Abstract: 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.

Abstract: 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.

Abstract: 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 Al2O3 film having a resistivity of 1×1012 &OHgr;·m or more, preferably 1×1013 &OHgr;·m or more, and having a stoichiometric ratio composition, which is deposited by, for example, an electron cyclotron resonance sputtering process.

Abstract: The inlet and outlet passages communicating with a water-cooled engine oil cooler for a vehicle, such as a motorcycle, are arranged for bypass of a regulated amount of oil from the inlet passage to the outlet passage to enhance the flowability of the cooled oil. Provision is made for a replaceable flow control orifice between the oil inlet and outlet passages to regulate oil viscosity. Also described is an arrangement providing for mounting the cooler to the crankcase or oil pan surface whereby air flowing past the cooler during movement of the vehicle assists the effects of the cooling liquid.

Abstract: The inlet and outlet passages communicating with a water-cooled engine oil cooler for a vehicle, such as a motorcycle, are arranged for bypass of a regulated amount of oil from the inlet passage to the outlet passage to enhance the flowability of the cooled oil. Provision is made for a replaceable flow control orifice between the oil inlet and outlet passages to regulate oil viscosity. Also described is an arrangement providing for mounting the cooler to the crankcase or oil pan surface whereby air flowing past the cooler during movement of the vehicle assists the effects of the cooling liquid.