Abstract

In recent years much attention has been directed to the mechanism and applications of UV induced refractive index changes in Ge-doped optical fibers. UV absorption bands at 190, 240, and 330 nm associated with Ge-Si wrong bonds are bleached by light of similar wavelength under emission of luminescence. The bleaching is accompanied by formation of other color centers, thus giving an overall rise in UV absorption, and consequently, an increase of the refractive index. Although the process is routinely used for writing index gratings in fibers, UV induced luminescence and index change are not well understood on a detailed level. Since it is difficult to monitor directly the induced index change we have conducted a systematic study of the associated photoluminescence.

© 1994 IEEE