Dispersion compensation using mismatched multicavity etalon all-pass filter

In this paper, we propose a novel mismatched multicavity etalon (MME) all-pass filter for fixed-value dispersion compensation and dispersion slope compensation. It is a multicavity Gires-Tournois (GT) etalon filter with unequal cavity lengths between adjacent cavities. A theoretical study is presented. Analytical expressions for the group delay and chromatic dispersion are derived to allow device designs to be made. The simulation results show that nearly linear group delay or quasi-flat chromatic dispersion response can be obtained by suitably choosing the reflectances of the reflectors and the cavity mismatch length. The chromatic dispersions and the bandwidth of the quasi-flat-dispersion band can be tailored by changing the reflectances of the reflectors and the mismatched cavity length. The dispersion slope compensation can be obtained by slightly modulating the reflectances of the reflectors. Increasing the number of cavities can enhance the performance and the design flexibility of the dispersion compensator.     

Electronic compensator for 100-Gb/s PDM-CO-OFDM long-haul transmission systems

We study an electronic compensator (EC) as a receiver for a 100-Gb/s polarization division multiplexing coherent optical orthogonal frequency division multiplexing (PDM-CO-OFDM) system without optical dispersion compensation.EC,including electrical dispersion compensation (EDC),least squares channel estimation and compensation (LSCEC),and phase compensation (PC),is used to compensate for chromatic dispersion (CD),phase noise,polarization mode dispersion (PMD),and channel impairments,respectively.Simulations show that EC is highly effective in compensating for those impairments and that the performance is close to the theoretical limitation of optical signal-to-noise rate (OSNR),CD,and PMD.Its robustness against those transmission impairments and fiber nonlinearity are also systematically studied.     

Spectral response characterization of an InP:Fe photorefractive wavelength-self-tunable single-sideband filter

We report the characterization of the spectral response of a wavelength-self-tunable single-sideband filter operating at 16-GHz radio frequency. We demonstrate, for what we believe to be the first time, simultaneous generation of three dynamic Bragg gratings inside the InP:Fe photorefractive crystal of such a filter. In addition, two signal processing configurations are tested. Finally, measurements are confronted with simulations on the device, which is dedicated to chromatic dispersion compensation in fiber-radio systems.     

基于SOA器件的色散补偿系统

基于半导体光放大器非线性效应提出一种连续可调谐的色度色散补偿方法.利用SOA的交叉相位调制效应,对10 Gbit/s和 40 Gbit/s RZ码系统的补偿效果和补偿范围进行了仿真分析.分析结果表明,该方法在10 Gbit/s传输系统中,可以实现补偿范围为400 ps/nm的正负色散.在40 Gbit/s传输系统中,可以实现补偿范围为40 ps/nm的正负色散.在理论分析基础上,进行了10 Gbit/s传输系统下连续动态色度色散测补偿实验.实验结果表明,该方法实现了-40～60 ps/nm范围内色度色散的连续可调谐补偿.     

Optical 10-20 and 20-40 Gbits/s pseudorandom bit sequence data multiplexing utilizing conversion-dispersion-based tunable optical delays

We experimentally demonstrate all-optical 2(7)-1 pseudorandom bit sequence data multiplexing using wavelength conversion, interchannel chromatic dispersion, and intrachannel dispersion compensation. Bit-rate tuning capability is demonstrated with 10-20 and 20-40 Gbits/s multiplexing, achieving a bit-error rate <10(-9) for both rates.     

Survey of systems experiments demonstrating dispersion compensation technologies

Chromatic dispersion compensation is an integral part of WDM transmission system design. Compensator properties such as insertion loss, dispersion slope and effective mode area have a large impact on WDM system performance due to nonlinear optical propagation effects. Dispersion compensator imperfections, such as multi-path interference, group delay ripple, insertion loss ripple and limited per-channel compensation bandwidth, place additional limitations on the achievable transmission distance and capacity. In this paper, a survey of key WDM transmission system experiments is undertaken to 1) review the development of chromatic dispersion compensation technologies, 2) discuss the device characteristics that most impact system design for each technology, and 3) hopefully enable the reader to better evaluate compensator technologies for specific applications.     

Dispersion-Induced Waveform Distortion Detection in 42.7 Gbps CS-RZ Signals by Optical Time Domain Level Monitoring

We propose a technique for chromatic dispersion monitoring based on optical time domain level monitoring.Experimental and simulation results show that the technique is effective for the monitoring of dispersion in 42.7-Gbps CS-RZ signals for dynamic dispersion compensation.     

Characterization of Birefringence and Dispersion Properties in an Arrayed Waveguide Grating

We have characterized polarization dependent loss(PDL), differential group delay(DGD), and chromatic dispersion of an AWG and a simple method was proposed to estimate the chromatic dispersion from the measured DGD of the device.     

Tunable chromatic dispersion and dispersion slope compensator using a planar lightwave circuit lattice-form filter

A tunable chromatic dispersion and dispersion slope compensator is proposed that has a single lattice-form filter configuration. Wavelength dependence is intentionally added to its tunable couplers, which produces dispersion slope compensation in addition to the dispersion compensation. Dispersion tunability of +/- 500 ps/nm and a slope of -4.9 ps/nm(2) over 40 GHz are successfully demonstrated, thus meeting the requirement for 40 Gbits/s differential quadrature phase shift keying transmission with an 80 km long nonzero dispersion-shifted fiber.     

