Rotational Metamaterials: Acoustic and Electromagnetic applications

Abstract

In recent years, metasurfaces have rapidly become a key research area in both theoretical and applied electromagnetics and acoustics. This thesis details our work on creating innovative metasurfaces to manipulate electromagnetic and acoustic waves across various frequencies. Rotation is vital for metamaterials as it precisely alters their structure, allowing fine-tuning of electromagnetic properties and enhancing wave control. In this thesis, we apply rotation to metamaterials to discover important applications. The first project introduces a reconfigurable, ultra-sparse ventilated metamaterial absorber for low frequencies, offering effective sound absorption for acoustic engineering and consumer electronics. The second project explores a microwave metasurface that positions the type-II Dirac point in a general location within reciprocal space. The third project involves a metasurface that generates a synthetic dimension in reciprocal space. The fourth project focuses on acoustic applications, featuring a metamaterial absorber with a lamina shape that uses the coherent coupling of weak resonances in Helmholtz resonators. This design allows broadband tunable absorption, achieving over 0.9 peak absorption while maintaining almost complete ventilation.

Date of Award	2025
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology
Supervisor	Bo HOU (Supervisor) & Xiaoxiao Wu (Supervisor)