Origin of Second Harmonic Generation from individual Silicon Nanowires

TL;DR

This study explores how resonant optical modes influence second harmonic generation in individual silicon nanowires, revealing size-dependent polarization behavior and different origins based on incident light polarization.

Contribution

It uncovers the size-dependent polarization behavior of SHG in silicon nanowires and distinguishes the different origins of SHG based on incident polarization, advancing understanding of nonlinear processes in nanostructures.

Findings

SHG polarization depends on nanowire size

Different SHG origins for parallel and perpendicular polarization

Resonant optical modes significantly influence SHG

Abstract

We investigate Second Harmonic Generation from individual silicon nanowires and study the influence of resonant optical modes on the far-field nonlinear emission. We find that the polarization of the Second Harmonic has a size-dependent behavior and explain this phenomenon by a combination of different surface and bulk nonlinear susceptibility contributions. We show that the Second Harmonic Generation has an entirely different origin, depending on whether the incident illumination is polarized parallel or perpendicularly to the nanowire axis. The results open perspectives for further geometry-based studies on the origin of Second Harmonic Generation in nanostructures of high-index centrosymmetric semiconductors.