BER Performance Degradation of a PDM-QPSK Self-Coherent Detection Optical Transmission System Due to Cross Polarization Effects

摘要

Analysis is carried out to evaluate analytically the bit error rate (BER) performance of a polarization division multiplex (PDM) quadrature phase shift keying (QPSK) optical transmission system with self-coherent detection (SCD) considering the effect of cross-polarization (XPol) induced crosstalk. Analytical expressions are developed for the signal and crosstalk photocurrents at the output of SCD receiver and the signal to crosstalk plus noise ratio (SCNR) for a given misalignment angle at the polarization beam splitter (PBS) induced by nonlinear birefringence. Considering the pdf of the misalignment angle to be Maxwellian distributed, the average BER is derived. Performance results are evaluated for several system parameters and power penalty due to XPol induced crosstalk is found. It is noticed that system suffers significant power penalty due to the effect of XPol. Penalties in signal power are found to be 2.68, 12.76 and 27.59 dB for misalignment angle of 10, 15 and 20 degree respectively at a data rate of 100 Gbps and BER of 10~(-9) compared to the signal power without crosstalk.