Error correcting coding of a 220 Mbit/s coherent optical communication channel
Coherent optical communication systems that employ semiconductor lasers have exhibited degraded performance caused by laser phase noise. A rate 1/2, constraint length of seven, convolutional code with hard decision, Viterbi decoding has been applied to an experimental 220 Mbit/s optical FSK channel. Code testing has demonstrated the ability to improve system efficiency and significantly reduce the effect of laser linewidth on bit error rate performance, verifying prior theoretical work.