Double-stage phase-diversity (DSPD) experiment using 100 Mbit/s FSK coherent optical communication system

An experimental 100 Mbit/s FSK coherent optical communication system employing a double-stage phase-diversity (DSPD) scheme has been constructed, and the bit error rate (BER) has been measured. A heterodyne-like second IF signal can be obtained as expected. A sensitivity 0.6 dB worse than that of heterodyne is achieved.