Causality Implications for Absorption by EM Metasurfaces

A causal electromagnetic (EM) metasurface is backed by a lossless substrate and partially absorbs obliquely incoming rays. The integral of the absorbed power along the entire frequency axis is analytically evaluated, and the obtained sum rules indicate the global absorption by such a generic configu...

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Main Author: Constantinos Valagiannopoulos
Format: Article
Language:English
Published: MDPI AG 2025-05-01
Series:Nanomaterials
Subjects:
Online Access:https://www.mdpi.com/2079-4991/15/11/793
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author Constantinos Valagiannopoulos
author_facet Constantinos Valagiannopoulos
author_sort Constantinos Valagiannopoulos
collection DOAJ
description A causal electromagnetic (EM) metasurface is backed by a lossless substrate and partially absorbs obliquely incoming rays. The integral of the absorbed power along the entire frequency axis is analytically evaluated, and the obtained sum rules indicate the global absorption by such a generic configuration. The beneficial influence of the plasma frequency and damping factor on the total absorbance score as well as the opposite effect of the angle of excitation, is noted. An overall lossless behavior at the incidence direction where the propagating waves into the substrate turn into evanescent is identified, once the magnetic field is parallel to the interface. The reported results can be useful in the tailoring of spectrally dependent absorption by a whole class of planar structures and, accordingly, in the forward and inverse design of lossy photonic metasurface setups.
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spelling doaj-art-133179db19d54ef48396fc823632aee72025-08-20T02:23:44ZengMDPI AGNanomaterials2079-49912025-05-01151179310.3390/nano15110793Causality Implications for Absorption by EM MetasurfacesConstantinos Valagiannopoulos0School of Electrical & Computer Engineering, National Technical University of Athens, GR-15780 Athens, GreeceA causal electromagnetic (EM) metasurface is backed by a lossless substrate and partially absorbs obliquely incoming rays. The integral of the absorbed power along the entire frequency axis is analytically evaluated, and the obtained sum rules indicate the global absorption by such a generic configuration. The beneficial influence of the plasma frequency and damping factor on the total absorbance score as well as the opposite effect of the angle of excitation, is noted. An overall lossless behavior at the incidence direction where the propagating waves into the substrate turn into evanescent is identified, once the magnetic field is parallel to the interface. The reported results can be useful in the tailoring of spectrally dependent absorption by a whole class of planar structures and, accordingly, in the forward and inverse design of lossy photonic metasurface setups.https://www.mdpi.com/2079-4991/15/11/793absorptioncausalityLorentz oscillatormetasurface
spellingShingle Constantinos Valagiannopoulos
Causality Implications for Absorption by EM Metasurfaces
Nanomaterials
absorption
causality
Lorentz oscillator
metasurface
title Causality Implications for Absorption by EM Metasurfaces
title_full Causality Implications for Absorption by EM Metasurfaces
title_fullStr Causality Implications for Absorption by EM Metasurfaces
title_full_unstemmed Causality Implications for Absorption by EM Metasurfaces
title_short Causality Implications for Absorption by EM Metasurfaces
title_sort causality implications for absorption by em metasurfaces
topic absorption
causality
Lorentz oscillator
metasurface
url https://www.mdpi.com/2079-4991/15/11/793
work_keys_str_mv AT constantinosvalagiannopoulos causalityimplicationsforabsorptionbyemmetasurfaces