Work

Continuous modal spectrum in nonreciprocal cavities [Invited]

Year: 2026

Type: article

Abstract: Nonreciprocal systems enable asymmetric energy transport and suppress backscattering, giving rise to unconventional wave phenomena. Here, we show that nonreciprocal cavities based on unidirectional waveguides exhibit a continuous modal spectrum, in contrast to conventional cavities with discrete eigenmodes. Using a ferrite-loaded microwave cavity as an example, we demonstrate that enforcing unidirectionality, by tailoring the waveguide geometry, drives a transition from discrete to continuous spectra, accompanied by strong spatial localization of electromagnetic fields. Our results reveal that dissipation alone fails to regularize these singular responses, highlighting the need for additional mechanisms to control localization in nonreciprocal systems.

Source: Optical Materials Express

DOI: 10.1364/ome.609553

Authors: Filipa R. Prudêncio, David E. Fernandes, Mário G. Silveirinha

Language: English

Topic: Metamaterials and Metasurfaces Applications

Subfield: Electronic, Optical and Magnetic Materials

Field: Materials Science

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $1,843

Funders: Science Foundation Ireland, Instituto de Telecomunicações, Fundação para a Ciência e a Tecnologia