US Patent 7646986 Optical receiving device and optical receiving method

The present invention provides an optical receiving device, in which a portion of an optical signal is deflected for optical axis detection only when the optical axis is misaligned to thereby achieve a high S/N ratio of a received signal. A condensing section 100 condenses a received optical signal. An optical element 110 includes a transmission region 111 and a deflecting region 112, and receives the optical signal, which has been condensed through the condensing section 100. A signal light receiving section 120 receives the transmitted light, which has been transmitted through the transmission region 111. A detection light receiving section 130 receives deflected light, which has been deflected through the deflecting region 112 and performs a photoelectric conversion on the received light to thereby output a detection intensity signal that indicates an intensity of the deflected light. An optical axis detection section 140 detects an optical axis misalignment based on the detection intensity signal outputted from the detection light receiving section 130 to output an optical axis detection signal. An optical axis adjustment section 150 performs an optical axis adjustment based on the optical axis detection signal.