Abstract: A photocoupler according to the present invention includes: an optical waveguide including a substrate, at least a first dielectric layer provided on the substrate, the first dielectric layer having a tapered structure whose thickness varies in an x-direction in which light is propagated after coupling, and a second dielectric layer provided on the first dielectric layer; a light incidence component provided above the optical waveguide, which causes light incident thereon to be directed toward a surface of the optical waveguide at a prescribed angle; and a bonding section for bonding the light incidence component to the optical waveguide. The bonding section has an edge surface which makes contact with the surface of the waveguide in a straight line and has a portion which makes contact with neither the light incidence component nor the surface of the optical waveguide. The tapered structure of the first dielectric layer has a shape set such that a radiation pattern of light with a wavelength .lambda.

Abstract: The optical pickup device according to the present invention, includes: a light emitting diode for emitting a light beam; a collimating lens for collimating the light beam; an objective lens for focusing the collimated light beam from the collimating lens onto a recording medium; a beam splitter for splitting the light beam returned from the recording medium into two light beams; a servo error signal detector for receiving one of the two light beams and detecting a servo error signal; a diffracting element for diffracting the one of the two light beams from the beam splitter to direct the one of the two light beams toward the servo error signal detector; and an optical waveguide element for receiving the other one of the two light beams and detecting a magneto-optical signal, the other one of the two light beams from the beam splitter being incident upon the optical waveguide element without passing through the diffracting element, wherein the beam splitter is disposed between the collimating lens and the dif

Abstract: A mode splitter and the magneto-optical pick-up device including the mode splitter. The mode splitter includes a tapered waveguide portion whose thickness gradually becomes thin so that a light of at least one mode can be cut off. An emission position of a light wave can be varied depending on its mode. In this mode splitter, the emission position of the light wave of each mode can be adjusted by changing a thickness of the tapered waveguide, thereby improving the degree of freedom in designing the device.

Abstract: An optical coupler of the present invention includes: an optical waveguide including a substrate, a first dielectric layer formed on the substrate, a second dielectric layer which is formed on the first dielectric layer and has a refractive index lower than a refractive index of the first dielectric layer, and a third dielectric layer which is formed on a part of the second dielectric layer and has a refractive index equal to or lower than the refractive index of the second dielectric layer; and a light introducing portion made of a transparent material having a refractive index higher than the refractive index of each of the dielectric layers, the light introducing portion being formed on the optical waveguide and introducing converged incident light into the optical waveguide, wherein the light introducing portion is provided across a surface of the second dielectric layer and a surface of the third dielectric layer and has, as a light incident surface, a flat portion allowing the incident light introduced

Abstract: A method for producing a tapered waveguide layer is disclosed. The method includes the steps of: forming a resist pattern on a substrate; setting the substrate in an apparatus for forming a film such that particles constituting the film reach the substrate from a direction which is oblique relative to the substrate; forming the film on a region of a surface of the substrate which is not covered by the resist pattern, the film having a thickness distribution corresponding to a shadow which the resist pattern creates on the substrate in accordance with an angle between the substrate and the direction; and removing the resist pattern, thereby forming the tapered waveguide layer consisting of the film on the substrate.

Abstract: The optical pickup of the invention includes a hologram mirror for directing an optical axis of a light beam emitted from a light source to be perpendicular to the recording face of a recording medium. The hologram mirror includes: a light transmissive substrate having a first surface and a second surface which are opposite to each other, the light beam from the light source entering the substrate from the first surface; a transmissive holographic element, formed on the first substrate, for diffracting the light beam incident thereon to generate a plurality of diffracted beams; and a reflective film, formed on the second surface of the substrate, for reflecting the diffracted beams, wherein the holographic element includes a blazed grating which is designed to make a predetermined one of the diffracted beams most intense.

Abstract: A mode splitter and the magneto-optical pick-up device including the mode splitter are provided. The mode splitter includes a tapered waveguide portion whose thickness gradually becomes thin so that a light of at least one mode can be cut off. An emission position of a light wave can be varied depending on its mode. In this mode splitter, the emission position of the light wave of each mode can be adjusted by changing a thickness of the tapered waveguide, thereby improving the degree of freedom in designing the device.

