Nonlinear optical response of nanoparticle single layers: Polarization and structural effects

Metallic nanoparticles embedded in a dielectric matrix are simple structures which combine the ease of preparation with unique nonlinear properties, characterizing waveguiding effects which are of interest for optical switching applications. In this work, the linear and nonlinear optical response of Gallium nanoparticle layers are investigated. Gallium is adopted as the metallic constituent due to its high second-order nonlinear response and to the possibility of positioning the phase transition between the solid and the liquid state in the range from liquid nitrogen to room temperature. Here we focus our attention on the nonlinear response at the second harmonic generated frequency as obtained by impinging with femtosecond high repetition-rate laser pulses on monolayers of Ga nanoparticles (with radii ranging from 6 to 80 nm) embedded in different dielectric matrices, i.e. SiO_x and TiO₂.