Ricoh Company, Ltd.

Tohoku University

Other

Japan Science and Technology Agency

Shigeyoshi Misawa

Hiroyoshi Funato

Kiyoshi Yokomori

Magane Aoki

Tami Isobe

Yoshinobu Nakayama

Syunsuke Fujita

Hiroaki Fukuda

Migaku Takahashi

Itaru Fujimura

Shin Saito

Toshiyuki Kawasaki

Masakiyo Tsunoda

Tomoyuki Ogawa

Hiroyuki Inoue

Kazuhiro Fujita

Masahiko Nakayama

Ikuo Maeda

Toshihiro Kanematsu

Motonobu Kourogi

Shigeru Oouchida

Shunsuke Fujita

Widiyatmoko Bambang

Osamu Nakamoto

Takahito Uga

An information recording apparatus has a plurality of fine particles forming an array on a plane in close proximity of each other, each of the plural particles including a ferromagnetic metal, a light-emitting device for exciting a near-field light, and a photo-electric conversion element for detecting a near-field light traveled along the fine particles. Summary information may be recorded for plural information recording parts.

Information recording apparatus and method, information reproducing method and fade-in memory, with summary information corresponding to plurality of information recording elements

A disclosed optical recording medium includes multiple recording layer units in each of which one or more recording layers and one or more middle layers are stacked alternately; and one or more spacer layers. In the disclosed optical recording medium, the recording layer units and the spacer layers are stacked alternately in a depth direction of the optical recording medium.

Multilayer optical information recording medium, optical head, and optical drive

An information recording apparatus comprises a plurality of fine particles forming an array on a plane in close proximity of each other, each of the plural particles including a ferromagnetic metal, a light-emitting device for exciting a near-field light, and a photo-electric conversion element for detecting a near-field light traveled along the fine particles.

Information recording method and apparatus using plasmonic transmission along line of ferromagnetic nano-particles with reproducing method using fade-in memory

An optical frequency comb generator includes an oscillator () for oscillating modulating signals of a preset frequency, and an optical resonator () formed by an incident side reflecting mirror () and an outgoing side reflecting mirror (), arranged parallel to each other. The optical resonator causes resonation in light incident via the incident side reflecting mirror (). The optical frequency comb generator also includes an optical phase modulation unit () arranged between the incident side reflecting mirror () and the outgoing side reflecting mirror () for phase modulating the light, resonated by the optical resonator (), by the modulating signals supplied from the oscillator (), and for generating a plurality of sidebands centered about the frequency of the incident light at a frequency interval of the modulating signal. The outgoing side reflecting mirror () sets the transmittance from one frequency to another responsive to the light intensity of the generated sidebands.

Optical frequency comb generator

An imaging device includes a first focusing element on which rays from an object are incident, a second focusing element from which the rays are emitted toward an imaging surface, and a roof mirror having surfaces which are connected to each other at an angle of 90.degree. so that a ridge line is formed, the roof mirror being arranged so that the ridge line intersects optical axes of the first focusing element and the second focusing element at a position on a plane including the optical axes.

Imaging device

A wavelength conversion element includes a substrate made of LiTaO.sub.3 of non-linear medium, a three-dimensional waveguide formed in the substrate and a second harmonic generation portion for defining a change in refractive index in the waveguide with a period .LAMBDA. and generating a second harmonic of a fundamental wave introduced into the wave guide, where .LAMBDA.=2 m.pi./{.beta.(2.omega.)-2.beta.(.omega.)}, m is a natural number, .omega. is a frequency of fundamental harmonic, .beta.(.omega.) is a propagation constant of the fundamental wave, and .beta.(2.omega.) is a propagation constant of second harmonic.

Wavelength conversion element

A focal point position detector has a light source for emitting light; an optical system for converging light from the light source to an optical recording medium; a coupler for coupling light from the optical recording medium thereto; a waveguide concave mirror for converging light from the coupler; a waveguide convex mirror for slightly reducing a converging degree of light from the waveguide concave mirror; and photodetectors for receiving light from the waveguide convex mirror, The coupler, the waveguide concave and convex mirrors and the photodetectors are integrally formed on a substrate, An apparatus for recording and reproducing optical information has a light source; an optical system for converging light emitted from the light source; an optical waveguide; a coupler for coupling the converged light to the optical waveguide; two waveguide mirrors arranged such that reflected light from the coupler is continuously reflected on the waveguide mirrors; and a photodetector for detecting the light reflected on the waveguide mirrors. The coupler, the optical waveguide, the waveguide mirrors and the photodetector are integrally formed on the same substrate.

Apparatus for recording and reproducing optical information having an

A wavelength conversion element includes a substrate made of LiTaO.sub.3 of non-linear medium, a three-dimensional waveguide formed in the substrate and a second harmonic generation portion for defining a change in refractive index in the waveguide with a period .LAMBDA. and generating a second harmonic of a fundamental wave introduced into the wave guide, where .LAMBDA.=2m.pi./{.beta.(2.omega.)-2.beta.(.omega.)}, m is a natural number, .omega. is a frequency of fundamental harmonic, .beta.(.omega.) is a propagation constant of the fundamental wave, and .beta.(2.omega.) is a propagation constant of second harmonic.

