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A compact single-polarization erbium-doped fiber laser by exploiting vernier effect

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Chinese Optics Letters 2009年第11期7卷 993-995页

作者：毛向桥延凤平傅永军王琳彭健刘利松简水生 Institute of Lightwave Technology Key Lab of All Optical Network and Advanced Telecommunication Network of Ministry of EducationBeijing Jiaotong University

A compact single-polarization fiber laser with fiber Bragg gratings inscripted in a polarization-maintaining erbium-doped germanosilicate fiber is demonstrated experimentally. The single-wavelength and single- polarization regime of our studied laser is achieved by applying a radial stress upon one of two gratings and stretching the other one axially to adjust the reflection peak match. Two single-wavelength and single- polarization lasing lines are realized respectively with fine power stability.

关键词： Crystal resonators Erbium Fiber lasers Fibers Lasers Polarization

Effectively modeling piecewise planar urban scenes based on structure priors and CNN

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Science China(Information Sciences) 2019年第2期62卷 206-210页

作者： Wei WANG Wei GAO Zhanyi HU School of network Engineering Zhoukou Normal University national Laboratory of Pattern Recognition Institute of Automation Chinese Academy of Sciences University of Chinese Academy of Sciences

Dear editor,Piecewise planar stereo methods can approximately reconstruct the complete structures of a scene by overcoming challenging difficulties (e.g.,poorly textured regions) that pixel-level stereos appear powerless. In general, these methods have three basic steps:(1) over-segmenting the image into several regions (superpixels) without overlapping;(2) generating candidate planes from initial 3D points;(3) assigning the optimal plane for each superpixel using a global method. However,

关键词： Effectively modeling piecewise planar urban scenes based on structure priors and CNN Hs MRF

A novel method of rapidly modeling optical properties of actual photonic crystal fibres

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Chinese Physics B 2010年第8期19卷 1-7页

作者：王立文娄淑琴陈卫国李宏雷 Key Lab of All Optical network & Advanced Telecommunication network of EMC Beijing Jiaotong University Institute of Lightwave Technology Beijing Jiaotong University

The flexible structure of photonic crystal fibre not only offers novel optical properties but also brings some difficulties in keeping the fibre structure in the fabrication process which inevitably cause the optical properties of the resulting fibre to deviate from the designed properties. Therefore, a method of evaluating the optical properties of the actual fibre is necessary for the purpose of application. Up to now, the methods employed to measure the properties of the actual photonic crystal fibre often require long fibre samples or complex expensive equipments. To our knowledge, there are few studies of modeling an actual photonic crystal fibre and evaluating its properties rapidly. In this paper, a novel method, based on the combination model of digital image processing and the finite element method, is proposed to rapidly model the optical properties of the actual photonic crystal fibre. Two kinds of photonic crystal fibres made by Crystal Fiber A/S are modeled. It is confirmed from numerical results that the proposed method is simple, rapid and accurate for evaluating the optical properties of the actual photonic crystal fibre without requiring complex equipment.

关键词： photonic crystal fibre digital image processing finite element method modeling optical properties

Theoretical and experimental investigation of the mode-spacing of fiber Bragg grating Fabry-Perot cavity

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Chinese Optics Letters 2009年第9期7卷 775-777页

作者：任文华陶沛琳谭中伟刘艳简水生 Institute of Lightwave Technology Key Laboratory of All Optical Network and Advanced Telecommunication Network of Ministry of EducationBeijing Jiaotong University

The mode-spacing of the fiber Bragg grating Fabry-Perot （FBG F-P） cavity is calculated by using the effective cavity length which contains the effective length of the FBG. The expression of the effective length, defined by using the phase-time delay, is obtained and simplified as a function of the peak reflectivity at the Bragg wavelength, the band edges, and the first zero-reflectivity wavelength. The effective length is discussed from the energy penetration depth point of view. Three FBG F-P cavities are fabricated in order to validate the effective length approach. The experimental data fits well with the theoretical predictions. The limitation of this method is also pointed out and the improved approach is proposed.

关键词： Cavity resonators Fabry Perot interferometers Fiber optic components Fiber optic sensors Reflection

DRAGON-Lab―Next generation internet technology experiment platform

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Science in China(Series F) 2008年第11期51卷 1908-1918页

作者： WANG JiLong LI ZhongHui LV GuoHan JIANG CaiPing LI Xing ZHANG QianLi national Laboratory for Information Science and Technology Tsinghua University Beijing 100084 China network Research-Center Tsinghua University Beijing 100084 China

Testbed technology is very important in the development of the Internet. Similar to the present internet, next generation internet also starts from testbed. There are two kinds of testbeds, testbed networks like CNGI-CERNET2, Internet2, Geant; testbed systems like PlanetLab, NS2. DRAGON-Lab can be viewed as both testbed network and testbed system. DRAGON-Lab is an independent AS （autonomous system） and connected to multiple real networks. On the other hand, DRAGON-Lab integrates many resources of its own, partners＇ and internet＇s, so as to provide open service. DRAGON-Lab has a large scale, provides open service, supports remote visualized experiments and programmable experiments. More details will be introduced in this paper.

