Method and system for measuring an optical power attenuation value of a multimode device under test, receive device and computer-readable memory

Patent metadata

Field	Value
Publication number	US-2016337034-A1
Application number	US-201615220715-A
Country	US
Kind code	A1
Filing date	Jul 27, 2016
Priority date	Jan 28, 2015
Publication date	Nov 17, 2016
Grant date	—

Abstract

There is provided a method for measuring an optical power attenuation value of a multimode DUT. The method generally has, using an optical source, propagating test light along a multimode device link having a first multimode device, the multimode DUT and a second multimode device serially connected to one another; said propagating including inducing a preferential attenuation of high-order optical fiber modes of the test light along the first multimode device and along the second multimode device; using an optical power detector, detecting an optical signal resulting from the propagation of the test light along the multimode device link and transmitting an output signal based on the detected optical signal; and using a processor, determining the optical power attenuation value of the multimode DUT based on the output signal.

First claim

What is claimed is:

1 . A method for measuring an optical power attenuation value of a multimode DUT, the method comprising:
using an optical source, propagating test light along a multimode device link having a first multimode device, the multimode DUT and a second multimode device serially connected to one another; said propagating including inducing a preferential attenuation of high-order optical fiber modes of the test light along the first multimode device and along the second multimode device; using an optical power detector, detecting an optical signal resulting from the propagation of the test light along the multimode device link and transmitting an output signal based on the detected optical signal; and using a processor, determining the optical power attenuation value of the multimode DUT based on the output signal.

2 . The method of claim 1 wherein said propagating is performed at an end of the multimode device link and wherein said detecting is performed at another end of the multimode device link.

3 . The method of claim 1 wherein said propagating and said detecting are performed at a same end of the multimode device link.

4 . The method of claim 3 wherein said propagating further includes scrambling the optical fiber modes of the test light along the second multimode device after said inducing the preferential attenuation along the second multimode device.

5 . The method of claim 3 wherein said determined optical power attenuation value of the multimode DUT is equivalent to an optical attenuation power value of the multimode DUT as would be measured using a light-source power meter approach.

6 . A system for measuring an optical power attenuation value of light being propagated along a multimode DUT, the system comprising:
a first multimode device and a second multimode device having a respective one of a first mode conditioner and a mode filter each being configured to induce a preferential attenuation of high-order optical fiber modes of light; an optical source configured for generating test light to be propagated along a multimode device link including the first multimode device, the multimode DUT and the second multimode device serially connected to one another; an optical power detector connectable to the multimode device link configured for detecting an optical signal resulting from the propagation of the test light and for transmitting an output signal based on the detected optical signal; and a processor configured for determining the optical power attenuation value based on the output signal.

7 . The system of claim 6 wherein the optical source and the optical power detector are both connectable to a same end of the multimode device link for use as an optical time-domain reflectometer, the detected optical signal comprising backscattering and reflected light resulting from the propagation of the test light along the multimode device link.

8 . The system of claim 7 wherein the second multimode device further comprises a light returning device downstream from the mode filter of the second multimode device, the light returning device being configured to provide a backscattering conversion factor that is substantially independent of a modal distribution of light.

9 . The system of claim 8 wherein the second multimode device further comprises a first portion of gradient-index multimode optical fiber upstream from the mode filter and a second portion of gradient-index multimode optical fiber downstream from the mode filter and upstream from the light returning device.

10 . The system of claim 9 wherein the light returning device of the second multimode device comprises a portion of step-index multimode optical fiber.

11 . The system of claim 10 wherein the light returning device of the second multimode device further comprises a third portion of gradient-index multimode optical fiber serially connected to the portion of step-index multimode optical fiber downstream thereof.

12 . The system of claim 11 wherein the step-index multimode optical fiber has a length of less than one meter.

13 . The system of claim 8 wherein the second multimode device has an end connectable to the multimode DUT and another end having a reflective surface.

14 . The system of claim 6 wherein the optical source and the optical power detector are connectable at opposite ends of the multimode device link.

15 . The system of claim 6 wherein the optical source and another optical power detector are connectable to one end of the multimode device link and wherein another optical source and the optical power detector are connectable to an opposite end of the multimode device link for performing optical power attenuation value measurements in both propagation directions along the multimode device link.

16 . The system of claim 6 wherein the mode filter of the second multimode device includes a portion of multimode optical fiber wrapped about a mandrel having a diameter adapted for inducing the preferential attenuation.

17 . A receive device for use in measuring an optical power attenuation value of a multimode DUT using a reflectometric method, the receive device comprising:
a first portion of gradient-index multimode optical fiber; a mode filter having an end connected to the first portion of gradient-index multimode optical fiber, the mode filter inducing a preferential attenuation of high-order optical fiber modes of light being propagated along the mode filter; a second portion of gradient-index multimode optical fiber connected to another end of the mode filter; and a light returning device connected to the second portion of gradient-index multimode optical fiber configured to provide a backscattering conversion factor that is substantially independent of a modal distribution of light.

18 . The receive device of claim 17 wherein the light returning device of the second multimode device comprises a portion of step-index multimode optical fiber.

19 . The receive device of claim 18 wherein the light returning device of the second multimode device further comprises a third portion of gradient-index multimode optical fiber serially connected to the portion of step-index multimode optical fiber downstream thereof.

20 . The receive device of claim 19 wherein the step-index multimode optical fiber has a length of less than one meter.

Assignees

• Exfo Inc

Inventors

• Ruchet Bernard
• He Gang

Classifications

• H04B10/07955 Primary

  Monitoring or measuring power · CPC title

• H04B10/2581

  Multimode transmission · CPC title

• H04B10/071

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

• G01M11/3145

  Details of the optoelectronics or data analysis · CPC title

• G01M11/33

  with a light emitter being disposed at one fibre or waveguide end-face, and a light receiver at the other end-face · CPC title