Nippon Telegraph and Telephone Corporation

Tohoku University

Keisuke Kasai

Hiroyuki Ishii

Naoki Fujiwara

Kei Watanabe

Masataka Nakazawa

Mikitaka Itoh

A configuration of a DFB laser-based wavelength tunable laser is well known, but long resonators have difficulty in forming uniform resonators due to production variations, thereby inducing limitation in narrowing the spectral linewidth in the DFB laser-based wavelength tunable laser as well. In the semiconductor laser device of the present invention, a semiconductor laser that oscillates in a single mode and a low-loss lightwave circuit using SiOglass are arranged on the common substrate. The lightwave circuit is configured such that part of output light from the semiconductor laser propagates through a certain length of an optical path, and then is reflected by a reflector and is fed back to the semiconductor laser. Output light from the semiconductor laser and an input waveguide of the lightwave circuit can also be configured to be optically connected directly to each other. The present invention can provide a compact laser device with a narrowed spectral linewidth and stable wavelength controllability.

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Sendai, Japan

Keisuke Kasai