contact cascaded dual-layer sub-wavelength grating is presented. It can broaden the spectral peak linewidth, modify the spectral lineshape and improve the optical variable effect of basic sub-wavelength gratings. It is a kind of security grating configuration with potential for achieving application in industry. The mechanisms for the broadened linewidth and improved lineshape are analyzed and validated with the vector diffraction theory. The structural parameters of dual-layer gratings with special requirements of change in color are optimized and their optical variable characteristics are also studied. The results show the spectral lineshape of dual-layer gratings cascaded in phase is similar to that of basic gratings with a linewidth twice that of basic gratings; the out-of-phase arrangement yields lineshape exhibiting broadened peaks and narrower bases with a wider linewidth. Dual-layer gratings always show optical variable effect when tilted at traditional or nontraditional incident illumination and the optical variable velocity of the former is the quicker than that of the latter which can be used to design and fabricate anisotropic optical variable image devices..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1031 (2008)
Correction of Refractive Index Distribution in Volume Hologram Grating Recorded Linearly
Liu Qiuping, He Xingdao, and Zhou Xiaochun
Some wrong points are found about the formula of the refractive index distribution in volume hologram grating recorded linearly in some literatures when the nonlinear recording spectral properties of volume hologram are discussed. The formula of the refractive index distribution is discussed again when recorded linearlSome wrong points are found about the formula of the refractive index distribution in volume hologram grating recorded linearly in some literatures when the nonlinear recording spectral properties of volume hologram are discussed. The formula of the refractive index distribution is discussed again when recorded linearly. The light intensity ratio and the total light intensity refractive index modulation coefficient are added into the formula, and the diffraction spectral of gratings versus different light intensity ratio and total light intensity refractive index modulation coefficient are calculated in the coupled-wave theory. The calculational results show that the primary peak values of diffraction spectrum reduce slightly when the light intensity refractive index modulation coefficient or the light intensity ratio decreases, but the secondary peak value, decreases obviously and the bandwidth becomes narrow greatly with those conditions..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1037 (2008)
Fiber Optics and Optical Communications
Variational Study on Influence of High-Order Dispersion and Fifth-Order Nonlinearity on Propagation Properties of Gaussian Pulse in Optical Fibers
Gan Guirong, and Luo Kaiji
The evolution equations for the parameters of Gaussian pulse with propagation distance in optical fibers is derived, considering high-order dispersion and the fifth-order nonlinearity by means of variational method from the modified nonlinear Schrdinger (MNLS) equation. Then, the relations between amplitude and width,The evolution equations for the parameters of Gaussian pulse with propagation distance in optical fibers is derived, considering high-order dispersion and the fifth-order nonlinearity by means of variational method from the modified nonlinear Schrdinger (MNLS) equation. Then, the relations between amplitude and width, frequency and chirp, width and chirp are obtained. The analytical solution about the pulse width and pulse center evolution on the propagation distance is obtained. The graph of the pulse width evolution with transmission distance is described. The results show that the high-order dispersion and fifth-order nonlinearity in fiber will affect Gaussian pulse parameters of evolution, but the adiabatic relation between the pulse width and amplitude has not been changed. High-order dispersion causes the compression of Gaussian pulse width spread, and the fifth-order nonlinearity causes Gaussian pulse width, which may offset the pulse width or the influence of the initial chirp in a certain degree, and thus realize the conformal pulse transmission..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1041 (2008)
Propagation Characteristics of Surface Plasmon Polaritons in a Metal Heterowaveguide Array
Zhou Lin, and Zhu Yongyuan
A new scheme of one-dimensional metal heterowaveguide array is proposed that the core layer of the metal waveguide is periodically modulated. Numerical results reveal that, periodic modulation of the core layer of metal waveguide induces the periodic modulation of the effective refraction index of the surface plasmon pA new scheme of one-dimensional metal heterowaveguide array is proposed that the core layer of the metal waveguide is periodically modulated. Numerical results reveal that, periodic modulation of the core layer of metal waveguide induces the periodic modulation of the effective refraction index of the surface plasmon polaritons (SPP) in the waveguide, which opens up an SPP band gap around a certain waveband, such as waveband around 1550 nm. Further numerical results reveal that, the SPP mode resonance with high quality for example Q=556 can be obtained at some wavelength by introducing a proper defect waveguide layer. The results can be applied to the subwavelength Bragg reflectors, light emitters and filters, and could be also availabe for the future integrated optics..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1047 (2008)
All Optical Multi-Wavelength Conversion and Data Format Conversion Based on Dual-Pumped Fiber Optical Parametric Amplifier
Jiang Yang, Yu Jinlong, Zhang Aixu, Wang Wenrui, Hu Hao, Zhang Litai, and Yang Enze
