Realization of Z$_2$ topological photonic insulators made from multilayer transition metal dichalcogenides

• DOI: 10.48550/arxiv.2407.05908
• Publication Date: 2024-07-08
• Authors: Tommi Isoniemi; Paul Bouteyre; Xuerong Hu; Fedor A. Benimetskiy; Yue Wang; M. S. Skolnick; D. N. Krizhanovskii; A. I. Tartakovskii
• Keywords: Realization (probability); Topological insulator

Monolayers of semiconducting transition metal dichalcogenides (TMDs) have long attracted interest for their intriguing optical and electronic properties. Recently TMDs in quasi-bulk form started to show considerable promise nanophotonics thanks high refractive indices, large anisotropy, wide transparency windows reaching the visible, robust room temperature excitons promising nonlinear optics. Adherence TMD layers any substrate via van der Waals forces is a further key enabler nanofabrication sophisticated photonic structures requiring heterointegration. Here, we capitalize on these attractive properties realize topological spin-Hall lattices made arrays triangular nanoholes 50 100 nm thick WS$_2$ flakes exfoliated SiO$_2$/Si substrates. High quality are achieved taking advantage anisotropic dry etching dictated by crystal axes WS$_2$. Reflectance measurements at gap opening near-infrared trivial phases. Unidirectional propagation along domain interface demonstrated real space circularly polarized laser excitation samples with both zigzag armchair boundaries. Finite-difference time-domain simulations used interpret spectroscopy results. Our work opens way future nanophotonic devices based layered (van Waals) materials platform.