Refractive-index changes in fused silica produced by heavy-ion implantation followed by photobleaching

Abstract

The changes in refractive index, optical absorption, and volume of synthetic fused silica resulting from the implantation of germanium and silicon ions at energies of 3 and 5 MeV are reported. Implantation changes the density and generates ultraviolet color centers in the silica, which increases the refractive index at visible wavelengths by ~1%. Irradiation of the implanted samples with 249-nm light from a KrF excimer laser photobleaches the color centers and reduces the index by more than 0.1%. Photobleaching is used to write a 4.3-microm pitch diffraction grating in the implanted silica.