Third-order polarizability of interlayer excitons in hetero-bilayers

TL;DR

This paper presents a microscopic study of the third-order polarizability of interlayer excitons in hetero-bilayers, focusing on nonlinear optical processes like two-photon absorption and third-harmonic generation.

Contribution

It introduces a fully microscopic approach using Fowler's, Karplus', and Svendsen's methods to analyze nonlinear optical properties of interlayer excitons in hetero-bilayers.

Findings

Calculated dynamical polarizability of interlayer excitons.

Analyzed two-photon absorption and third-harmonic generation.

Discussed selection rules for intra-excitonic transitions.

Abstract

In this paper, we employ a fully microscopic approach to the study of interlayer excitons in hetero-bilayers. We use Fowler's and Karplus' method to access the dynamical polarizability of non--interacting interlayer excitons in a $\mathrm{WSe}_{2}/\mathrm{WS}_{2}$--based van der Waals heterostructure. Following from the calculation of the linear polarizability, we consider Svendsen's variational method to the calculation of the dynamic third--order polarizability. With this variational method, we study both two--photon absorption and third--harmonic generation processes for interlayer excitons in a $\mathrm{WSe}_{2}/\mathrm{WS}_{2}$ hetero--bilayer, discussing the various selection rules of intra--excitonic energy level transitions.