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Main Authors: Bau, Enrico, Aigner, Andreas, Biechteler, Jonas, Heimig, Connor, Goelz, Thorsten, Maier, Stefan A., Tittl, Andreas
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2502.13941
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author Bau, Enrico
Aigner, Andreas
Biechteler, Jonas
Heimig, Connor
Goelz, Thorsten
Maier, Stefan A.
Tittl, Andreas
author_facet Bau, Enrico
Aigner, Andreas
Biechteler, Jonas
Heimig, Connor
Goelz, Thorsten
Maier, Stefan A.
Tittl, Andreas
contents We introduce a platform to achieve ultra-strong coupling (USC) between light and matter using widely available materials. USC is a light-matter interaction regime characterized by coupling strengths exceeding 10% of the ground state energy. It gives rise to novel physical phenomena, such as efficient single-photon coupling and quantum gates, with applications in quantum sensing, nonlinear optics, and low-threshold lasing. Although early demonstrations in plasmonic systems have been realized, achieving USC in dielectric platforms, which offer lower losses and high Q-factors, remains challenging due to typically low mode overlap between the photonic field and the material resonance. Here we leverage dielectric dual gradient metasurfaces supporting quasi-bound states in the continuum to spatially encode both the spectral and coupling parameter space and demonstrate USC to an epsilon-near-zero (ENZ) mode in an ultra-thin SiO2 layer. The strong out-of-plane electric fields in our tapered bar structure overlap exceptionally well with those of the ENZ mode, resulting in a normalized coupling strength of 0.101 and a mode splitting equivalent to 20% of the ENZ mode energy; a four- to five-fold increase compared to previous approaches. The strong field confinement of our approach opens new possibilities for compact and scalable polaritonic devices, such as tunable frequency converters and low-energy optical modulators.
format Preprint
id arxiv_https___arxiv_org_abs_2502_13941
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Spatially Encoded Polaritonic Ultra-Strong Coupling in Gradient Metasurfaces with Epsilon-Near-Zero Modes
Bau, Enrico
Aigner, Andreas
Biechteler, Jonas
Heimig, Connor
Goelz, Thorsten
Maier, Stefan A.
Tittl, Andreas
Optics
Materials Science
Applied Physics
We introduce a platform to achieve ultra-strong coupling (USC) between light and matter using widely available materials. USC is a light-matter interaction regime characterized by coupling strengths exceeding 10% of the ground state energy. It gives rise to novel physical phenomena, such as efficient single-photon coupling and quantum gates, with applications in quantum sensing, nonlinear optics, and low-threshold lasing. Although early demonstrations in plasmonic systems have been realized, achieving USC in dielectric platforms, which offer lower losses and high Q-factors, remains challenging due to typically low mode overlap between the photonic field and the material resonance. Here we leverage dielectric dual gradient metasurfaces supporting quasi-bound states in the continuum to spatially encode both the spectral and coupling parameter space and demonstrate USC to an epsilon-near-zero (ENZ) mode in an ultra-thin SiO2 layer. The strong out-of-plane electric fields in our tapered bar structure overlap exceptionally well with those of the ENZ mode, resulting in a normalized coupling strength of 0.101 and a mode splitting equivalent to 20% of the ENZ mode energy; a four- to five-fold increase compared to previous approaches. The strong field confinement of our approach opens new possibilities for compact and scalable polaritonic devices, such as tunable frequency converters and low-energy optical modulators.
title Spatially Encoded Polaritonic Ultra-Strong Coupling in Gradient Metasurfaces with Epsilon-Near-Zero Modes
topic Optics
Materials Science
Applied Physics
url https://arxiv.org/abs/2502.13941