By the combination of data intensity modulated pump and continuous wave pump or sinusoidal intensity modulated pump, all optical multi-wavelength conversion and multi-wavelength conversion with data format conversion are presented by using a dual-pumped fiber optical parametric amplifier (FOPA). The operation principleBy the combination of data intensity modulated pump and continuous wave pump or sinusoidal intensity modulated pump, all optical multi-wavelength conversion and multi-wavelength conversion with data format conversion are presented by using a dual-pumped fiber optical parametric amplifier (FOPA). The operation principle is analyzed with respect to the gain. Experimentally, the multi-wavelength conversion and multi-wavelength conversion with data format conversion between non-return-to-zero (NRZ) and return-to-zero (RZ) are demonstrated under the bit rate of 2.5Gb/s. The experimental results indicate that the dual-pumped fiber optical parametric amplifier is able to implement multi-wavelength conversion to achieve normal and invert pattern with some degree of regeneration. The data format conversion gives the signal with duty ratio of 30% and improved extinction ratio..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1051 (2008)
Effects of Er3+ and Yb3+ Concentration on Gain and Noise Coefficient of Fiber Amplifier
Wu Yuexiang, Ma Xiaoming, and Zhao Xiaoji
The influence of concentration of rare-earth ions Er3+ and Yb3+ on gain and noise characteristics of Er3+/Yb3+ co-doped double-clad fiber amplifier is analyzed based on rate equation and light propagation equation. The numerical simulation result shows that, the amplifier has better noise characteristic with lower Er3+The influence of concentration of rare-earth ions Er3+ and Yb3+ on gain and noise characteristics of Er3+/Yb3+ co-doped double-clad fiber amplifier is analyzed based on rate equation and light propagation equation. The numerical simulation result shows that, the amplifier has better noise characteristic with lower Er3+ concentration and larger gain with lower Yb3+ concentration, and there is an optimal Er3+ concentration to get the largest gain..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1057 (2008)
A Novel Compact Soft-Lithography Based Polymeric Multimode Power SplitterLi Shu
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A novel compact polymeric multimode power splitter was designed and fabricated, with its overall length 30% shorter than the conventional Y-junction splitter. Using the simulation software BeamProp, we have done selective analysis to determine the parameters of the splitter. By using soft-lithography the 1×8 polymA novel compact polymeric multimode power splitter was designed and fabricated, with its overall length 30% shorter than the conventional Y-junction splitter. Using the simulation software BeamProp, we have done selective analysis to determine the parameters of the splitter. By using soft-lithography the 1×8 polymeric power splitters were prototyped and the measurement was in a good agreement with the calculated result. This splitter caters for the trend of micromation of the optical communication devices and the technology used features unique advantages of fast-easy producing, low-cost fabrication and possible mass-production..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1062 (2008)
Image Processing
Novel Image Fusion Algorithm for Multi-Band Polarimetric Image Based on Visible Light
Zhang Jingjing, and Fang Yonghua
An novel image fusion algorithm of remote polarimetric image based on wavelet transform is proposed. At first, three polarimtric images in each band of two bands are decomposed into images of low frequency band and high frequency band by wavelet transform. The fused low frequency approximate coefficients are obtained wAn novel image fusion algorithm of remote polarimetric image based on wavelet transform is proposed. At first, three polarimtric images in each band of two bands are decomposed into images of low frequency band and high frequency band by wavelet transform. The fused low frequency approximate coefficients are obtained with average method, and the fused high frequency detailed coefficients are obtained with different area-based feature selection method by setting each coefficient equaling the corresponding input image wavelet coefficients that has the greatest multi-window local deviation. One image in 555 band and the other in 665 band are obtained. Then, the algorithm decomposes the two images in one band into parts with low frequency band and high frequency band by wavelet transform, it adopt the minimum low frequency image wavelet coefficients as the fused low frequency image wavelet coefficients, and high frequency image fusion rules based on the texture detection algorithm of texture homogeneity measurement are used to adjust high frequency image wavelet coefficients. The low frequency component and orientation detail component of image are fused pertinently, features and details from different images are fused successfully and the quality of these fusion images is compared. The experimental result shows that the fused images present the polarization information, acquire more spectral information and higher contrast, and object detection and recognition can be more easy with fused images..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1067 (2008)
Depth Characteristic-Based Image Region Partition and Regional Disparity Estimation for Multi-View Video Coding
Yang Haitao, Chang Yilin, Huo Junyan, Xiong Lianhuan, and Lin Sixin
Based on depth characteristic of multi-view images, an image region partition and regional disparity estimation algorithm via block matching is proposed. Firstly, based on the concept of the depth object, the number of regions is determined and corresponding regional disparities are estimated. Then, the initial image rBased on depth characteristic of multi-view images, an image region partition and regional disparity estimation algorithm via block matching is proposed. Firstly, based on the concept of the depth object, the number of regions is determined and corresponding regional disparities are estimated. Then, the initial image region partition is obtained by minimizing the block matching error. When the number of the blocks in a region is less than a threshold, the region is eliminated, and all the blocks in this region are reassigned to other regions according to the region merging algorithm. The region merging process is iteratively executed to obtain valid region partition results. Experimental results show that the proposed algorithm can effectively partition image regions with different depths and accurately estimate corresponding regional disparities..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1073 (2008)
