Yokogawa Electric Corporation

Nippon Telegraph and Telephone Corporation

Mitsubishi Heavy Industries Limited

Ando Electric Company

Other

The University of Tokyo

Vokogawa Electric Corporation

Jx Nippon Oil Energy Corporation

Toyota School Foundation

Hotate, Kazuo

Yoshihiro Kumagai

Eiji Yoshida

Masataka Nakazawa

Akio Ichikawa

Satoshi Matsuura

Kazuo Hotate

Rikihiro Iida

Takashi Yari

Madoka Takahashi

Kazuya Saito

Masayoshi Honma

Kazushi Oishi

Masahito Ishioka

Shin-Ichirou Tezuka

Masato Kishi

Yuka Asahina

An optical fiber characteristic measurement device () includes a light detector () configured to detect Brillouin scattered light (LS) obtained by causing light to be incident on an optical fiber (FUT); a signal processor () configured to obtain, on the basis of a detection signal (S) which is output from the light detector, a first Brillouin gain spectrum (B) which is a spectrum of the Brillouin scattered light obtained in a case where a spectral width of the light incident on the optical fiber is a first width and a second Brillouin gain spectrum (B) which is a spectrum of the Brillouin scattered light obtained in a case where the spectral width of the light incident on the optical fiber is a second width larger than the first width; and a measurer () configured to measure characteristics of the optical fiber on the basis of the first Brillouin gain spectrum and the second Brillouin gain spectrum.

Optical fiber characteristic measurement device, optical fiber characteristic measurement program, and optical fiber characteristic measurement method for measuring characteristics of optical fiber based on Brillouin gain spectrum

An optical fiber characteristic measurement apparatus () includes: a light source () configured to output a laser beam of which frequency is modulated; an incident part (, and) configured to make the laser beam output from the light source be incident from one end and another end of an optical fiber (FUT) as continuous light (L) and pulsed light (L), respectively; a light detector () configured to detect light projected from the optical fiber and output a detection signal (D); and a detector (and) configured to detect, in a first period (T) in which scattering light based on the continuous light and the pulsed light is projected from the optical fiber and a second period (T) shorter than the first period, in which the scattering light is not projected from the optical fiber, the scattering light based on integrated values acquired by integrating the detection signal for a predetermined time.

Optical fiber characteristics measurement apparatus and optical fiber characteristics measurement method

Provided is an optical fiber characteristics measurement device that is provided with: a light source for emitting laser light modulated by a specified modulation frequency; an incident means for receiving the laser light from the light source as continuous light and pulse light from one end and the other end of an optical fiber, respectively; and a light detector for detecting light emitted from the optical fiber, the optical fiber characteristics measurement device measuring the characteristics of the optical fiber using the detection results of the light detector, wherein the optical fiber characteristics measurement device is characterized in being provided with a synchronous detector that extracts, from among the detection signals output from the light detector, detection signals obtained by detecting the light in the vicinity of a measurement point set in the optical fiber, and synchronously detects the extracted detection signals using a synchronization signal having a specified period.

Optical fiber characteristics measurement device and method

An optical fiber characteristic measuring device of the present invention includes: a light source which emits laser light modulated at a predetermined modulation frequency; an incident section which causes the laser light from the light source as continuous light and pulsed light to be incident from one end and other end of an optical fiber respectively; a timing adjuster which causes light emitted from the optical fiber to pass therethrough at a predetermined timing; and a light detector which detects the light which passes through the timing adjuster, and measures a characteristic of the optical fiber by using a detection result of the light detector, and the device includes: a synchronous detector which synchronously detects the detection result of the light detector by using a synchronization signal having a predetermined frequency; and a frequency setter which changes the frequency of the synchronization signal in a case where the modulation frequency at the light source is an integer multiple of the frequency of the synchronous signal.

Optical fiber characteristic measuring device and method

The object of the present invention is to provide an optical pulse generator which very stably generates for a long period of time a high cycling frequency optical pulse chain. In order to obtain this object, in a ring type resonator R, the present invention provides an optical path length regulator 14 which performs high precision optical path length adjustment and an optical path length regulator 60 which performs wide range optical path length adjustment, and extracts a clock signal by converting an optical pulse emitted from the ring type resonator R to an electrical signal by a clock extractor 42, detects the frequency difference between a base frequency signal output form a synthesizer 52 by a frequency difference detector 50, and controls said optical path length regulator 14 and said optical path length regulator 60.

Optical pulse generator

According to the present invention, damage to a photo-detector disposed in clock signal extractor by means of an optical pulse having an optical power exceeding a rated value is prevented. A ring resonator generates a repetitive, high-frequency optical pulse. Optical branching circuit branches a portion of the optical pulse circulating through ring resonator, while optical branching circuit further branches a portion thereof to protective device. Pumping source generates an excitation light for exciting a rare-earth doped optical fiber. Optical multiplexer couples the optical pulse branched by optical branching circuit, and the excitation light. Upon excitation by means of the excitation light, rare-earth doped optical fiber amplifies and emits the incoming optical pulse. The optical power of the excitation light is adjusted such that the output of rare-earth doped optical fiber reaches a saturation power. Optical switch blocks the incoming optical pulse during the time period when pumping source is not emitting an excitation light, and during a fixed time period following the emission of the excitation light. In this manner, the entry of an excessively large optical pulse exceeding the saturation power into photo-detector at the time of starting up the power source is prevented. Optical attenuator attenuates the optical power of the optical pulse emitted from optical switch to an optical power which the photo-detector is capable of photo-detecting. Photo-detector converts the optical pulse emitted from protective device into an electronic signal; narrow band filter extracts a clock signal from the output of photo-detector; and electric amplifier amplifies the output of narrow band filter, and outputs a clock signal. Phase shifter adjusts the phase of this clock signal; electric amplifier amplifies the output of phase shifter, and outputs a clock signal to optical modulator. Optical modulator modulates the intensity of the light circulating through the ring resonator based on the clock signal, and generates an optical pulse.

Growing community of inventors

Tokyo, Japan

Yoshihiro Kumagai