CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2019-183665, filed on Oct. 4, 2019, the entire contents of which are incorporated herein by reference.

FIELD

The embodiments discussed herein are related to an optical semiconductor device and a reception apparatus.

BACKGROUND

A 90-degree hybrid circuit is a circuit that separates, by causing phase-modulated signal light and local oscillator (LO) light to interfere with each other, the signal light into I-axis components and Q-axis components on a complex plane and performs demodulation. Examples of a phase modulation method include quadrature phase shift keying (QPSK) and quadrature amplitude modulation (QAM).

In the prior art, a 90-degree hybrid circuit using four optical couplers and channel-type bending waveguides has been proposed.

International Publication Pamphlet No. WO 2016/051698 and 2009/098829, Japanese Laid-open Patent Publication No. 2011-257513, 2012-27211, and 2012-191302, and U.S. Pat. No. 10,126,498 are disclosed as related art.

SUMMARY

According to an aspect of the embodiments, an optical semiconductor device includes a first optical coupler including a first input port, a second input port, a first output port, and a second output port; a first optical branching device including a third input port, a fourth input port, a third output port, and a fourth output port; a second optical coupler including a fifth input port, a sixth input port, a fifth output port, and a sixth output port; a second optical branching device including a seventh input port, a seventh output port, and an eighth output port; a first single mode waveguide configured to connect the second input port and the third output port; a second single mode waveguide configured to connect the fourth output port and the fifth input port; a third single mode waveguide configured to connect the sixth input port and the seventh output port; and a fourth single mode waveguide configured to connect the eighth output port and the first input port.

The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention.

