Abstract

Metal nanostructures have recently gained significant attention in nanophotonics, and play an important role in applications such as biosensing, imaging, and solar cells [1-3]. The optical properties of metal nanostructures are governed by plasmon resonances, which can give rise to high local electromagnetic fields near surfaces. The latter greatly enhance nonlinear optical phenomena, like second-harmonic generation (SHG). The spectral locations of the resonances are governed by the metal structure itself and the optical properties of the surrounding medium, and thus a dielectric coating on the nanostructure can shift the plasmon resonance [4]. In this paper we show that a thin layer of titanium dioxide (TiO₂) can be used to strongly enhance the second-order nonlinearity of silver nanoisland films through the spectral shift of a plasmon resonance.

© 2015 IEEE