Precise Nanoruler for Retrieving Asymmetry of Fano-Resonant Metasurfaces by Second-Harmonic Generation

Abstract

Achieving geometric parameters at the nanoscale is highly desired in the applications including sensing and measurement. We demonstrate that second-harmonic generation (SHG) can be a very useful tool to quantitatively reflect the structural asymmetry of Fano metasurfaces with high sensitivity. A horizontal shift of the nanobar as small as 10 nm leads to a 13% change in our proposed SHG intensity ratio, which is clearly observable.