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Theoretical analysis of transmission characteristics for all fiber,multi-cavity Fabry-Perot filters based on fiber Bragg gratings

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Science in china(Series F) 2008年第9期51卷 1391-1400页

作者： XU Ou1,2.LU ShaoHua1,2.DONG XiaoWei1,2.LI Bin1,2.NING TiGang1,2.& JIAN ShuiSheng1,2.1 Key Lab of All Optical Network & Advanced Telecommunication Network of EMC,beijing jiaotong {2.,beijing 100044,china 2.institute of lightwave Technology,beijing jiaotong {2.,beijing 100044,china Key Lab of All Optical Network & Advanced Telecommunication Network of EMC Beijing Jiaotong University Beijing 100044 China institute of lightwave Technology Beijing Jiaotong University Beijing 100044 China

The characteristics of transmission spectra for the all fiber, multi-cavity Fabry- Perot （FP） configuration based on fiber Bragg gratings （FBG） are theoretically analyzed and modeled. The general transmission matrix function for the structure with any number of cavities is derived, and explicit expression of the power trans- mission coefficient for symmetrical two-cavity FP is presented. The general condi- tions for flat-top single resonant peak at the central wavelength in FBG stop band are derived and verified in the numerical simulation section. The transmission peaks of single-cavity and two-cavity FP structures are compared and discussed, and results show that compared to the single-cavity FP, flatness of the top and steepness at the edge of transmission peak can be improved by introducing one more cavity. The resonant transmission peak properties of two-cavity structure are investigated in detail for various values of cavity length and FBGs with different reflection characteristics, and the design guidelines for transmission-type filters are presented. The results show that the steepness of peak slope can be improved by increase of FBG reflectivities, and these kinds of filters can be used as nar- row-band single-channel selectors and multi-channel wavelength de-multiplexing by properly choosing the length of cavities and reflectivities of FBGs.

关键词： fiber Bragg gratings Fabry-Perot cavity transmission-type filter

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Analysis of coupling from core mode to counter-propagating radiation modes in tilted fiber Bragg gratings

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Science china(Information Sciences) 2010年第5期53卷 1078-1088页

作者： LU ShaoHua 1,2., XU Ou 1,2., FENG SuChun 1,2., DONG XiaoWei 1,2., PEI Li 1,2.& JIAN ShuiSheng 1,2.1 Key Laboratory of All Optical Network & Advanced Telecommunication Network of EMC, beijing jiaotong university, beijing 100044,{2. 2.institute of lightwave Technology, beijing jiaotong university, beijing 100044,{2. 1. Key Laboratory of All Optical Network & Advanced Telecommunication Network of EMC Beijing Jiaotong University Beijing 100044 China2. Institute of Lightwave Technology Beijing Jiaotong University Beijing 100044 China

Radiation-mode coupling is stronger and more efficient in tilted fiber Bragg gratings than in other fiber gratings; it has good advantage in such fields as optical communication and optical sensors. A simplified coupled-mode theory (CMT) approach is proposed for what we believe to be the first time, whose validity is demonstrated by comparing its simulation results with that of the complete CMT equations. With the simplified CMT approach, a theoretical spectral analysis of coupling from core mode to counter-propagating radiation modes in reflective tilted fiber Bragg gratings is presented. The influence of grating length, refractive index modulation amplitude and tilt angle is exhaustively investigated on the transmission spectrum characteristics. The different dependences between s-polarized and p-polarized radiation-mode coupling on grating tilt angle are discussed, and the coupling strength of 45 -tilted gratings shows the greatest polarization dependence with the limitation of backward-propagating radiation-mode coupling.

