Surface plasmon resonance enhanced second-harmonic generation in Kretschmann configuration

• Published in: Optics communications 2005-04, Vol.248 (1-3), p.249-256
• Main Authors: Naraoka, Ryo, Okawa, Haruki, Hashimoto, Kazuhiko, Kajikawa, Kotaro
• Format: Article
• Language: English
• Subjects: Exact sciences and technology; Frequency conversion; harmonic generation, including high-order harmonic generation; Fundamental areas of phenomenology (including applications); Kretschmann geometry; Nonlinear optics; Optics; Physics; Second-harmonic generation; Surface plasmon resonance; Thin gold film
• ISSN: 0030-4018; 1873-0310
• DOI: 10.1016/j.optcom.2004.11.094

We report second-harmonic generation (SHG) from a thin gold film at surface plasmon resonance (SPR) in an attenuated total reflection (ATR) geometry having the Kretschmann configuration. The SHG intensity was observed to be 350–400 larger than the reflected SHG intensity in the Fresnel reflection geometry at the surface of the thin gold film. A similar enhancement was observed in the case of a thin gold film covered with a hemicyanine monolayer. These results suggest that the SHG source of the thin gold film is located outside this film. Simulation based on this model yields an enhancement factor of ∼285, in agreement with the experimental results, whereas the simulation supposing that the SHG source is located inside the gold thin film gives a factor of over 6000. This model is consistent with a hydrodynamic model of SHG in a metal, in which the nonlinear current runs outside the bulk metal and the electron density penetrates from the metal to the air at their interface.