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New control algorithm for automatic PMD compensation system

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Chinese Optics Letters 2012年第3期10卷 27-30页

作者：张锦南谷月袁学光田凤张晓光陶金晶 Institute of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications Network Operation Supporting Center China Mobile Group Beijing Co.Ltd.

A new cross-tracking method is proposed to improve the convergent speed of the control algorithm in real-time polarization mode dispersion（PMD）compensation *** cross-tracking algorithm is compared with the previously used dithering particle swarm optimization（DPSO）and gradient particle swarm optimization（GPSO）algorithms,and it is proven to offer the best performance among the three *** transmission of a 43-Gb/s differential quadrature phase-shift keying（DQPSK）signal over a 1 200-km fiber span using a compensator based on digital signal processing（DSP）is demonstrated via the cross-tracking algorithm.

关键词： Algorithms Quadrature phase shift keying signal processing Tracking (position)

Fiber nonlinearity compensation for CO-OFDM transmission with 10.7-Gb/s NRZ-OOK neighbors

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Chinese Optics Letters 2012年第11期10卷 17-20页

作者：邓明亮易兴文张静张洪波邱昆 Key Laboratory of Optical Fiber Sensing and Communication Networks Ministry of EducationUniversity of Electronic Science and Technology of China

Fiber nonlinearity limits the use of coherent optical orthogonal frequency division multiplexing （CO- OFDM） to upgrade wavelength-division multiplexing （WDM） systems using legacy non-return-to-zero-on- off-keying （NRZ-OOK） channels. This letter proposes to compensate for the fiber nonlinearity of COOFDM with NRZ-OOK neighbors by combining digital signal processing （DSP）-based self-phase modulation （SPM） post-compensation with pilot-tone-based cross-phase modulation （XPM） compensation. The simulation results demonstrate that the optimum low-pass filter bandwidth for pilot-tone-based XPM compensation depends on the pilot-to-signal ratio value and launch optical power. Our method allows a 4-dB increase in the launch power for a 40-Gb/s single polarization CO-OFDM channel placed in the middle of six 10.7-Gb/s NRZ channels in a 50-GHz space and 1 200-km WDM system.

关键词： Legacy systems Phase modulation signal processing Wavelength division multiplexing

Numerical Analysis of Alternating-Current Small-signal Response in Graphene Nanoribbons

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Chinese Physics Letters 2010年第8期27卷 172-175页

作者：陈志东张进宇余志平 Institute of Microelectronics Tsinghua University Beijing 100084

Alternating-current small-signal admittances of armchair graphene nanoribbons are investigated using the method of non-equilibrium Green＇s function. The calculated ac admittances show an oscillatory response between inductive and capacitive behaviors, which is a result of the finite length of the graphene nanoribbon. The effects of hydrogen-passivated edges on ac response are demonstrated. At low frequency, the edge effects transform the inductive behavior in a metallic graphene nanoribbon into a capacitive one. Finally, the effects of variations in the width and bandgap of a graphene nanoribbon on its dynamic response are investigated.

关键词： ALTERNATING currents NUMERICAL analysis signal processing GRAPHENE NANOSTRUCTURED materials GREEN'S functions ENERGY gaps (Physics)

Magneto-Optic Fiber Gratings Useful for Dynamic Dispersion Management and Tunable Comb Filtering

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Chinese Physics Letters 2010年第6期27卷 225-228页

作者： WU Bao-Jian LU Xin QIU Kun Key Lab of Broadband Optical Fiber Transmission and Communication Networks of the Ministry of Education University of Electronic Science and Technology of China Chengdu 611 731

Intelligent control of dispersion management and tunable comb filtering in optical network appfications can be performed by using magneto-optic fiber Bragg gratings （MFBGs）. When a nonuniform magnetic field is applied to the MFBG with a constant grating period, the resulting grating response is equivalent to that of a conventional chirped grating. Under a linearly nonuniform magnetic field along the grating, a linear dispersion is achieved in the grating bandgap and the maximal dispersion slope can come to 1260ps/nm2 for a l0-mm-long fiber grating at 1550nm window. Similarly, a Gaussian-apodizing sarnpled MFBG is also useful for magnetically tunable comb filtering, with potential application to clock recovery from return-to-zero optical signals and optical carrier tracking.

