Characterization of photosensitivity in germanosilicate

Abstract

Permanent UV-induced refractive index changes in germanium doped silica glasses have been a subject of intense investigation for the last decade [1]. In optical fibers UV-induced Bragg-gratings have many possible applications. In planar waveguides less work has been carried out, partly because the technology is not yet developed to the same maturity as for optical fibers. UV-induced refractive index changes in planar structures offer great possibilities as a new way of producing diffractive elements such as Bragg-gratings in existing waveguides [2] and writing buried channel waveguides directly [3,4]. The performance of the technique highly depends on the photosensitivity of the glasses used, making an investigation of the different glass types important. In this work we describe a characterization of the photosensitivity of germania doped silica glasses deposited by plasma enhanced chemical vapor deposition (PECVD). The degree of refractive index change is measured after UV-exposures at 193 nm and 244 nm.