Nippon Telegraph and Telephone Corporation

Yuichi Tomori

Naoki Fujiwara

Yasuo Shibata

Nobuhiro Kikuchi

Nobuhiro Nunoya

An optical semiconductor device and optical semiconductor integrated circuit are provided by combining, on a semiconductor substrate, materials having different refractive indices and different temperature dependence of the refractive indices. In particular, it becomes possible to control the temperature dependence of the oscillation wavelength with a propagating region having a material and/or structure whose temperature dependence of the refractive index is different from that of a gain region of the semiconductor laser. In addition, they can be configured to have a plurality of interfaces formed along the waveguide direction of the optical waveguide so that the light reflected off the first interface is weakened by the light reflected from the remaining interfaces. Also, they can be configured with the interfaces inclined to the propagating direction so that the waveguide loss due to the reflection and refraction between the optical waveguides whose refractive indices differ from each other can be reduced.

Optical semiconductor device and optical semiconductor integrated circuit

An integrated optical waveguide has a first optical waveguide, a second optical waveguide, and a groove. The second optical waveguide is coupled to the first optical waveguide and has a refractive index that is different from the first optical waveguide. The groove is disposed so as to traverse an optical path of the first optical waveguide and is separated from an interface between the first optical waveguide and the second optical waveguide by a predetermined spacing. The spacing from the interface and the width of the groove are determined such that reflection at a boundary between the first optical waveguide and the second optical waveguide is weakened. A semiconductor board may be disposed at a boundary between the first optical waveguide and the second optical waveguide. In this case, the width of the groove and the thickness of the semiconductor board are determined such that light reflected off an interface between the first optical waveguide and the groove is weakened by light reflected from an interface between the groove and the semiconductor board, and by light reflected from an interface between the semiconductor board and the second optical waveguide.

An integrated optical waveguide has first, second, and third optical waveguiding regions. The second optical waveguiding region has a refractive index different from that of the first optical waveguiding region. The second optical waveguiding region has an interface surface with the first optical waveguiding region that is inclined with respect to the waveguide direction of the first optical waveguiding region. The third optical waveguiding region has an interface surface with the second optical waveguiding region that is disposed such that a refraction direction through the interface surface is in line with the waveguide direction.

Growing community of inventors

Yokohama, Japan

Yuichi Tomori