Patent ID: 8649685
Filing Date: 2014-02-11
Classification: H04B,H04L

Abstract:
1. A light receiving device comprising: a 90 degrees hybrid circuit to receive an optical signal fed into the light receiving device and a local oscillation optical signal and to mix the optical signal and the local oscillation optical signal per two polarized waves at right angles to each other, and to output an optical signal of a real part and an imaginary part of polarized waves; a plurality of photoelectric conversion circuits to respectively receive optical signals of the real part and the imaginary part of two polarized waves at right angles to each other output from the 90 degrees hybrid circuit and to convert the optical signals into a plurality of electrical signals; a plurality of converters to respectively digitalize the plurality of the electrical signals with a given sampling clock frequency; a plurality of fixed distortion compensators to compensate an output signal of each converter for waveform distortion with a fixed compensation amount that is different from each other; a plurality of phase shift detector circuits to detect a sampling phase shift from an output signal of the plurality of the fixed distortion compensators; a phase-adjusting-amount determiner to determine a sampling phase adjusting amount with use of an output signal of the plurality of the phase shift detector circuits; and a phase adjusting circuit to reduce a phase difference between the sampling clock frequency and the received optical signal based on a determination result of the phase-adjusting-amount determiner.