SnO2 nanoparticles in silica:: Nanosized tools for femtosecond-laser machining of refractive index patterns

We show that SnO2 nanoclusters in silica interact with ultrashort infrared laser pulses focused inside the material generating a hydrostatic compression and photoelastic response of the surrounding glass. This effect, together with the laser-induced nanocluster amorphization, gives rise to positive or negative refractive-index changes, up to 10(-2), depending on the beam-power density. This result points out a wide tuning of the refractive index patterns obtainable in silica-based optical technology. (c) 2006 American Institute of Physics.