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

Metal nanocluster composite glasses, prepared by sequential copper and nickel implantation in fused silica, are analyzed by the Z-scan method. The role of laser-composite interaction effects in the analyses is discriminated, and a phenomenological model is proposed that effectively reproduces the experimental findings. Spatially modulated reduction of both the linear refractive index and the absorbance are suggested as the mechanisms responsible for the observed transmittance Z-scan curves. The third-order fast nonlinearity of the examined composite in terms of intensity-dependent refractive index 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].