共查询到20条相似文献,搜索用时 15 毫秒
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Lu Zhang Qianggao Hu Shengzhi Zhao Shuihua Liu Yuanzhong Xu 《Lightwave Technology, Journal of》2006,24(2):797-804
The impact of polarization dependence loss (PDL) on the degree of polarization (DOP) feedback signal in polarization mode dispersion (PMD) compensation is analyzed. PDL affects DOP only in the presence of PMD, and in the presence of PMD and PDL, DOP relates not only to both PMD and PDL vectors but also to the principal states of polarization (SOPs) components of the output signal; on the other hand, it adds new frequency dependence and is no longer independent of system bit rate. The PDL minimum endangering PMD compensation is determined by the step size of the PMD compensating algorithm and the differential group delay (DGD) value in optical fiber systems. DOP could no longer act as the feedback signal in PMD compensation unless the PDL in the fiber system has been effectively eliminated before PMD compensation. 相似文献
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可补偿二阶偏振模色散的两级自适应补偿器研究 总被引:1,自引:1,他引:0
研制了对于10Gbit/s非归零码(NRZ)和归零码(RZ)光纤通信系统的二阶偏振模色散(PMD)自适应补偿实验系统。实验中运用光纤链路中的偏振度(DOP)作为反馈控制信号,采用粒子群优化算法(PSO)作为偏振模色散自适应补偿的搜索和跟踪控制算法,粒子群优化作为补偿搜索算法具有收敛速度快、抗噪声和避免陷入局部极值的优点;作为跟踪算法可以快速跟踪偏振模色散的随机变化。实验证明,该补偿系统可以同时补偿一阶和二阶偏振模色散。不论对于非归零码还是归零码,补偿后眼图恢复很好。补偿搜索时间为几百毫秒。跟踪系统对于链路中突发的偏振模色散变化的响应恢复时间小于20ms,实现了准实时的一阶和二阶偏振模色散自适应补偿与跟踪。 相似文献
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介绍了10Gb/s的光纤通信系统中,优化算法在偏振模色散(PMD)自适应补偿技术中的应用。偏振模色散在线监测技术建立在偏振度(DOP)的基础上,偏振度随着微分群时延(DGD)的增加而减小。为了使用DOP做为PMD的监测反馈信号,需要在传输线路中模拟DGD的状态,为此设计了一个PMD仿真器。在光纤输入复用器端使用一个偏振控制器(PC)来调整光信号的偏振态,在光纤输出复用器端使用一个起偏器。随后信号到达控制计算机,优化程序运行,寻找全局最优点并通过PC来控制PMD。对现代非线性优化算法进行了讨论,比较了它们在PMD自适应补偿技术中的优缺点。在实验过程中选择遗传算法,取得良好效果。在很短时间内一阶二阶PMD能达到最大补偿效果,其动态补偿时间不超过10ms。 相似文献
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We propose a simple method for tracking and separating time-varying principal states of polarization (PSP) occurring in a fiber-optic transmission link with polarization mode dispersion (PMD) for use in PMD compensation. The proposed method uses as a feedback monitoring signal the bandpass-filtered RF power at bit-rate frequency for NRZ signal format. We demonstrated the operating principle of the method through theoretical simulation and experiment using an automatically adaptive PMD compensator employing a single polarization beam splitter (PBS). The effects of electrical filtering on the PSP tracking performance were also investigated by using three types of filters, i.e., a low-pass filter (LPF), a band-pass filter (BPF), and a high-pass filter (HPF). The simulation results showed that only a BPF centered at bit-rate frequency was found to allow for tracing and separation of two PSPs via PBS. The proposed method, when applied to a conventional PMD compensator that alternately controls a polarization controller and a delay line, enables separation of PSP control from differential-group-delay (DGD) control, thus allowing fast tracking of rapidly changing PSP in a PMD-impaired optical fiber link and reducing compensation time. 相似文献
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Sangin Kim 《Lightwave Technology, Journal of》2004,22(8):1872-1876
In this paper, the formula of an optimal compensation vector, which is defined as an input polarization-mode dispersion (PMD) vector of the compensator, for second-order PMD compensation has been derived from the minimization of the root-mean-square (rms) pulse-broadening factor. The derived optimal compensation vector is a linear combination of frequency-averaged PMD vectors and output states of polarization, which shows a similar trend to the previously reported optimal first-order PMD compensation. The rms pulse-broadening factor after optimal second-order PMD compensation has been semianalytically calculated and compared with the previously reported simulation result. They are in good agreement. The formula of the optimal second-order compensation vector derived in this paper provides indispensable information for feedforward second-order PMD compensation. 相似文献
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提出了一种新偏振模色散(PMD)补偿的方法,直接从被补偿光纤中提取偏振色散矢量的大小和方向信息,根据算法调节偏振模色散补偿器的各参量,使得补偿器的快轴与被补偿光纤的慢轴对准,从而使得偏振模色散得到补偿。这种方法的优点是减少了搜索的自由度。建立了40Gb/s偏振模色散前馈补偿系统,并通过数值模拟.对40Gb/s的非归零(NRZ)码的偏振模色散进行了自适应补偿。通过对补偿前后的眼图、偏振度(DOP)和Q值进行对比和分析,结果表明,这种偏振模色散补偿的前馈方法是非常有效的。 相似文献
