The Furukawa Electric Co., Ltd.

Satoshi Koyanagi

Junji Yoshida

Naoki Tsukiji

Takeshi Aikiyo

Takeo Shimizu

Akira Mugino

A semiconductor laser device and module for use in a dense wavelength division multiplexed optical communications system are shown. The laser device preferably has cavity lengths greater than 1000 &#x3bc;m, and compressive strain multi-quantum well active layer, and front-facet reflectivity of less than about 4%. Higher optical outputs by longer cavity lengths are achieved. Preferred modules use these laser diodes with external wavelength-selective reflectors that have narrow bandwidths of 3 nm or less, and which include a plurality of longitudinal mode subpeaks within the bandwidth. Relationships between reflectivity value of the front facet and the peak reflectivity of the wavelength-selective reflector for long cavity length laser device are also disclosed, with the relationships providing higher output power along with a stabilized output spectrum.

Semiconductor laser devices, and semiconductor laser modules and optical communication systems using the same

A semiconductor laser device and module for use in a dense wavelength division multiplexed optical communications system are shown. The laser device preferably has cavity lengths greater than 1000 &mgr;m, and compressive strain multi-quantum well active layer, and front-facet reflectivity of less than about 4%. Higher optical outputs and longer cavity lengths are achieved. Preferred modules use these laser diodes with external wavelength-selective reflectors that have narrow bandwidths of 3 nm or less, and which include a plurality of longitudinal mode subpeaks within the bandwidth. Relationships between reflectivity value of the front facet and the peak reflectivity of the wavelength-selective reflector for long cavity length laser device are also disclosed, with the relationships providing higher output power along with a stabilized output spectrum.

A semiconductor laser module comprising a semiconductor laser device having an emitting surface from which excited light is emitted and a reflecting surface opposite to the emitting surface, and an optical feedback medium for feeding most of optical power emitted from the emitting surface of the semiconductor laser device back to the semiconductor laser device by coupling means and emitting part of the optical power. The semiconductor laser device has a low reflectance multilayer coating formed on the emitting surface and having a reflectance of 10 to 10%. The low reflectance multilayer coating has a reflection spectrum in the form of a curve having a maximum value at the central wavelength of reflection and minimum values on both sides of the central wavelength of reflection.

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Tokyo, Japan

Satoshi Koyanagi