Optical pulse reflectometry and optical pulse reflectometer

Patent metadata

Field	Value
Publication number	US-11828676-B2
Application number	US-201917596368-A
Country	US
Kind code	B2
Filing date	Jun 11, 2019
Priority date	Jun 11, 2019
Publication date	Nov 28, 2023
Grant date	Nov 28, 2023

Abstract

The purpose of this invention is to provide an optical pulse testing method and optical pulse testing device capable of measuring the loss at an end farther than an axially misaligned connection point at which inter-mode crosstalk occurs independently from the crosstalk value at the point. In this optical pulse testing method, a matrix (loss and crosstalk) representing the mode coupling at a near-end connection point is calculated, and an OTDR waveform having the effects of crosstalk eliminated therefrom is obtained by numerical processing using the calculated matrix representing the mode coupling.

First claim

The invention claimed is:

1. An optical pulse testing method comprising:
inputting a test light pulse in a fundamental mode to one end of an optical fiber under test having a connection point, the test light pulse having a wavelength that can propagate in the fundamental mode and a first higher-order mode;
measuring one intensity distribution of each of a fundamental mode component and a first higher-order mode component of a return light of the test light pulse with respect to a distance from the one end;
inputting another test light pulse in the first higher-order mode to the one end of the optical fiber under test, the another test light pulse having a wavelength that can propagate in the fundamental mode and the first higher-order mode;
measuring other intensity distribution of each of a fundamental mode component and a first higher-order mode component of a return light of the test light pulse with respect to the distance from the one end;
calculating a coupling efficiency between fundamental mode groups, a coupling efficiency between the fundamental mode and a first higher-order mode group, and a coupling efficiency between the first higher-order mode groups at the connection point of the optical fiber under test, which are calculated from one or both of one backscattered light intensity of the one intensity distribution and another backscattered light intensity of the other intensity distribution;
obtaining a mode coupling matrix at the connection point of the optical fiber under test, which has the coupling efficiencies as elements;
correcting the one backscattered light intensity and the another backscattered light intensity using the mode coupling matrix; and
calculating loss on an opposing end side from the connection point of the optical fiber under test, the loss is calculated from the corrected backscattered light intensities.

2. The optical pulse testing method according to claim 1 , wherein the backscattered light intensities are corrected using Formula (C1),

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Assignees

• Nippon Telegraph & Telephone

Inventors

• Nakamura Atsushi
• Okamoto Keiji
• Oshida Hiroyuki

Classifications

• G01M11/3145 Primary

  Details of the optoelectronics or data analysis · CPC title

• G01M11/3154

  Details of the opto-mechanical connection, e.g. connector or repeater · CPC title