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建立了自适应偏振模色散补偿系统,利用偏振度作为反馈信号,对40 Gb/s的RZ和NRZ码分别进行了PMD补偿的数值模拟,结果显示,采用DOP作反馈信号、用二段补偿器和三段补偿器对二种码型的PMD补偿均是有效的.但由于高阶PMD的影响对NRZ码的补偿效果要优于RZ码,特别是存在偏振相关色散的影响时,对RZ码的补偿的影响在明显大于NRZ码,这说明,对于RZ码补偿偏振相关色散是必要的. 相似文献
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The system performances in second- and third-order polarization mode dispersion (PMD) compensations have been calculated analytically and a proper approach for the higher order PMD compensation has been investigated. The investigation has revealed that the frequency averaged higher order terms of the fiber link's PMD vector should be used as the coefficient vectors in emulating the frequency dependent compensation vector for higher order PMD compensation. 相似文献
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The basic property of degree of polarization (DOP) degradation of optical signal induced by polarization mode dispersion (PMD) in high-speed optical fiber transmission is investigated in detail. The DOP of the optical signal reflects the degree of waveform degradation caused by PMD, therefore, it is proposed to be used as the control signal judging the best compensation point for the optical adaptive PMD compensation techniques. However, the signal DOP is not only affected by PMD, but also by various factors, such as the modulation format, modulator chirp, fiber nonlinearity, amplified spontaneous emission (ASE), and so on. We use numerical simulations and experiments to explore the basic DOP property to detect PMD with these factors. We also show that using the signal DOP as control signal is especially useful for the optical duo-binary modulation because of its high sensitivity and wide PMD detection range 相似文献
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The adaptive polarization mode dispersion(PMD) compensation in high-speed transmission system has become more and more necessary for the link PMD causing strong signal distortions.A dynamic adaptive PMD compensator in 40 Gb/s polar-multiplex differential quadrature phase shift keying(PM-DQPSK) system is reported.Experimental results show that the PMD compensator can track the average polarization state variation at 65 rad/s without any lost of the optimum tracking.The 1st-order PMD compensation is demonstrated experimentally,and the compensator can increase the maximal tolerable PMD value by 26 ps from 17 ps to 43 ps in an optical transmission system. 相似文献
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Hok Yong Pua Peddanarappagari K. Benyuan Zhu Allen C. Demarest K. Rongqing Hui 《Lightwave Technology, Journal of》2000,18(6):832-841
An adaptive polarization-mode dispersion (PMD) compensation system has been developed to cancel the effects of first-order PMD by producing a complementary PMD vector in the receiver. Control parameters for the PMD compensation system comprised of a polarization controller and a PMD emulator are derived from the nonreturn-to-zero (NRZ) signal in the channel to be compensated. Estimates of the link's differential group delay (DGD) and principal states of polarization (PSPs) based on this signal are reliable when the signal power is equally split between the link's two PSP's; however this condition cannot be assumed. To meet this requirement, we scramble the state of polarization (SOP) of the input signal at a rate much greater than the response time of the PMD monitor signal so that each sample represents many different SOP alignments. This approach allows the effective cancellation of the first-order PMD effects within an optical fiber channel 相似文献
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基于VLPSO算法的100Gbit/s光传输系统的偏振模色散自适应补偿 总被引:1,自引:1,他引:0
针对标准粒子群优化(PSO)算法后期迭代效率不高和容易陷入局部极值问题,提出了一种基于变异机制的局部粒子群优化(VL-PSO,varied local particle swarm optimization)算法。在单信道100 Gbit/s光传输系统中,以VL-PSO算法作为逻辑控制算法,进行二阶偏振模色散(PMD)归零(RZ)码自适应补偿实验。结果表明,搜索补偿后,眼图张开度明显增大,平均搜索补偿时间为1.650 ms;并且VL-PSO算法能够实时跟踪补偿PMD的变化,跟踪时间小于0.431 ms。 相似文献
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针对光纤传输中的偏振模色散(PMD)问题,研究和比较了现有PMD的光域补偿方法.利用等效啁啾技术,提出了一种基于啁啾光纤光栅的光域补偿方案,用具有光敏性质的保偏光纤制成啁啾光纤光栅,将其作为PMD补偿器中的时延线,实现了PMD的自适应反馈补偿.实验结果显示,该方案能有效补偿光纤传输中的PMD问题,提高光信号的传输质量. 相似文献
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偏振模色散(PMD)已成为高速光纤通信系统发展的严重障碍。文章介绍了偏振模色散的概念,对现有的主要偏振模色散的补偿方法进行了分析和比较。指出用保偏光纤(PMF)和偏振控制器(PC)来补偿PMD是目前比较可行的方法,而用光子晶体光纤(PCF)进行PMD补偿的方法也在进一步研究之中。 相似文献