Imaging Systems
Reconstruction Algorithm of Cone-Beam Phase X-Ray Computer-Tomography Based on Grating Imaging
Chen Xin, Sun Yi, and Zhu Peiping
X-ray phase contrast imaging always provides high density resolution for weakly absorbing material, and shows wide prospect of application in many fields such as medicine, biology and material science. However, due to the limitation of interferometic imaging method, diffraction enhanced imaging method and in-line imagiX-ray phase contrast imaging always provides high density resolution for weakly absorbing material, and shows wide prospect of application in many fields such as medicine, biology and material science. However, due to the limitation of interferometic imaging method, diffraction enhanced imaging method and in-line imaging method, these methods need either highly coherent or highly monochromatic X-ray, and cannot provide a large field of view, none of them is very widely used. Grating imaging overcomes the limitations of above imaging methods and enables phase contrast imaging to develop into the form of cone-beam imaging. The research of the reconstruction algorithm of cone-beam phase X-ray computer tomography (CT) is studied, based on the characteristic of cone-beam grating imaging and the theory of Feldkamp-Davis-Kress (FDK) reconstruction algorithm. This method belongs to filtered back-projection and can reconstruct the phase item of object directly with the derivative of the phase term as projection, and the algorithm is proved by simulated results..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1079 (2008)
Structured Light Encoding Stripe Edge Detection Based on Grey Curve Intersecting Point
Wu Haibin, Yu Xiaoyang, and Guan Congrong
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1085 (2008)
Bulk Effects in Hyper-Numerical Aperture Optical Lithography
Zhou Yuan, and Li Yanqiu
To control critical dimension (CD) effectively, bulk effect is studied in hyper-numerical aperture (NA) optical lithography and a novel optimization strategy for resist film stacks is developed to balance bulk effect with appropriate swing effect. Firstly, the incident angle distribution of imaging light is evaluated bTo control critical dimension (CD) effectively, bulk effect is studied in hyper-numerical aperture (NA) optical lithography and a novel optimization strategy for resist film stacks is developed to balance bulk effect with appropriate swing effect. Firstly, the incident angle distribution of imaging light is evaluated based on NA and coherence factor σ settings, so that the average energy () absorbed per unit volume in the resist at the resist bottom surface is calculated over the whole range of incident angle. Secondly, the analytic relationship between and resist thickness (d) is obtained by fitting with least-squares procedure and the derivative of with respect to d is calculated. Lastly, the resist film stacks are optimized to minimize the derivative of . With the optimized thin-film stack structure design, the CD variation with resist thickness is obtained by using commercial software Prolith 9.0. The results show that the optimization strategy can effectively overcome CD variation from the bulk effect over the thickness range of 30～40 nm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1091 (2008)
Instrumentation, Measurement and Metrology
Evaluation of Step Height Standard Using Nano-Measuring Machine Integrated with Focusing Sensor
Guo Tong, Chen Jinping, Fu Xing, and Hu Xiaotang
Evaluation of step height standard with high accuracy is realized using a nano-measuring machine (NMM) integrated with a focusing sensor. The measuring range of the system is up to 25 mm×25 mm×5 mm. The operating principle of the NMM is described. NMM has high accuracy positioning and scanning performance thrEvaluation of step height standard with high accuracy is realized using a nano-measuring machine (NMM) integrated with a focusing sensor. The measuring range of the system is up to 25 mm×25 mm×5 mm. The operating principle of the NMM is described. NMM has high accuracy positioning and scanning performance through real-time measurement and feedback of built-in laser interferometers and angular sensors. The focusing sensor is only used as a zero point sensor, intersected at the same point with the three laser beams, which eliminates Abbe error. The output signal of the focusing sensor is introduced into the digital signal processing (DSP) controller of the NMM. The NMM will also measure data in z direction at the same time, which minimizes the influence of the focusing sensor's nonlinearity. According to the international standard of ISO 5436-1:2000, a calibrated step height is measured. The root-mean-square (RMS) deviation of 14 times measurements is 0.237 nm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1096 (2008)
A Method for Automatic Recognition of Emission-Line Stars Based on Detection of Spectral Lines
Liu Zhongtian, Qiu Kuanmin, and Yang Jinfu
Aiming at the LAMOST project, the largest sky survey project implemented in China, a novel method for automatic recognition of emission-line stars (ELS) based on detection of spectral lines is proposed. This method consists of three main steps: 1) the integral information of spectral lines is calculated by obtaining thAiming at the LAMOST project, the largest sky survey project implemented in China, a novel method for automatic recognition of emission-line stars (ELS) based on detection of spectral lines is proposed. This method consists of three main steps: 1) the integral information of spectral lines is calculated by obtaining the correlations of the features of spectral lines; 2) the stellar Balmer lines are detected based on the features of stellar spectral lines; 3) the ELSs are automatically recognized by using the threshold of the correlations and the results of the stellar Balmer lines. In the experiments with all observed spectra from the sloan digital sky survey (SDSS) DR4, 242 peculiar celestial bodies with the stellar emission lines are obtained. According to the Simbad reference database, they are the celestial bodies include ELSs, cataclysmic variable stars (CVS), and unknown peculiar celestial bodies, etc.. The extensive experiments with observed spectra show that the proposed method can automatically recognize ELS effectively..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1101 (2008)
