Thin layers of metal clusters in silica glass were formed by high dose ion implantation of Ag, Ni and Cu using a metal vapor vacuum arc (MEVVA) ion source. Characterization of the implanted layers was performed using Rutherford backscattering spectroscopy, transmission electron microscopy, x-ray diffraction, and optical measurements. The nonlinear optical properties of the implanted samples were studied by the z-scan method, using a self mode-locked Ti: sapphire laser delivering linearly polarized pulses of 130fs long at a wavelength of 790nm at 76MHz. The variation of the intensity-dependent refractive index n 2 with the ion species and the implantation conditions were studied. An n 2 value of about 0.6 cm2/GW was measured for one of the Cu and Ni co-implanted samples. The correlation between n 2 and the cluster size was also analyzed. Ellipsometry spectra of the samples were measured in the visible range from 0.4 to 0.7 [.proportional]m and in the near infrared range from 0.9 to 1.6 [.proportional]m. Preliminary results are reported on our attempt to deduce the effective complex refractive indices of the implanted layers by fitting of the ellipsometry spectra using a simple single uniform layer on substrate model and the Maxwell-Garnett effective medium approximation.