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Mirror-coupled plasmonic bound states in the continuum for tunable perfect absorption
Publikationstyp
Journal Article
Date Issued
2023-11-01
Sprache
English
Author(s)
Journal
Volume
17
Issue
11
Article Number
2300294
Citation
Laser & Photonics Reviews 17 (11): 2300294 (2023)
Publisher DOI
Scopus ID
Publisher
Wiley
Tailoring critical light-matter coupling is a fundamental challenge of nanophotonics, impacting fields from higher harmonic generation and energy conversion to surface-enhanced spectroscopy. Plasmonic perfect absorbers (PAs), where resonant antennas couple to their mirror images in adjacent metal films, excel at obtaining different coupling regimes by tuning the antenna-film gap size. However, practical PA applications require constant gap size, making it impossible to maintain critical coupling beyond singular wavelengths. Here, a new approach for plasmonic PAs is introduced by combining mirror-coupled resonances with the unique loss engineering capabilities of plasmonic quasi-bound states in the continuum. This novel combination allows to tailor the light–matter interaction within the under-coupling, over-coupling, and critical coupling regimes using flexible tuning knobs including asymmetry parameter, dielectric gap, and geometrical scaling factor. The study demonstrates a pixelated PA metasurface with optimal absorption over a broad range of mid-infrared wavenumbers (950–2000 cm<sup>−1</sup>) using only a single gap size and applies it for multispectral surface-enhanced molecular spectroscopy. Moreover, the asymmetry parameter enables convenient adjustment of the quality factor and resonance amplitude. This concept expands the capabilities and flexibility of traditional gap-tuned PAs, opening new perspectives for miniaturized sensing platforms towards on-chip and in situ detection.
Subjects
critical coupling (CC)
enhanced absorption
mirror BICS
near-fields enhancements
perfect absorber (PA)
plasmonic bound states in the continuums (BICS)
surface-enhanced infrared absorbance spectroscopy (SEIRAS)
DDC Class
600: Technology