The University of Tokyo

Fujitsu Corporation

Sharp Kabushiki Kaisha Corporation

Qd Laser, Inc.

Nec Corporation

Consiglio Nazionale Delle Ricerche-infm Istituto Nazion

Yasuhiko Arakawa

Nobuaki Hatori

Tsuyoshi Yamamoto

Mitsuru Sugawara

Hirofumi Yoshikawa

Makoto Suzuki

Teruhisa Kotani

Hiroji Ebe

Hisao Sudo

Makoto Izumi

Tatsuya Usuki

Takahiro Doe

Denis Guimard

Shiro Tsukamoto

Takanori Shimizu

Motomu Takatsu

Masashige Ishizaka

Shigeru Aomori

Manabu Matsuda

Shinichi Hirose

Roberto Cingolani

Ken Morito

Kenichi Kawaguchi

Tazuko Kitazawa

Takeo Kageyama

Koji Otsubo

Yoshiaki Nakata

Pier Paolo Pompa

Yasutaka Kuzumoto

Massimo De Vittorio

Michio Arai

Kazuya Takemoto

Osamu Wada

Tetsu Tatsuma

Ferruccio Pisanello

Stefania Sabella

Shuichi Tojo

Luigi Martiradonna

Tomohiro Nozawa

Masatoshi Kitamura

Kanna Aoki

Tiziana Stomeo

Alessandro Massaro

Satoshi Iwamoto

Rosaria Rinaldi

Katsuaki Tanabe

Takashi Kita

Mitsuru Fujitsu Limited Sugawara

An infrared photodetection system is provided that is capable of measuring infrared light up to high-temperature regions while improving a temperature resolution for low-temperature regions without increasing image-acquisition time even if the measuring temperature range varies. The infrared photodetection system is set up to exhibit sensitivity spectrum SSPfor high sensitivity (for low temperature use) and sensitivity spectrum SSPfor low sensitivity (for high temperature use) in the transmission band of the bandpass filter when different voltages are applied to a quantum-dot infrared photodetector. The infrared photodetection system then integrates temperature data for the infrared light detected using sensitivity spectrum SSPand temperature data for the infrared light detected using sensitivity spectrum SSP, in order to output a temperature distribution in a measurement region.

Infrared photodetection system

A high detectivity infrared photodetector is provided. An infrared photodetectorincludes n-type semiconductor layersandand a photoelectric conversion layer. The photoelectric conversion layerincludes quantum dots, a barrier layer, and a single-sided barrier layer. The single-sided barrier layeris inserted between the barrier layerand the n-type semiconductor layerand has a wider band gap than does the barrier layer. Letting y be an energy level difference between the bottom of the conduction band of the single-sided barrier layerand the bottom of the conduction band of the n-type semiconductor layer, z be a voltage in volts applied to the photoelectric conversion layer, and d be a thickness in nanometers of the photoelectric conversion layer, the infrared photodetectorsatisfies y&#x2265;27&#xd7;exp(0.64&#xd7;z/(d&#xd7;10000)).

Infrared photodetector

An image projection device includes: a first mirror oscillating to scan an image light beam forming an image projected onto a retina of a user; a light source emitting the image light beam and a detection light beam to the first mirror at different timings; a second mirror having a first region reflecting the image light beam reflected by the first mirror to the retina and a second region reflecting the detection light beam reflected by the first mirror in a direction different from a direction in which the image light beam is reflected, and scanning neither the image light beam nor the detection light beam reflected by the first mirror; a detector detecting the detection light beam reflected by the second region; and a controller adjusting oscillation of the first mirror and an emission timing of the image light beam based on a detection result by the detector.

Image projection device

A quantum dot infrared detector includes a quantum dot-stacked structure in which quantum dot layers each containing quantum dots stacked on top of one another and intermediate layers. The quantum dots are sandwiched between the intermediate layers in the height direction of the quantum dots. The quantum dots have conduction band quantum confinement levels that include a conduction band ground level, a conduction band first excitation level at a higher energy position than the conduction band ground level, and a conduction band second excitation level at a higher energy position than the conduction band ground level. An energy gap between the conduction band first excitation level and the conduction band bottom of the intermediate layer and an energy gap between the conduction band second excitation level and the conduction band bottom of the intermediate layer are each smaller than twice thermal energy.

Quantum dot infrared detector

The present invention is an image projection device that includes: a light sourcethat emits a laser beam; a scanning mirrorthat two-dimensionally scans the laser beamemitted from the light source; and a projection mirrorthat projects scanned light onto a retinaof an eyeballof a user to project an image onto the retina, the scanned light being composed of the laser beamthat has been scanned by the scanning mirror, wherein the laser beamemitted from the light sourceis scanned by using a part of an operating range of the scanning mirror

Image projection device and projection device

An image projection device includes: one light source unit emitting an image light beam, which forms an image, of visible light and a checking light beam of visible light; an optical system projecting the image light beam emitted from emitted from the one light source unit onto a first surface region of an eye of a user to project the image light beam onto a retina of the user, and projecting the checking light beam emitted from the one light source unit onto a second surface region, which is distant from the first surface region, of the eye of the user; a light detector detecting a reflected light that is the checking light beam reflected by the eye of the user; and a controller controlling at least one of the one light source unit and the optical stem based on a detection result of the reflected light by the light detector.

