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    Impurity Modes of One-dimensional Photonic Crystals Containing Single-negative Materials
    Acta Photonica Sinica   
    Abstract1569)      PDF (654KB)(547)       Save
    The photonic band gap structure of one-dimensional photonic crystal containing single-negative materials with an impurity layer is studied by using transfer matrix method.The impurity is double layers positive-index materials.Investigations show that the frequency of the impurity mode is insensitive to scaling and disorder of lattice.When the thickness and layers of the impurity increase,the impurity mode frequency will decrease and its rate of change will increase,and the velocity of the impurity mode vanished into the edge of low-frequency will become faster and faster.
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    Cited: Baidu(292)
    OPTICAL AND ELECTRICAL PROPERTIES OF TRANSPARENT CONDUCTIVE ITO FILMS PREPARED BY SOL-GEL PROCESS
    Zhou Yinsui, Wang Jun, Yang Xiaodong, Dong Qingyan, Gao Aihua, Hu Xiaoyun, Lu Zhiguo
    Acta Photonica Sinica    2002, 31 (9): 1077-1080.  
    Abstract473)      PDF (828KB)(807)       Save
    The thin films of indium tin oxide(ITO)are applied extensively because of their high transparency(95% transmittance between 400nm and 600nm, 300nm thickness)and low electrical resistivity(the lowest around 10-3Ω·cm, 300nm thickness). Transparent and conductive ITO films had been prepared by the sol gel process, and the effects of every factor on the optical and electrical properties of the files had been investigated during the process. Optical transmittance of around 97% was observed in the visible region of the 50nm thick films, the maximum transmittance value was 99.55%. Resistivities of 2.0Ω·cm were obtained and the minimum resistivity value was 0.31Ω·cm.
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    Cited: Baidu(233)
    Design and Study of the Dome-screen Projector Optical System
    Sun Xin;Bai Jiaguang;Wang Zhonghou
    Acta Photonica Sinica   
    Abstract1724)      PDF (664KB)(823)       Save
    An optical system of Dome-screen projector which plays important roll in the pilot-training process was proposed.The lens system adopted the Reverse-Telephoto configuration which had an effective focal length of 5.5mm,an F-number of F/4 ,a field of view of 175°,and a working wavelength in the range of visible spectrum.A discussion about the relationship between the screen radius and the field curve was presented to explain why this system had an advantage in reducing the field curve.A relatively convenient method of choosing the appropriate screen radius was given at the end of the discussion.
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    Cited: Baidu(178)
    TWO KINDS OF NONLINEAR HIGHER-ORDER SQUEEZING EFFECTS IN A NEW TYPE OF TWO-MODE LIGHT FIELD OF SUPERPOSITION STATE
    Yang Zhiyong, Hou Xun
    Acta Photonica Sinica    1998, 27 (4): 289-299.  
    Abstract326)      PDF (2986KB)(818)       Save
    In this paper, the nonllnear higher order squeezing theory of two-mode and multi-mode radiative ligh fields, based upon the developlng of current squeezing theories,is established by Yang Zhiyong and Hou Xun firstly.So the two kinds of nonlinear higher-order squeezing, both Nth-power Y-squeezing and Nth-power H-squeezing,of two-mode and multi-mode radiative light fields are also defined in new theory.And then a new type of two-mode light field of superposition state |ψ> thatlinear superposition principle in quantum mechanlcs is satisfied, is constructed.According to thedefinition mentioned above,the two kinds of nonlinear higher-order squeezing effects of the state |ψ>are therefore studied in detail.lt is found that |ψ> is a new type of nonclassical light field in whichthere exists eigher any order Nth power Y-squeezing or any order Nth-power H-squeezing.And under some certain conditlons.this two kinds of nonlinear higher-order squeezing effects present the properties of periodic and alternating changes between the naximum squeezing and the minimumsqueezing.The definition of Nth power squeezing of single-mode radiative light field amplitude proposed in reference 7 is only the specific example of this paper under the condition of k= 1.
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    Cited: Baidu(159)
    DIGITAL IMAGE SHARPNESS EVALUATION FUNCTION
    Li Qi, Feng Huajun, Xu Zhihai, Bian Meijuan, Shen Su, Dai Ruichun
    Acta Photonica Sinica    2002, 31 (6): 736-738.  
    Abstract862)      PDF (234KB)(2774)       Save
    Gradient function,frequency spectrum function and entropy function are main tools for evaluating digital image sharpness.This paper discussed their application in autofocus technology and studied feature of evaluation functions.Experimental results show that gradient function′s advantage is rapid speed and it can be used in real-time process,and frequency spectrum function has good sensibility and is qualified for higher accuracy.
