Nonlinear optical characteristics of monolayer MoSe₂

Abstract

In this study, we utilized picosecond pulses from an Nd:YAG laser to investigate the nonlinear optical characteristics of monolayer MoSe 2 . Two‐step growth involving the selenization of pulsed‐laser‐deposited MoO 3 film was employed to yield the MoSe 2 monolayer on a SiO 2 /Si substrate. Raman scattering, photoluminescence (PL) spectroscopy, and atomic force microscopy verified the high optical quality of the monolayer. The second‐order susceptibility χ (2) was calculated to be ∼50 pm V −1 at the second harmonic wavelength ∼810 nm, which is near the optical gap of the monolayer. Interestingly, our wavelength‐dependent second harmonic scan can identify the bound excitonic states including negatively charged excitons much more efficiently, compared with the PL method at room temperature. Additionally, the MoSe 2 monolayer exhibits a strong laser‐induced damage threshold ∼16 GW cm −2 under picosecond‐pulse excitation . Our findings suggest that monolayer MoSe 2 can be considered as a promising candidate for high‐power, thin‐film‐based nonlinear optical devices and applications.