Abstract: An optical head device includes a light source for emitting light; a collection optical system for collecting the light emitted by the light source to an information memory medium including at least one of a track having a mark or a space selectively arranged, and a track having a prescribed groove; a light detector having a plurality of detection areas for receiving the light reflected by the information memory medium and outputting a signal in accordance with a light amount of the light received; a division element for dividing the light reflected by the information memory medium and allowing the light to be received by the light detector; a switch element for receiving a first signal and a second signal, which are respectively obtained in accordance with the reflected light incident on a first prescribed area and a second prescribed area of the division element and outputting either one of the first signal or the second signal, the first and second prescribed areas being obtained by dividing the division e

Abstract: A light source device can attain a stable output of a harmonic even when there occurs a change in the ambient temperature or fluctuation in the output power. The light source device is provided with a semiconductor laser source (4), an optical waveguide-type QPM-SHG device (5) for generating a second harmonic from light emitted from the semiconductor laser source (4), a wavelength control means (7) for controlling a wavelength of light emitted from the semiconductor laser source (4), a means for slightly fluctuating wavelength (8) for changing a wavelength of light emitted from the semiconductor laser source (4) and a means for detecting a change in output light power of the optical waveguide-type QPM-SHG device (5) that occurs when a wavelength of light emitted from the semiconductor laser source (4) is changed.

Abstract: The present invention aims to simplify a mass production process of an optical waveguide device and to reduce cost as well as noise. The optical waveguide device includes an optical waveguide whose entrance end face and exit end face are substantially parallel to each other. A SHG device is mass-produced by optically polishing an optical material substrate with a large area and then cutting the substrate. This method can mass-produce the optical waveguide devices having a uniform device length. The angle between the exit end face of the optical waveguide and the direction of an optical axis of the optical waveguide at the exit end face is not 90°, thereby reducing return light from the exit end face.

Abstract: An optical waveguide device is provided that can reduce external interference noise. The optical waveguide device includes a substrate, an optical waveguide formed on the substrate, a periodic polarization inversion region formed on the optical waveguide, and an optical thin film formed in a portion of the optical waveguide. The optical waveguide (refractive index: N2) and the optical thin film (refractive index: N1) differ in refractive index dispersion, and the magnitude relationship between the refractive indexes is reversed depending on wavelength. The relationship N1>N2 is established for light having a shorter wavelength, while the relationship N2>N1 is established for light having a longer wavelength.

Abstract: An optical information recording/reproducing device reproduces digital data recorded in a form of interference fringes produced by two coherent beams in a hologram disk, by projecting a coherent beam to the hologram disk and receiving a reproduction signal beam obtained by diffraction by means of a two-dimensional photodetector array. The holographic optical information recording/reproducing device includes a tunable coherent light source that emits the coherent beam, and a control section controls and optimizes a wavelength of the tunable coherent light source according to position information of the reproduction signal beam on the two-dimensional photodetector array.

Abstract: It is an object of the present invention to provide a short-wavelength coherent light source that includes a semiconductor laser and a wavelength converting device and is controlled to have a desired wavelength. The coherent light source includes the following: a semiconductor laser having a first wavelength; an optical waveguide-type QPM-SHG device used as a wavelength converting device for converting the wavelength of the semiconductor laser by half; a wavelength separating function; a diffraction grating; and a photo-detector. The semiconductor laser beam acting as fundamental light is separated with the wavelength separating function, and the wavelength is controlled with the diffraction grating. Thus, the wavelength of harmonic light generated by wavelength conversion is controlled to a desired wavelength.

Abstract: An optical pickup and an optical information recording/reproducing device are provided, each of which is capable of forming a super-resolution spot to conduct micro-mark recording, and does not undergo signal degradation due to an increased sidelobe in a reproducing operation. A variable phase filter having three regions to produce a phase difference in a radial direction is used, to provide a phase difference of &pgr; between the center region and the side regions in a recording operation, so that a super-resolution spot is formed on a recording layer of the optical disk. In a reproducing operation, a phase difference is nullified between the regions of the variable phase filter, so that a normal light spot at a diffraction limit having a smaller sidelobe is formed. The variable phase filter can be formed with a homogeneous-alignment liquid crystal element.

Abstract: An optical waveguide device includes a dielectric substrate; and an optical waveguide formed in the dielectric substrate, the optical waveguide having a longitudinal axis and an outgoing surface disposed at an angle other than a right angle relative to a plane perpendicular to the longitudinal axis.

Abstract: An optical head device includes a light source for emitting light; a collection optical system for collecting the light emitted by the light source to an information memory medium including at least one of a track having a mark or a space selectively arranged, and a track having a prescribed groove; a light detector having a plurality of detection areas for receiving the light reflected by the information memory medium and outputting a signal in accordance with a light amount of the light received; a division element for dividing the light reflected by the information memory medium and allowing the light to be received by the light detector; a switch element for receiving a first signal and a second signal, which are respectively obtained in accordance with the reflected light incident on a first prescribed area and a second prescribed area of the division element and outputting either one of the first signal or the second signal, the first and second prescribed areas being obtained by dividing the division e