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    Cited: Baidu(138)
    Vector Graphical Objects Watermarking Scheme in Wavelet Domain
    Li Yuanyuan;Xu Luping
    Acta Photonica Sinica   
    Abstract1650)      PDF (589KB)(700)       Save
    A vector graphics authentication technique by embedding digital watermarks is proposed. The vertices coordinate pairs of the vector objects are generated by mapping a 2-D graphics into a sequence. We embed the watermarks into the vector graphics by modifying the DWT magnitude coefficients according to the watermark value, and leaving the angle coefficients unchanged. The experimental results show that the proposed technique successfully survives vector graphical processing operations.
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    Cited: Baidu(112)
    An Experimental Method of Eliminating Zero-order Diffraction in Digital Off-axis Holography
    Lü Qieni;Ge Baozhen;Zhang Yimo
    Acta Photonica Sinica   
    Abstract1363)      PDF (608KB)(677)       Save
    An experimental method of eliminating zero-order diffraction in the reconstructed image of off-axis digital holography is presented. Holographic diffraction grating acts as a beam splitter,and an off-axis holography system is formed. The holograms of object with different recording parameters are obtained by adjusting reflecting mirror in recording optical system to vary incidence orientation of the object beam in CCD to introduce phase shift. The zero-order image can be eliminated by numerically processed the hologram of object with different recording parameters. The theoretical analysis has been done in detail,and the experimental results are also given. The experimental results show that the method presented in this paper is feasible,simple in optical structure and easy in operation and data processing.
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    Cited: Baidu(102)
    Research on the Relationship of the Change in Forward Voltage with Temperature of Light Emitting Diode
    Li Bingqian, Bu Liangji, Gan Xiongwen, Fan Guanghan
    Acta Photonica Sinica    2003, 32 (11): 1349-1351.  
    Abstract309)      PDF (1156KB)(1274)       Save
    Physical mechanism of the forward voltage changes with the operator temperature is analyzed in this paper, and a measurement system is built to research these changes. The linear fitted method is used to analyze the experiment data, and the coefficient of the forward voltage changes with temperature is gotten for many types light emitting diodes, it is very important parameter for the thermal control and device structure design of ultra-high-brightness, power LED devices and assemble.
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    Cited: Baidu(101)
    Effect of the atmospheric turbulence on laser communication system
    Xing Jianbin;Xu Guoliang;Zhang Xuping;Wang Guanghui;Ding Tao
    Acta Photonica Sinica   
    Abstract1673)      PDF (808KB)(1104)       Save
    First,transmission equation of the laser transmitting through atmospheric turbulence channel was analyzed,ignoring other noises in the system,atmosphere turbulence was the only cause for Bit Error Rate(BER).Then,the amplitude variance and intensity variance of the laser signal were discussed,and the relationship betwwen BER and the laser communication system was deduced.The result indicated that in the weak variance condition intensity variance should be below 0.67 for communication system with BER below 10-9;with turbulence intensity C2n increasing,BER increased rapidly;adopting laser with longest wave to communicate can decrease BER effecively.
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    Cited: Baidu(92)
    FOURIER TRANSFORMATION IN FREELY GROWING DENDRITE OF PURE SUBSTANCE
    Geng Xingguo, Fu Hengzhi, Li Jianguo
    Acta Photonica Sinica    1998, 27 (6): 504-507.  
    Abstract356)      PDF (1060KB)(394)       Save
    The transport of temperature wave near dendritic tip is treated with Fourier transformation in order to take the heat potential distribution near dendritic tip.Furthermore,the evolution of characteristic interface morphology is determined by the distribution function of temperature.The effect of anisotropic interface energy can also be considered with Fourier transformation.
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    Cited: Baidu(88)
    A Region-based Remote Sensing Image Fusion Method
    Li Huihui;Guo Lei;Liu Hang
    Acta Photonica Sinica   
    Abstract1593)      PDF (2910KB)(891)       Save
    A region-based image fusion method was proposed.The source images firstly were split into different regions with various spatial characteristics and then performed the different fusion methods for each particular region independently.Experiments were implemented with two categories of remote sensing image fusion—multispectral image vs.panchromatic image and multispectral image vs.radar image.The results show that using the proposed method which could be not only obtained better quality fusion result,but also easily controlled the contribution of these components in the fused product and chosen the appropriate fusion method,which satisfied the user′s needs.