Acid Orange Ⅱ Detection by Fluorescence Spectra
Liu Zhouyi, Zhu Tuo, Gu Endong, and Liu Ying
Acid orange Ⅱ is forbidden in food industry. For food security detection of acid orange Ⅱ, the experiment based on fluorescence spectra is reported. The result shows that the emitted fluorescence range is 310～390 nm when the sample is excited by ultraviolet radiation in 230～290 nm, the peak wavelength is 350 nm, and thAcid orange Ⅱ is forbidden in food industry. For food security detection of acid orange Ⅱ, the experiment based on fluorescence spectra is reported. The result shows that the emitted fluorescence range is 310～390 nm when the sample is excited by ultraviolet radiation in 230～290 nm, the peak wavelength is 350 nm, and the best excitation wavelength is 250 nm. The polarized fluorescence peak is constant, when a vertical polarizer is used. The intensity of fluorescence spectrum decreases in a linear law, with polarization angle increasing, and the polarization degree is calculated as 0.783. The orientation characteristics of molecule are considered. Moreover, analysis shows that the existence of structure of benzene and naphthalin in molecule is a reason of fluorescence, and single-line excitated state of nitrogen-bond by exciting light is another. The research can contribute to the detection of food security characteristic experssion, study of characterization of acid orange Ⅱ..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1106 (2008)
Calculation Analysis and Experimental Observation on Laser Diode Self-Mixing Interference
Hu Xianfeng
Ratio of self-mixing interference amplitude and static light intensity from a laser diode is only a few percent based on experimental observation. Feedback light decreases threshold current of laser diode and increases the static light intensity. The feedback light makes laser diode operate over the actual threshold cuRatio of self-mixing interference amplitude and static light intensity from a laser diode is only a few percent based on experimental observation. Feedback light decreases threshold current of laser diode and increases the static light intensity. The feedback light makes laser diode operate over the actual threshold current. The output intensity of laser diode is calculated with a three-mirror Fabry-Pérot cavity system. An equation between light frequency and feedback light is found from the main maximum condition of interference function. Signal waveform of self-mixing interference and ratio of the signal amplitude with the static light intensity are calculated, and the results are coincident with that measured experimentally. There are 15 resonance modes of complex cavity in the case of τrC/τi=22.8 at the same time. The variations of these resonance modes with external cavity length are less than 2.6×10-2 cm-1 and far less than 3.1 cm-1resonance mode width of Fabry-Pérot cavity. The variation of the light frequency is within the resonance mode width of inherent cavity..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1111 (2008)
Machine Vision
A Method of Image Resolution Calibration for Automatic Microscopic Zooming Based on NCCO
Sun Minglei, Zong Guanghua, Dong Dai, and Shi Jingxin
Pattern matching tool of normalized cross correlation operator (NCCO) computation C*(x) for ideal images can be determined by analytical expression Z(x). Compared with C*(x), C(x) of NCCO matching between images containing noise shows a little difference. But there is a property of zero similarity invariance (ZSI). A mPattern matching tool of normalized cross correlation operator (NCCO) computation C*(x) for ideal images can be determined by analytical expression Z(x). Compared with C*(x), C(x) of NCCO matching between images containing noise shows a little difference. But there is a property of zero similarity invariance (ZSI). A method of image resolution calibration in microscopic vision was proposed. Firstly, similarity functions of rectangular feature in x direction Z(x) were derived and proved. Then C(x)=0 was solved as an approximation of solution of Z(x). The detailed ZSI based calibrating algorithm was illuminated. The results of simulating image experiments show that the calibration accuracy of the algorithm can reach 0.1～0.2 pixel. Finally, the practical experiments were conducted on a hybrid microassembly workcell. Experimental results show that the calibration precision of the algorithm can reach 0.08 pixel. The ZSI based calibrating algorithm is a method with practical value and subpixel precision..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1117 (2008)
Materials
Investigation of a Step-Structure Photonic Crystal Fiber with Flattened Dispersion
Yuan Jinhui, Hou Lantian, Zhou Guiyao, Wei Dongbin, and Wang Haiyun
Based on the multi-pole method, a kind of step-structure photonic crystal fiber (PCF) is put forward. It has achieved flattened and ultra-flattened dispersion within the wave band of 1.1～1.8 μm by altering three structural parameters of the inner four rings (the diameter of the two inner rings holes, the diameter of thBased on the multi-pole method, a kind of step-structure photonic crystal fiber (PCF) is put forward. It has achieved flattened and ultra-flattened dispersion within the wave band of 1.1～1.8 μm by altering three structural parameters of the inner four rings (the diameter of the two inner rings holes, the diameter of the two outer rings holes, and the pitch), the absolute value of dispersion coefficient merely changing from 0.05～2 ps/(km·nm). Moreover, the effective mode-field area also has been stimulated, which is only 1/30 of that of conventional PCFs, showing that the PCFs with flattened and ultra-flattened dispersion do well in confining the light field compared with conventional PCFs. With numerical calculation and theoretic analysis, the design basis of this kind of step-structure PCF to achieve flattend and ultra-flattend dispersion within the wave band of 1.1～1.8 μm is concluded..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1167 (2008)
