Surface second-harmonic generation in Au:TiO

The Surface Second-Harmonic Generation (SSHG) in Au:TiO2 thin films of nanocermets is studied with samples of different metallic volume fractions using an IR Nd:YAG pulsed laser. We worked in a reflection geometry by varying the incidence angle and the directions of the incident beam polarization and of an analyzer of the Second Harmonic beam. We show that the SH signal is not due to electric dipolar processes only but can be treated within the general a, b, and d formalism where surfaces and bulk SH currents are well distinguished, and by describing the dielectric function of cermets within the effective-medium theory. The effective values obtained for a, b, and d are attributed to gold but the rather small discrepancies between them and those given by models are understandable by the fact that our samples are heterogeneous and not semi-infinite