Nonlinear Optical Properties of Vertically-Aligned MoS2 Nanosheets

This paper deals with the nonlinear optical (NLO) response of vertically-aligned MoS2 (VA-MoS2) nanosheets on a quartz substrate prepared by chemical vapor deposition (CVD). Scanning electron microscopy confirmed that VA-MoS2 nanosheets were grown in specific experimental conditions. X-ray diffraction, Raman, and UV-Vis spectroscopies indicated the high-quality crystalline nature of the 2H-MoS2 prototype with excitonic features. The NLO characterization of the VA-MoS2 sample was performed by a Z-scan optical setup in the visible region (lambda = 532 nm). Our VA-MoS2 sample exhibited a highly unpredictable nonlinear refractive index (similar to 10-5 cm(2) W-1) and nonlinear absorption coefficient (similar to 1 cm W-1), suggesting its potential applications in nonlinear optical devices. It was shown that free-carrier nonlinearity may have contributed to the observed enhanced nonlinear optical properties.