Refractive index profiles of ion-implanted fused silica

The refractive index change and the refractive index profiles in ion-implanted fused silica are determined by measurement of the angular dependence of reflectivity at HeNe laser wavelength. The dependence of the index profiles on the ion energy, the ion dose, and the annealing is investigated for implantations with helium and argon ions. The implantation of inert gas ions into fused silica leads to an increase of the refractive index with a saturation value of the relative index change Δn/ns = (0.93 ± 0.03) × 10−2. The increase of the refractive index is caused almost completely by a volume compaction due to the radiation damage, and the shape of the index profiles corresponds to the depth distribution of ion energy into atomic collision processes. For the implantation of He+ ions with energies above 100 keV the index change and the depth of the profile are sufficient for the formation of optical waveguides.