Chirality-Dependent Second Harmonic Generation of MoS2 Nanoscroll with Enhanced Efficiency

Materials with high second harmonic generation (SHG) efficiency and reduced dimensions are favorable for integrated photonics and nonlinear optical applications. Here, we fabricate MoS₂ nanoscrolls with different chiralities and study their SHG performances. As a 1D material, MoS₂ nanoscroll shows reduced symmetry and strong chirality dependency in the polarization-resolved SHG characterizations. This SHG performance can be well explained by the superposition theory of second harmonic field of the nanoscroll walls. MoS₂ nanoscrolls with certain chiralities and diameters in our experiment can have SHG intensity up to 95 times stronger than that of monolayer MoS₂, and the full potential can still be further exploited. The same chirality-dependent SHG can be expected for nanoscrolls or nanotubes composed of other noncentrosymmetric 2D materials, such as WS₂, WSe₂, and hBN. The characterization and analysis results presented here can also be exploited as a nondestructive technique to determine the chiralities of these nanoscrolls and nanotubes.