Enhanced second-harmonic generation from WS$_2$/ReSe$_2$ heterostructure
Abstract
Van der Waals stacking presents new opportunities for nonlinear optics with its remarkable tunability and scalability. However, the fundamental role of interlayer interactions in modifying the overall nonlinear optical susceptibilities remains elusive. In this letter, we report an anisotropic enhancement of second-harmonic generation (SHG) from a WS/ReSe heterobilayer, where the individual composite layers possess distinctive crystal phases. We investigate polarization-resolved response and twist-angle dependence in SHG and reveal that band alignment alone is insufficient to explain the observed anisotropy in the modified SHG response. Spectral shifts in excitonic features highlight band renormalization, supporting the role of hybridization between the two layers. Furthermore, SHG enhancement is highly anisotropic and can even be suppressed in some orientations, suggesting possible intensity-borrowing mechanisms within the heterostructure. Our work demonstrates the ability to tune both the intensity and polarization dependence of nonlinear optical responses with van der Waals stacking of distinctive crystal phases.
Cite
@article{arxiv.2509.03491,
title = {Enhanced second-harmonic generation from WS$_2$/ReSe$_2$ heterostructure},
author = {Kanchan Shaikh and Taejun Yoo and Zeyuan Zhu and Qiuyang Li and Amalya C. Johnson and Hui Deng and Fang Liu and Yuki Kobayashi},
journal= {arXiv preprint arXiv:2509.03491},
year = {2026}
}