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Optimized optical phase conjugation conf iguration for f iber nonlinearity compensation in CO-OFDM systems

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Chinese Optics Letters 2011年第6期9卷 31-35页

作者：李炉焦乔耀军纪越峰 Key laboratory of Information Photonics and optical Communications Ministry of Education Beijing University of Posts and Telecommunications

The optimized optical phase conjugation （OPC） configuration is proposed for the 40-Gb/s CO-OFDM system. The proposed configuration for nonlinear cancellation is systematically depicted in transmission links with lumped amplification. Numerical simulations are performed to demonstrate effectiveness. Simulation results show that mid-span spectral inversion （MSSI） can partially compensate for nonlinear distortions. Moreover, its optimized configuration can further improve system performances and increase nonlinear compensation effectiveness. Compared with MSSI, the maximal Q factor, nonlinear threshold, and transmission distance of optimized OPC configuration increase by over 1.6 dB, 2 dB, and 2 times, respectively.

关键词： optical phase conjugation Optimization Telecommunication systems

Joint nonlinearity and chromatic dispersion pre-compensation for coherent optical orthogonal frequency-division multiplexing systems

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Chinese Physics B 2011年第11期20卷 296-300页

作者：乔耀军刘学君纪越峰 Key laboratory of Information Photonics and optical Communications of Ministry of Education Beijing University of Posts and Telecommunications

This paper introduces a joint nonlinearity and chromatic dispersion pre-compensation method for coherent optical orthogonal frequency-division multiplexing systems. The research results show that this method can reduce the walk- off effect and can therefore equalize the nonlinear impairments effectively. Compared with the only other existing nonlinearity pre-compensation method, the joint nonlinearity and chromatic dispersion pre-compensation method is not only suitable for low-dispersion optical orthogonal frequency-division multiplexing system, but also effective for high- dispersion optical orthogonal frequency-division multiplexing transmission system with higher input power but without optical dispersion compensation. The suggested solution does not increase computation complexity compared with only nonlinearity pre-compensation method. For 40 Gbit/s coherent optical orthogonal frequency-division multiplexing 20 × 80 km standard single-mode fibre system, the suggested method can improve the nonlinear threshold （for Q 〉 10 dB） about 2.7, 1.2 and 1.0 dB, and the maximum Q factor about 1.2, 0.4 and 0.3 dB, for 2, 8 and 16 ps/（***） dispersion coefficients.

关键词： fibre optics nonlinearity chromatic dispersion coherent optical orthogonal frequency-division multiplexing

Generation of linearized optical single sideband signal for broadband radio over fiber systems

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Chinese Optics Letters 2009年第4期7卷 339-343页

作者：王涛昌庆江苏翼凯 State Key Lab of Advanced optical Communication systems and Networks Department of Electronic Engineering Shanghai Jiao Tong University

We propose a new scheme to generate broadband linearized optical single-sideband （OSSB） signal for radio over fiber systems. By using an unbalanced dual parallel Mach-zehnder modulator （DPMZM） followed by optical filtering, a linearized OSSB signal is obtained. With coherent detection, radio frequency （RF） signal can be recovered with simultaneously suppressed second-order distortion and third-order intermodulation. This scheme can be used to realize broadband systems with wide dynamic range.

关键词： Light modulators

A novel TS-EIA-PTS PAPR reduction algorithm for optical OFDM systems

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Optoelectronics Letters 2015年第5期11卷 375-378页

作者：袁建国李璋超马骏王永林金朝庞宇 Key laboratory of optical Communication and Networks Chongqing University of Posts and Telecommunications

Because the partial transmit sequence(PTS) peak-to-average power ratio(PAPR) reduction technology for optical orthogonal frequency division multiplexing(O-OFDM) systems has higher computational complexity, a novel two-stage enhanced-iterative-algorithm PTS(TS-EIA-PTS) PAPR reduction algorithm with lower computational complexity is proposed in this paper. The simulation results show that the proposed TS-EIA-PTS PAPR reduction algorithm can reduce the computational complexity by 18.47% in the condition of the original signal sequence partitioned into 4 sub-blocks at the remaining stage of n-d=5. Furthermore, it has almost the same PAPR reduction performance and the same bit error rate(BER) performance as the EIA-PTS algorithm, and with the increase of the subcarrier number, the computational complexity can be further reduced. As a result, the proposed TS-EIA-PTS PAPR reduction algorithm is more suitable for the practical O-OFDM systems.

关键词： PAPR multiplexing iterative partitioned transmit blocks remaining retain iteration multipath

Electro-optic tuning in ferroelectric capacitor with photonic crystal nanobeam cavity

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Science China(Information Sciences) 2025年

作者： Tongtong WANG Yong ZHANG Danyang YAO Zhi JIANG Dongxin TAN Jie WEN Qiyu YANG Xuetao GAN Yan LIU Yue HAO Genquan HAN State Key Discipline laboratory of Wide Band Gap Semiconductor Technology School of MicroelectronicsXidian University Key laboratory of Light Field Manipulation and Information Acquisition Ministry of Industry and Information TechnologyShaanxi Key Laboratory of Optical Information Technology School of Physical Science and TechnologyNorthwestern Polytechnical University Hangzhou Institute of Technology Xidian University

Silicon photonics has provided a platform for the convergency of photonic devices and electronic circuits, facilitating the development of optical telecommunications and optical interconnects on chip[1]. As the basic building block of optical communication systems, electro-optic tuning is expected to be more compact, high bandwidth, energy efficient, and allow for CMOS-compatible fabrication in the future[2]. Resonator-based electro-optic tuning has attracted more and more interest due to the small footprint, enhanced light-matter interactions and high energy efficiency. Compared with microring and microdisk resonators, photonic crystal nanobeam cavities （PCNBCs） realize higher quality factors, stronger light-matter interactions, ultrasmall mode volume and a much larger free spectral range （FSR）[3].

