US 11,885,707 B2
Fiber span characterization utilizing paired optical time domain reflectometers
Michael J. Cahill, Hampton (AU); and Ian Peter McClean, Brixham (GB)
Assigned to II-VI Delaware, Inc., Wilmington, DE (US)
Filed by II-VI Delaware, Inc., Wilmington, DE (US)
Filed on Nov. 17, 2021, as Appl. No. 17/528,317.
Prior Publication US 2023/0152183 A1, May 18, 2023
Int. Cl. G01M 11/00 (2006.01); H04B 10/071 (2013.01)
CPC G01M 11/3145 (2013.01) [G01M 11/3127 (2013.01); G01M 11/3181 (2013.01); H04B 10/071 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A system for characterizing an optical fiber span extending between a first optical node at a near-end termination of the optical fiber span and a second optical node at a far-end termination of the optical fiber span, comprising
a near-end optical time domain reflectometer (OTDR) coupled to the near-end termination of the optical fiber span;
a far-end OTDR coupled to the far-end termination of the optical fiber span,
the near-end OTDR and the far-end OTDR each including a light source for injecting an optical probe operating at a same probe wavelength into the optical fiber span, a receive component for measuring back-reflected light from the optical probe, and a processing module for generating an OTDR trace based on the back-reflected light measurements, the near-end and far-end processing modules configured to control an operation of both the near-end and far-end OTDRs such that only one of the near-end and far-end OTDRs are in operation at any point in time, the near-end processing module producing a near-end OTDR trace and the far-end processing module producing a far-end OTDR trace; and
a characterization element in communication with both the near-end OTDR and the far-end OTDR, the characterization element for combining the near-end OTDR trace with the far-end OTDR trace in a trace-stitching procedure to create as an output an end-to-end OTDR trace that characterizes the optical fiber span, wherein the characterization element is configured to estimate an optical path length based on measurements performed by the near-end and far-end OTDRs, utilizing the estimated optical path length to determine a mid-point of the optical path length as used by the trace-stitching procedure.