Abstract: A display apparatus of the present invention includes at least one display element having a display screen and an optical element for transiting an image from an input end face thereof to an output end face thereof. The optical element includes a first optical block and a second optical block each having a plurality of optical fibers combined together. The first optical block is connected to the display screen. One end face of the second optical block constitutes the output end face of the optical element. The numerical aperture of the optical fiber of the first optical block is smaller than the numerical aperture of the optical fiber of the second optical block. A diameter of the optical fiber of the first optical block is smaller than the diameter of the optical fiber of the second optical block.

Abstract: An optical recording and reproducing apparatus records two rows of a plurality of pit patterns with respect to one track by modulating two light beams and by converging the modulated two light beams in parallel onto the track. The plurality of pit patterns are detected and judged by a multiple hologram on which reflected object waves of all kinds of pit patterns are recorded, thereby enabling to carry out recording of information. With the arrangement, since multiple values recording and reproducing can be carried out with respect to a magneto-optical disk, the recording capacity becomes greater than the conventional case and the reproduced signal having little crosstalk can be obtained according to the present way of reproducing.

Abstract: A polarization detector includes a polarization diffraction element having a substrate with two facing surfaces which are placed in parallel with each other, a first diffraction grating formed on one surface of the substrate, and a second diffraction grating formed on the other surface of the substrate, with light being incident upon the first diffraction grating. Further, each grating pitch of the first diffraction grating and the second diffraction grating are nearly equal to a wavelength of the incident light. A limiting member is also included for limiting an incident region of the incident light with respect to the polarization diffraction element. The limiting member is formed on a light incident side of the first diffraction grating. Further, a converging lens is included for respectively converging light transmitted through the first diffraction grating and the second diffraction grating and light diffracted by the first diffraction grating and the second diffraction grating into different beam spots.

Abstract: A display apparatus of the invention includes: a plurality of display devices arranged in one direction, each of the plurality of display devices having a display area; and a plurality of image transmission means corresponding to the respective display devices, one end face of each of the image transmission means being coupled to a display area of the corresponding one of the display devices, other end faces of the image transmission means corresponding to the adjacent ones of the display devices being in contact with each other, the plurality of image transmission means being bent toward the one direction in which the display devices are arranged.

Abstract: An optical information reproducing apparatus of the invention includes a light emitting and receiving unit and an optical system. The optical system converges light from the light emitting and receiving unit on a recording medium and converges the light after reflected by the recording medium. The light emitting and receiving unit includes: a semiconductor laser device disposed on a substrate for generating light; a photo detector formed, integrally with the substrate, on the substrate on which the semiconductor laser device is disposed, for outputting a signal corresponding to the intensity of light incident thereon; and a beam splitter provided on an optical axis of the reflected light, the beam splitter leading part of the reflected light to the photo detector.

Abstract: An optical pick-up device comprising an optical system including a light source and an optical diffraction grating element and a light receiving element, wherein the optical diffraction grating element guides the 0th-order diffracted lights of a light beam emitted from the light source onto a recording medium and guides the first-order diffracted lights of a reflected light from the recording medium onto the light receiving element to produce a plurality of focused light spots having the same light amount, wherein the optical diffraction grating element includes diffraction gratings having a configuration in which grooves and flat lands each positioned between the adjacent grooves are successively alternately formed, wherein the diffraction gratings have the same groove depth, groove width and groove tilt angle in order to obtain a constant 0th-order diffraction efficiency and first-order diffraction efficiency in the optical diffraction grating element while the pitches of the diffraction gratings are made d