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    Cited: Baidu(85)
    Study on the Surface Deformation of Flat Reflector Under Gravity Load
    Li Fu; Ruan Ping; Zhao Baochang
    Acta Photonica Sinica   
    Abstract1337)      PDF (607KB)(757)       Save
    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 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.
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    Cited: Baidu(76)
    THE PROPERTIES OF BOTH N-TH POWER Y-SQUEEZING AND N-TH POWER H-SQUEEZING IN THE MULTI-MODE EVEN-COHERENT STATE LIGHT FIELD
    Xu Dingguo, Hou Yao, Yang Zhiyong, Hou Xun
    Acta Photonica Sinica    1999, 28 (6): 481-493.  
    Abstract290)      PDF (3034KB)(565)       Save
    In this paper, the properties of N-th p0wer Y-squeezing, N-th power H-squeezing, N-Yminimum uncertainty state and N-H minimum uncertainty state in the multi-mode even-coherent state light field |ψ,e〉q is studied in detail,that is based upon utilizing the theory 0f generalized nonlinear equal-order higher-order squeezing of multi-mode radiative light field, which is proposed by Yang Zhiyong and Hou Xun recently, lt ls f0und that, l ), When N, the number of squeezing-order, is even number, the state |ψ,e〉q is always stayed in N-Y minimum uncertainty state; and when N is 0dd number, the state |ψ,e〉q, under some certain c0nditi0ns, can present any order N-th p0wer Y-squeezing which changes periodically1 2 ) When q. N, the products of cavity modes number and squeezingxirder number, is even number, the state |ψ,e〉q is also always stayed in N-H minimum uncertainty state,and when q. N is odd number under some other conditions the state |ψ,e〉q can also present any order N-th power H-squeezing that changes periodically too 1and 3) the squeezing depth and degree of both N-th power Y-squeezing and N-th power H-squeezing are related nonlinearly to the probability amplitudeyq(e), to the squeezing parameter Rj,to the initial phase of each mode ψj(or to the sum of the initial phase of each mode ∑j=1qψj), to the squeezing order number N and to the cavity-mode number q,the later is more intensive than the former.
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    Cited: Baidu(75)
    STRUCTURE OF BASIC PERIOD OF ONE-DIMENSIONAL PHOTONIC CRYSTAL AND THE CHARACTERS OF FORBIDDEN BANDS
    Chen Weizong, Shen Ying, Hu Manli, Pu Tao, Liu Jun
    Acta Photonica Sinica    2001, 30 (12): 1453-1456.  
    Abstract712)      PDF (821KB)(1848)       Save
    The propagation properties of light radiation in one-dimensional photonic crystal were studied by characteristic matrix method of optical conductance.The effect of the structure of basic period of one-dimensional photonic crystal on characters of forbidden bands has been analyzed.The application of these properties was pointed out.
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    Cited: Baidu(73)
    Er3+/Yb3+ Codoped Phosphate Glass Planar Waveguides by Ag+-Li+ Ion Exchange
    Acta Photonica Sinica   
    Abstract1614)      PDF (296KB)(647)       Save
    A chemically stable Er3+/Yb3+ codoped phosphate glass is prepared and used in fabrication of planar waveguides for optical amplifiers and lasers. The weight loss rate of this phophate glass is 4.7×10-5g·cm-2·hr-1, which is smaller than that of Kiger′s commercial phosphate glass QX/Er. Planar optical waveguides are formed by Ag+-Li+ ion exchange and the effective refractive indices are determined by m-lines at 632.8nm. Diffusion parameters such as ion exchange depth, surface refractive indices, variation of refractive index and diffusion coefficient are calculated based on refractive index profiles obtained by Inverse WKB method.
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    Cited: Baidu(70)
    COMPARISON OF EXTENDED JONES MATRICES FOR TWISTED NEMATIC LIQUID CRYSTAL DISPLAYS AT OBLIQUE ANGLES OF INCIDENCE
    Wang Qian, Yu Feihong, Pan Weimin, Chen Jun, Guo Haicheng
    Acta Photonica Sinica    2000, 29 (4): 330-338.  
    Abstract639)      PDF (2446KB)(957)       Save
    Detailed formulas were derived using Yeh′s formulation of the extended 2×2 Jones matrix and applied to twisted nematic liquid crystal displays(LCDs)at oblique angles of incidence.Numerical comparisons of this extended Jones matrix method with the exact 4×4 Berreman matrix and with the extended Jones matrix of Lien are presented.The different extended Jones matrix formulations differ in their approach to boundary conditions matching between the model birefringent layers.We show that the Yeh′s version is a more accurate approximations to the full 4×4 matrix.This extended Jones matrix method is fast,direct and simple.It is also physically more intuitive.
