Patent ID: 8184994

Claim:
An optical receiving circuit that receives and demodulates an optical signal subjected to phase modulation and wavelength division multiplexing, comprising: an interfering unit that causes a reference signal for phase comparison to interfere with the optical signal to output resulting signals as positive-phase signals and negative-phase signals; a wavelength separator having a plurality of input ports receiving the positive-phase signals and the negative-phase signals, the positive-phase signals and negative-phase signals being adjacent to each other, the wavelength separator further having a plurality of output ports, and separating according to wavelength, the positive-phase signals and the negative-phase signals, and from the output ports, outputting for each wavelength, a separated positive-phase signal and negative-phase signal in a state of being adjacent to each other; and a plurality of balanced receivers respectively provided for each wavelength, where a given balanced receiver for a given wavelength performs balanced reception and demodulation of the separated positive-phase signal and negative phase signal of the given wavelength.