Evaluation of crosstalk penalty in multichannel ASK heterodyne optical communication systems

The bit error rate (BER) 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 intrachannel crosstalk. To main a BER below 10¿9, the power penalty increases from 0.2 to 1 dB when the level of crosstalk increases from ¿15 to ¿10 dB. The theory predicts a minimum channel spacing of three times the bit rate if the design criterion is to keep the crosstalk penalty below 0.1 dB. The minimum channel spacing increases to five times the bit rate for multichannel systems when crosstalk from the nearest neighbours on both sides is included.