Patent ID: 8588560
Filing Date: 2013-11-19
Classification: H04B

Abstract:
1. An optical 90-degree hybrid circuit comprising: a first input waveguide; a first demultiplexing optical coupler including at least two first input ports and at least two first output ports, wherein the first input waveguide is connected to one of the first input ports and light inputted into the first input waveguide is branched; a second input waveguide; a second demultiplexing optical coupler including at least two second input ports and at least two second output ports, wherein the second input waveguide is connected to one of the second input ports and light inputted into the second input waveguide is branched; two first arm waveguides connected to two of the first output ports; two second arm waveguides connected to two of the second output ports; a 90-degree phase shift section installed in one of the four arm waveguides composed of the two first arm waveguides and the two second arm waveguides to shift a phase of light by 90 degrees; a first optical coupler connected to one of the two first arm waveguides and one of the two second arm waveguides; a second optical coupler connected to the other of the two first arm waveguides and the other of the two second arm waveguides; a third input waveguide; an optical splitter connected to the third input waveguide and branching light inputted into the third input waveguide into two lights; a first optical waveguide connecting the optical splitter and the one remaining port of the first input ports; and a second optical waveguide connecting the optical splitter and the one remaining port of the second input ports, wherein an optical path length of the first optical waveguide is different from that of the second optical waveguide.