一种基于偏振的PMD不敏感OSNR监测技术

在分析偏振模色散(PMD)引起传输信号去偏振导致偏振分光光信噪比(OSNR)监测方法测量误差问题的基础上,提出一种用扰偏振器和偏振分束器来克服PMD影响,实现OSNR精确监测的方案.波分复用传输信号经扰偏振器扰偏后解复用分离出待测信道信号,偏振分束器将待测信号分成偏振正交的两个支路信号,然后通过检测到的两支路信号功率之间的关系来得到信道的OSNR.仿真实验证实了新方法对PMD影响不敏感.     

基于偏振实现OSNR和PMD的同时监测

在介绍偏振度(DOP)监测方法工作原理,分析偏振模色散(PMD)导致传输信号去偏问题的基础上,提出了一种采用扰偏器和偏振分束器实现光信噪比(OSNR)和PMD同时监测的方案.波分复用传输信号经扰偏器扰偏后解复用分离出待测信道信号,偏振分束器将待测信号分成偏振正交的两个支路,然后通过检测两支路信号功率之间的关系得到信道的OSNR和PMD值,系统中使用了电放大器,以提高监测灵敏度.     

波分复用系统中偏振模色散特性的研究

推导了双折射光纤中两个波长的光波所满足的耦合非线性薛定谔方程。建立了研究两信道波分复用(WDM)系统中偏振模色散效应的模型。基于这一模型,在考虑偏振模色散情况下,数值模拟了在两信道WDM系统中光信号的传输变化,并且分析了在此系统中偏振模色散的影响     

偏振分光法光信噪比监测技术研究

偏振分光法是基于偏振特性分离信号和噪声的光信噪比(OSNR)监测技术,光纤的非线性效应和偏振模色散会引起传输信号偏振态的改变,影响OSNR的测量准确性.在介绍偏振分光法工作原理和设计流程的基础上,定量分析了非线性效应对偏振分光法测量精度的影响,最后提出了一种附加光滤波器的双通带偏振分光法OSNR测量方案,仿真实验证明该测量方法可提高OSNR的测量精度.     

干涉型光纤传感器阵列消PIF技术的研究

针对低双折射光纤双光束干涉型传感器两臂偏振态随机变化引起的信号衰落,提出了一种新型消偏振方式,它可以在可见度略有下降的情况下,较好地消除偏振态变化引起的信号可见度的随机变化。该方案是通过相互正交的两个偏振态来补偿由于其中一个偏振态变化导致的干涉信号衰落。通过自动增益控制电路可以使传感信号稳定,能够在信噪比有所下降的情况下消除偏振衰落的影响,实现了干涉型光纤传感器的消偏振衰落。     

基于脉冲位置调制系统的偏振模色散监测方案

为了实现对脉冲位置调制传输系统光纤信道中偏振模色散的动态监测,提出了一种新型偏振膜色散监测方案,并基于监测原理构建了数学模型。该方案基于单边带内不同偏振信号相位差实现,具有结构简单、易于实现、成本低等优点。结果表明,本方案可以实现对光信号的差分群延时与偏振态的动态监测,即当差分群延时在0ps~100ps范围内时,可准确监测;同时证实了其与信号速率关系较小,能够适应不同速率的系统,且可对脉冲位置调制传输系统的偏振模色散进行实时动态监测。该方案是一个高效可行的偏振模色散监测方案。     

折射率导模高双折射光子晶体光纤的偏振特性

本文应用全矢量模型,研究一种折射率导模高双折射光子晶体光纤的特性.重点研究了该种光纤的偏振特性,包括基模场的线偏振特性,模式的双折射及偏振模色散.研究表明,由于在包层中采用两种不同尺寸的空气孔,基模中两个正交偏振模简并被打破,呈现出较高的模式双折射,模式双折射比普通的保偏光纤高至少一个量级,在波长1540nm,其拍长可达0.4067mm.改变光子晶体光纤的结构参数,将获得更高的双折射和更大的群时延差.分析结果与实验测量结果相吻合.     

DWDM系统中偏振模色散的影响

本文导出了四波长光波在双折射光纤中传输所满足的一般非线性耦合方程.研究了色散平坦光纤中4×10Gb/sDWDM系统的偏振模色散特性;在此基础上,进一步研究了偏振模色散对不同信道间隔的4×10Gb/sDWDM系统的影响,结果表明偏振模色散限制了DWDM系统有效带宽内的信道数量及其传输码率.     

ICA在偏振复用系统信号分离中的应用

光纤偏振复用系统中两束偏振态相互正交的光在一根光纤中传输时,由于偏振模色散和偏振耦合等因素,会产生串扰。文章针对这一问题,将基于互信息最小化的ICA(独立分量分析)算法应用到光纤通信偏振复用系统输出信号的分离中。仿真结果表明,采用该方法在无需任何先验知识的情况下,可以很好地分离出原始信号。     

WDM系统中同步幅度调制技术对PMD的抑制

引入了随机扰动双折射单模光纤模型,导出了双波长的光波在随机双折射光纤中的非线性脉冲传输方程;在此基础上,研究了偏振模色散对2×10Gb／sWDM系统中脉冲序列传输的影响,并采用同步幅度调制控制技术有效地降低了偏振模色散的影响。     

