Performance Analysis And Application Of Polarization Mode Dispersion Emulator And Compensator

Polarization mode dispersion (PMD) for optical fiber communication links is emerged as a main complication limiting both transmission capacity and distance in high bit rate communication system. For the purpose of searching for appropriate compensation solution to the PMD in optical fiber, performance of various PMD emulators and compensation properties are summarized and analyzed in detail. A type of PMD compensator which was proved by experiment as an effective compensation to installed communication lines is reported.A comparison is made for the existing three types of PMD emulators: the emulator using rotatable sections (short for R-type), the emulator with polarization controllers (C-type) and the heater-based emulator (H-type). The statistical characteristics of the PMD emulators including probability distribution of the differential group delay (DGD), high-order polarization mode dispersion (PMD) and frequency autocorrelation function (ACF) are analyzed in detail and emulation performance is compared. It is found that the number of segments is a determining factor for the performance of PMD emulator. Judging by overall performance, C-type emulator is the best and capable of generating sufficient PMD emulation with ten segments, however, for the same effect, fifteen-segments is needed for R-type and over twenty segments will be required for H-type emulators.By utilizing Muller matrix approach, a detailed statistical analysis on the polarization dependent loss (PDL) dependence of DGD in cascaded planar lightwave circuit (PLC) based PMD compensator is presented. For PDL values ranging from 0 to 10 dB, the DGD distributions were calculated with Monte Carlo simulation for cascaded PLC circuits of 3, 4, 5 and 15 segments. Based on comparison with Maxwell distribution, it was found that an optimized segment number for cascaded PLC circuit with PDL is around 4, and that DGD distribution exhibits a severe deviation away from the Maxwellian as PDL is above 8 dB.The effect on transmission properties caused by PMD in optical transmission system of different per-channel bit rate is simulated by OptiSystem, an engineering emulation software. It is demonstrated that the performance of the optical fiber communication system is deteriorated by PMD. The quality of the optical pulse in the system can be improved significantly after being compensated by an originallydesigned compensator. The conclusion of the research can be applied in a variety of systems. The PMD compensator is fabricated and tested in four 60km-long installed fiber cables. The result of the experiment proved that this kind of PMD compensator is of practical use for present optical fiber communication systems.