Multichannel ASK system design influenced by significant laser phase noise

Results from an improved bit-error-rate analysis appropriate to heterodyne ASK receivers influenced by an interfering optical channel are reported. The analysis takes into account the effects of receiver noise and phase noise. The leading order influence of phase noise in the signal of an interfering channel is now accounted for in an exact way. The results indicate a somewhat larger phase noise influence from the signal in the interfering channel than is predicted from a stationary phase evaluation of that contribution. For no phase noise in the two channels a required electrical channel separation of three times the bit rate for 1 dB penalty due to crosstalk is found. The separation increases to 11.3 times the bit rate for an IF linewidth of 0.27 times the bit rate for the received channel and a linewidth of 0.54 for the interfering channel.