关键词： MAGNETOOPTICS BRAGG gratings DISPERSION COMB filters OPTICAL communications MAGNETIC fields GAUSSIAN processes signal processing

Broadband Convergence of 40 GHz-ROF and 10-Gb/s WDM-PON Systems in the Duplex Access Network

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Chinese Physics Letters 2010年第5期27卷 106-108页

作者：张丽佳忻向军刘博张琦王拥军余重秀 Key Laboratory of Information Photonics and Optical Communications (Ministry of Education) Beijing University of Posts and Telecommunications Beijing 100876

A broadly converged 40G-ROF and 10-Gb/s WDM-PON multi-service access system is proposed and exper- imentally demonstrated. This scheme consists of an integrated system of 40G-ROF and 10-Gb/s WDM-PON simultaneously transmitting independent 2.5-Gb/s wireless and 10-Gb/s wire signal. At the base station, it employs a remodulation scheme, which is achieved by remodulating the upstream OOK signal on the DPSK downstream signal, to reduce the cost of the base station. The transmission experiment is carried out over a 25-km-long single mode fiber （SMF-28）. The results show that the sensitivities of downstream PON and ROF signal are -14.5 dBm and -21.5 dBm, respectively, and the sensitivity of upstream signal is -25.3 dBm.

关键词： BROADBAND communication systems CONVERGENCE (Telecommunication) WAVELENGTH division multiplexing COMPUTER networks -- Access control MODULATION (Electronics) SENSITIVITY analysis WIRELESS sensor networks signal processing

Suprathreshold Stochastic Resonance in a Single Comparator

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Chinese Physics Letters 2007年第1期24卷 275-278页

作者：王仁国龙长才 Department of Physics Huazhong University of Science and Technology Wuhan 430074

Stochastic resonance usually appears when stimulus is too weak to overcome barriers in a nonlinear system. Unusually, we demonstrate that in a simple competitor as a prototype model, stochastic resonance can still occur when the stimulus is predominantly suprathreshold. This result provides new knowledge for understanding of mechanism underlying information process in biological systems and aIso finds appfications in signal processing.

关键词： RESONANCE NONLINEAR systems SYSTEMS theory signal processing

Inversion for Sound Speed Profile by Using a Bottom Mounted Horizontal Line Array in Shallow Water

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Chinese Physics Letters 2010年第8期27卷 106-109页

作者：李风华张仁和 State Key Laboratory of Acoustics Institute of Acoustics Chinese Academy of Sciences Beijing 100190

Ocean acoustic tomography is an appealing technique for remote monitoring of the ocean environment. In shallow water, matched field processing （MFP） with a vertical line array is one of the widely used methods for inverting the sound speed profile （SSP） of water column. The approach adopted is to invert the SSP with a bottom mounted horizontal line array （HLA） based on MFP. Empirical orthonormal functions are used to express the SSP, and perturbation theory is used in the forward sound field calculation. This inversion method is applied to the data measured in a shallow water acoustic experiment performed in 2003, Successful results show that the bottom mounted HLA is able to estimate the SSP. One of the most important advantages of the inversion method with bottom mounted HLA is that the bottom mounted HLA can keep a stable array shape and is safe in a relatively long period.

关键词： OCEAN tomography SPEED of sound REMOTE sensing signal processing EMPIRICAL research INVERSION (Geophysics)

Stimulated Brillouin scattering phase conjugation of light beams carrying orbit angular momentum(Invited Paper)

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Chinese Optics Letters 2017年第3期15卷 21-23页

作者：陈旭东昌成成蒲继雄 Fujian Key Laboratory of Light Propagation and Transformation College of Information Science and Engineering Huaqiao University Xiamen 361021 China

We investigate the stimulated Brillouin scattering （SBS） properties of light beams carrying orbit angular momentum （OAM）. The phase conjugation of light beams carrying OAM is experimentally achieved in an SBS mirror with a random phase plate. The spectrum and the pulse width compression of SBS light are measured. It is shown that the phenomena of pulse compression is observed and OAM conservation is confirmed in the SBS process. The OAM transfer from photons to phonons may find potential applications in photon-phonon conversion-based signal-processing schemes by using OAM multiplexing.

关键词： Angular momentum Brillouin scattering Light Phonons Photons signal processing Solid state lasers

High-Precision Calibration of Electron Beam Energy from the Hefei Light Source Using Spin Resonant Depolarization

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Chinese Physics Letters 2014年第12期31卷 40-44页

作者：蓝杰钦徐宏亮 National Synchrotron Radiation Laboratory University of Science and Technology of China Hefei 230029 Department of Mathematics and Physics Fujian University of Technology Fuzhou 350108

Electron beam in high-energy circular accelerator was found to spontaneously become transverse polar- ization by emitting spin-flip synchrotron radiation. It opens the possibility for accurate measurement of the average beam energy in the storage ring. Due to the fact that the average spin tune Us （the number of spin precession per orbital revolution） is proportional to the average beam energy E.

关键词： Electron beams Synchrotron radiation Strip transmission lines Magnetic fields Spin polarization signal processing