Abstract: A laser device includes a cavity and a control portion. The cavity has an optical amplifier, a wavelength selectable portion having a changeable transmission wavelength range, and a mirror. The control portion controls the wavelength selectable portion so that the transmission wavelength range of the wavelength selectable portion is changed to a given range. The control portion controls the wavelength selectable portion so that the cavity outputs a desirable lasing wavelength light and optical intensity of the desirable lasing wavelength light is a given value, after controlling the wavelength selectable portion so that the cavity outputs the desirable lasing wavelength light.

Abstract: A laser module has an optical amplifier, a first etalon and a wavelength selectable mirror. The first etalon has wavelength peaks at a given wavelength interval in transmission characteristics and transmits a light from the optical amplifier. The wavelength peaks are tunable. The wavelength selectable mirror acts as an external mirror of an external cavity laser including the optical amplifier, and has a relatively high reflection intensity at a part of wavelength range in an effective gain range of the optical amplifier. The effective gain range of the optical amplifier includes more than one wavelength peak of the first etalon. A reflection bandwidth where the wavelength selectable mirror has a relatively high reflection intensity is less than twice of the wavelength interval of the wavelength peaks of the first etalon.

Abstract: A laser device includes a cavity and a control portion. The cavity has an optical amplifier, a wavelength selectable portion having a changeable transmission wavelength range, and a mirror. The control portion controls the wavelength selectable portion so that the transmission wavelength range of the wavelength selectable portion is changed to a given range. The control portion controls the wavelength selectable portion so that the cavity outputs a desirable lasing wavelength light and optical intensity of the desirable lasing wavelength light is a given value, after controlling the wavelength selectable portion so that the cavity outputs the desirable lasing wavelength light.

Abstract: A laser module has an optical amplifier, a first etalon and a wavelength selectable mirror. The first etalon has wavelength peaks at a given wavelength interval in transmission characteristics and transmits a light from the optical amplifier. The wavelength peaks are tunable. The wavelength selectable mirror acts as an external mirror of an external cavity laser including the optical amplifier, and has a relatively high reflection intensity at a part of wavelength range in an effective gain range of the optical amplifier. The effective gain range of the optical amplifier includes more than one wavelength peak of the first etalon. A reflection bandwidth where the wavelength selectable mirror has a relatively high reflection intensity is less than twice of the wavelength interval of the wavelength peaks of the first etalon.

Abstract: A package for hermetically sealing a semiconductor laser which outputs light having a wavelength of 1.1 ?m or more is filled with a gas containing an oxidizing gas such as oxygen or ozone. The oxidizing gas in the package oxidizes hydrogen in the package to prevent hydrogen embrittlement of electrodes that applies stress on electrodes and to suppress variation in the emission wavelength which would otherwise result from the application of stress.

Abstract: A package for hermetically sealing a semiconductor laser which outputs light having a wavelength of 1.1 &mgr;m or more is filled with a gas containing an oxidizing gas such as oxygen or ozone. The oxidizing gas in the package oxidizes hydrogen in the package to prevent hydrogen embrittlement of electrodes that applies stress on electrodes and to suppress variation in the emission wavelength which would otherwise result from the application of stress.

Abstract: The optical semiconductor device comprises a multiple quantum well structure of an AlGaInAs system material formed on an InP semiconductor substrate. The multiple quantum well structure comprises a barrier layer of a below 1.0 .mu.m of PL wavelength and a below 4.5 nm of film thickness active layer alternately laid one on another. An above 0.5% compressive strain is applied to the active layer. Thus the AlGaInAs/InP system optical semiconductor can have good temperature characteristics.

Abstract: An optical device comprises a light emitting device for emitting a light beam whose radiation angle is less than 15 degree and having a light emitting end surface on which a antireflection layer is formed, an optical fiber having a flat light incident end surface on which a antireflection layer is formed and a diffraction grating formed therein, and a substrate for supporting the light emitting device and the optical fiber so as to oppose the antireflection layer of the light emitting device to the antireflection layer of the optical fiber.

Abstract: In a method of machining a surface of a bore of an aluminum cylinder block for internal combustion engines, the bore surface is machined to be formed with a number of recesses which are to be formed into oil reservoirs. The bore surface is then pressed uniformly to be plastically deformed so that each recess is narrow at its opening and broad in its inner part. The machining for formation of the recesses and the working for plastic deformation for narrowing the opening are combined together so that the bore surface is machined to have oil reservoir recesses each of which is narrow at its opening and broad at its inner part.

Abstract: An optical semiconductor device includes first and second cladding layers, a light guide layer sandwiched between the first and second cladding layers, and a layer structure provided in the light guide layer. The layer structure has a first periodic variation in a refractive index in a predetermined direction, and a second periodic variation in an optical gain in the predetermined direction. The first periodic variation has a period identical to that of the second periodic variation. The first periodic variation and the second periodic variation have a phase difference.

Abstract: The present invention provides a glycol dispersion comprising calcium carbonate and glycol prepared by wet-grinding under the specified conditions a glycol slurry composed of glycol and calcium carbonate satisfying the specified dispersibility and particle size. The glycol dispersion of the present invention is good in dispersion stability in glycol and is capable of improving running property of audio tapes, video tapes, etc., thus contributing to improvement in properties such as sound and image.

Abstract: The present invention provides a glycol dispersion consisting of calcium carbonate and glycol prepared by wet grinding a glycol slurry composed of glycol and calcium carbonate surface-treated with at least one of surface treating agents selected from the group consisting of copolymers (A) of at least one of .alpha., .beta.-monoethylenically unsaturated carboxylic acids and their salts with .alpha., .beta.-monoethylenically unsaturated carboxylic acid esters and salts (B) of copolymers of .alpha., .beta.-monoethylencially unsaturated carboxylic acids with .alpha., .beta.-monoethylencially unsaturated carboxylic acid esters as material for wet grinding. The glycol dispersion of the present invention is good in dispersion stability in glycol as well as affinity with polyester and contributes to improvement of the surface properties of polyester. Furthermore, proper selection of a specific grade of calcium carbonate and specific grinding conditions enable provision of highly functional polyester products.