Influence of Baseband Filtering on Laser Phase Noise in Coherent Optical Transmission Systems

The statistical properties of the baseband signal disturbed by laser phase noise in a coherent optical transmission system are calculated. Based on the derived autocorrelation function and the probability density function of the received baseband signal the temporal representation and the inherent eye-pattern of the filter input and output signal have been simulated. Depending on the system parameters the baseband filtering results in an improvement of the eye-pattern and of the bit error rate. Finally a method for the analytical calculation of the probability density function and the bit error rate at the filter output is presented.