Near bandgap second-order nonlinear optical characteristics of MoS2 monolayer transferred on transparent substrates

Abstract

We have investigated the second-order nonlinear optical (NLO) properties of CVD-grown MoS2 monolayer (ML) transferred onto transparent substrates such as fused silica and polyethylene terephthalate. The physical properties of the transferred MLs were characterized by optical and NLO methods. We measured the second-order susceptibility χ(2) in the spectral range of λ= 1064–1600 nm in which the corresponding second harmonic radiation resonates with the exciton levels. It was found that χ(2) is strongly enhanced by up to a factor of 5 near the A- and B-exciton levels due to two-photon resonance. The absolute χ(2) values of our samples determined by both reflection and transmission geometry are on par with that of as-grown MLs. Our results imply that the cavity-confinement scheme can be employed for maximizing the nonlinear optical efficiency of atomically thin transition metal dichalcogenides for transparent/flexible optoelectronics applications, especially when oriented stacking of transferred MLs are controllable.