Hamamatsu-Photonics K.k.

The University of Tokyo

Hiroyasu Fujiwara

Akira Higuchi

Shohei Hayashi

Toru Hirohata

Minoru Niigaki

Kazutoshi Nakajima

Wei Dong

Tetsushi Shimomura

Motoichi Ohtsu

Tadashi Kawazoe

Masamichi Yamanishi

A terahertz wave lens includes a substrate having a surface provided with an uneven structure that changes a phase of the terahertz wave. The uneven structure includes a plurality of holes that are periodically arranged. The uneven structure includes a plurality of regions where the plurality of holes are arranged. A height of the hole in a thickness direction of the substrate and a width of the pillar differ for each of the regions. Outer end portions of the uneven structure in the thickness direction are located on the same plane.

Terahertz wave optical element and method for producing terahertz wave optical element

A terahertz wave lens concentrates or collimates a terahertz wave. The terahertz wave lens includes a substrate having a surface provided with an uneven structure that changes a phase of the terahertz wave. The uneven structure includes a plurality of pillars that are periodically arranged. The uneven structure includes a plurality of regions where the plurality of pillars are arranged. A height of the pillar in a thickness direction of the substrate and a width of the pillar differ for each of the regions. A distance (period) between centers of the pillars adjacent to each other is constant. Outer end portions of the uneven structure in the thickness direction are located on the same plane.

Terahertz wave lens and method for producing terahertz wave lens

A photodetector element according to an aspect of the present disclosure includes a semiconductor layer with an uneven structure on one surface side that is constituted of projection portions and recess portions, and converts light into surface plasmons, and a metal film that is provided on the one surface side of the semiconductor layer in a manner corresponding to the uneven structure and a Schottky junction is formed between the metal film and the semiconductor layer. The semiconductor layer is constituted of n-type conductive silicon, and the other surface side of the semiconductor layer serves as an incident surface for light. The metal film is constituted of a material including nickel which form the Schottky junction when combined with the semiconductor layer.

Photodetector element

A photodetection element is a photodetection element having an incidence surface for light on a back surface of a semiconductor layer, and includes a periodic nano-concave/convex structure provided on a front surface of the semiconductor layer and having convex portions and concave portions constituting a longitudinal resonator and a transverse resonator for the light incident from the incidence surface, the periodic nano-concave/convex structure converting the light into surface plasmons, and a metal film provided to cover the periodic nano-concave/convex structure, a height and an arrangement pitch of the convex portions in the periodic nano-concave/convex structure are set such that a resonance wavelength of the longitudinal resonator and a resonance wavelength of the transverse resonator match, and a thickness of the metal film is equal to or greater than 20 nm.

Photodetection element having a periodic nano-concave/convex structure

A photodetection element includes a semiconductor layer having, on one surface side, a periodic concave/convex structure that includes periodic convex portions and concave portions and converts light into surface plasmon, and a metal film provided on the one surface side of the semiconductor layer in correspondence to the periodic concave/convex structure, and in the periodic concave/convex structure, a Schottky junction portion that has a Schottky junction with the metal film is provided on a base end side of the convex portion, and a non-Schottky junction portion that does not have a Schottky junction with the metal film is provided on a distal end side of the convex portion.

Photodetection element

When light is incident to an antenna layer AAof a photocathode AA, light of a specific wavelength included in the incident light couples with surface plasmons in the antenna layer AAwhereupon near-field light is outputted from a through hole AA. The intensity of the output near-field light is proportional to and greater than the intensity of the light of the specific wavelength. The output near-field light has a wavelength that can be absorbed in a photoelectric conversion layer AA. The photoelectric conversion layer AAreceives the near-field light outputted from the through hole AA. A region of the photoelectric conversion layer AAaround the through hole AAabsorbs the near-field light and generates photoelectrons (e) in an amount according to the intensity of the near-field light. The photoelectrons (e) generated in the photoelectric conversion layer AAare outputted to the outside.

Photocathode, electron tube, field assist type photocathode, field assist type photocathode array, and field assist type electron tube

A signal waveform measuring apparatusA is configured from: a signal optical system, a reference optical system, a time difference setting unitsetting a time difference between signal light Land reference light L, a wavelength conversion elementincluding an aggregate of crystals of a dye molecule and generating converted light L, which has been wavelength-converted to a shorter wavelength than incident light made incident on the crystal aggregate, at an intensity proportional to an r-th power (r&#x3e;1) of the intensity of the incident light, a photodetectordetecting the converted light L, generated at the elementat the intensity that is in accordance with the intensity of the signal light L, the intensity of the reference light L, and the time difference between the two, and a signal waveform analyzerperforming analysis of the detection result of the converted light Land thereby acquiring a time waveform of the signal light L. A signal waveform measuring apparatus and a measuring method that enable a time waveform of signal light to be measured with good precision by a simple configuration are thereby realized.

Signal waveform measuring apparatus and method comprising a wavelength conversion element

There is disclosed a waveguide structure that propagates surface plasmon waves, comprising: a quantum well structure, disposed on a semiconductor substrate; wherein the quantum well structure has a quantum well layer, in turn having an intersecting region that intersects a hypothetical plane substantially orthogonal to an alignment direction of the quantum well structure with respect to the semiconductor substrate, and a real part of a dielectric constant of the quantum well structure is negative for THz waves of a predetermined wavelength.

Waveguide structure and optical device

A wavelength-converted light generating apparatusA includes: an excitation light sourcesupplying excitation light Lof a predetermined wavelength; and a wavelength conversion element, in which an aggregateof crystals of a dye molecule is held by a holding substrateand which, by incidence of the excitation light L, generates converted light Lthat has been wavelength-converted. The excitation light sourcesupplies the excitation light Lof a wavelength longer than an absorption edge of the dye molecule to the wavelength conversion element. The wavelength conversion element, by incidence of the excitation light Lon the crystal aggregate, generates and outputs the converted light (for example, visible light) Lthat has been wavelength-converted to a shorter wavelength than the excitation light (for example, near-infrared light) L. A wavelength-converted light generating apparatus and generating method capable of favorably generating light of a shorter wavelength than incident light of a predetermined wavelength by wavelength conversion is thus realized.

Wavelength-converted light generating apparatus and generating method

When light is made incident into antenna layers, andof a photodetector, specific wavelength components of light contained in the incident light combine with surface plasmons of the antenna layers, and, and surface plasmon resonance occurs. Thereby, near-field lights are outputted from through-holesof the antenna layers, and. The near-field light outputted from each through-holereaches a light absorbing layervia light receiving surfaces, and. The light absorbing layergenerates a charge of an amount according to the amount of received light. Since cycle intervals &#x39b;a, &#x39b;b, and &#x39b;c of convex portionsin the antenna layers, andare different from each other, the wavelength component of light that combines with a surface plasmon differs in each of the antenna layers, and. Consequently, a plurality of wavelength components of light can be detected.

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Hamamatsu, Japan

Hiroyasu Fujiwara