Efficient and Anisotropic Second Harmonic Generation in Few-Layer SnS Film

Group-IV monochalcogenide ferroelectric materials possess fascinating nonlinear optical properties and electro-optical effects which play a vital role in 2D ferroelectrics, multiferroics and nonlinear optoelectronics. However, the studies of nonlinear optical properties of group-IV monochalcogenides are still in their infancy stage. Herein, the preparation of few-layer SnS by the molecular beam epitaxy (MBE) method is reported and the efficient second harmonic generation (SHG) of SnS monochalcogenide is systematically scrutinized by using ultrafast nonlinear optical spectroscopy. The obtained thickness-dependent SHG is highly related with the coherence length. Second-order nonlinear susceptibility of few-layer SnS is also obtained. Polarization-dependent SHG studies reveal its intrinsic anisotropy pattern and can be utilized to identify the crystalline orientation of few-layer SnS film.

Automated summary

The study reports the preparation of few-layer SnS using the MBE method and systematically investigates its second harmonic generation, showing a close relationship between SHG and thickness as well as coherence length. The research also obtained the second-order nonlinear susceptibility of SnS, and polarization-dependent SHG can be used to identify the crystalline orientation.