Preparation and characterization of few-layer MoS2 nanosheets and their good nonlinear optical responses in the PMMA matrix

Abstract

Due to the relatively weak van der Waals (VDW) force between interlayers, few-layer MoS₂ nanosheets are prepared using a simple ultrasonic exfoliation method and incorporated into PMMA. The good nonlinear optical (NLO) property of the MoS₂/PMMA composite for the nanosecond pulsed laser at both 532 and 1064 nm has been first reported. The size, thickness and atomic structure of MoS₂ nanosheets have been characterized by transmission electron microscopy (TEM) and atomic force microscopy (AFM). The interesting dependence of interlayer separation with respect to the layer number of MoS₂ has been successfully quantified. The average interlayer separation of the MoS₂ nanosheets increases and deviates much from the theoretical value with reducing the layer number. Such few-layer MoS₂ nanosheets have been homogeneously incorporated into solid-state PMMA, which shows low optical limiting thresholds, 0.4 and 1.3 J cm⁻², and low limiting differential transmittance (T_C), 2% and 3% for the nanosecond laser operating at 532 nm and 1064 nm, respectively. The results suggest that MoS₂ nanosheet incorporated PMMA is a promising candidate of the solid NLO material for optical limiting applications.