Revealing antenna-molecule coupling using virtual gain from synthetic complex frequency analysis
Abstract
Synthetic complex frequency waves (CFWs) enhance spectral and spatial resolution by compensating loss through virtual gain. This approach is particularly useful in nano-photonics where loss is intrinsically linked to strong field confinement and system size. Here, we apply CFWs to metasurfaces composed of Fano-resonant plasmonic antennas with lithographically tunable coupling between the weak and strong coupling regimes and where loss may be reduced to the Drude damping limit. We quantitatively assess the impact of the virtual gain to find that, while reducing loss, internal coupling rates remain invariant. While the exceptional point associated with strong light-matter coupling is invariant under virtual gain, the cooperativity of Fano interference is enhanced. When the metasurfaces are functionalised with a molecular monolayer, CFWs are thus able to reveal a molecule's vibrational modes, even when obscured by loss, and allow direct extraction of the plasmon-molecule coupling strength. We thus use CFW analysis as a quantitative tool for revealing and assessing light matter-coupling.
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BibTeX
@misc{millard2026revealing,
title = {{Revealing antenna-molecule coupling using virtual gain from synthetic complex frequency analysis}},
author = {Toby Severs Millard and Xiaofei Xiao and Mayela Romero-Gómez and Tom Aktaş-Vincent and Nathaniel J. Huáng and Chris C. Phillips and Stefan A. Maier and Olga Kazakova and Rupert F. Oulton},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2608.30146},
eprint = {2608.30146},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.30146},
}
RIS
TY - UNPB
TI - Revealing antenna-molecule coupling using virtual gain from synthetic complex frequency analysis
AU - Toby Severs Millard
AU - Xiaofei Xiao
AU - Mayela Romero-Gómez
AU - Tom Aktaş-Vincent
AU - Nathaniel J. Huáng
AU - Chris C. Phillips
AU - Stefan A. Maier
AU - Olga Kazakova
AU - Rupert F. Oulton
PY - 2026
DA - 2026/08/31
PB - arXiv
DO - 10.48550/arxiv.2608.30146
UR - https://arxiv.org/abs/2608.30146
AB - Synthetic complex frequency waves (CFWs) enhance spectral and spatial resolution by compensating loss through virtual gain. This approach is particularly useful in nano-photonics where loss is intrinsically linked to strong field confinement and system size. Here, we apply CFWs to metasurfaces composed of Fano-resonant plasmonic antennas with lithographically tunable coupling between the weak and strong coupling regimes and where loss may be reduced to the Drude damping limit. We quantitatively assess the impact of the virtual gain to find that, while reducing loss, internal coupling rates remain invariant. While the exceptional point associated with strong light-matter coupling is invariant under virtual gain, the cooperativity of Fano interference is enhanced. When the metasurfaces are functionalised with a molecular monolayer, CFWs are thus able to reveal a molecule's vibrational modes, even when obscured by loss, and allow direct extraction of the plasmon-molecule coupling strength. We thus use CFW analysis as a quantitative tool for revealing and assessing light matter-coupling.
ER -