Abstract: A semiconductor laser device includes a current blocking structure having a p-n-p-n structure, provided on a first conductivity type semiconductor substrate, an active region buried in a stripe shaped groove produced in the current blocking structure, a lower cladding layer grown by liquid phase epitaxy approximately filling the stripe groove, an active layer on the lower cladding layer in the stripe groove, a waveguide layer on the active layer completely filling the groove, and a diffraction grating on the waveguide layer.

Abstract: In an optical semiconductor device in which a light emitting element and a light receiving element for monitoring light from the light emitting element are mounted integrally, a spherical lens is provided at a light receiving portion of the light receiving element, the lens having a light receiving area larger than that of said light receiving portion and the spherical surface of the spherical lens is oriented to the light emitting element.

Abstract: A semiconductor laser device in which the thickness and position of an active layer grown in a groove are made more controllable. The inventive device includes a buffer layer of a first conductivity type formed on a semiconductor substrate of the same conductivity type, a first current blocking layer of a second conductivity type formed over the first buffer layer, the aforementioned groove being formed through the first and current blocking layer to the buffer layer, the active layer buried in the groove, and mesas formed on both side of the groove. With this structure, during crystal growth of the active layer, atoms which would otherwise diffuse into the groove and make it difficult to control the thickness and position of the active layer diffuse into portions outside the mesas and grow thereon.

Abstract: A semiconductor light receiving device, including; a photo diode having a polyimide film as a surface protection film, and a hermetically sealed package including the photo diode in an ambient gas including oxygen.

Abstract: In order to prevent the output characteristic of a semiconductor laser from being saturated at higher temperatures due to the thyristor effect of a combination of the semiconductor layers thereof, an intermediate layer of a conductivity type the same as that of the substrate and opposite that of the first semiconductor layer is provided between the substrate and the first layer. Due to the relatively low carrier density of the intermediate layer, oscillation can be stably carried out even at higher temperatures without triggering the thyristor structure.