Abstract: A semiconductor light emitting device includes a first conductive clad layer that is group III-V semiconductor mixed crystal, an active layer, and a second conductive clad layer. The second conductive clad layer has a laminated structure of at least three layers including a first layer, a second layer, and a third layer disposed in this order closer to the active layer. The second layer and the third layer are included in a striped ridge, and the second layer is positioned at a skirt of the ridge. The surface of the first layer is a flat part at both sides of the ridge. When Al compositions of the first layer, second layer, and third layer are X1, X2, and X3, respectively, the relation X2>X1, X3 is satisfied. When film thicknesses of the first layer, second layer, and third layer are D1, D2, and D3, the relation D2<D3 is satisfied.

Abstract: A semiconductor light emitting device includes a first conductive clad layer that is group III-V semiconductor mixed crystal, an active layer, and a second conductive clad layer. The second conductive clad layer has a laminated structure of at least three layers including a first layer, a second layer, and a third layer disposed in this order closer to the active layer. The second layer and the third layer are included in a striped ridge, and the second layer is positioned at a skirt of the ridge. The surface of the first layer is a flat part at both sides of the ridge. When Al compositions of the first layer, second layer, and third layer are X1, X2, and X3, respectively, the relation X2>X1, X3 is satisfied. When film thicknesses of the first layer, second layer, and third layer are D1, D2, and D3, the relation D2<D3 is satisfied.

Abstract: In a dual-wavelength semiconductor laser in which a first semiconductor laser element and a second semiconductor laser element are integrated onto a substrate made of a compound semiconductor, a constituent material of an etching stopper of the first semiconductor laser element is a material which allows diffusion of impurities less easily than a constituent material of an etching stopper of the second semiconductor laser element.

Abstract: In a dual-wavelength semiconductor laser in which a first semiconductor laser element and a second semiconductor laser element are integrated onto a substrate made of a compound semiconductor, a constituent material of an etching stopper of the first semiconductor laser element is a material which allows diffusion of impurities less easily than a constituent material of an etching stopper of the second semiconductor laser element.

Abstract: A semiconductor laser device includes: a semiconductor laser chip which is composed of a semiconductor substrate and a plurality of semiconductor layers stacked on an element formation face of the semiconductor substrate and which outputs an irradiation light for irradiating an optical disk; and a light receiving element which receives the irradiation light reflected by the optical disk as a feedback light. The semiconductor laser chip includes on one face thereof an electrode facing an optical element and is fixed in a package so that at least one of sub-beams reflected by the optical disk is incident on the one face. A chip exposing portion for exposing a region of the one face where the sub-beam is incident is formed in the electrode.

Abstract: An optical pick-up apparatus includes: a semiconductor laser light source that generates an optical beam; a diffraction grating that divides the optical beam into a main beam and side beams; an optical element that guides the main beam and the side beams that are generated by the diffraction grating onto an optical information medium; and a photodetector that detects a signal from reflected light reflected from the optical information medium. The semiconductor laser light source is configured with a 2-wavelength semiconductor laser device in which a semiconductor laser chip that generates an optical beam having a wavelength of ?1 and a semiconductor laser chip that generates an optical beam having a wavelength of ?2 are integrated into one chip or are arranged in proximity to each other.

Abstract: A semiconductor laser device includes: a semiconductor laser chip which is composed of a semiconductor substrate and a plurality of semiconductor layers stacked on an element formation face of the semiconductor substrate and which outputs an irradiation light for irradiating an optical disk; and a light receiving element which receives the irradiation light reflected by the optical disk as a feedback light. The semiconductor laser chip includes on one face thereof an electrode facing an optical element and is fixed in a package so that at least one of sub-beams reflected by the optical disk is incident on the one face. A chip exposing portion for exposing a region of the one face where the sub-beam is incident is formed in the electrode.

Abstract: An optical pick-up apparatus includes: a semiconductor laser light source that generates an optical beam; a diffraction grating that divides the optical beam into a main beam and side beams; an optical element that guides the main beam and the side beams that are generated by the diffraction grating onto an optical information medium; and a photodetector that detects a signal from reflected light reflected from the optical information medium. The semiconductor laser light source is configured with a 2-wavelength semiconductor laser device in which a semiconductor laser chip that generates an optical beam having a wavelength of &lgr;1 and a semiconductor laser chip that generates an optical beam having a wavelength of &lgr;2 are integrated into one chip or are arranged in proximity to each other.

Abstract: A semiconductor laser device includes a semiconductor laser element for emitting laser light onto a recording medium; beam dividing element provided in an optical path between the semiconductor laser element and the recording medium; a hologram optical element including a diffraction grating formed in a light-transmitting substrate, the hologram optical element located in an optical path between the beam dividing element and the semiconductor laser element; a servo-signal light-receiving element provided in an optical path of diffracted light transmitted through the diffraction grating for receiving the diffracted light; an information-signal light-receiving element for receiving light divided by the beam-dividing element, which is different from light divided by the beam-dividing element which is received by the diffraction grating; and a polarizing element provided in an optical path between the beam dividing element and the information-signal light-receiving element, wherein the semiconductor laser element