Patent ID: 9048956
Filing Date: 2015-06-02
Classification: H04B,H04J

Abstract:
1. A coherent optical receiver device, comprising: a coherent optical receiver receiving optical multiplexed signals in a lump in which signal light is multiplexed; a variable optical attenuator; a local oscillator connected to the coherent optical receiver; a first controller controlling the variable optical attenuator by means of a first control signal based on an output signal of the coherent optical receiver; a splitter extracting a part of the optical multiplexed signals output from the variable optical attenuator to the coherent optical receiver; a photodetector; and a second controller; wherein: the coherent optical receiver comprises a 90-degree hybrid circuit, a photoelectric converter, and an impedance conversion amplifier, and selectively detects the signal light interfering with local oscillation light output by the local oscillator out of the optical multiplexed signals; the variable optical attenuator is disposed in the optical path of the optical multiplexed signals in a stage preceding the photoelectric converter, inputs the optical multiplexed signals, and outputs them to the coherent optical receiver controlling the intensity of the optical multiplexed signals based on the first control signal; the photodetector outputs a light-receiving signal that the part of the optical multiplexed signals is converted into an electric signal to the second controller; the second controller controls the variable optical attenuator by means of a second control signal based on the light-receiving signal; and the variable optical attenuator controls the intensity of the optical multiplexed signals based on the second control signal, and outputs them to the coherent optical receiver.