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    Cited: Baidu(70)
    A Contourlet Domain Image Denoising Method Based on Mathematical Morphology
    Acta Photonica Sinica   
    Abstract1600)      PDF (635KB)(723)       Save
    A Contourlet domain image denoising method is proposed based on mathematical morphology.By using Contourlet Transform,the noised image is decomposed into a low frequency subband and a set of multisacle and multidirectional high frequency subbands.The high frequency coefficients of the original image are processed by mathematical morphological operator.The noise which have small or no at all support area are removed,and the small features which have large or consecutive support area are preserved.The denoising image will be gotten by performing the inverse Contourlet Transform to these estimated coefficients.Experimental results show that the denoising effect of this proposed method is better than that of other methods based on Contourlet transform.
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    Cited: Baidu(69)
    The Study of Fiber Bragg Grating Pressure Sensor with High Pressure-resistance
    Sun An;Qiao Xueguang;Jia Zhenan;Guo Tuan;Chen Changyong
    Acta Photonica Sinica   
    Abstract1806)      PDF (494KB)(705)       Save
    The pressure responses of polymer packaged fiber Bragg grating (FBG) sensor are analyzed, a special kind of pressure-resistant polymer is used to coat FBG in a metal tube. A kind of soft elastic material is used to reduce the friction between tube and polymer, and to eliminate chirp effect caused by different friction distribution to improve the pressure response of FBG. The pressure response sensitivity is 0.036 nm/MP, the response curve is linear, and the whole measuring range can reach 40 MP at least.
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    Cited: Baidu(68)
    SIMULTANEOUS STATIC-STRAIN,TEMPERATURE AND VIBRATION MEASUREMENT USING A SINGLE FIBRE-OPTIC SENSOR
    Zeng Xiangkai, Rao Yunjiang, Yu Banmei, Wang Yiping, Zhu Tao, Ran Zengling
    Acta Photonica Sinica    2001, 30 (10): 1254-1258.  
    Abstract500)      PDF (564KB)(1062)       Save
    A novel fibre-optic sensor integrating an in-fibre Bragg grating (FBG) and an extrinsic Fabry-Perot interferometer (EFPI) in series,used for simultaneous static strain,temperature and vibration measurement,is presented in this paper.This sensor system simultaneously measures the three parameters using the method of low coherence interferometric signal demodulation combined with optical spectrum measurement of the FBG and EFPI.The experimental results show that a static strain accuracy of ±20με,a temperature accuracy of ±1℃ and a vibration resolution of ~1nm have been achieved with good repeatability.
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    Cited: Baidu(68)
    Study on the Visible Emission Mechanism of Nanocrystalline ZnO Thin Films
    Song Guoli;Sun Kaixia
    Acta Photonica Sinica   
    Abstract1705)      PDF (1520KB)(858)       Save
    Nanocrystalline ZnO thin films is a promising material for short-wave laser and luminescence etc, due to its wide band gap (3.37 eV) and high exciton binding energy(60 meV)at room temperature. The high-quality nanocrystalline ZnO thin films is prepared by using sol-gel, grow on quartz glass subtractes, Photoluminescence spectra and Absorption spectra of nanocrystalline ZnO thin films with excitation wavelength 330 nm are measured at room temperature. Two emission bands are observed, one being a strong and narrow ultraviolet emission band its central wavelength is 392 nm and the other being weak and wide green visible band its central wavelength is 519 nm. Crystal structure of samples are examined by X-ray diffraction (XRD) pattern, the mean grain size of nanocrystalline ZnO thin films are calculated by with DebyeScherrer formula. The results indicate that nanocrystalline ZnO thin films has a hexagonal wurtzite structure and polycrystalline, and showed sharp diffraction peak for ZnO(002),which indicate that as-sputered film were highly caxis oriented. The grain increases with annealing temperature, Absorption spectra of ZnO thin films indicated that the band gap of the thin films was 3.30 eV . Photoluminescence spectra showed that ZnO thin films emitted strong UV Photoluminescence .The intensities of PL peaks decrease with increasing annealing temperature. In particular the mechanism behind the visible luminescence has also been discussed in this paper.It should be said that the mechanism behind the visible luminescence is still a question to debate. In this paper the visible emission processes of nanocrystalline ZnO. The experiments prove that the luminescence emission peak located 519nm corresponds to the transition from the shallow level of oxygen vacancy to the shallow level of zinc vacancy or electron transition from deep level of oxygen vacancy to valence band.
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    Cited: Baidu(66)