Third-order polarizability of interlayer excitons in heterobilayers

Abstract

In this paper, we employ a fully microscopic approach to the study of interlayer excitons in heterobilayers. We use Fowler's and Karplus' method to access the dynamical polarizability of noninteracting interlayer excitons in a WSe2/WS2-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 WSe2/WS2 heterobilayer, discussing the various selection rules of intraexcitonic energy level transitions.