Supercavity mode in a single metallic resonator

Bound states in the continuum are exotic nonradiating modes with very high quality factors enabling enhanced wave-matter interactions. While they typically require array-type of systems, versions of such states have been reported in single dielectric resonators, giving rise to suppressed scattering states termed supercavity modes. In this work, we experimentally demonstrate a supercavity mode in an all-metallic resonator open for probing by free-space microwaves. Our design exploits careful tailoring of the boundaries around the resonator, which supports an octupole mode fostering a significant increase in the quality factor. The main advantage of the resonator is its simplicity and robustness, and it may be utilized as a stand-alone unit for energy harvesting and sensing or as an element for advanced functional material designs.

Automated summary

In this work, we present an experimental demonstration of a supercavity mode in an all-metallic resonator open for probing by free-space microwaves. By careful tailoring of the boundaries around the resonator, we were able to significantly increase the quality factor, making it suitable for energy harvesting, sensing, and advanced functional material designs.