Abstract: An optical information reproducing device includes a light source for generating a light beam, an optical system for converging the light beam generated by the light source on a magneto-optical recording medium on which recording information is recorded and for converging a return light beam reflected from the magneto-optical recording medium, beam splitting means for splitting the return light beam into split light beams, first detecting means for receiving one of the split light beams to detect the intensity of the one of the split light beams, servo signal generating means for generating a tracking error signal and a focusing error signal based on the output of the first detecting means, an optical waveguide disposed between the beam splitting means and the first detecting means, the optical waveguide crossing an optical axis of the one of the split light beams, an optical coupler disposed on the optical waveguide for separating part of the one of the split light beams from the one of the split beams to fo

Abstract: An optical scan device comprising a light source and an optical diffraction grating element movable relatively to the light source, which is designed to substantially linearly scan a recording medium in a predetermined direction with a uniform light amount of a light beam emitted from the light source as the optical diffraction grating element moves relatively to the light source. The optical diffraction grating element comprising diffraction gratings having a configuration in which grooves and flat lands each positioned between the adjacent grooves are successively alternately formed, wherein the diffraction gratings have the same groove depth, groove width and groove tilt angle in order to obtain a constant 0th-order diffraction efficiency and first-order diffraction efficiency in the optical diffraction grating element while the pitches of the diffraction gratings are made different by setting a different land width for each diffraction grating.

Abstract: An optical information recording and reproducing device is provided. The device includes a light source for emitting a light beam, a first diffraction element for splitting the light beam into at least three diffracted beams, an optical system guiding the diffracted beams to a recording medium, and a second diffraction element including at least one division line and a diffraction surface from which the diffracted beams are diffracted. The diffraction surface is divided into at least two regions by the division line or lines. One of the division lines is at a predetermined angle against the direction of a track on the recording medium, and the regions split each of the diffracted beams into at least two parts to diffract the parts in different directions. The device also includes an optical detecting element for detecting the light beams diffracted with the second diffraction element.

Abstract: An optical integrated circuit is disclosed. The optical integrated circuit includes: a dielectric waveguide having at least a waveguide layer for transmitting light in a first direction; a first reflector for reflecting the light in a substantially opposite direction to the first direction, the first reflector being formed on an end face of the waveguide layer; a grating coupler having a grating for diffracting at least a part of the light in a second direction which is different from the first direction, the grating coupler being formed at a surface of the waveguide layer; and a light detector for detecting the diffracted light, the light detector being optically connected with the dielectric waveguide.

Abstract: An optical pickup apparatus for reading out information from an optical disk. The optical pickup includes a light source; and an optical device having a grating pattern for splitting a light beam from said the source into a zero-order diffracted beam and plus and minus first-order diffracted beams. The grating pattern has the center portion and one or more side portions. The efficiency of the center portion for the zero-order diffracted beam is greater than the efficiency of the side portions for the zero-order diffracted beam.

Abstract: An optical device includes: a first dielectric slab waveguide having an effective refractive index N.sub.1 ; a second dielectric slab waveguide having an effective refractive index N.sub.2 ; and a third dielectric slab waveguide having a length 1 and an effective refractive index N.sub.3, the third dielectric slab waveguide being formed between the first dielectric slab waveguide and the second dielectric slab waveguide so as to connect the first dielectric slab waveguide with the second dielectric slab waveguides optically; wherein the length I and the effective refractive index N.sub.3 substantially satisfy following equations; ##EQU1## where .lambda. is a free-space wavelength of light traveling in the optical device and the light travels from the first dielectric slab waveguide to the third dielectric slab waveguide at an incident angle .THETA. in a single mode.

Abstract: An optical pickup device in which a main beam and a pair of sub-beams are used and a diffraction device is disposed between a recording medium and a light receiving device such as a photodetector is disclosed. The diffraction device comprises first to third diffraction regions. The second and third regions receive light beams from the recording medium which are substantially identical in amount to each other. The light receiving device comprises a first to a fourth light receiving regions. The first and second light receiving regions are juxtaposed, and separated by a line. The main beam which has been diffracted by the first diffraction region is focused onto said line. The main beam which has been diffracted by the second diffraction region is focused onto the first light receiving region. The main beam which has been diffracted by the third diffracting region is focused onto the second light receiving region.