Analysis of Bending Loss Oscillations in Photonic Crystal Fibers
Cui Li, Zhao Jianlin, Zhang Xiaojuan, and Yang Dexing
The bending losses in refractive index-guiding photonic crystal fiber (PCF) and photonic band-gap fiber are analyzed by using equivalent straight fiber approximation and finite difference frequency domain (FDFD) method with anisotropic perfectly matched layers (PML) boundary conditions. The bending loss oscillations inThe bending losses in refractive index-guiding photonic crystal fiber (PCF) and photonic band-gap fiber are analyzed by using equivalent straight fiber approximation and finite difference frequency domain (FDFD) method with anisotropic perfectly matched layers (PML) boundary conditions. The bending loss oscillations in the two kinds of PCFs are observed by simulating the relationship between the bending loss and bending radius, and the origin of the loss oscillations was analyzed. The cladding modes corresponding to loss peaks are identified. Results show that the oscillations are caused by the coupling between the fundamental mode and the cladding modes. Moreover, the origin of oscillations in index-guiding PCF is similar to that of conventional double-clad fiber, while the oscillations in the photonic band-gap fiber are caused by two different kinds of cladding modes..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1172 (2008)
Optical Design and Fabrication
Vector analysis of Focusing Performance of Multilevel Circular Diffractive Microlens
Liu Yuling, Sui Chenhua, and Li Bo
A rigorous vector analysis model based on body-of-revolution (BOR) finite-difference time-domain (FDTD) method is presented, many design examples of multilevel circular microlens are analyzed by this model, and the influence of design parameters and fabrication error on the focusing performance of the designed microlenA rigorous vector analysis model based on body-of-revolution (BOR) finite-difference time-domain (FDTD) method is presented, many design examples of multilevel circular microlens are analyzed by this model, and the influence of design parameters and fabrication error on the focusing performance of the designed microlens is investigated. The results show that the electric field magnitude on focus increases, and the focal radius and focal depth minish when the zone number is increased but other parameters such as focal length and incident wavelength are constant. The focusing effect is intensified when adding step number only, but after the step number adds to 8～10, the focusing effect tends to be stable. It's suggested that the step number is set as 8～10 in actual fabrication. When binary mask is used to lithograph the multilevel, fabrication error is easily generated. Two kinds of multilevel microlens with alignment error or system etching error are designed, which generate the above error in the third etching process of fabricating eight levels. Analysis result shows that the alignment error has passive influence on the focusing effect of multilevel microlens, so it should be avoided in fabrication, but the system etching error has little influence on the focusing effect of multilevel microlens..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1124 (2008)
Deterministic Figuring in Optical Machining by Ion Beam
Dai Yifan, Zhou Lin, Xie Xuhui, Jiao Changjun, and Li Shengyi
Ion beam figuring (IBF) is introduced to overcome the disadvantages of conventional polishing processes in optical machining. The principle and method of IBF are introduced, and the key techniques required to implement an IBF process are also discussed. To demonstrate an IBF process, a 98 mm planar ceramic glass was pIon beam figuring (IBF) is introduced to overcome the disadvantages of conventional polishing processes in optical machining. The principle and method of IBF are introduced, and the key techniques required to implement an IBF process are also discussed. To demonstrate an IBF process, a 98 mm planar ceramic glass was processed on an IBF system. Its surface figure accuracy root-mean-square (RMS) is improved from initial 0.136λ to final 0.010λ(λ=632.8 nm) through two IBF processes, and the mean iterative convergence ratio is 3.7. The result shows that the IBF is a deterministic process, which results in a high surface figure accuracy without edge effect and a corresponding high convergence ratio of surface figure. Due to the unique characteristic of the sputtering process in IBF, machining an aspheric surface is no more difficult than machining a planar surface..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1131 (2008)
Optical Analysis and Experiments of Two-Dimensional Grating Light Modulator Array
Sun Jiyong, Huang Shanglian, Zhang Jie, Zhang Zhihai, and Wang ning
Diffraction characteristic of a two-dimensional (2D) grating light modulator is analyzed with scalar diffraction theory, the optical analysis method of the projection system based on grating light modulator is proposed. The processing is simulated with Matlab software. Diffraction light distribution of the 2D modulatorDiffraction characteristic of a two-dimensional (2D) grating light modulator is analyzed with scalar diffraction theory, the optical analysis method of the projection system based on grating light modulator is proposed. The processing is simulated with Matlab software. Diffraction light distribution of the 2D modulator is the coherent superposition of diffraction light distribution of modulators, and the distribution is similar to that of a single modulator. The diffraction light can be divided and imaged by the projection lens based on the anti-Fourier transform process. If the first-order diffraction light is used as the projection light, the modulator with 2kπ phase difference shows a bright pixel in the image plane, but the modulator with (2k-1)π phase difference shows a black pixel. A projection system based on a static micro-electromethanical system (MEMS) grating light modulator array was setup, and a static image is gotten. The result proves the feasibility of grating light modulator for projection display..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1136 (2008)
