Abstract: A nitride semiconductor laser diode includes a second conductive cladding layer formed on an active layer, and including a ridge portion having a raised cross-sectional shape, and flat portions located on both sides of the ridge portion; a light-absorbing layer formed on each of the flat portions, and having an optical absorption coefficient larger than the second conductive cladding layer. The light-absorbing layer includes a first region provided at a side of a light-emitting facet, and having a distance Di1 from a line-symmetric axis in a longitudinal direction of the ridge portion to a side surface of the light-absorbing layer; and a second region provided at a side opposite to the light-emitting facet, and having a distance Di2 from the line-symmetric axis to the side surface of the light-absorbing layer. A relationship between the Di1 and the Di2 is represented by Di1<Di2.

Abstract: The optical pickup device according to the present invention includes: a light source which emits light at first, second and third wavelengths; an optical path combining unit which combines vectors of the light at the first, second and third wavelengths which is emitted by the light source, and matches optical axes of the light at the first wavelength and the light at the third wavelength; a light condensing unit which condenses the light from the optical path combining unit onto the optical information storage medium; a diffraction element which diffracts light at the first, second and third wavelength which is reflected from the optical information storage medium, in a first direction and a second direction respectively; a first photo detector which receives light at the first, second and third wavelength that is diffracted in the first direction by the diffraction element; a second photo detector which receives light at the first and third wavelength that is diffracted in the second direction by the diffra

Abstract: An optical pickup has a semiconductor laser, a diffractive optical element that has first diffraction regions and second diffraction regions and diffracts a beam emitted by the semiconductor laser, an objective lens that focuses the diffracted beam on an optical disc, and a detection unit that detects a tracking error signal using the diffracted beam reflected by the optical disc. When a zero order diffraction beam is focused on the optical disc, a first order diffraction beam is diffracted by the first diffraction regions to be focused at a position between the objective lens and the optical disc, and diffracted by the second diffraction regions to be focused at a position beyond the optical disc. The first order diffraction beam has a beam width that, on the optical disc in a radial direction thereof, is two times or greater a track pitch of the optical disc.

Abstract: An optical pickup wherein a main beam and at least two sub-beams are collected on a disc and a tracking error signal is detected from push pull signals generated from each beam. A phase of the push pull signal generated from the first sub-beam is shifted from a phase of the push pull signal generated from the second sub-beam by substantially 180°. A phase difference is given to a part of the first sub-beam (10) and a part of the second sub-beam (11) by a diffraction optical element (2) which generates the first sub-beam (10) and the second sub-beam (11).

Abstract: The optical pickup device according to the present invention includes: a light source which emits light at first, second and third wavelengths; an optical path combining unit which combines vectors of the light at the first, second and third wavelengths which is emitted by the light source, and matches optical axes of the light at the first wavelength and the light at the third wavelength; a light condensing unit which condenses the light from the optical path combining unit onto the optical information storage medium; a diffraction element which diffracts light at the first, second and third wavelength which is reflected from the optical information storage medium, in a first direction and a second direction respectively; a first photo detector which receives light at the first, second and third wavelength that is diffracted in the first direction by the diffraction element; a second photo detector which receives light at the first and third wavelength that is diffracted in the second direction by the diffra

Abstract: An optical pickup comprises: first and second semiconductor lasers (11, 14); a hologram element (17) for diffracting light reflected by an optical information recording medium (9 or 12); and a plurality of photodetectors (18-23). The hologram element (17) has two or more different diffraction regions. The plurality of photodetectors (18-23) are provided away from the first and second semiconductor lasers (11, 14) at both sides thereof along an extended line of a line between light emission positions of the first and second semiconductor lasers (11, 14). The diffracted light generated from the light beam of the first wavelength (10) by the hologram element (17) and the diffracted light generated from the light beam of the second wavelength (13) by the hologram element (17) are collected at substantially the same position at one side, and part (18, 19) of the plurality of photodetectors (18-23) are provided at the position.

