Profile Characterization of Optical Fibers-A Comparative Study

The refractive index profiles of several multimode optical fibers were measured by four of the current state-of-the-art techniques. These include interference microscopy on slab samples, transverse interference microscopy on whole fiber samples, the focusing method, and the refracted near-field method. The profile of the parent preform of one of the fibers was also measured by both the focusing method and by a ray-tracing approach. Comparisons of the results and the measurement methods are made emphasizing the applicability and use of the various techniques.