Design and Analysis of a Variable-Focus Optical System Based on Electrowetting
Peng Runling, Chen Jiabi, and Zhuang Songlin
A new design method for a variable-focus optical system without mechanical movements is proposed. It is quite different from that for traditional variable-focus optical systems, and changes the focal length of the system by regulating the relative position of the lenses with a motor. An extended Young's equation suA new design method for a variable-focus optical system without mechanical movements is proposed. It is quite different from that for traditional variable-focus optical systems, and changes the focal length of the system by regulating the relative position of the lenses with a motor. An extended Young's equation suited for double-liquid variable-focus lenses is derived by means of Helmholtz free energy minimization method. The traditional Young's equation based on vapor-liquid-solid tri-phase systems is extended to liquid-liquid-solid systems. Based on the cylindrical double-liquid variable-focus lenses, a new-type variable-focus optical system is presented. The conditions under which the optical system with appropriate applied voltages cannot only change the focal length but also keep the image plane stable simultaneously are researched. The corresponding simulation results show that the zoom ratio of the system can reach about 1∶1.5..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1141 (2008)
Design on Liquid Crystal Adaptive Optical System for 600 mm Telescope
Cao Zhaoliang, Mu Quanquan, Hu Lifa, Peng Zenghui, Liu Yonggang, and Xuan Li
In order to verify the validity of liquid crystal adaptive optics with a 600 mm telescope, Zemax software is used to design the liquid crystal adaptive optical system. The design demands are given according to the parameters of telescope, the turbulence and the liquid crystal. The optical system is designed with the abIn order to verify the validity of liquid crystal adaptive optics with a 600 mm telescope, Zemax software is used to design the liquid crystal adaptive optical system. The design demands are given according to the parameters of telescope, the turbulence and the liquid crystal. The optical system is designed with the above demands with Zemax software, and the characteristic of the system is evaluated. The focal length of the whole optical system is 35 m and the F number is 58. The limited line resolution at the image plane is 44.8 μm. It satisfies the sampling theorem because the size of the imaging CCD is 16 μm. Designed modulation tranfer function (MTF) of the liquid crystal adaptive optical system is almost the same as the diffraction limited MTF. Optical path difference (OPD) aberration of the system is about 0.1λ. The results show that the adaptive optical system has better optical characteristics..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1147 (2008)
Design and Simulation Analysis of a Micro Optical Switch
Li Wei, Liang Jingqiu, Li Xiaoqi, Zhong Yanchao, Liang Zhongzhu, and Sun Degui
A new polyimide (PI)-cantilever MEMS optical switch of electromagnetic actuation is proposed, and the structure of the optical switch is designed and simulated. The optimal dimension of the permanet magnet is designed and the structure of the PI-cantilever is optimized by finite element method. The relation of restorinA new polyimide (PI)-cantilever MEMS optical switch of electromagnetic actuation is proposed, and the structure of the optical switch is designed and simulated. The optimal dimension of the permanet magnet is designed and the structure of the PI-cantilever is optimized by finite element method. The relation of restoring force and electromagnetic force versus the displacement of the cantilever is interpreted. With 75 mA current pulse input,the distance of PI-cantilever equation is about 1.02 mm, which is able to change the propagation direction of the optical beam between through state and reflection state..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1151 (2008)
OPTOELECTRONICS
Effects of Pyrimidine Ring with -NH2 on Transient Luminescence Properties in Ruthenium Complexes Bonding to DNA
Zhu Weiling, Liu Xuewen, Wang Hui, Yu Huijuan, Chao Hui, Zheng Kangcheng, and Ji Liangnian
To study the effects of the pyrimidine ring with -NH2 on transient luminescence properties in ruthenium complexes bonding to DNA, transient luminescence dynamics process of two ruthenium complexes [Ru(bpy)2(dpbpd(NH2)2)]2+ and [Ru(phen)2(dpbpd(NH2)2)]2+bonding to calf thymus DNA(ctDNA) have been studied by using time-rTo study the effects of the pyrimidine ring with -NH2 on transient luminescence properties in ruthenium complexes bonding to DNA, transient luminescence dynamics process of two ruthenium complexes [Ru(bpy)2(dpbpd(NH2)2)]2+ and [Ru(phen)2(dpbpd(NH2)2)]2+bonding to calf thymus DNA(ctDNA) have been studied by using time-resolved spectroscopy, and the results are compared with results in previous researches. Two complexes both show biexponential decay in emission on bonding to DNA, and the luminescence lifetime is within tens of nanoseconds, about ten times shorter than the luminescence lifetime (several hundreds nanoseconds) of dppz-kind ruthenium complexes. It is attributed to that the hydrogen-bonds may form between N or -NH2 of pyrimidine ring and water molecule, base pairs or phosphoric skeleton. The hydrogen-bonds can quicken the nonradiative decay of the excitated state, weaken the luminescence intensity, and shorten the luminescence lifetime. The conclusion offers an argument to study the interaction mechanism for the complex bonding to DNA..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1155 (2008)