关键词： Internet testbed system confederation

Robust quantum secure direct communication and authentication protocol against decoherence noise based on six-qubit DF state

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Chinese Physics B 2015年第5期24卷 239-246页

作者：昌燕张仕斌闫丽丽韩桂华 Department of network Engineering Chengdu University of Information Technology

By using six-qubit decoherence-free （DF） states as quantum carriers and decoy states, a robust quantum secure direct communication and authentication （QSDCA） protocol against decoherence noise is proposed. Four six-qubit DF states are used in the process of secret transmission, however only the ｜0＇〉 state is prepared. The other three six-qubit DF states can be obtained by permuting the outputs of the setup for ｜0＇〉. By using the ｜0＇〉 state as the decoy state, the detection rate and the qubit error rate reach 81.3%, and they will not change with the noise level. The stability and security are much higher than those of the ping-pong protocol both in an ideal scenario and a decoherence noise scenario. Even if the eavesdropper measures several qubits, exploiting the coherent relationship between these qubits, she can gain one bit of secret information with probability 0.042.

关键词： quantum secure direct communication decoherence noise authentication six-qubit decohevencefree state

Research and Optimization of GPSR Routing Protocol for Vehicular Ad-Hoc network

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China Communications 2022年第10期19卷 194-206页

作者： Jianming Cui Liang Ma Ruirui Wang Ming Liu School of Information Engineering Chang'an UniversityXi'an 710064China national Computer network Emergency Response Technical Team/Coordination Center of China Beijing 100029China

Security is one of the most critical issues to Vehicular Ad-hoc networks (VANETs) since the information transmitted is asynchronous and distributed. Vulnerability and instability are two of the challenges remain to be addressed by the research community and the industry. In this paper, we first proposed a trust reliability based model and extended the GPSR protocol to TM-GPSR protocol. Then, we improved the LET-GPSR protocol based on the link connection time prediction. On this basis, combined the decision index of the TM-GPSR and LET-GPSR protocols, we proposed the RC-GPSR routing protocol. We built the standard testing platform on the NS2 and SUMO, the average end-to-end delay and packet delivery rate of GPSR protocol and the three updates protocols under different node density, node speed, and malicious node ratio are simulated and evaluated. The results showed that under the same conditions, compared with GPSR protocol, RC-GPSR protocol has a lower average end-to-end delay and a higher packet delivery rate, which effectively improves the link stability and security.

关键词： VANET GPSR protocol trust reliability link connection time

Suppression of stimulated Brillouin scattering with phase modulator in soliton pulse compression

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Chinese Optics Letters 2009年第7期7卷 656-658页

作者：吕博龚桃荣陈明王目光李唐军陈根祥简水生 Key Lab of All Optical network and Advanced Telecommunication network of Ministry of Education of China Institute of Lightwave Technology Beijing Jiaotong University

A phase modulator is employed in the scheme of soliton pulse compression with dispersion shifted fiber （DSF）. Stimulated Brillouin scattering （SBS） effect, as a negative influence here, can be dramatically suppressed after optical phase modulation. The experimental result shows that the launched power required for high-order soliton pulse compression has been significantly increased by 11 dB under the condition of 100-MHz phase modulation. Accordingly, the experiment of picosecond pulse compression generated from electro-absorption sampling window （EASW） has also been implemented.

关键词： Laser produced plasmas Laser pulses Light polarization Phase modulation Pulse compression Solitons Ultrasonics

Multi-pair massive MIMO amplify-and-forward relaying system with low-resolution ADCs:performance analysis and power control

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Science China(Information Sciences) 2018年第2期61卷 164-181页

作者： Qimei CUI Yinjun LIU Yinsheng LIU Weiliang XIE Yong ZHAO national Engineering Laboratory for Mobile network Security Beijing University of Posts and Telecommunications State Key Laboratory of Rail Traffic Control and Safety Beijing Jiaotong University China Telecom Corporation Limited

In this paper, we focus on a general multi-pair massive MIMO amplify-and-forward(AF) relaying system where the relay antennas employ low-resolution analog-to-digital converters(ADCs) to reduce the hardware cost. First, considering the effect of low quantization on channel estimation, a tight closed form approximation of the system ergodic achievable rate is derived. Second, some asymptotic analysis is presented to reveal the impacts of the system parameters on the achievable rate. Particularly, the generalized power scaling schemes are characterized. The results indicate that in some cases, when the number of relay antennas grows without bound, the impact of the finite resolution ADCs on data transmission can be eliminated. To enhance the achievable rate of the quantized systems, the optimal user and relay power control schemes are proposed. Furthermore, to reap all the benefits of low-resolution ADCs, another power control scheme is also designed to minimize the total power consumption while guaranteeing the quality-of-service(Qo S)requirement of each user, which can help draw some useful insights into the optimal ADC resolution from power saving perspectives. The simulation results confirm the accuracy of our theoretical analysis and the effectiveness of the proposed power control schemes.

关键词： massive MIMO relaying system imperfect CSI low quantization power control