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-μm pitch diffraction grating in the implanted silica.
Optics Letters
Department of Electronics

Albert, J, Malo, B., Hill, K.O., & Johnson, D.C. (1992). Refractive-index changes in fused silica produced by heavy-ion implantation followed by photobleaching. Optics Letters, 17(23), 1652–1654. doi:10.1364/OL.17.001652