Linear and nonlinear optical characterization of Ga nanoparticle monolayers

Single layers of quasi-spherical metal nanoparticles of uniform and controlled size were fabricated by evaporation–condensation in ultrahigh vacuum, exploiting the partial wetting of Ga with respect to the underlying SiOx matrix. The net linear and nonlinear optical response of such self-assembled liquid Ga nanoparticles was determined using CW optical methods as well as pulsed laser excitation. Second, harmonic generation was observed in transmission using femtosecond laser pulses. The fluence, polarization and azimuth angle dependence as well as the second-harmonic (SH) signal dependence on particle size are presented and discussed.