Intent

This is a method for measuring the refractive index profile, including core, cladding, and barrier layers of single-mode and class Ia multimode fibers. It is destructive in the sense that a freshly cleaved end is required. Scans are generally taken along a diameter of the fiber end, and data are displayed as relative index of refraction as a function of radius. It is possible to obtain normalized core-cladding index differences with an accuracy of +/-0.001; absolute values of index are less precise. A spatial resolution of less that 1 µm is obtainable; 0.2 micro;m has been reported. Core or cladding diameter may be measured to an accuracy of 1 µm. FOTP-44 may be used in conjunction with FOTP-58 or FOTP-177 to determine the core diameter and numerical aperture of