Origin of the Fano interference and its tunability with near-field interactions in a guided mode-resonant metasurface

Fuente: arXiv
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Autores principales: Nag, Amitrajit, Basu, Jaydeep K.
Formato: Preprint
Publicado: 2025
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author Nag, Amitrajit
Basu, Jaydeep K.
author_facet Nag, Amitrajit
Basu, Jaydeep K.
contents Asymmetric resonances emerging from the Fano interference are a well-known phenomenon in fields like atomic physics and grating optics, and they have recently started to gain interest in artificially engineered dielectric, metallic, or composite metasurfaces and metamaterials. The guided mode-resonant metasurface belongs to this class with grating-waveguide responses and shows asymmetric resonances. Here, we have theoretically studied the origin of the resonance, finding out the root of the Fano interference. We have followed the ab initio theory derived from the Feshbach formalism for the electromagnetic scattering. We have numerically simulated the metasurface to obtain different field parameters required for the ab initio theory; in this regard, we have used the multipole decomposition of the scattering fields for the induced moments. Motivated by our recent experiments, we have used a planewave and polarized dipole sources to excite the metasurface, and studied subsequent effects, like the resonance redshift and the resonance linewidth narrowing for the metasurface. These happened due to the change of the excitation, and we have numerically quantified them. The change of the excitation source bears the novelty of the work. Thus, it helps comprehend the experimental observations qualitatively. This work could help explain and explore possibilities to observe asymmetric resonances in metasurfaces for various excitation conditions, and the key results of resonance shift and linewidth narrowing could be significant for precision applications and fundamental optical studies.
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id arxiv_https___arxiv_org_abs_2505_06610
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Origin of the Fano interference and its tunability with near-field interactions in a guided mode-resonant metasurface
Nag, Amitrajit
Basu, Jaydeep K.
Optics
Asymmetric resonances emerging from the Fano interference are a well-known phenomenon in fields like atomic physics and grating optics, and they have recently started to gain interest in artificially engineered dielectric, metallic, or composite metasurfaces and metamaterials. The guided mode-resonant metasurface belongs to this class with grating-waveguide responses and shows asymmetric resonances. Here, we have theoretically studied the origin of the resonance, finding out the root of the Fano interference. We have followed the ab initio theory derived from the Feshbach formalism for the electromagnetic scattering. We have numerically simulated the metasurface to obtain different field parameters required for the ab initio theory; in this regard, we have used the multipole decomposition of the scattering fields for the induced moments. Motivated by our recent experiments, we have used a planewave and polarized dipole sources to excite the metasurface, and studied subsequent effects, like the resonance redshift and the resonance linewidth narrowing for the metasurface. These happened due to the change of the excitation, and we have numerically quantified them. The change of the excitation source bears the novelty of the work. Thus, it helps comprehend the experimental observations qualitatively. This work could help explain and explore possibilities to observe asymmetric resonances in metasurfaces for various excitation conditions, and the key results of resonance shift and linewidth narrowing could be significant for precision applications and fundamental optical studies.
title Origin of the Fano interference and its tunability with near-field interactions in a guided mode-resonant metasurface
topic Optics
url https://arxiv.org/abs/2505.06610