Realization of Z₂ Topological Photonic Insulators Made from Multilayer Transition Metal Dichalcogenides

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanophotonics

Background:

• Semiconducting transition metal dichalcogenides (TMDs) possess unique optical and electronic properties.
• Quasi-bulk TMDs offer high refractive indices, optical anisotropy, and transparency for nanophotonics.
• Van der Waals forces enable heterointegration of TMDs for complex photonic structures.

Purpose of the Study:

• To realize topological spin-Hall photonic lattices using WS2 flakes.
• To investigate the optical properties of these engineered nanostructures.
• To demonstrate the potential of TMDs for advanced nanophotonic device fabrication.

Main Methods:

• Fabrication of triangular nanoholes in WS2 flakes via anisotropic dry etching.
• Room temperature reflectance measurements to identify photonic band gaps.
• Circularly polarized laser excitation to observe unidirectional light propagation.
• Finite-difference time-domain (FDTD) simulations for optical analysis.

Main Results:

• Successful creation of topological spin-Hall photonic lattices in WS2.
• Observation of a photonic gap opening in the near-infrared spectrum.
• Demonstration of unidirectional light propagation along domain interfaces.
• Validation of simulation results with experimental optical spectroscopy.

Conclusions:

• WS2-based topological photonic lattices exhibit tunable optical properties.
• The study confirms the feasibility of using TMDs for complex nanophotonic devices.
• This work highlights the potential of van der Waals materials for future photonic technologies.