Patent ID: 7865082
Filing Date: 2011-01-04
Classification: H04B

Abstract:
1. An optical receiver comprising: a variable dispersion compensating section that compensates wavelength dispersion of an input optical signal of a differential M-phase modulation format, where M=2n when n is a natural number; a delay interfering section that performs delay interference processing in which a one-bit delayed branched component and an optically phase-controlled branched component, of the optical signal dispersion-compensated by the variable dispersion compensating section, are made to interfere with each other; a photoelectric converting section that performs photoelectric conversion detection with respect to an optical signal from the delay interfering section, to thereby output a demodulated electric signal corresponding to the differential M-phase modulation format; an error monitor section that monitors information relating to an error rate of the electric signal output from the photoelectric converting section; and a control section that controls a dispersion compensation amount in the variable dispersion compensating section and an optical phase control amount in the delay interfering section, wherein the optical receiver further comprises a signal quality adjusting section that enables adjustment of a signal-to-noise ratio of the optical signal input to the photoelectric converting section, and the control section controls the signal quality adjusting section to deteriorate the signal-to-noise ratio of the optical signal input to the photoelectric converting section, to thereby realize a state in which the information monitored by the error monitor section corresponds to a preset target error rate, and then starts control of the variable dispersion compensating section and the delay interfering section.