Enhancement of optical switching parameter and third-order optical nonlinearities in embedded Si nanocrystals: a theoretical assessment

TL;DR

This paper provides a theoretical analysis of third-order nonlinear optical properties of silicon nanocrystals embedded in silica, revealing size-dependent enhancements in nonlinearities and optical switching capabilities.

Contribution

It introduces a detailed atomistic pseudopotential model to evaluate nonlinearities in Si nanocrystals, highlighting size effects on optical properties.

Findings

Si nanocrystals exhibit higher third-order nonlinearities than bulk silicon.

Wider two-photon absorption threshold in nanocrystals enhances optical switching.

Size up to 3 nm significantly influences nonlinear optical responses.

Abstract

Third-order bound-charge electronic nonlinearities of Si nanocrystals (NCs) embedded in a wide band-gap matrix representing silica are theoretically studied using an atomistic pseudopotential approach. Nonlinear refractive index, two-photon absorption and optical switching parameter are examined from small clusters to NCs up to a size of 3 nm. Compared to bulk values, Si NCs show higher third-order optical nonlinearities and much wider two-photon absorption threshold which gives rise to enhancement in the optical switching parameter.