Refractive index measurement of ion‐exchanged glass waveguides by reflection method

Abstract

AbstractIt is important to measure the refractive index profile in an optical waveguide. In particular, there has been a demand for the development of simple methods to measure precisely the refractive index profile in a waveguide with a small number of propagation modes. One of the methods which can provide relatively high resolution is the edge reflection method using an optical fiber as a probe. This method has been used to evaluate a rod lens.In this study, the edge reflection method was used to evaluate a diffused‐type glass waveguide with small dimensions. To increase the sensitivity to reflected light, the fibers for incident light and reflected light detection were located with a certain angle, that is, an oblique incident light system was used. In addition, to increase the spatial resolution, the refractive index profile in the direction of interest was expanded by angle lapping of the edge of the test fiber. By using this method, it was possible to measure easily the refractive index profile in a silver‐diffused glass optical waveguide with two propagating modes.