An apparatus for recording and reproducing optical information includes an optical integration detecting element arranged on an optical path of light from a laser beam source to an optical information recording medium. The optical integration detecting element has an optical waveguide layer formed on a substrate; a photodetector connected to the optical waveguide layer; a first gap layer formed on the optical waveguide layer and having a refractive index lower than that of the optical waveguide layer; a second gap layer formed on the first gap layer and having an opening portion and a refractive index lower than that of the optical waveguide layer; an adhesive layer having a refractive index higher than that of the optical waveguide layer and adhered to the first gap layer such that the opening portion of the second gap layer is filled with the adhesive layer; and a prism adhesively fixed to an upper portion of the adhesive layer and constructed by a dielectric substance having a refractive index higher than that of the optical waveguide layer.

Apparatus for recording and reproducing optical information and prism

A magneto-optical signal detection device comprising a thin film type optical waveguide unit having a substrate on which a waveguide is formed. The unit has a coupling portion for coupling two polarization components simultaneously in a same plane of the waveguide as a TE mode and a TM mode. The modes TE and TM are included in reflection light reflected from a magneto-optical recording medium and perpendicular to each other. The unit also has a TE-TM mode separating portion having a taper boundary. A waveguide layer is gradually thinned in the taper boundary toward an outer end thereof.

Mode splitter and magneto-optical signal detection device

An optical head for detecting defocuses of a target comprises a waveguide element having a substrate and an optical waveguide layer formed thereon. An optical coupler and one or more pairs of photodetectors are integrated with the waveguide layer. Light reflected back from the target is coupled with the waveguide layer through the coupler and then waveguided toward the photodetectors while being collected. Each of the photodetectors can detect the waveguided light so that a focus error signal can be obtained from the difference of the outputs of the photodetectors. The photodetectors of each pair are spaced from each other in a propagation direction of the waveguide layer so that one of the photodetectors can block off a fraction of the waveguided light from the other photodetector when the target surface is in focus. In another form, two pairs of photodetectors are spaced forward and rearward from the focused position of the waveguided light, respectively, with respect to a propagation direction of the waveguide layer so as to receive different portions of the waveguided light.

Focus detecting optical head

A high efficiency prism coupling device that comprises a substrate, an optical waveguide layer disposed on the substrate, a gap adjuster layer disposed on the waveguide layer and a prism secured to the gap adjuster layer through a dielectric adhesive agent. The gap adjuster layer has a refractive index which is lower than that of the waveguide layer. The gap adjuster layer has a recess formed therein for guiding an incident beam to the waveguide layer through a bottom portion thereof. The adhesive agent is disposed in and around the recess and has a refractive index which is higher than that of the waveguide layer. The prism is made from a dielectric material and disposed above the recess of the gap adjuster layer through the adhesive agent. The prism has a refractive index which is higher than that of the waveguide layer. The incident beam is introduced from outside through the prism, the adhesive agent and the bottom portion of the recess to the waveguide layer.

High efficiency prism coupling device and method for producing the same

A waveguide type optical detection apparatus which is provided on an optical integrated circuit that has a waveguide for transmitting a light from point to point through the waveguide, one or more sets of two adjacent photodetectors provided on the waveguide, and one or more light-insensitive areas existing between the two adjacent photodetectors of each set. The waveguide type optical detection apparatus includes a waveguide focusing part and one or more reflection parts, the waveguide focusing part being provided on the waveguide for allowing a light beam passing through the waveguide to be focused on each of the two adjacent photodetectors of each set, and the reflection parts provided adjacent to each of the light-insensitive areas for reflecting each of light beams sent from the waveguide focusing means forward each of the two adjacent photodetectors of each set so that the light beams are received by the photodetectors. The waveguide type optical detection apparatus can be applied to a pickup for an optical disk and a photodetector array for an optical spectrum analyzer.

Waveguide type optical detection apparatus

An optical information record/read apparatus comprises a light source for emitting light, a converging optical system for converging the emitted light from the light source on the optical record medium so that the converged light is reflected by the optical record medium, and an optical waveguide element having a waveguide layer. A light coupling system is provided for coupling the reflected light from the optical record medium with the waveguide layer so that the light coupled with the waveguide layer is then propagated, as a guided light, within the waveguide layer. At least a part of the light coupling system is integrally formed with the optical waveguide element. A light detecting system for detecting the guided light propagated within the waveguide layer is integrally formed with the optical waveguide element. A waveguide reflection optical system for reflecting the guided light within the waveguide layer toward the light detecting system while converging the same is formed as a part of an end face of the waveguide layer.

Optical information record/read apparatus

An optical pick-up for use in an optically information recording and reproducing apparatus is provided. The pick-up includes a substrate on which an optical waveguide layer is formed and a grating coupler is formed on the optical waveguide layer. Photosensors are also provided to receive light travelling along the waveguide from the grating coupler. A beam splitter is also formed on the substrate for splitting the light from the grating coupler into two separate light beams before reception by the photosensors. If the substrate is opaque, the substrate is formed with an opening through which light emitted from a light source passes. An objective lens is also provided for focusing the light emitted from the light source onto the information recording surface of an optical disc. A quarter wavelength plate may also be provided to change the nature of polarization of the light used.

Growing community of inventors

Tokyo, Japan

Shigeyoshi Misawa