Patent ID: 8086113

Claim:
An optical receiver comprising: an optical mixer that mixes a received optical signal and a local oscillator light in at least two phases and thereby extracts a real part and an imaginary part of each of orthogonal polarized wave components corresponding to each optical phase; a photo-detector that converts the real part and the imaginary part of each of orthogonal polarized wave components corresponding to each optical phase into electric analog signals; an analog-to-digital convertor that converts the electric analog signals obtained by the photo-detector into digital signals; and a circuit that multiplies the real part and the imaginary part of each of the orthogonal polarized wave components, adds multiplication results of each of the orthogonal polarized wave components, averages results of the addition, and generates a signal for corresponding phase of one of the real part and the imaginary part of each of the orthogonal polarized wave components to the optical mixer to control the optical mixer so that a result of the averaging becomes to zero or close to zero.