BER Performance of Self-Coherent PDM-QPSK Optical Transmission System in Presence of GVD and PMD Using Exact Probability Density Function

Abstract

A technique is described to estimate the bit error rate (BER) of a polarization division multiplexed (PDM) quadrature phase-shift keying (QPSK) transmission scheme considering the resultant impact of polarization mode dispersion (PMD) as well as group velocity dispersion (GVD) where the link is of single mode fiber (SMF). The analytical approach is undertaken considering polarization diversity self-coherent receiver. The exact probability density function (pdf) of the phase variations due to differential group delay (DGD) and GVD is analysed from its moments by Monte-Carlo method. BER is calculated from received conditional BER by averaging the random phase fluctuation pdf. BER is evaluated for different parameters of the system. PDM-QPSK self-coherent approach doubles the spectral efficiency than QPSK but introduces higher power penalty. It is found that for BER of $10^{-9}$ and data rate of 100 Gbps at CD of 1700 ps/nm and DGD of 0.5T, the PDM-QPSK requires 2.09 dB additional power comparing with QPSK doubling the data rate.