Fujikura Limited

National Institute for Materials Science

Daiichiro Tanaka

Kuniharu Himeno

Masakazu Nakayama

Masashi Ikeda

Masaaki Ohtsuka

Masakazu Oohashi

Koji Omichi

Naoto Hirosaki

Ken Sakuma

Naoki Kimura

Ryokichi Matsumoto

Masakazu Ohashi

Yoshihiro Terada

Yuu Ishii

Yasuhiro Ouchi

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

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

An optical fiber that includes a core containing a first concentration of germanium, an inner cladding arranged on the core, the inner cladding containing a second concentration of germanium and having a first diffusion coefficient, and an outer cladding arranged on the inner cladding, the outer cladding having a second diffusion coefficient, where the first diffusion coefficient is larger than the second diffusion coefficient, and where the first concentration of germanium is about 200% or more of the second concentration of germanium. An optical fiber constructed in this manner can be spliced with an optical fiber having a different MFD, such as a single-mode optical fiber or an erbium-doped optical fiber, with low splice loss and a sufficient splicing strength.

Optical fiber and optical fiber coupler, erbium-doped optical fiber amplifier, and optical waveguide using the same

An optical fiber coupler is comprised of a fusion-elongated portionin which an optical fiberwhich is designed and fabricated for use at a wavelength in the vicinity of 1.55 &#x3bc;m and an optical fiberwhich is designed and fabricated for use at a wavelength in the vicinity of 0.98 &#x3bc;m are fused and elongated. The propagation constant difference between optical fibersandis 10rad/&#x3bc;m or smaller.

Optical fiber coupler and optical fiber therefor

There is provided a polarization maintaining optical fiber coupler and a method of manufacturing this polarization maintaining optical fiber coupler in which manufacturing is simplified and excess loss is reduced. A polarization maintaining optical fiber coupler is provided in which, in at least one of the polarization maintaining optical fibers forming the fused and extended portion, the ratio of the [diameter of the core/the diameter of the cladding] or [the distance between the two stress applying portions/the diameter of the cladding] is greater than the ration of the [diameter of the core/the diameter of the cladding] or [the distance between the two stress applying portions/the diameter of the cladding in the portions of the polarization maintaining optical fibers that do not form the fused and extended portion]. In addition, in this polarization maintaining optical fiber coupler, in the fused and extended portion, the stress applying portions are enveloped by the cladding. Moreover, polarization maintaining optical fibers are used in which the distance between adjacent outer circumferences of the two stress applying portions is 20 &#x3bc;m or more.

Polarization maintaining optical fiber coupler and method of manufacturing same

Growing community of inventors

Sakura, Japan

Daiichiro Tanaka