Orthogonal-Polarization Heterodyne OSNR Monitoring Insensitive to Polarization-Mode Dispersion and Nonlinear Polarization Scattering

An in-band optical signal-to-noise-ratio (OSNR) monitoring technique that utilizes the polarization orthogonality and heterodyne mixing is proposed. The technique is not only insensitive to polarization-mode dispersion but also robust to nonlinear polarization scattering induced by interchannel cross-phase modulation. Moreover, the technique places no special requirements on the signal properties, such as modulation format and bit rate. The monitoring technique is demonstrated experimentally in both linear and nonlinear systems     

用偏振模色散模拟器加偏振片实现带内光信噪比检测

提出了一种基于偏振模色散(PMD)模 拟器加偏振片的带内检测光信噪比(OSNR)的方法,理论分析了检测方 法的工作原理,证明了方法不受光纤链路色散和PMD的影响,并且与信号偏振态 、调制格式及传输 速率无关。测试结果表明:在9dB到34dB的测量范围 内,本文检测方 法的测量误差在0.5dB内;在1dB的测量误差范围内,对偏振相关损 耗(PDL)的容忍范围为1dB。     

OSNR Monitoring Method for OOK and DPSK Based on Optical Delay Interferometer

We describe a simple method to measure the optical signal-to-noise ratio (OSNR) of on-off-keying (OOK) and differential phase-shift-keying (DPSK) signals by using an optical delay interferometer (ODI) having a sinusoidal and tunable passband. This OSNR monitoring method is independent of chromatic dispersion, polarization-mode dispersion, and noise polarization. We show experimentally that accurate OSNR measurements are made for a 10-Gb/s OOK signal by using a 1-bit ODI and a 40-Gb/s DPSK signal by using a partial-bit ODI with the OSNR ranging from 5 to 25 dB.     

ASE噪声偏振化对偏振分光光信噪比监测的影响

偏振相关损耗(PDL)引起的自发辐射(ASE)噪声偏振化是导致偏振分光方法监测光信噪比(OSNR)不准确的重要因素,分别研究了ASE噪声与信号偏振平行和偏振正交2种情况下OSNR监测的误差,推导得出了误差计算公式并通过仿真实验得到验证.理论分析和信真实验结果表明:测量误差随着ASE噪声偏振度(DOP)的增加而变大,且与待测信道本身的OSNR基本无关;比较而言,ASE噪声与信号偏振平行时对监测的影响更严重.当与信号偏振平行的ASE噪声的DOP为0.75时,误差值达6 dB.     

100Gb/s RZ-ODQPSK实现方法性能比较

光差分正交移相键控(0DQPSK)调制格式在高速光纤通信系统中有着巨大的应用潜力.文章给出了高速0DQPSK调制格式的三种实现方式(串联调制、并联调制和双驱动单调制器调制),在建立仿真模型的基础上,对光信噪比(0SNR)、色散、偏振模色散(PMD)以及光纤非线性四个方面的容纳能力进行了对比、分析和研究.     

Polarization independent coherent optical receiver

This paper describes an optical heterodyne receiver for DPSK signals which can receive an optical signal having an arbitrary polarization state. This is achieved by splitting the received signal between two orthogonal polarization axes and processing the resulting two signals as in a conventional DPSK heterodyne receiver. The sum of the two demodulated signals provides a baseband signal independent of the polarization state of the received optical signal. When the receiver noise is dominated by the shot noise of the photodetectors, the receiver provides a BER of 10^-9for an average number of 22 photon/bit. In comparison, a conventional optical heterodyne receiver requires under the same noise condition 20 photon/bit to achieve the same BER for a received optical signal polarized along the polarization axis of the local optical signal.     

一种改进的ISFA信道估计算法

设计了一种基于符号内频域平均(ISFA)的信道估计算法,用于偏振复用光正交频分复用(PDM-O-OFDM)系统的信道估计和传输信道色散损伤的均衡。算法采用凯撒窗函数对基于导频的ISFA算法进行改进,提高了信道估计后处理的精度,改善了长距离PDM-O-OFDM系统的误码率(BER)和光信噪比(OSNR)性能。通过仿真试验,确定了算法的相关参数,分析了算法对长距离系统中色散损伤的均衡性能。仿真结果表明,改进算法对于传输距离超过700km系统的均衡效果优于原算法,其中900km处的OSNR代价比原算法低0.35dB。     

Detailed Theoretical and Experimental Characterization of 10 Gb/s Clock Recovery Using a Q-Switched Self-Pulsating Laser

A detailed characterization of the clock recovery properties of a self-pulsating, three-section distributed feedback laser is presented by directly comparing simulation and experimental results for the dependence of the RMS timing jitter of the recovered clock signal on important properties of the input signal. These properties include the duty cycle, peak power, extinction ratio, state-of-polarization, optical signal-to-noise ratio (OSNR), and waveform distortion due to residual group velocity dispersion and polarization mode dispersion. The permissible range for each of these is identified in terms of the RMS timing jitter of the recovered clock signal being less than 2 ps. In particular, the self-pulsating laser is effective for input signals degraded by amplified spontaneous emission noise as it provides this level of jitter performance for input OSNRs larger than 8.8 dB (0.1 nm noise bandwidth).