Oclaro Japan, Inc.

Hitachi, Ltd.

Yuki Wakayama

Kouji Nakahara

Nobuhiko Kikuchi

Kazunori Shinoda

Takeshi Kitatani

An optical multilevel transmitter includes a semiconductor quadrature optical modulator configured to separately modulate and output in-phase and quadrature electric field components and a semiconductor nonlinear characteristic compensation circuit configured to generate, from in-phase and quadrature drive signals to be inputted to the semiconductor quadrature optical modulator, two signals for correcting each other and to add the two correcting signals to the corresponding drive signals.

Optical multilevel transmitter and optical transponder

In the semiconductor laser including a diffraction grating in which a first diffraction grating region with a first pitch, a second diffraction grating region with a second pitch and a third diffraction grating region with the first pitch, an anti-reflection film coated on an end facet to the light-emitting side, and a reflection film coated on an opposite end facet, the first diffraction grating region is greater than the third diffraction grating region, and the second diffraction grating region is formed, in such a manner that phases of the first and third diffraction grating regions are shifted in a range of equal to or more than 0.6 &#x3c0; to equal to or less than 0.9 &#x3c0;, phases are successive on a boundary between the first and second diffraction grating regions and the phases are successive on a boundary between the second and third diffraction grating regions.

Semiconductor laser and optical semiconductor device

In a BH laser which uses InGaAlAs-MQW in an active layer, Al-based semiconductor multi-layer films including an InP buffer layer and an InGaAlAs-MQW layer, and an InGaAsP etching stop layer are formed in a mesa shape, and a p type InP burial layer is buried in side walls of the mesa shape. An air ridge mesa-stripe of a lateral center that is substantially the same as that of the mesa shape is formed on the mesa shape. According to the present structure, a leakage current can be considerably reduced, the light confinement coefficient can be made to be larger than in a BH laser in the related art, and thereby it is possible to implement a semiconductor laser with a low leakage current and a high relaxation oscillation frequency.

Growing community of inventors

Tokyo, Japan

Yuki Wakayama