Fujikura Limited

National Institute for Materials Science

Fuji Jukogyo Kabushiki Kaisha

The University of Tokyo

Hokkaido University

Chiba University

Koji Omichi

Yoshihiro Terada

Ken Sakuma

Naoto Hirosaki

Akira Sakamoto

Shunichirou Hirafune

Daiichiro Tanaka

Katsuhiro Takenaga

Kunimasa Saitoh

Kazuhiko Aikawa

Kentaro Ichii

Naoki Kimura

Hideki Soejima

Masakazu Ohashi

Munehisa Fujimaki

Kazuyuki Hayashi

Katsuaki Izoe

Hitoshi Uemura

Hideyuki Hosoya

Manabu Kudoh

Kenichi Ohmori

Akihiko Yoshikawa

Shingo Matsushita

Yoji Okabe

Yoshikazu Kaifuchi

Rintaro Morohashi

Hirokuni Ogawa

Qi Wu

Yutaka Endoh

Daigo Fujita

Ryujiro Nomura

An optical fiber sensor includes: a central core disposed at a center of an optical fiber; and an outer peripheral core that spirally surrounds the central core. The effective refractive index nof the outer peripheral core is lower than the effective refractive index nof the central core. A ratio between the effective refractive index nand the effective refractive index nmatches a ratio between an optical path length of the central core and an optical path length of the outer peripheral core.

Optical fiber sensor

A method for detecting a non-superconducting transition of a superconducting wire including a substrate, a superconducting layer having a critical temperature of 77 K or more, and a metal stabilization layer includes, adhesively attaching an optical fiber where a plurality of fiber Bragg gratings are formed in a core along a longitudinal direction thereof to the superconducting wire; measuring in advance a Bragg wavelength shift of the fiber Bragg gratings for a temperature variation of the superconducting wire, and determining a relational expression based on the shift for a temperature calculation of the superconducting wire; determining temperature variations of the fiber Bragg gratings before and after the non-superconducting transition of the superconducting wire using the relational expression; and calculating a propagation rate of the non-superconducting transition based on both a time difference of temperature increases of the fiber Bragg gratings, and an interval between each of the fiber Bragg gratings.

Method for detecting non-superconducting transition of superconducting wire

Optical pulses are output from a light source to an optical fiber at one selected emission wavelength, a reflection light reflected at a fiber Bragg grating at the optical fiber is received at an optical receiver and is converted to a reflection signal by an optical to electrical conversion, a fiber Bragg grating which reflects the reflection light is identified by the signal processing unit when an intensity of the reflection signal obtained by the optical receiver is over a predetermined threshold value, and a measurement step that calculates acoustic frequencies at the fiber Bragg grating based on a temporal change of the intensity of the reflection signal at the fiber Bragg grating is repeated more than two times while changing an emission wavelength of the light source. The acoustic frequency at each fiber Bragg grating is calculated to determine an acoustic distribution along a longitudinal direction of the fiber.

Method of measuring acoustic distribution and distributed acoustic sensor

A fan-in/fan-out device includes a plurality of single-core fibers which are connected to a plurality of first cores of a multicore fiber and which include an elongated portion extending in a longitudinal direction so as to reduce a diameter and being connected to a first end portion of the multicore fiber at a second end portion in an extending direction of the elongated portion, where a refractive index distribution of each of the single-core fibers has a single peak, a relative refractive index difference of a second core with respect to a second cladding in each of the single-core fibers is 0.8% or more; and a second mode field diameter of the second end portion of the elongated portion is greater than a first mode field diameter of the first end portion of the multicore fiber.

Fan-in/fan-out device for multicore fiber

Displacement measuring device with light irradiation system, first and second FBGs and detecting system. The first FBG has first transmittance distribution or first reflectance distribution. The second FBG has second transmittance distribution or second reflectance distribution. The detecting system detects light passed through the first and second FBGs of which at least one of the first transmittance distribution and the second transmittance distribution changes in a wavelength direction with a change amount different from that of the other, according to a displacement amount of an object, or amplitude of the light passed through the first and the second FBGs of which at least one of the first reflectance distribution and the second reflectance distribution changes in the wavelength direction with a change amount different from that of the other, according to the displacement amount of the object, and acquires an index to indicate the displacement amount based on the amplitude.

Displacement measuring device and displacement measuring method

The polarization-maintaining fiber of the invention includes a core () made of germanium doped silica glass; a stress-applying part () made of boron doped silica glass; a cladding () made of pure silica glass; and a polyimide coating layer () with a thickness of 10 &#x3bc;m or less that surrounds the outer periphery of the cladding ().

Polarization-maintaining fiber and optical fiber sensor using same

A method for manufacturing an optical fiber grating that includes first and second gratings that configure an optical resonator, the method including: forming the first grating by radiating ultraviolet light to an optical fiber so that a irradiation intensity Z satisfies the following Equation 1: Z&#x2266;(&#x394;&#x3bb;/x+0.04556Y+1.2225Y)/(0.05625Y+1.6125Y) . . . Equation 1, where, Z represents an irradiation intensity (mJ/mm) of the ultraviolet light, &#x394;&#x3bb;represents the maximum shift amount of a reflection center wavelength of the first grating that is allowed as long as reflection wavelengths of the first grating and second grating overlap each other, x represents a shift amount of the reflection center wavelength per temperature change of 1&#xb0; C. (nm/&#xb0; C.) in the first grating, and Y represents an intensity (W) of the wave-guided light.

