OPTICAL PHASE NOISE SUPPRESSION CIRCUIT, PHASE FLUCTUATION DETECTION CIRCUIT, AND PHASE FLUCTUATION DETECTION METHOD

摘要

PROBLEM TO BE SOLVED: To provide an optical phase noise suppression circuit for reducing optical phase fluctuation, and to suppress signal transmission characteristic degradation of an optical DPSK transmission system.;SOLUTION: In this optical phase noise suppression circuit, a transmitted DPSK optical signal is branched; monitor signals differentially received by two delay interferometers having phase differences of π/2 and 0 are generated; the two differentially-received monitor signals are mixed by a mixing means; a branched main signal of the DPSK optical signal is subjected to phase modulation by a phase modulation means by using the mixed signal. Then, the phase fluctuation of the main signal is canceled by subjecting a coefficient of -1 to phase modulation because the two mixed monitor signals are proportional to the phase fluctuation of the main signal.;COPYRIGHT: (C)2011,JPO&INPIT