We report observation of strong and anisotropic third harmonic generation (THG) in monolayer and multilayer ReS2. The third-order nonlinear optical susceptibility of monolayer ReS2, χ(3) is on the order of 10−18 m2/V2, which is about one order of magnitude higher than reported results for hexagonal-lattice transition metal dichalcogenides such as MoS2. A similar magnitude for the third-order nonlinear optical susceptibility was also obtained for a multilayer sample. The intensity of the THG field was found to be dependent on the direction of the incident light polarization for both monolayer and multilayer samples. A point group symmetry analysis shows that such anisotropy is not expected from a perfect 1T lattice, and must arise from the distortions in the ReS2 lattice. Our results show that THG measurements can be used to characterize lattice distortions of two-dimensional materials, and that lattice distortions are important for the nonlinear optical properties of such materials.
@article{arxiv.1612.03228,
title = {Strong and Anisotropic Third Harmonic Generation in Monolayer and Multilayer ReS$_2$},
author = {Qiannan Cui and Rodrigo A. Muniz and J. E. Sipe and Hui Zhao},
journal= {arXiv preprint arXiv:1612.03228},
year = {2017}
}