Reference transmission schemes for phase noise immunity

Abstract

We consider an optical communication system where a reference signal is transmitted along with a phase modulated information carrying signal. This system has the potential of alleviating the effect of phase noise considerably. We jointly optimize the bandwidth of the receiver and the powers of the two signals. The scheme achieves a performance that is close to that of ideal phase modulation systems when the ratio of bit rate to laser linewidth is large, and a performance that is identical to that of frequency modulation when the ratio is small. We also introduce a centered filter structure which achieves a far better performance than traditional filters due to increased the phase coherence.