We used a two-stages three degrees high-order polarization mode dispersion (PMD) compensating structure. The former stage adopts polarization controller and fixed time-delayed line that is consisted of polarization-maintaining fiber. The second stage adopts a nonlinear chirped fiber grating that is made by hydrogen-doped G652 fiber, which is used to adjust the magnitude of PMD. Use this kind of fiber grating of which the time delay can be adjusted to form the second stage, and then realize the first-order and high-order of
PMD compensating on a 40Gb/s OTDM system. The compensator can be used as chromatic dispersion and PMD compensation. The result of experiments revealed that signal’s eye digraph and pulse shape are recovered distinctly.
The proposed methods of Polarization Mode Dispersion (PMD) mitigation can be divided into three main approaches: (i) electrical PMD compensation, (ii) optical PMD compensation, and (iii) mitigation by use of robust modulation formats, increased power margin etc. In this paper, we discussed each of these sententiously, with less emphasis on comparing the first and the second, but with more emphasis on the third. We quantify the benefits of using different techniques for compensation of PMD in fiber-optic communication systems by means
of numerical simulations. This is done both with respect to PMD-induced pulse broadening and in terms of system outage probability for different data formats [nonreturn-to-zero (NRZ) and return-to-zero (RZ)]. With our experimental results, we find that RZ performs better than NRZ, furthermore, it is comparable with 2-3 DOF
PMD compensator, and can be expected to be a practical alternative in particular if used in combination with error correcting codes. We also study the trade-off between power margin and acceptable PMD. Moreover, it is generally believed that a PMD compensator with a polarization controller and a variable delay line can only
compensate the PMD to the first order. Our experimental results show that, the counterintuitive fact that this scheme can also partially compensate for higher order PMD. We also investigate the benefit of using a polarizer as compensation element where the optical average power can be used as a feedback signal.
In this paper, we successfully demonstrated automatic PMD compensation in 40Gbit/s NRZ transmission for the first time. Using a PMD monitor of 20GHz intensity extracted from the receive 40Gbit/s
NRZ base band signal, we accomplished the feedback control of an optical PMD compensator consisting of a polarization controller and a polarization-maintaining fiber. And we report the statistical assessment of an adaptive optical PMD compensator at 40Gbit/s. The mitigator, described in, is experimentally tested in many PMD conditions (not limited to first order) covering Maxwellian-like PMD statistics. Experimental results, including bit error rate measurements, are successfully compared with theory, hereby demonstrating the compensator efficiency at 40Gbit/s. Furthermore, this letter introduces a two-stage PMD compensator. Our experimental results shows that, the compensators based on the two-stages of compensator can be used to PMD compensation in a 40Gbit/s OTDM system with 60 km high PMD fiber. The first-order PMD was max.274ps before PMD compensation. It was smaller than 7ps after PMD compensation. At the same time, the tunable FBG have a function of dispersion compensation.
With increasing bit-rate polarization mode dispersion (PMD) is becoming major system impairment. As the birefringence of a fiber changes randomly along a fiber link and the state-of-polarization (SOP) of an optical signal changes with environmental conditions, PMD effects on the data signal are stochastic and time varying. Consequently analysis of impairment caused by PMD is difficult. In order to assess the PMD impairment in optical transmission system, a great many of samples of the systems under different conditions have been studied previously. The former studies have been shown that PMD-induced system impairment depend on many transmission factors, such as modulation formats, receiver characteristics, etc. Recently the effects of transmission characteristics on PMD impairments have been taken into account. In this paper, we take these effects into account together for the first time to our knowledge. Firstly we show in both experiments and simulations that the imperfection of transmitters, primarily timing and amplitude jitters, could significantly increase the PMD-induced penalty in optical fiber transmission systems, especially when the instantaneous DGD is large, which is relevant situation for outage occurrence. Then we introduce a novel method to analyze the effects of transmission and transmitter imperfection on PMD impairments synthetically. Furthermore, we try to establish a new standard of estimating the PMD impairments.