Multispectral Non-Hierarchical Metastructures for Radiation Management and Limits of Perfect Absorption

We have designed and experimentally realized an optically transparent, broadband, and polarization-insensitive metastructure. The proposed metastructure demonstrates farfield radiation management capabilities in widely separated electromagnetic regimes, namely, near-perfect absorption of farfield radiation at microwave frequencies and curated emission at infirared wavelengths. The metastructure provides a functional alternative to the hierarchical designs of radar-infrared bi-stealth as it accommodates the contrasting multispectral functionalities in a consolidated configuration. Furthermore, we also look beyond the notions of perfect absorption and highlight the prospects of arbitrarily large power absorption using evanescent fields, provided that we make a transition to the conjugate impedance matching condition.