Performance of Lincoded Optical Heterodyne CPFSK Transmission System Affected by Polarization Mode Dispersion in a Single Mode Fiber

A theoretical analysis for evaluating the performance of a lincoded continuous phase optical frequency shift keying (CPFSK) optical transmission system with delay line demodulation receiver is presented. It accounts for the combined effects of signal phase distortion due to polarization mode dispersion (PMD) and group velocity dispersion (GVD) in a single mode fiber. The analysis is carried out for three different linecoding schemes, i.e., alternate mark inversion, order-1 and delay modulation coding, to investigate the efficacy of the linecoding in counteracting the effect of PMD in CPFSK optical transmission system. The average bit error rate (BER) performance results are evaluated with line codes and compared with NRZ-CPFSK system at a bit rate of 10 Gb/s considering Maxwellian probability distribution for the mean differential group delay (DGD) due to PMD. The results show that the penalty improvement of line coded systems is within 0.5 dB to 1.95 dB with respect to NRZ data at a BER of 10^-9.