关键词： fiber optics tilted fiber Bragg gratings coupled-mode theory radiation-mode coupling

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Theoretical analysis of polarization properties for tilted fiber Bragg gratings

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Science china(Information Sciences) 2010年第2期53卷 390-397页

作者： XU Ou 1 , LU ShaoHua 2.& JIAN ShuiSheng 2.1 Faculty of Information Engineering, Guangdong university of Technology, Guangzhou 510006, china {2. of lightwave Technology, beijing jiaotong university, beijing 100044, china 1. Faculty of Information Engineering Guangdong University of Technology Guangzhou 510006 China2. Institute of Lightwave Technology Beijing Jiaotong University Beijing 100044 China

The polarization properties for tilted fiber Bragg gratings (TFBGs) are investigated theoretically based on coupled-mode theory and Mueller matrix method. The expression of wavelength-related polarizationdependent loss (PDL) for TFBGs with different tilt angles is derived and calculated. Simulation results are compared, and the results indicate that the polarization capability of TFBGs with 45° angle is stronger than other TFBGs with smaller angles. The degree of polarization for unpolarized light passing TFBGs is also simulated to further evaluate the polarization properties for various tilt angles. In addition, the relationship between physical parameters of a TFBG and its polarization capability is discussed.

关键词： coupled-mode theory degree of polarization (DOP) Mueller matrix method polarization dependent loss (PDL) tilted fiber Bragg gratings

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An efficient algorithm for solving supply chain network equilibria and equivalent supernetwork based traffic network equilibria

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Science china(Technological Sciences) 2010年第12期53卷 3264-3274页

作者： XU Meng1 & GAO ZiYou2.1 MOE Key Laboratory for Urban Transportation Complex Systems Theory and Technology, beijing jiaotong university, beijing 100044,{2. 2.institute of Systems Science, School of Traffic and Transportation, beijing jiaotong university, beijing 100044,{2. 1. MOE Key Laboratory for Urban Transportation Complex Systems Theory and Technology Beijing Jiaotong University Beijing 100044 China2. Institute of Systems Science School of Traffic and Transportation Beijing Jiaotong University Beijing 100044 China

This paper is concerned with the algorithm of the supply chain network equilibrium model and its equivalent supernetwork based traffic network equilibrium model with elastic demands. Both models are further written as nonlinear complementarity problems. Semismooth least squares reformulations of the complementarity problems are presented and their convergence properties are investigated. Considering the drawbacks of Quasi-Newton method (using the Fischer-Burmeister function), a semi-smooth Levenberg-Marquardt-type method is proposed to solve the problems. Numerical examples show that the Levenberg-Marquardt-type method can solve the supply chain network equilibrium model and its equivalent supernetwork based traffic network equilibrium model significantly, and is more efficient than the Quasi Newton method and the modified projection method. Furthermore, the Levenberg-Marquardt-type method with the equivalent supernetwork based complementarity formulation can be implemented faster than with the supply chain network equilibrium complementarity formulation.

关键词： supply chain networks traffic network equilibrium supernetwork nonlinear complementarity problem Levenberg Marquardt-type method

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RST transforms resistant image watermarking based on centroid and sector-shaped partition

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Science china(Information Sciences) 2012年第3期55卷 650-662页

作者： ZHAO Yao1,2., NI RongRong1,2. & ZHU ZhenFeng1,2. 1institute of Information Science, beijing jiaotong university,{2., china 2.4} Key Laboratory of Advanced Information Science and Network Technology,{2., china 1. institute of Information Science Beijing Jiaotong University Beijing 100044 China2. Beijing Key Laboratory of Advanced Information Science and Network Technology Beijing 100044 China

A novel digital watermarking scheme featuring centroid-based sectoring is proposed in this paper. To get higher robustness against geometric attacks, such as rotation, scaling, and translation (RST), a delicate synchronization mechanism was developed and incorporated into the proposed approach. During the process of watermark embedding, the original image was partitioned into sectors based on the image centroid. Synchronization information as well as the message bits is then embedded into these sectors. With the help of the centroid-based sectoring and synchronization information, the proposed approach is capable of restoring the correct sectoring even if it has experienced severe geometric distortion. This attribute ensures the correct recovery of embedded watermarks and contributes to the robustness of the proposed scheme. A series of experiments have been conducted to verify the feasibility and effectiveness of the proposed approach. Experimental results show that the proposed scheme possesses good robustness against RST attacks and considerable robustness against other common image processing attacks.

