Optical pulse testing device and optical pulse testing method

Patent metadata

Field	Value
Publication number	US-11199473-B2
Application number	US-201916973396-A
Country	US
Kind code	B2
Filing date	Jun 4, 2019
Priority date	Jun 11, 2018
Publication date	Dec 14, 2021
Grant date	Dec 14, 2021

Abstract

An object of the present invention is to provide an optical pulse test apparatus that can test an optical fiber cable at once in a short period of time. The optical pulse test apparatus according to the present invention includes: an optical pulse signal generation unit 11 that emits an optical pulse with a width that is n times as large as a pulse width T corresponding to desired spatial resolution; a light reception unit 12 that receives reflected light and back-scattered light from n FUTs; an optical path control unit 13 that switches paths connected to the n FUTs are connected at an interval T, inject the optical pulse, as a test optical pulse having the pulse width T, sequentially into the paths, then switches the paths at an interval ts that is shorter than the time period T, and emit the reflected light and the back-scattered light from the n FUTs sequentially onto the light reception unit 12 at an interval n×ts; and an arithmetic processing unit 14 that divides the electrical signal output from the light reception unit 12 , with an interval equal to the interval ts at which switching the paths is performed, into discrete signals respectively corresponding to the FUTs, and calculates the reflectance distributions of the reflected light and the back-scattered light of the respective FUTs.

First claim

The invention claimed is:

1. An optical pulse test apparatus operable to simultaneously measure reflectance distributions of reflected light and back-scattered light from n optical fibers, n being an integer equal to or larger than 2, the optical pulse test apparatus comprising:
an optical pulse signal generation unit configured to emit an optical pulse with a width that is n times as large as a pulse width T corresponding to desired spatial resolution;
a light reception unit configured to receive reflected light and back-scattered light from n optical fibers, and output an electrical signal;
an optical path control unit configured to switch paths connected to the n optical fibers at an interval T, inject the optical pulse from the optical pulse signal generation unit, as a test optical pulse having the pulse width T, sequentially into the paths, then switch the paths at an interval is that is shorter than the time period T, and emit the reflected light and the back-scattered light from the n optical fibers sequentially onto the light reception unit at an interval n×t s ; and
an arithmetic processing unit configured to divide the electrical signal output from the light reception unit, with an interval equal to the interval is at which the optical path control unit performs switching, into discrete signals respectively corresponding to the n optical fibers, and calculate reflectance distributions of the reflected light and the back-scattered light of the n respective optical fibers from the discrete signals.

2. The optical pulse test apparatus according to claim 1 , wherein the paths each include a dummy fiber that has a length enabling none of the reflected light and the back-scattered light from any of the n optical fibers to reach the optical path control unit while the optical path control unit performs switching at the interval T.

3. The optical pulse test apparatus according to claim 1 , wherein
the optical pulse signal generation unit includes a continuous light generation unit and a light pulsing unit configured to pulse the continuous light from the continuous light generation unit, and
the light reception unit performs coherent detection on the reflected light and the back-scattered light from the n optical fibers by using the continuous light from the continuous light generation unit.

4. The optical pulse test apparatus according to claim 1 , wherein
the optical pulse signal generation unit performs optical frequency encoding on the optical pulse at the interval T, and
the optical path control unit sequentially injects the optical frequency encoded test optical pulse into the paths.

5. An optical pulse test method of simultaneously measuring reflectance distributions of reflected light and back-scattered light from n optical fibers, n being an integer equal to or larger than 2, the method comprising:
emitting an optical pulse with a width that is n times as large as a pulse width T corresponding to desired spatial resolution;
switching paths connected to n optical fibers at an interval T, injecting the emitted optical pulse, as a test optical pulse having the pulse width T, sequentially into the paths, then switching the paths at an interval is that is shorter than the time period T, and emitting the reflected light and the back-scattered light from the n optical fibers sequentially onto a light reception unit at an interval n×t s ;
receiving, by the light reception unit, the reflected light and the back-scattered light from the n optical fibers and outputting an electrical signal; and
dividing the electrical signal output from the light reception unit with an interval that is equal to the interval is at which switching the paths is performed, into discrete signals respectively corresponding to the n optical fibers, and calculating the reflectance distributions of the reflected light and the back-scattered light of the n respective optical fibers from the discrete signals.

6. The optical pulse test method according to claim 5 , further comprising providing, to each of the paths, a dummy fiber that has a length enabling none of the reflected light and the back-scattered light from any of the n optical fibers to reach an optical path control unit performing the switching, during switching the paths at the interval T.

7. The optical pulse test method according to claim 5 , wherein
pulsing the continuous light from a continuous light generation unit is performed in emitting the optical pulse, and
coherent detection on the reflected light and the back-scattered light from the n optical fibers is performed by using the continuous light from the continuous light generation unit in receiving the reflected light and the back-scattered light.

8. The optical pulse test method according to claim 5 , wherein
optical frequency encoding on the optical pulse at the interval T is performed in emitting the optical pulse, and
sequentially injecting the optical frequency encoded test optical pulse into the paths is performed in switching the paths.

Assignees

• Nippon Telegraph & Telephone

Inventors

• Iida Hiroyuki
• Manabe Tetsuya
• Koshikiya Yusuke
• Hirota Hidenobu
• Uematsu Takui

Classifications

• G01M11/3118 Primary

  using coded light-pulse sequences · CPC title

• H04B10/071

  using a reflected signal, e.g. using optical time domain reflectometers [OTDR] · CPC title

• A61B5/02444

  Details of sensor (A61B5/02427 takes precedence) · CPC title

• G01M11/3136 Primary

  for testing of multiple fibers · CPC title