Abstract: An optical path coupling member aligns an optical axis directed to a light condensing member of the first wavelength light having a shortest wavelength with that of the third wavelength light having a longest wavelength. A diffraction element condenses +2nd order diffracted light of the first wavelength light and +1st order diffracted light of the second wavelength light and third wavelength light into a first photodetector, the ?2nd order diffracted light of the first wavelength light and ?1st order diffracted light of the third wavelength light into a second photodetector, and ?1st order diffracted light of the remaining second wavelength light into a photodetector, using ±2nd order diffracted light of the first wavelength light and ±1st order diffracted light of the second wavelength light and third wavelength light as signal light from an optical information recording medium. Consequently, the overall size of the optical pickup apparatus is reduced.

Abstract: An optical pickup has a semiconductor laser, a diffractive optical element that has first diffraction regions and second diffraction regions and diffracts a beam emitted by the semiconductor laser, an objective lens that focuses the diffracted beam on an optical disc, and a detection unit that detects a tracking error signal using the diffracted beam reflected by the optical disc. When a zero order diffraction beam is focused on the optical disc, a first order diffraction beam is diffracted by the first diffraction regions to be focused at a position between the objective lens and the optical disc, and diffracted by the second diffraction regions to be focused at a position beyond the optical disc. The first order diffraction beam has a beam width that, on the optical disc in a radial direction thereof, is two times or greater a track pitch of the optical disc.

Abstract: An optical path coupling member aligns an optical axis directed to a light condensing member of the first wavelength light having a shortest wavelength with that of the third wavelength light having a longest wavelength. A diffraction element condenses +2nd order diffracted light of the first wavelength light and +1st order diffracted light of the second wavelength light and third wavelength light into a first photodetector, the ?2nd order diffracted light of the first wavelength light and ?1st order diffracted light of the third wavelength light into a second photodetector, and ?1st order diffracted light of the remaining second wavelength light into a photodetector, using ±2nd order diffracted light of the first wavelength light and ±1st order diffracted light of the second wavelength light and third wavelength light as signal light from an optical information recording medium. Consequently, the overall size of the optical pickup apparatus is reduced.

Abstract: An optical semiconductor device both capable of recording and reproducing information with respect to plural optical disks having different track pitches and capable of shortening an assembly time and achieving a cost reduction without the need to make a highly-precise assembly adjustment is provided. An optical semiconductor device is constituted by a semiconductor laser element, an emitted light beam branching element for branching a light beam emitted from the semiconductor laser element into a main beam and a plurality of sub beams, an objective lens for focusing the main beam and the sub beams onto an optical disk, and a light-receiving element for signal detection for detecting each of the main beam and the sub beams reflected by the optical disk.

Abstract: An optical pickup comprises: first and second semiconductor lasers (11, 14); a hologram element (17) for diffracting light reflected by an optical information recording medium (9 or 12); and a plurality of photodetectors (18-23). The hologram element (17) has two or more different diffraction regions. The plurality of photodetectors (18-23) are provided away from the first and second semiconductor lasers (11, 14) at both sides thereof along an extended line of a line between light emission positions of the first and second semiconductor lasers (11, 14). The diffracted light generated from the light beam of the first wavelength (10) by the hologram element (17) and the diffracted light generated from the light beam of the second wavelength (13) by the hologram element (17) are collected at substantially the same position at one side, and part (18, 19) of the plurality of photodetectors (18-23) are provided at the position.

Abstract: There is provided an optical pickup compliant with a three-beam method, a phase difference method, a push-pull method and a three-beam push-pull method, comprising: an emission light source (105) for emitting two or more light components of different wavelengths; a diffraction element (107); a light collector (103); a hologram element (108); a plurality of photodetectors (206); and operation means for performing an operation on outputs of the plurality of photodetectors (206). The plurality of photodetectors (206) are at least eight photodetectors (P1 to P8) which are necessary for the execution of the three-beam method, the phase difference method, and the push-pull method. The operation means includes a switch (212) for switching between a terminal for obtaining a sub signal of the three-beam push-pull method and a terminal for obtaining a tracking signal of the three-beam method.