Intrinsic multipolar contents of nanoresonators for tailored scattering
Abstract
We introduce a theoretical and computational method to design resonant objects, such as nanoantennas or meta-atoms, exhibiting tailored multipolar responses. In contrast with common approaches that rely on a multipolar analysis of the scattering response of an object upon specific excitations, we propose to engineer the \textit{intrinsic} (i.e., excitation-independent) multipolar content and spectral characteristics of the natural resonances -- or quasinormal modes -- of the object. A rigorous numerical approach for the multipolar decomposition of resonances at complex frequencies is presented, along with an analytical model conveying a direct physical insight into the multipole moments induced in the resonator. Our design strategy is illustrated by designing a subwavelength optical resonator exhibiting a Janus resonance that provides side-dependent coupling to waveguides over the full linewidth of the resonance and on a wide angular range for linearly-polarized incident planewaves. The method applies to all kinds of waves and may open new perspectives for subwavelength-scale manipulation of scattering and emission.
Keywords
Cite
@article{arxiv.1907.04598,
title = {Intrinsic multipolar contents of nanoresonators for tailored scattering},
author = {Tong Wu and Alexandre Baron and Philippe Lalanne and Kevin Vynck},
journal= {arXiv preprint arXiv:1907.04598},
year = {2020}
}