Effect of laser illumination on the morphology and optical property of few-layer MoS2 nanosheet in NMP and PMMA

Abstract

Two-dimensional (2D) materials and laser interaction is a very important research topic due to the unique properties of 2D materials, making them a promising candidate for high-power applications such as optical limiters and saturable absorbers for mode locking laser generation. In this paper, we have analysed the morphology and optical property changes of few-layer molybdenum disulfide (MoS₂) nanosheet in NMP solution under the illumination of a Q-switched laser with operational wavelength of 532 and 1064 nm with respect to various laser energy densities. The experimental results show significant changes caused by the oxidization of MoS₂ into molybdenum oxide (MoO₃). Due to the stronger absorption in the visible range, the 532 nm wavelength has a stronger oxidization effect than the 1064 nm illumination wavelength. The nonlinear optical absorption properties of MoS₂ in liquid NMP and in solid PMMA have been studied by using the z-scan technique and the results are compared. It has been shown experimentally that the nonlinear optical absorption properties of MoS₂ in NMP disappeared but without changes in MoS₂/PMMA composites after laser illumination. This confirms that MoS₂ is much more stable within PMMA for preserving nonlinear absorption properties under high laser density illumination.