Concurrent three-dimensional characterization of the refractive-index and residual-stress distributions in optical fibers

A three-dimensional index-stress distribution (3DISD) measurement method for determining concurrently the refractive-index distributions (RIDs) and residual-stress distributions (RSDs) in optical fibers is presented. The method combines the quantitative-phase microscopy technique, the Brace-Kohler compensator technique, and computed tomography principles. These techniques are implemented on a common apparatus to enable concurrent characterization of the RID and the RSD. Measurements are performed on Corning SMF-28 fiber in an unperturbed section and in a section exposed to CO2 laser radiation. The concurrent measurements allow for the first accurate comparison of the collocated RID and RSD. The resolutions of the refractive index and stress are estimated to be 2.34 x 10(-5) and 0.35 MPa, respectively. (C) 2012 Optical Society of America