Performance Analysis and Compensation of Polarization Effects in Fiber Optics Communication Systems

Abstract

The optical communication system has become a major part of global infrastructure in past years because of its several benefits. The main objective of optical communication is to increase spectral effeciency and to utilize minimum bandwidth over long distances with minimum possible errors during transmission of signals. Spectral effeciency can be increased by using polarization multiplexing along with QPSK and QAM. Capacity can be increased by employing orthogonal polarization between adjacent WDM channels. However, depolarization of orthogonal states due to birefringence leads to degradation which limits bandwidth and capacity of systems. The objective of dissertation is to analyze and compensate polarization effects in fiber optics communication systems and for this purpose VPI transmission maker and OptiSystem software is used which allows design of various communication systems. Firstly, investigation of effects of second order polarization mode dispersion models on first order PMD compensator using duobinary and vestigial side band modulation is presented. Comparison of models is done in terms of bit error rate at various differential group delays for different received optical powers. These effects are studied for testing and verification of new technologies in PMD presence. Secondly, transmission analysis of 112Gbps DP-QPSK and DP-16 QAM using coherent receivers with digital signal processing is studied using optical power spectrum, OSNR tolerance, transmitter polarizing angle, different fiber lengths and constellation diagrams. These multilevel modualtion formats increases spectral effeciency and bandwidth utilization of system. Digital signal processing is used to compensate the effects of polarization demultiplexing, frequency offset and carrier phase offset. Thirdly, polarization interleaving method is proposed in DWDM systems for long haul transmission system to maintain orthogonality between adjacent channels to remove PMD and non linear effects.