Anisotropic Second Harmonic Generation From Monocrystalline Gold Flakes

TL;DR

This paper demonstrates that monocrystalline gold flakes exhibit polarization-dependent second-harmonic generation, providing a non-destructive method to characterize crystal quality and orientation in nanoscale plasmonic devices.

Contribution

It reveals the anisotropic nonlinear optical response of monocrystalline gold, highlighting its potential for directional enhancement and characterization of crystal orientation.

Findings

Polarization dependence observed in SHG from {111} gold surface

Absence of polarization dependence in polycrystalline films

Potential for rapid, non-destructive crystal characterization

Abstract

Noble metals with well-defined crystallographic orientation constitute an appealing class of materials for controlling light-matter interactions on the nanoscale. Nonlinear optical processes, being particularly sensitive to anisotropy, are a natural and versatile probe of crystallinity in nano-optical devices. Here we study the nonlinear optical response of monocrystalline gold flakes, revealing a polarization dependence in second-harmonic generation from the {111} surface that is markedly absent in polycrystalline films. Apart from suggesting an approach for directional enhancement of nonlinear response in plasmonic systems, we anticipate that our findings can be used as a rapid and non-destructive method for characterization of crystal quality and orientation that may be of significant importance in future applications.