Calibration and standardization issues for the optical time-domain reflectometer

Abstract

We review some of the issues related to the specification and assurance of optical time-domain reflectometer (OTDR) performance. These include selection of appropriate performance parameters, definition of terms, test procedures, measurement difficulties, and use of standard reference fibers. Some recommendations are given for an OTDR calibration program.

Group index and tome delay measurements of a standard reference fiber

“…Along with attenuation, distance measurement accuracy is one of the principal quantities which is susceptible to accurate calibration in these devices [1]. The SRFs provided to contractors are also characterized for spectral attenuation; although, we do not discuss these measurements here.…”

“…Using eq (1) and the propagation of error formula, we can estimate the total uncertainty in the length determination of a long fiber.…”

“…Experimentally, the effective group index may be obtained from eq (1) by an inverse process where propagation delay information is available on a fiber of known length.…”

“…The technique is illustrated in figure 1. The procedure is as follows: (1) The physical length of the fiber Lp is measured by placing a fiber sample in a vacuum chuck mounted on a translation stage, and noting the distance on the translation micrometer required to align either end of the fiber with crosshairs in the microscope eye piece.…”