Charge Multiplication of CCD Based on Electrons Multiplication
He Weiji, Chen Qian, Qu Huiming, and Qin Jian
A charge multiplication model of charge carrier multiplier (CCM) in electron-multiplication charge-couple-device (EMCCD) was proposed. The EMCCD architecture and the theory of CCM with its performance on electrons multiplication were analyzed. The transform function of charge multiplication in CCM was presented based oA charge multiplication model of charge carrier multiplier (CCM) in electron-multiplication charge-couple-device (EMCCD) was proposed. The EMCCD architecture and the theory of CCM with its performance on electrons multiplication were analyzed. The transform function of charge multiplication in CCM was presented based on Z transform, as well as the amplitude-frequency response. The results show that amplitude-frequency response of CCM increases as the charge multiplication ratio increases. Then gain-fluctuation was studied with the gain-fluctuation factor, and the relation between gain-fluctuation factor, charge multiplication ratio α and CCM stages N was obtained. The numerical results show that the gain-fluctuation factor increases as α increases for α≤0.15 and N=400, but the gain-fluctuation factor decreases as α increases for α≥0.15. Those numerical results are validated with practical experience..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1161 (2008)
Remote Sensing and Sensors
Analysis on Effect Factors of Ground-Based Electro-Optic System Detection Ability on Space Object
Zhang Jihua, Yao Dongsheng, and Tan Bin
The detection ability of an electro-optic system is related to sky luminance, the electro-optic (EO) system and detector. The primary specification for expressing detection ability is signal-to-noise ratio. Based on analysis of the effect factors, a calculation formula of detection ability, including the imaging numberThe detection ability of an electro-optic system is related to sky luminance, the electro-optic (EO) system and detector. The primary specification for expressing detection ability is signal-to-noise ratio. Based on analysis of the effect factors, a calculation formula of detection ability, including the imaging number, is derived. The influence of the sky luminance, parameters of the EO system, and the dispersion of the object on the detection ability is mainly analyzed. Simulation is conducted through an example according to the space object model, and the theoretical results show that the space-object can be detected when elevation is greater than 30°. Theoretical results fit with the experimental research. The effects of sky luminance, parameters of system, dispersion of imaging point on detection ability under different conditions are quantitatively learned. Moreover, the scientific basis for the optimization design of the system and development of practical work is provided..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1178 (2008)
Algorithm for Airborne Spotlight Synthetic Aperture Imaging Ladar Data Processing
Guo Liang, Xing Mengdao, Liang Yi, and Tang Yu
Synthetic aperture imaging ladar is new active imaging system, which can offer a finer azimuth resolution than that achievable in conventional synthetic aperture radar (SAR) system. The frequency-modulated-continuous-wave (FMCW) signal is analyzed, and the frequency scaling algorithm, which is suitable for airborne synSynthetic aperture imaging ladar is new active imaging system, which can offer a finer azimuth resolution than that achievable in conventional synthetic aperture radar (SAR) system. The frequency-modulated-continuous-wave (FMCW) signal is analyzed, and the frequency scaling algorithm, which is suitable for airborne synthetic aperture imaging lidar (SAIL) system using FMCW signal in spotlight model, is deduced. And then, simulation of phase screen (PS) distorted by atmospheric turbulence following the von Karman spectrum by using Fourier transform is implemented in order to simulate turbulence. Finally, simulation shows that in the vacuum azimuth preprocessing can remove the ambiguity of the image and the modified algorithm can eliminate the loss of peak power about 8.6～9.3 dB and the defocusing phenomenon, while considering the effect of the atmospheric turbulence, if the synthetic aperture length does not exceed the similar Fried parameter of the atmosphere for SAIL, a well focused image can be obtained..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1183 (2008)
Adjustment of Optical Elements and Error Analysis for Laser Remote Sensing Polarization Imaging System
Zhang Xuguo, Jiang Yuesong, and Lu Xiaomei
The experimental setup for polarization imaging based on dual-rotating-retarder technique is modified, and a method to obtain two images encoded by polarization degree and intensity with a single measurement process is proposed. The optical intensity method is used to the laser remote sensing polarization imaging equipThe experimental setup for polarization imaging based on dual-rotating-retarder technique is modified, and a method to obtain two images encoded by polarization degree and intensity with a single measurement process is proposed. The optical intensity method is used to the laser remote sensing polarization imaging equipment. Through the application of Stokes and Mueller matrices for polarization elements, the principle, method and process of corresponding optical elements adjustment are given. The influence of laser central wavelength variation, polarizer angle error, wave plate phase retardance and angle errors on the whole system is analyzed. The results show that the emitted Stokes error caused by the angle error of polarizer and wave plate is less than 0.001, and can be neglected. The error caused by the retardance accuracy of wave plate is about 0.02, so the wave plate with higher accuracy should be selected. The influence caused by variation of laser central wavelength is the largest, and cannot be neglected, so a filter should be added to control the central wavelength of the received light at 808 nm. Telescope coated with aluminium has little influence on the polarization degree of scattered light, and it is suitable for the laser remote sensing polarization imaging system..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1191 (2008)
