Nippon Telegraph and Telephone Corporation

Masaki Kohtoku

Yasuyuki Inoue

Takuya Tanaka

Shin Kamei

Josuke Ozaki

Tsutomu Kitoh

Nobuhiro Kikuchi

Yoshihiro Ogiso

Mikitaka Itoh

Tomohiro Shibata

Norihide Kashio

To provide a Mach-Zehnder (MZ) type semiconductor optical modulation element that can be used as a modulator, which is ultrafast and excellent in electrical stability. A semiconductor optical modulation element of a Mach-Zehnder type that performs modulation of light using a refractive index modulation region where a refractive index of the light guided to an optical waveguide is modulated and an input and output region where multiplexing/demultiplexing of the light split in the refractive index modulation region is performed, characterized in that in the refractive index modulation region of the optical waveguide, an n-type clad layer, an i core layer, and a p-type clad layer are stacked in the order from a top layer on a substrate surface equivalent to a (100) plane of a sphalerite-type seminsulating semiconductor crystal substrate, the n-type clad layer is formed in a ridge shape in an inverted mesa direction, and a capacitancl-oaded electrode is provided on the n-type clad layer.

Semiconductor optical modulation element

An optical wavelength multiplexing/de-multiplexing circuit having a low loss and a flat transmission spectrum is provided. The optical wavelength multiplexing/de-multiplexing circuit compensates a temperature dependence of a center transmission wavelength which remains in an athermal AWG, and has an excellent accuracy of the center transmission wavelength in a whole operating temperature range or has a comparatively wide operable temperature range. The temperature dependence of the transmission wavelength in the athermal MZI is modulated and set so as to cancel the temperature dependence of the center wavelength which remains in the athermal AWG. The present invention focuses particularly on an optical coupler in the MZI and modulates the temperature dependence of the transmission wavelength in the MZI by providing the optical coupler itself with a mechanism which changes a phase difference between two outputs by temperature.

Optical wavelength multiplexing/ de-multiplexing circuit

Growing community of inventors

Atsugi, Japan

Masaki Kohtoku