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A novel construction scheme of QC-LDPC codes based on the RU algorithm for optical transmission systems

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Optoelectronics Letters 2016年第2期12卷 132-135页

作者：袁建国梁梦琪王永林金朝庞宇 Key laboratory of optical Communication and Networks Chongqing University of Posts and Telecommunications

A novel lower-complexity construction scheme of quasi-cyclic low-density parity-check(QC-LDPC) codes for optical transmission systems is proposed based on the structure of the parity-check matrix for the Richardson-Urbanke(RU) algorithm. Furthermore, a novel irregular QC-LDPC(4 288, 4 020) code with high code-rate of 0.937 is constructed by this novel construction scheme. The simulation analyses show that the net coding gain(NCG) of the novel irregular QC-LDPC(4 288,4 020) code is respectively 2.08 d B, 1.25 d B and 0.29 d B more than those of the classic RS(255, 239) code, the LDPC(32 640, 30 592) code and the irregular QC-LDPC(3 843, 3 603) code at the bit error rate(BER) of 10^(-6). The irregular QC-LDPC(4 288, 4 020) code has the lower encoding/decoding complexity compared with the LDPC(32 640, 30 592) code and the irregular QC-LDPC(3 843, 3 603) code. The proposed novel QC-LDPC(4 288, 4 020) code can be more suitable for the increasing development requirements of high-speed optical transmission systems.

关键词： classic codes parity decoding encoding irregular Richardson correction iteration triangular

A novel construction method of QC-LDPC codes based on the subgroup of the finite field multiplicative group for optical transmission systems

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Optoelectronics Letters 2016年第1期12卷 61-64页

作者：袁建国周光香高文春王永林金朝庞宇 Key laboratory of optical Communication and Networks Chongqing University of Posts and Telecommunications

According to the requirements of the increasing development for optical transmission systems,a novel construction method of quasi-cyclic low-density parity-check(QC-LDPC) codes based on the subgroup of the finite field multiplicative group is ***,this construction method can effectively avoid the girth-4 phenomena and has the advantages such as simpler construction,easier implementation,lower encoding/decoding complexity,better girth properties and more flexible adjustment for the code length and code *** simulation results show that the error correction performance of the QC-LDPC(3 780,3 540) code with the code rate of 93.7% constructed by this proposed method is excellent,its net coding gain is respectively 0.3dB,0.55dB,1.4dB and 1.98dB higher than those of the QC-LDPC(5 334,4 962) code constructed by the method based on the inverse element characteristics in the finite field multiplicative group,the SCG-LDPC(3 969,3 720) code constructed by the systematically constructed Gallager(SCG) random construction method,the LDPC(32 640,30 592) code in ITU-T G.975.1 and the classic RS(255,239) code which is widely used in optical transmission systems in ITU-T G.975 at the bit error rate(BER) of ***,the constructed QC-LDPC(3 780,3 540) code is more suitable for optical transmission systems.

关键词： Bit error rate Convolutional codes Error correction Inverse problems Light transmission optical communication Satellite communication systems Transmissions

Performance evaluation for 160-Gb/s optical phase conjugation systems considering dispersion mapping and third-order dispersion

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Chinese Optics Letters 2007年第2期5卷 63-65页

作者：李建强徐坤周光涛伍剑林金桐 Key laboratory of optical Communication and Lightwave Technologies Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876

The impact of third-order dispersion （TOD） is investigated by numerical simulations in 160-Gb/s singlechannel systems incorporated with dispersion mapping and optical phase conjugation （OPC）. System performances using retrun-to-zero （RZ） or carrier-suppressed RZ （CSRZ） modulation format are evaluated on the optimized dispersion map. The results indicate that even though TOD has been fully compensated, the intra-channel nonlinearity induced by local TOD would degrade the system performance in nonlinear regime. The scheme with an optimized dispersion map provides a much higher performance and offers a larger tolerance on a variation of pre-compensation. CSRZ modulation format is more robust due to its tradeoff between tolerances on intra-channel nonlinearity and dispersion.

关键词： Computer simulation Dispersion (waves)

Fiber Nonlinearity Post-Compensation by optical Phase Conjugation for 40Gb/s CO-OFDM systems

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Chinese Physics Letters 2011年第6期28卷 164-167页

作者： QIAO Yao-Jun LIU Xue-Jun JI Yue-Feng Key laboratory of Information Photonics and optical Communications(Ministry of Education) Beijing University of Posts and TelecommunicationsBeijing 100876

Fiber nonlinearity impairments in a 40-Gb/s coherent optical orthogonal frequency division multiplexing(CO-OFDM)system are post-compensated for by a new method of fiber nonlinearity post-compensation(FNPC).The FNPC located before the CO-OFDM receiver includes an optical phase conjugation(OPC)unit and a subsequent 80-km-high nonlinear fiber(HNLF)as a fiber nonlinearity *** OPC unit is based on a four wave mixing effect in a semiconductor optical *** fiber nonlinearity impairments in the transmission link are post-compensated for after OPC by transmission through the HNLF with a large nonlinearity *** results show that the nonlinear threshold(NLT)(for Q>10 dB)can be increased by about 2.5 dB and the maximum Q factor is increased by about 1.2 dB for the single−channel 40-Gb/s CO-OFDM system with periodic dispersion *** the 50-GHz channel spacing wavelength-division-multiplexing system,the NLT increases by 1.1 dB,equating to a 0.7 dB improvement for the maximum Q factor.

关键词： fiber amplifier nonlinearity