The Furukawa Electric Co., Ltd.

Michio Okubo

Kiyofumi Muro

Yasuo Oeda

Shusuke Kaya

Takao Ninomiya

Seiji Uchiyama

A semiconductor laser device includes a layer structure of a first conductive cladding layer, an active layer, and a second conductive cladding layer sequentially grown on a first conductive semiconductor substrate; and a light emitting facet from which a laser beam having a first wavelength is emitted. Refractive indexes of the first and the second conductive cladding layers with respect to the first wavelength are lower than an effective refractive index with respect to the first wavelength. With respect to a light having a second wavelength incident on the light emitting facet from outside, the refractive index of at least one of the first and the second conductive cladding layers is equal to or higher than the effective refractive index with respect to the second wavelength.

Semiconductor laser device, semiconductor laser module, and optical fiber amplifier

A semiconductor laser device is formed by laminating optical confinement layers and active layers so as to dispose each of said active layers between said optical confinement layers, wherein one of the opposite ends perpendicular to the junction planes of the individual layers in the semiconductor multi-layer film is coated with a low reflection film and the other of the ends is coated with a high reflection film, wherein the low reflection film is an Al O film having a resistivity of 1&times;10 &OHgr;&middot;m or more, preferably 1&times;10 &OHgr;&middot;m or more, and having a stoichiometric ratio composition, which is deposited by, for example, an electron cyclotron resonance sputtering process. The present invention has realized a semiconductor laser device exhibiting a prolonged duration of operating life and having high driving reliability, which is advantageous in that a catastrophic optical damage hardly occurs and a lowering of the optical output after driving at a constant current is suppressed, and thus, it is preferably used as an optical transmitter for the optical communication.

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Tokyo, Japan

Michio Okubo