Laser-irradiation effects during Z-scan measurement on metal nanocluster composite glasses

Metal nanocluster composite glasses, prepared by sequential copper and nick el implantation in fused silica, are analyzed by the Z-scan method. The rol e of laser-composite interaction effects in the analyses is discriminated, and a phenomenological model is proposed that effectively reproduces the ex perimental findings. Spatially modulated reduction of both the linear refra ctive index and the absorbance are suggested as the mechanisms responsible for the observed transmittance Z-scan curves. The third-order fast nonlinea rity of the examined composite in terms of intensity-dependent refractive i ndex is therefore evaluated to be lower than similar to 5 x 10(-12) cm(2) W -1. (C) 2000 Optical Society of America [S0740-3224(00)00902-4].