Monolayer transition metal dichalcogenide (TMD) semiconductors such as MoSe2 host strongly bound excitons which are known to exhibit a strong resonant third-order nonlinear response. Although there have been numerous studies of the ultrafast nonlinear response of monolayer TMDs, a study of the steady-state nonlinear response is lacking. We report a comprehensive study of the steady-state two-color nonlinear response of excitons in hBN-encapsulated monolayer MoSe2 at 7 K. We observe differential transmission (DT) signals associated with the neutral and charged exciton species, which is strongly dependent on the polarization of the pump and probe. Our results are compared to a theoretical model based on a T-matrix formulation for exciton-exciton, exciton-trion, and trion-trion correlations. The parameters are chosen such that the theory accurately reproduces the experimental DT spectrum, which is found to be dominated by two-exciton correlations without strong biexciton binding, exciton-trion attractive interactions, and strong spin mixing through incoherent relaxation.
@article{arxiv.2109.12160,
title = {Steady-state nonlinear optical response of excitons in monolayer MoSe$_2$},
author = {Muhed S. Rana and Joshua R. Hendrickson and Christopher E. Stevens and Michael R. Koehler and David G. Mandrus and Takashi Taniguchi and Kenji Watanabe and Nai H. Kwong and Rolf Binder and John R. Schaibley},
journal= {arXiv preprint arXiv:2109.12160},
year = {2021}
}