Second-harmonic generation from silver and aluminum films in total internal reflection

Abstract

We have measured optical second-harmonic generation (SHG) in the total-internal-reflection regime from opaque silver and aluminum films. A recent hydrodynamic theory of SHG from metal surfaces by Sipe shows that at large angles of incidence the SHG in total internal reflection will be sensitive to the normal component of the harmonic surface current. We find that the phenomenological parameter a which estimates the size of this normal component has a value of 0.9 for silver and 1.5 for aluminum. By calibrating the reflected SHG from the opaque metal films to the transmitted SHG from quartz we determine that the theoretical and experimental conversion factors for reflected SHG agree to within 20% for silver and 40% for aluminum. For thin metal films we observe new interference structure in the wings of the surface-plasmon resonance, which also is in good agreement with the theory. We conclude that for incident 1.06-μm radiation the SHG from silver and aluminum films is well described by Sipe’s hydrodynamic model.