Matsushita Electric Industrial Co., Ltd.

Shoichi Takasuka

Hideyuki Nakanishi

Akio Yoshikawa

Shinichi Ijima

Naoki Nakanishi

Teruhiro Shiono

Kazutoshi Onozawa

Kazuhiko Yamanaka

Yukio Saitoh

Shin'ichi Ijima

An optical semiconductor device comprising an emitted beam branching section () which branches an emitted light beam from a laser device (), a reflected light beam branching section () which branches a reflected light beam from an information recording medium () into light beams different from each other in focused state, servo signal sensing photodetectors () which receive the branched reflected light beam in a defocused state, a first diffraction grating provided in the emitted light beam branching section for diffracting the reflected light beam having passed through the reflected light beam flux branching section, and a signal sensing photodetector () which receives the reflected light beam diffracted by the first diffraction grating.

Optical element with diffraction grating, semiconductor device, and optical information recording device employing the same

An optoelectronic device that provides an excellent reproduction signal and a stable servo control while preventing deterioration of S/N ratio caused by stray light. The optoelectronic device has a semiconductor laser () that emits light beams on an information-recording medium (), a hologram optical element () having a diffraction grating region () and located between the semiconductor laser () and the information-recording medium (), and a photodetector () for receiving light that is diffracted at the diffraction grating region () of the hologram optical element (), among returning light beams from the information-recording medium (), and the optoelectronic device has also a diffraction grating region () in the vicinity of the diffraction grating region () of the hologram optical element () so as to prevent stray light other than diffracted light from the diffraction grating region () from entering the photodetector ().

Optoelectronic device

A semiconductor laser element has the following configuration: a dual-wavelength monolithic laser where semiconductor lasers with emission wavelengths of 650 nm and 780 nm are integrated on one chip is soldered on a heat sink which then is soldered on a can package. Two beam emission points of the semiconductor laser element are positioned so that beam spots, formed on an optical disk, of light beams emitted from the two semiconductor lasers are aligned substantially along a pit-row direction in the optical disk. Thus, an optical head device and an optical recording and reproducing apparatus can be obtained that can record information on or reproduce recorded information from optical information recording media with different optical characteristics and recording densities from one another and that do not cause instability in tracking servo operation.

Optical head device and optical recording and reproducing apparatus having lasers aligned in a tangential direction

A first diffractive optical element pattern with a pattern pitch that is no greater than a wavelength of incident light is formed on a first main surface of substrate such as a glass plate. Second diffractive optical element patterns are formed at positions that are respectively incident to positive first-order diffracted light and negative first-order diffracted light produced by the first diffractive optical element pattern. Negative first-order diffracted light produced by each second diffractive optical element pattern is incident upon a boundary face of the substrate at an angle that is smaller than the critical angle, and so exits the substrate.

Diffractive optical element that polarizes light and an optical pickup using the same

A semiconductor laser device is provided which can carry out recording and reproduction with respect to optical disks with different formats. In this semiconductor laser device, a receiving/emitting optics integrated substrate, in which two semiconductor laser elements with different emission wavelengths and a plurality of receiving optics are integrated, is disposed in a case and is sealed with a hologram element. A composite prism is placed on the hologram element. The distances, when measured in air, from the two semiconductor laser elements to a focusing means, for example, a collimator lens are set to be substantially equal. Thus, a small and inexpensive semiconductor laser device can be obtained. In addition, a single collimator lens can be employed, and thus the optical configuration is facilitated.

Semiconductor laser device and optical pickup device using the same

A movable enclosure contains optical components, such as an objective lens, a semiconductor laser, a mirror, and a photodetector. The movable enclosure is supported by a fixed member via a plurality of wires that are positioned in parallel. This construction allows the movable enclosure to move in a tracking direction and a focusing direction. The plurality of wires are insulated from one another to be also used as power-supplying lines and signal lines for the semiconductor laser and the photodetector.

Optical pickup with improved optical properties

An optical device includes a light-emitting element for irradiating light onto an information recording medium, a diffraction grating for splitting light emitted from said light-emitting element into a plurality of beams, a focussing member for focussing the plurality of beams onto the information recording medium, a deflection member for deflecting the plurality of beams after they have been reflected from the information recording medium; and a photodetector for receiving the plurality of beams after they have been deflected by the deflection member. The diffraction grating has a first grating region and a second grating region, which have different diffraction efficiencies. The zero-order diffraction light in the first grating region is used as the main beam for reproducing the information signal, and the &plus;1-order or &minus;1-order diffraction light in the second grating regions is used as sub-beams for reproduction of the tracking error signal. Thus, the light amount of both the main beam and the sub-beams can be increased without increasing the light emission of the semiconductor laser element , and the S/N ratio of the main beam and the sub-beams can be enhanced.

Optical device with diffraction grating having plural grating regions

An optical pickup that is equipped with a photodetector unit, irradiates an optical disc with a laser beam, and receives returning light reflected by the optical disc, where the optical pickup is constructed to (1) divide the laser beam into a main beam, a preceding sub-beam, and a succeeding sub-beam, (2) direct the main beam, the preceding sub-beam, and the succeeding sub-beam toward the optical disc, and (3) divide returning lights of the main beam, the preceding sub-beam, and the succeeding sub-beam respectively into first-fourth main returning lights, first-fourth preceding returning lights, and first-fourth succeeding returning lights, and the photodetector unit includes: first-fourth main photodetectors that respectively receive the first-fourth main returning lights; first-fourth preceding photodetectors that respectively receive the first-fourth preceding returning lights; and first-fourth succeeding photodetectors that respectively receive the first-fourth succeeding returning lights. A tracking error signal appropriate to the optical disc to be reproduced is selected from three tracking error signals detected according to the detection signals from the photodetectors, and a tracking servo is driven according to the selected tracking error signal.

Photodetector unit, and optical pickup, optical reproduction apparatus, and optical recording apparatus equipped with the same

An optical device includes a light-emitting element for irradiating light onto an information recording medium, a diffraction grating for splitting light emitted from said light-emitting element into a plurality of beams, a focussing member for focussing the plurality of beams onto the information recording medium, a deflection member for deflecting the plurality of beams after they have been reflected from the information recording medium; and a photodetector for receiving the plurality of beams after they have been deflected by the deflection member. The diffraction grating has a first grating region and a second grating region, which have different diffraction efficiencies. The zero-order diffraction light in the first grating region is used as the main beam for reproducing the information signal, and the &plus;1-order or &minus;1-order diffraction light in the second grating regions is used as sub-beams for reproduction of the tracking error signal. Thus, the light amount of both the main beam and the sub-beams can be increased without increasing the light emission of the semiconductor laser element and the S/N ratio of the main beam and the sub-beams can be enhanced.

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Osaka, Japan

Shoichi Takasuka