Method for manufacturing optical fiber grating, optical fiber grating, and fiber laser

An incandescent lamp color light emitting diode lamp comprises a semiconductor blue light emitting diode chip having a center emission wavelength in a range of from 400 nm to 480 nm and a phosphor that absorbs light emitted from the diode chip to emit light having a different wavelength than the light emitted from the diode chip. The phosphor is represented by a general formula of M(Si, Al)(O, N):Eu. The main phase is an &#x3b1;-SiAlON phosphor having an &#x3b1; SiAlON structure, wherein M is at least one element of Ca, Y, Mg, Li, Sc, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sr and p is from 0.75 to 1.0; and q is between 0.02 and 0.09. The diode lamp emits light having an emission color produced by a mixture of the light emitted from the semiconductor blue light emitting and the light emitted from the &#x3b1;-SiAlON. The chromaticity range thereof falls within the range defined by chromaticity coordinates (x, y) of (0.4775, 0.4283), (0.4594, 0.3971), (0.4348, 0.4185), and (0.4214, 0.3887) on the XYZ chromaticity diagram.

Phosphor and an incandescent lamp color light emitting diode lamp using the same

A method of producing a zinc oxide-based semiconductor crystal, including: introducing at least zinc and oxygen on a surface of a substrate; and growing a zinc oxide-based semiconductor crystal on the substrate, wherein a total or partial portion of the zinc is ionized in a vacuum atmosphere of 1&#xd7;10Torr or less and is introduced to the surface of the substrate to grow the ZnO based semiconductor crystal. As a result, it is possible to provide a method of producing a zinc oxide based semiconductor crystal capable of growing a zinc oxide semiconductor crystal having excellent surface flatness and crystallinity and including an extremely small amount of impurities at a high growth rate.

Method of producing zinc oxide semiconductor crystal

A physical quantity measuring apparatus utilizing optical frequency domain reflectometry includes a tunable laser; a first polarization maintaining fiber; a polarization maintaining coupler; a second polarization maintaining fiber; a third polarization maintaining fiber; a sensor consists of a fiber Bragg grating formed in a core of the third polarization maintaining fiber; a fourth polarization maintaining fiber; a photodiode detects Bragg reflected light from the sensor and reference light from the referential reflecting end; a controller that detects modulation of an interference intensity between the Bragg reflected light and the reference light; and an incidence part that inputs the measuring light, wherein the incidence part being provided on the first polarization maintaining fiber or on both the second polarization maintaining fiber and the third polarization maintaining fiber.

Physical quantity measuring apparatus utilizing optical frequency domain reflectometry and method for temperature and strain measurement using the apparatus

A physical quantity measuring apparatus utilizing optical frequency domain reflectometry of the invention includes a tunable laser; a first polarization-maintaining fiber; a polarization-maintaining coupler; a second polarization-maintaining fiber; a third polarization-maintaining fiber; a sensor consists of fiber Bragg gratings formed at a core of the third polarization-maintaining fiber; a fourth polarization-maintaining fiber; a photodiode detects Bragg reflected light from the sensor and reference light from the referential reflecting end; a controller detects a modulation of an interference intensity between the Bragg reflected light and the reference light, based on an intensity change of multiplexed light of the Bragg reflected light and the reference light; an incidence part inputs the measuring light; and an optical path-length adjuster arranged on the third polarization-maintaining fiber; the incidence part provided on the first polarization-maintaining fiber, or on both the second and third polarization-maintaining fibers.

Physical quantity measuring apparatus utilizing optical frequency domain reflectometry, and method for simultaneous measurement of temperature and strain using the apparatus

A light emitting device comprises at least two lead wires, a light emitting element that is disposed on an end portion of at least one of said lead wires and connected electrically with the end portion and the other lead wire, and a phosphor that absorbs at least part of the light emitted from said light emitting element and emanates light having different wavelengths from the wavelength of the light emitted from said light emitting element, wherein the excitation spectrum of said phosphor has a flat region in a wavelength range including a primary wavelength of the light from said light emitting element.

Light emitting device and a lighting apparatus

This two input two output type optical switch includes four one input two output type optical switches which are arranged to oppose one another, each of these one input two output type optical switches including a Y branch portion in which one optical waveguide is branched into two optical waveguides. And two refractive index adjustment means are provided in the vicinity of each Y branch portion. Switching over of the optical path is performed by half of the refractive index adjustment means functioning alternately. Moreover, a light output intensity variable attenuation function which attenuates by any desired amount the intensity of the light which is being outputted is implemented, at some input port and/or output port, by operating at least one of the refractive index adjustment means which is not currently being used for switching over of the optical path.

Growing community of inventors

Sakura, Japan

Koji Omichi