Optical nonlinearity in silicon nanoparticles: Effect of size and probing intensity

Abstract

Self-phase modulated optical fringe patterns are used to study the nonlinear optical response of nanocrystalline silicon produced by laser-induced etching. Intensity-dependent changes in the refractive index are calculated for various sizes of nanocrystallites. Raman spectroscopy is used to determine the sizes of nanocrystals, which are also confirmed from atomic force microscopic images. These results are in agreement with self-phase modulation model. It invokes the change in refractive index of nanoparticles of silicon with decrease of size of nanoparticles.