用于多信道色散补偿的Gires-Tournois干涉仪的特性分析

从Gires-Tournois(G-T)干涉仪的特性着手，分析一种基于G－T干涉仪的多信道色散补偿方法。该方法利用G－T干涉仪色散曲线的周期特性，同时对1.55μm窗口内的多个通信波长进行色散补偿，并实现色散补偿量的动态可调谐。     

Application of Automatic Chromatic Dispersion Compensation for Realization of All-Optical Network

We have studied the algorithm for the automatic chromatic dispersion compensation using bit error rate (BER) and Q-factor optimization for realization of dynamically reconfigurable all-optical network. We have made sure good performance using the compensation system by laboratory experiments.     

Angular spectrum of diffracted wave fields with apochromatic correction

We report on compensation of diffraction-induced angular dispersion of ultrashort pulses up to a second order. A strategy for chromatic correction profits from high dispersion of kinoform-type zone plates. Ultraflat dispersion curves rely on a saddle point that may be tuned at a prescribed wavelength. Validity of our approach may reach the few-cycles regime.     

具有电色散补偿的10 Gb/s脉冲转换器的研制

设计并研制了带电色散补偿功能的10 Gb/s脉冲转换器。电色散补偿通过时域均衡的方法,消除光纤色散带来的码间串扰;将电色散补偿芯片纳入脉冲转换器设计中,从而提高了其传输距离。所研制的样品光发射部分采用分布反馈激光器加电吸收调制器集成光源,接收部分采用带互阻放大器的雪崩光电二极管光电探测器模块,电色散补偿芯片对光电探测器输出的码流执行色散补偿算法。对样品进行的测试结果表明该脉冲转换器背对背接收灵敏度为-24.6 dBm,经过100 km G.652光纤传输后接收灵敏度为-20.8 dBm。未加电色散补偿功能时,采用相同的光源传输距离仅为50 km。     

光数字相干接收机中色散补偿模块设计与优化

在高速光纤通信数字相干接收系统中,色散补偿模块的结构和性能将直接决定其是否具有实用价值.设计了比传统的有限脉冲响应(FIR)滤波器结构简单的偶对称型FIR滤波器,并通过数值仿真分析了FIR滤波器长度选取对补偿效果的影响.研究结果表明,在接收端光信噪比(OSNR)代价不高于1 dB的情况下,FIR滤波器长度折衷选取为最大...     

Performance Analysis of High-speed Optical Pulse Transmission in Dispersion-managed Nonlinear Birefringent Fiber Using Quantum Well Laser Diode Sources

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Analyses of constraints on high speed optical code division multiplexing access (OCDMA) link parameters due to fiber optic chromatic dispersion

In direct sequence-optical code division multiplexing access (DS-OCDMA) system networks, data rate and data spreading technique involved in such systems require a high chip rate. Transmission link in these systems is significantly affected by the fiber chromatic dispersion. In this study, we have developed and employed a simple model to estimate the G652 fiber dispersion effects. OCDMA technique has been employed to investigate fiber chromatic dispersion effects on multiple access interference (MAI). We have found that, at a short optical fiber length, the optical fiber dispersion has a significant impact on the high data rate transmission systems (higher than 750 Mbit/s). The performance and optimization of optical orthogonal code (OOC) in the OCDMA system is reported. We have demonstrated that, for a high data rate, even if dispersion compensated devices are not deployed, the BER can be significantly improved when the OOC desired length is selected. We have shown that when compensation dispersion devices are not deployed in the system, there is a trade off between the limited dispersion effects and the MAI.     

Performance Analysis of High-speed Optical Pulse Transmission in Dispersion-managed Nonlinear Birefringent Fiber Using Quantum Well Laser Diode Sources

This paper analyzes the high bit-rate optical pulse trasmission in single mode optical fiber with chromatic dispersion, polarization mode dispersion (small random birefringence) and nonlinearity. Numerical method employed can precisely describe their interactive effect on transmission performance. Different dispersion maps and the related performance are analysed. Various simulation results and discussion are given. The results show that chromatic dispersion compensation should be carefully designed. Appropriate dispersion management can also alleviate the effect of polarization mode dispersion.     

消热差光学系统设计

引入光学材料的规化热差系数T和规化色差系数C,和到对无热差光系统设计的材料选择具有指导作用的T-C图.提出基于热差互补原理的无热差光学系统设计方法,建立了一组既消热差又消色差的方程组.给出了应用这种设计方法设计的密接三片和三分离两种结构型式的无热差系统在不同温度时的像面位移、垂轴像差和各色传递函数曲线.     

Normalized LMS digital filter for chromatic dispersion equalization in 112-Gbit/s PDM-QPSK coherent optical transmission system

High bit rates optical communication systems pose the challenge of their tolerance to linear and non-linear fiber impairments. Coherent optical receivers using digital signal processing techniques can mitigate the fiber impairments in the optical transmission system, including the chromatic dispersion equalization with digital filters. In this paper, an adaptive finite impulse response filter employing normalized least mean square algorithm is developed for compensating the chromatic dispersion in a 112-Gbit/s polarization division multiplexed quadrature phase shift keying coherent communication system, which is established in the VPI simulation platform. The principle of the adaptive normalized least mean square algorithm for signal equalization is analyzed theoretically, and at the meanwhile, the taps number and the tap weights in the adaptive finite impulse response filter for compensating a certain fiber chromatic dispersion are also investigated by numerical simulation. The chromatic dispersion compensation performance of the adaptive filter is analyzed by evaluating the behavior of the bit-error-rate versus the optical signal-to-noise ratio, and the compensation results are also compared with other present digital filters.     

Practical design rules for single-channel ultra high-speed dense dispersion management telecommunication systems

In this work, we establish some efficient and practical design rules for the implementation of single-channel ultra-high speed (>160-Gbit/s) telecommunication systems based on dense dispersion management. Moreover, we analyze some of actual implementation issues such as slope compensation scenario, junction losses, polarization mode dispersion and chromatic dispersion fluctuations.