Patent ID: 7477848

Claim:
An optical receiving apparatus performing a receiving process on an optical signal undergone differential M-ary phase modulation in which M=2 n where n is a natural number, said optical receiving apparatus comprising: a variable dispersion compensation unit for variably performing dispersion compensation on the received optical signal; a delay interference unit for performing a delay interference process on the optical signal from said variable dispersion compensation unit; a photoelectric conversion detecting unit for performing photoelectric conversion detection on the optical signal from said delay interference unit to output a demodulated electric signal demodulated from the differential M-ary phase modulated optical signal; a clock signal extracting unit for extracting a clock signal from the demodulated electric signal fed from said photoelectric conversion detecting unit; and a dispersion compensation controlling unit for controlling a dispersion compensation amount in said variable dispersion compensation unit on the basis of the clock signal extracted by said clock signal extracting unit.