Enhanced second order nonlinearity using plasmonic resonance of nano-scale metallic cut-wires

Abstract

In this paper, we study quantitatively the enhanced second harmonic generation from periodic array of nano-scale golden cut-wires embedded in nonlinear dielectric. Geometrical parameters of this structure are varied so that the plasmonic resonance occurs in the wavelength of Nd:YAG laser (1064 nm), which its second-harmonic (with the wavelength 532 nm) is usually used in optical devices. Plasmonic resonance of these structures gives rise to the localization factor more than two times larger than that of the cut-wire structures with no plasmonic resonance. After then, surrounding medium of the cut-wire is considered a typical second-order nonlinear optical medium. In order to show the enhancement of the nonlinearity, unit cell of the cut-wires embedded in nonlinear medium is considered a homogeneous nonlinear medium with the effective nonlinear susceptibility. Nonlinear retrieval method, which is based on the transfer matrix approach, is used to determine the effective nonlinear susceptibility. The obtained results show the enhancement of the effective nonlinear susceptibility two orders of magnitude larger compared to the susceptibility of the embedding nonlinear dielectric. Efficiency of the second harmonic generation in these resonant structures surrounded with nonlinear dielectric is calculated to be 20 times more than that of the nonlinear dielectric with the same dimensions.