PERFORMANCE IMPROVEMENT OF OPTICAL-PHASE SHIFT KEYING RECEIVER IN PRESENCE OF ADJACENT CHANNEL INTERFERENCE

An optical heterodyne PSK receiver has been analysed using a modified Costas loop which includes an extra phase modulator. Emphasis has been given particularly on laser phase noise and adjacent channel interfer ence in presence of non-negligible loop propagation delay. It is found from the proposed system that the analysis is more tolerant to the lo op delay. Additional frequency control of the loop VCO helps in improv ing the system power penalty by more than 2.0 dB when the laser linewi dth (delta nu/R(b)) is greater than or equal to 0.005 and improves the restriction of stringent linewidth requirement.