Predicting microwave resonances in aqueous spheroids with a standing-wave approach
Phys. Rev. A 111, 063522 – Published 23 June, 2025
DOI: https://doi.org/10.1103/ljgk-x9cj
Abstract
High-index dielectric materials are promising candidates for photonic technologies that rely on enhanced light-matter interactions. Nanophotonic applications have been hindered by a lack of high-index transparent dielectrics in the visible regime. Despite its low index of refraction at visible wavelengths, water exhibits an index approaching 9 at 2.5 GHz, making it a promising model material for studying morphology-dependent resonances in centimeter-scale objects. Such Mie scattering resonances are well characterized in spheres but are much less understood in spheroids because of the mathematical complexity of multipolar expansions in spheroidal geometries. In this work we combine analytical, numerical, and finite-element methods to study microwave resonances in aqueous spheroids. We obtain three-dimensional standing-wave solutions in aqueous spheroids and show that this conceptually simple description of electromagnetic resonances maps surprisingly well onto the complex resonant landscape of certain spheroidal modes, as elucidated by finite-element simulations. In the process, we identify some size and shape regimes that yield uniquely intense spheroidal resonances.
