Crosstalk penalty in a two-channel ASK heterodyne detection system with non-negligible laser line width

Crosstalk penalties as a function of channel spacing were measured in a two-channel ASK heterodyne system using 1·55μm DFB lasers. For an IF linewidth/bit rate ratio of 0.5, the channel spacing in the IF domain must be greater than 13 times the bit rate for negligible crosstalk penalty.