Matched spatial filtering method for the sorting of optical fiber billets

Abstract

Continued progress in fiber optics will be impossible without the development of specialpurpose instruments and systems to measure and monitor the characteristics of optical fibers. One of the main parameters of optical fibers is the core index profile, which determines the bandwidth and several other operational characteristics of the fiber. The profile of the refractive index of the fiber core, in turn, depends on the index profile of the original billet. Methods for determining the index profiles of billets are being constantly improved. The majority of existing methods generally entail the solution of the inverse problem of reconstructing the profile of the refractive index [i]. This requires large expenditures of of machine time, complicates the measurement process, and limits the performance of such systems. Often in practice it is not necessary to know the quantitative parameters of the index profile, and it suffices merely to obtain an estimate of the degree to which the index profile of the billet corresponds to a certain "standard" profile. It is proposed that the index profile of optical fiber billets be monitored by a matched spatial filtering method [2], which does not have any limitations on the type of index profile. This method can be combined with any existing method of measurement of the index profiile of billets. It can be used to perform real-time monitoring operations.