关键词： digital watermarking geometrical transform attacks RST transforms

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A new method for counting trees with vertex partition

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Science china Mathematics 2008年第11期51卷 2000-2004页

作者： LIU YanPei institute of Mathematics, beijing jiaotong university,{2., china institute of Mathematics Beijing Jiaotong University Beijing 100044 China

A direct and elementary method is provided in this paper for counting trees with vertex partition instead of recursion, generating function, functional equation, Lagrange inversion, and matrix methods used before.

关键词： tree planted tree joint tree model vertex partition code 05C30 05C10

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Determination of the packing number D_λ(3,W_4^((3)),v)

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Science china Mathematics 2009年第11期52卷 2537-2548页

作者： WU Yan & CHANG YanXun institute of Mathematics,beijing {2. university,beijing 100044,china 1. institute of Mathematics Beijing Jiaotong University Beijing 100044 China

A t-hyperwheel(t≥3) of length l(or W l(t) for brevity) is a t-uniform hypergraph(V,E) ,where E = {e1,e2.. . .,el} and v1,v2.. . .,vl are distinct vertices of V = il=1 ei such that for i = 1,. . .,l,vi,vi+1 ∈ ei and ei ∩ ej = P,j ∈/{i-1,i,i + 1},where the operation on the subscripts is modulo l and P is a vertex of V which is different from vi,1 i l. In this paper,we investigate the maximum packing problem of MPλ(3,W 4( 3) ,v) . Finally,the packing number Dλ(3,W 4( 3) ,v) is determined for any positive integers v 5 and λ.

关键词： t-(v Γ λ) packing leave packing number group divisible(Γ t) -design candelabra(Γ t) -system

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The spectrum of （gv, g, 3, λ）-DF in Zgv

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Science china Mathematics 2009年第5期52卷 1004-1016页

作者： WANG XiaoMiao & CHANG YanXun institute of Mathematics, beijing jiaotong university,{2., china 1. institute of Mathematics Beijing Jiaotong University Beijing 100044 China

In this paper, the necessary and sufficient conditions for the existence of a (gv, g, 3, λ)- difference family in Zgv are established. As a consequence, the existence spectrum of a cyclic (3, λ)-GDD of type gv witho... 详细信息

关键词： difference family incomplete difference matrix perfect difference family

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Dispersion Compensators Based on Overlaped Linearly Chirped Fiber Gratings for DWDM Systems

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Chinese Journal of Lasers 2001年第6期10卷 18-22页

作者： LI Tangjun Ning Tigang WANG Muguang JIAN Shuisheng (institute of lightwave Technology, Northern {2. university, beijing 100044, china) 北方交通大学光波所北京 100044

By introducing a convergent lens in the phase mask setup and by tilting appropriately the fiber from the phase mask, a linearly chirped fiber grating with an appropriate chirp can be obtained conveniently. Using this method, two groups of fiber gratings, each of them is composed of 8 overlaped linearly chirped fiber gratings but with different center reflection wavelength separations (～0.8 nm and ～1.6 nm, respectively) are fabricated. Experimental results show that, the compensators based on the two groups of fiber gratings can be used to compensate for the dispersion of 8×2.5 Gb/s transmission over 100 km of standard single-mode fiber for multiple channels in optical time-division multiplexing (OTDM) and densed wavelength division multiplexing (DWDM).

关键词： fiber grating OTDM DWDM

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Numerical Analysis on Transmission Characteristics of a Bragg Grating Assisted Mismatched Fiber Coupler

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Chinese Journal of Lasers 2000年第2期9卷 167-174页

作者： WEI Daoping JIANG Zhong'ao ZHAO Yucheng JIAN Shuisheng (institute of lightwave Technology, Northern {2. Unversity, beijing 100044, china) 北方交通大学北京

Based on mode-coupled theory, a Bragg grating assisted mismatched fiber coupler is analyzed theoretically. At the same time, a detailed numerical analysis on transmission characteristics of the coupler is carried out when it considers the arcs of two fibers in the coupling region of the coupler or not, and the optimized design on the Bragg grating assisted mismatched fiber coupler for wavelength-division multiplexing/ demultiplexing is proposed.

关键词： wavelength-division multiplexing/ demultiplexing fiber Bragg gratings mismatched fiber couplers mode-coupled theory

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