公开(公告)号：US20250035510A1

公开(公告)日：2025-01-30

申请号：US18773248

申请日：2024-07-15

Applicant: EXFO Inc.

Inventor： Hongxin CHEN ,  Yves BRETON ,  Mathieu HUNEAULT

IPC: G01M11/00

Abstract: There is provided a method of measuring the PMD of an optical fiber under test (FUT). A polarization-sensitive optical time domain reflectometer (POTDR) is used to inject into the FUT and from a proximal end thereof, a test signal comprising a series of repeated light pulses and detecting a corresponding polarization-analyzed return light signal coming back from the optical fiber and representing back-reflected light from a light reflector connected to a distal end of the FUT, said return light signal comprising repeated reflected light pulses. The plurality of polarization-sensitive acquisitions defines at least one pair of acquisitions performed with mutually different but closely-spaced wavelengths and substantially the same state of polarization (SOP), a center of said wavelengths defining a center wavelength for said at least one pair. The process may be repeated for a plurality of pairs of acquisitions performed with at least one of a plurality of mutually-different center wavelengths and a plurality of mutually-different states of polarization (SOP). For each said acquisitions, respective amplitudes of at least part of the repeated reflected light pulses are averaged so as to obtain an averaged reflected power. The PMD is obtained by, for each said pairs of said acquisitions, computing a value of a difference between the two averaged reflected powers corresponding to said pair, followed by the mean-square value of computed values of difference over said at least one of a plurality of mutually-different center wavelengths and a plurality of mutually-different states of polarizations (SOPs) and, from said mean-square value, calculating a value of the PMD for the optical fiber under test.