A quantum cascade laser includes a semiconductor substrate and an active layer having a cascade structure, in which unit layered bodies, each composed of a quantum well light emitting layer and an injection layer, are stacked, wherein the unit layered body has a subband level structure having an upper laser level, a lower laser level, and a relaxation miniband composed of at least two energy levels with an energy spacing smaller than the energy difference (E) between the upper laser level and the lower laser level, the energy width of the relaxation miniband is smaller than the energy (E&#x2212;E) obtained by subtracting the energy difference (E) from the energy (E) of longitudinal optical phonons, and electrons subjected to the intersubband transition are relaxed in the relaxation miniband and are injected into a quantum well light emitting layer in a subsequent unit layered body.

Quantum cascade laser

A QCL () includes a first electrode (), a first contact layer () that is in contact with the first electrode () and is made of a first compound semiconductor, a second electrode () having a polarity opposite to that of the first electrode (), a second contact layer () that is in contact with the second electrode () and is made of a second compound semiconductor, and an active layer () disposed between the first contact layer () and the second contact layer () and including two or more active layer units. Each of the active layer units includes one or more quantum well layers made of a third compound semiconductor and one or more barrier layers made of a fourth compound semiconductor, and each of the quantum well layers and each of the barrier layers are alternately stacked. The vibrational energies of longitudinal optical phonons of the third compound semiconductor and the fourth compound semiconductor are higher than the vibrational energy of a longitudinal optical phonon of GaAs and lower than or equal to the vibrational energy of a longitudinal optical phonon of AlN.

A photoelectric conversion element includes a buffer layer, a BSF layer, a base layer, a photoelectric conversion layer, an emitter layer, a window layer, a contact layer, and a p-type electrode sequentially on one surface of a substrate, and includes an n-type electrode on the other surface of the substrate. The photoelectric conversion layer has at least one quantum dot layer. The at least one quantum dot layer includes a quantum dot and a barrier layer. A photoelectric conversion member including the buffer layer, the BSF layer, the base layer, the photoelectric conversion layer, the emitter layer, the window layer, and the contact layer has an edge of incidence that receives light in an oblique direction relative to the growth direction of the quantum dot. A concentrator concentrates sunlight and causes the concentrated sunlight to enter the photoelectric conversion member from the edge of incidence.

Photoelectric conversion element and photoelectric conversion device including the same

A nitride semiconductor device includes a GaN substrate in which an angle between a principal surface and an m-plane of GaN is &#x2212;5&#xb0; or more and +5&#xb0; or less, a first intermediate layer disposed on the principal surface of the substrate and made of AlGaN, 0&#x2264;z&#x2264;1, and a second intermediate layer disposed on a principal surface of the first intermediate layer, having an Al content different from that of the first intermediate layer, and made of AlInGaN, 0&#x2264;x1&#x2264;1, 0&#x2264;y1&#x2264;1. A quantum cascade laser includes the nitride semiconductor device.

Nitride semiconductor device and quantum cascade laser using the same

A photodetector including a substrate, a light absorption layer arranged over the substrate, the light absorption layer including a stack including a semiconductor layer that absorbs light of a wavelength having an electric field vector parallel to a normal direction of a substrate surface, a lower contact layer arranged on a first side of the light absorption layer, a lower electrode contacting with the lower contact layer, an upper contact layer arranged on a second side of the light absorption layer, and an upper electrode contacting with the upper contact layer. An uneven structure including polarization-selective shapes of projections or depressions on the second side of the upper contact layer is provided, the shapes of projections or depressions each having a size of a wavelength or less of incident light in the semiconductor layer and half the wavelength or greater and being periodically arranged in at least one direction.

Photodetector

A semiconductor light source includes a substrate, an optical waveguide having a reflection structure provided on the substrate with an oxide film in between and a semiconductor light emitting element provided on the optical waveguide. The optical waveguide includes a constant width core layer portion located in a center portion, tapered core layer portions that are provided on either side of the constant width core layer and of which the core width gradually increases and a constant width core layer portion for an optical wire waveguide. The semiconductor light emitting element is placed so as to cover at least a portion of the tapered core layer portions on both sides.

Semiconductor light emitting device and optical transceiver

A photoelectric conversion element includes a superlattice semiconductor layer including barrier sub-layers and quantum sub-layers (quantum dot sub-layers) alternately stacked and also includes a wavelength conversion layer containing a wavelength conversion material converting the wavelength of incident light. The wavelength conversion layer converts incident light into light with a wavelength corresponding to an optical transition from a quantum level of the conduction band of the superlattice semiconductor layer to a continuum level of the conduction band.

Photoelectric conversion element

A photoelectric conversion element according to the present invention includes a photoelectric conversion layer. The photoelectric conversion layer includes a p-type semiconductor layer, an n-type semiconductor layer, and a superlattice semiconductor layer which is interposed between the p-type semiconductor layer and the n-type semiconductor layer. The superlattice semiconductor layer has a superlattice structure in which barrier layers and quantum layers are stacked alternately and repeatedly, and is provided so as to form an intermediate energy band between an upper end of a valence band of the barrier layer and a lower end of a conduction band of the barrier layer. The intermediate energy band is formed from a region of the superlattice semiconductor layer, which is near to the p-type semiconductor layer, to a region of the superlattice semiconductor layer, which is near to the n-type semiconductor layer, and the intermediate energy band has a region having a wide band width and a region having a narrow band width.

Growing community of inventors

Kanagawa, Japan

Yasuhiko Arakawa