Frequency Dependent Localization Wave in Topological Waveguide by Geometry Engineering

A study conducted by Keita Funayama et al. was published in the Communications Physics.

Topological artificial crystals can exhibit one-way wave-propagation along the boundary with the wave being localized perpendicular to the boundary. The control of localization of such topological wave propagation is of great importance for enhancing coupling or avoiding unwanted coupling among neighboring boundaries toward topological integrated circuits. However, the effect of the geometry of topological boundaries on localization properties is not yet fully clear.

This work investigated valley-topological transport on representative valley-topological boundaries with micro-electro-mechanical systems. We showed that the zigzag and bridge boundaries, which have highly efficient wave transport, exhibit frequency independent and dependent wave localization, respectively. A simple analytic model is presented to systematically describe the frequency-dependent and independent wave behaviors by conventional exponential decay function and gaussian function. Our results provide opportunities to engineer frequency responses in topological circuits including frequency selective couplers through proper design of boundary geometries.

Title: Quantum Valley Hall Effect-based Topological Boundaries for Frequency-dependent and -independent Mode Energy Profiles
Authors: Funayama, K., Yatsugi, K., Iizuka, H.
Journal Name: Communications Physics
Published: December 19, 2024
https://doi.org/10.1038/s42005-024-01899-w