Second- and third-order optical susceptibilities in bidimensional semiconductors near excitons states

TL;DR

This paper investigates the nonlinear optical properties of monolayer TMD semiconductors near exciton states using SHG and FWM spectroscopy, revealing enhanced susceptibilities and potential for optoelectronic applications.

Contribution

It provides new measurements of second- and third-order optical susceptibilities in TMD monolayers near exciton energies, demonstrating their nonlinear optical capabilities.

Findings

Trions and excitons enhance nonlinear response.

Extracted susceptibilities align with literature.

Generated diverse nonlinear effects in visible spectrum.

Abstract

Semiconducting Transition Metal Dichalcogenides (TMDs) have significant nonlinear optical effects. In this work we have used second-harmonic generation (SHG) and the four-wave mixing (FWM) spectroscopy in resonance with the excitons in MoS2, MoSe2, and WS2 monolayers to characterize the nonlinear optical properties of these materials. We show that trions and excitons are responsible for enhancing the nonlinear optical response, and determine the exciton and trion energies by comparing with the photoluminescence spectra. Moreover, we extract the second and third order optical sheet susceptibility near exciton energies and compare with values found in the literature. We also demonstrate the ability to generate different nonlinear effects in a wide spectral range in the visible region for monolayer MoS2, opening the possibility of using two-dimensional materials for nonlinear optoelectronic and photonic applications.