Synthetic-Aperture Ladar (Ⅱ): Spatial Phase Biased Telescope for Transmitting Antenna
Liu Liren
A kind of phase-biased telescope used as the laser transmitting antenna for a synthetic-aperture laser imaging radar is reported. An additional quadratic phase can be produced onto the wavefront of laser illumination by using a spatial phase plate together with a defocusing in the telescope. Such an arrangement is flexA kind of phase-biased telescope used as the laser transmitting antenna for a synthetic-aperture laser imaging radar is reported. An additional quadratic phase can be produced onto the wavefront of laser illumination by using a spatial phase plate together with a defocusing in the telescope. Such an arrangement is flexible to generate a quadratic phase history necessary for the synthetic-aperture imaging along the azimuth-direction, particularly a phase history for a required imaging resolution..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1197 (2008)
Application of Electro-Optic Modulation in Passive Synthetic Aperture Imaging Detection
He Yuntao, Jiang Yuesong, and Wang Changwei
A new passive synthetic aperture imaging detection method is presented. The radiation signal of field of view is received and amplified, and then the amplitude and phase information of the amplified signal is modulated to an optical carrier by electro-optic modulator. The optical signal is transmitted by fibers and a fA new passive synthetic aperture imaging detection method is presented. The radiation signal of field of view is received and amplified, and then the amplitude and phase information of the amplified signal is modulated to an optical carrier by electro-optic modulator. The optical signal is transmitted by fibers and a fiber array is shaped by the end of the fibers .The image is formed synchronously and directly by an optical system using the fiber array. The imaging approach can be used in extremely high resolution detection at microwave, millimeter wave, and terahertz frequencies. The application of the electro-optic modulation technique in passived synthetic aperture imaging is analyzed deeply and the model of electro-optic modulation is established. And the approximation of small signal modulation in the electro-optic modulation is discussed. By simulating computation and analysis, the intensity constraint of the modulated signal in an electro-optic modulator is gained. Result shows that the full-width at half maximum (FWHM) and signal-to-noise ratio (SNR) with upconversion electro-optic modulation and optical information processing are both better than those with traditional downconversion imaging technique..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1201 (2008)
Scattering
Optical Transmission from Exponentially Distributed Rough Surface of Layered Medium Using Perturbation Method
Ren Xincheng, and Guo Lixin
The optical transmission with plane wave incidence on the rough surface of layered medium is studied, the formulae of the transmission coefficient for different polarization states is derived using the perturbation method. An exponentially distributed rough surface is presented for describing the practical rough surfacThe optical transmission with plane wave incidence on the rough surface of layered medium is studied, the formulae of the transmission coefficient for different polarization states is derived using the perturbation method. An exponentially distributed rough surface is presented for describing the practical rough surface of layered medium, the transmission coefficient of HH polarization with the scattering angle of transmission wave is obtained by numerical calculation. The numerical results show that the transmission coefficient almost does not change with permittivity of the substrate medium. The magnitude and curve of the angular distribution for the transmission coefficient are affected by the the permittivity of intermediate medium. As the mean layer thickness of intermediate medium increases twice over, the period of the curves will decrease one half. The rough surface influences the magnitude of the transmission coefficient and the amplitude of the curve, the correlation length of the rough surface influences the magnitude of the transmission coefficient, the amplitude and varying trend of the curves. The transmission coefficient decreases oscillatorily with increase of the incident wavelength..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1208 (2008)
Vision, Color, and Visual Optics
Investigations for Weighting Functions of Color-Difference Formulae Based on Small Suprathreshold Color Differences
Wang Zhehong, and Xu Haisong
Small suprathreshold color-difference (about 3 ΔE*ab units) chromaticity ellipses at 16 color centers in the a*b* plane of CIELAB space were measured using the psychophysical method of constant stimuli. The corresponding chroma weighting function SC_ZJU07 and hue weighting function SH_ZJU07 were respectively fitted basSmall suprathreshold color-difference (about 3 ΔE*ab units) chromaticity ellipses at 16 color centers in the a*b* plane of CIELAB space were measured using the psychophysical method of constant stimuli. The corresponding chroma weighting function SC_ZJU07 and hue weighting function SH_ZJU07 were respectively fitted based on the chroma- and hue-difference data of 16 non-neutral-color color centers from this study and RIT-Dupont datasets. The chroma and hue weighting functions of six CIELAB-based color-difference formulae together with SC_ZJU07 and SH_ZJU07 were compared, and the detailed analysis indicates that SC_ZJU07 and SH_ZJU07 perform best. For the chroma-difference data, the predicting performances of chroma weighting functions of all the six formulae are not good, while for the hue-difference data, the hue weighting functions of CIEDE2000 obviously outperform the others..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 6, 1215 (2008)
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