Chirality-Dependent Second Harmonic Generation of MoS<sub>2</sub> Nanoscroll with Enhanced Efficiency.

Qian, Qingkai; Zu, Rui; Ji, Qingqing; Jung, Gang Seob; Zhang, Kunyan; Zhang, Ye; Buehler, Markus J; Kong, Jing et al. · ACS Nano · 2020

basic_science · Level V

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Abstract

Materials with high second harmonic generation (SHG) efficiency and reduced dimensions are favorable for integrated photonics and nonlinear optical applications. Here, we fabricate MoS<sub>2</sub> nanoscrolls with different chiralities and study their SHG performances. As a 1D material, MoS<sub>2</sub> 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. MoS<sub>2</sub> nanoscrolls with certain chiralities and diameters in our experiment can have SHG intensity up to 95 times stronger than that of monolayer MoS<sub>2</sub>, 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 WS<sub>2</sub>, WSe<sub>2</sub>, 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.