Patent ID: 8649640
Filing Date: 2014-02-11
Classification: G02F,H04B,H04J

Abstract:
1. An optical 90-degree hybrid circuit comprising: a first demultiplexing optical coupler including a first input port and a second input port and branching light into two lights; a second demultiplexing optical coupler including a third input port and a fourth input port and branching light into two lights; a first arm waveguide connected via a through port of the first input port and via a cross port of the second input port; a second arm waveguide connected via a cross port of the first input port and via a through port of the second input port, having a length equal to that of the first arm waveguide; a third arm waveguide connected via a through port of the third input port and via a cross port of the fourth input port; a fourth arm waveguide connected via a cross port of the third input port and via a through port of the fourth input port, having a length equal to that of the third arm waveguide; a 90-degree phase shift section installed in one of the first to fourth arm waveguides to shift a phase of light by 90 degrees; a first optical coupler connected to the first arm waveguide and the third arm waveguide; and a second optical coupler connected to the second arm waveguide and the fourth arm waveguide, wherein the light is inputted into the second input port and the third input port.