Surface-enhanced optical third-harmonic generation in Ag island films

TL;DR

This paper reports significant enhancement of third-harmonic generation in silver island films due to local plasmon resonance, highlighting the role of nanoparticle morphology in nonlinear optical processes.

Contribution

It demonstrates a two-order magnitude enhancement of THG in silver nanoparticles and links this to plasmonic effects and local field resonance at the third-harmonic wavelength.

Findings

THG intensity is enhanced by over 100 times in Ag island films.

Enhancement is due to local plasmon excitation and resonance.

Diffuse, depolarized THG linked to hyper-Rayleigh scattering.

Abstract

Surface-enhanced optical third-harmonic generation (THG) is observed in silver island films. The THG intensity from Ag nanoparticles is enhanced by more than two orders of magnitude with respect to the THG intensity from a smooth and homogeneous silver surface. This enhancement is attributed to local plasmon excitation and resonance of the local field at the third-harmonic wavelength. The diffuse and depolarized component of the enhanced THG is associated with the third-order hyper-Rayleigh scattering in a 2-D random array of silver nanoparticles.