Evaluation of crosstalk penalty in two-channel ASK heterodyne optical communication systems.

The bit-error rate of a two-channel ASK heterodyne lightwave system employing envelope detection is evaluated analytically. The result is used to calculate the power penalty resulting from interchannel crosstalk. To maintain a bit-error rate below 10 sup (-9), the power penalty increases from 0.2 to 1 dB when the level of crosstalk increases from -30 to -20 dB. The theory predicts a minimum channel spacing of five times the bit rate if the design criterion is to keep the crosstalk penalty below 0.5 dB. The minimum channel spacing increases to 10 times the bit rate when the acceptable crosstalk penalty is limited to 0.2 dB.