Step-index optical waveguides have been obtained by means of silver ion implantation on fused silica substrates. Step index profiles have been reached using a sequential multiple ion implantation process with energies of implantation from 4.3 to 9 MeV and fluences of 10 14 -10 15 ions/cm 2 . Optical absorption spectra, propagation losses, intensity distribution, and effective refractive indices of the propagation modes of the waveguides are presented. An approach of refractive index profile of ion-implanted waveguides was fitted as function of polarizability, compaction, and stress. i