Quantum-hydrodynamic modal perspective on plasmonic gap structures

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Hauptverfasser: Zhang, Pu, Tserkezis, Christos, Mortensen, N. Asger
Format: Preprint
Veröffentlicht: 2024
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author Zhang, Pu
Tserkezis, Christos
Mortensen, N. Asger
author_facet Zhang, Pu
Tserkezis, Christos
Mortensen, N. Asger
contents Plasmonic gap structures are among the few configurations capable of generating extreme light confinement, finding applications in surface-enhanced spectroscopy, ultrasensitive detection, photocatalysis and more. Their plasmonic response undergoes a dramatic, quantum effect-driven transition as the gap size approaches zero. Modal analysis can reveal insights into the mechanisms governing this process, which are otherwise obscured by nonlocal damping effects. Here, we offer a fresh modal perspective on the transition of the plasmonic response using quantum hydrodynamic theory (QHT)-based quasinormal mode (QNM) analysis. Focusing on the bonding dipolar and charge-transfer plasmons of a nanosphere dimer, we examine the detailed mode transition through the touching regime as well as the asymptotic behavior compared with the classical results as the constituent nanoparticles either separate or overlap. The complex eigenfrequency particularly provides accurate information on the linewidth and quality factor of the plasmon modes. We introduce an index to characterize charge-transfer efficiency, especially for the charge-transfer plasmon. The significant role of nonlocal damping in the mode evolution is elucidated by our mode-resolved QHT-QNM analysis. The insights from our theoretical study provide an integrated understanding of mode evolution in plasmonic gap structures, which can further advance gap structure-based applications.
format Preprint
id arxiv_https___arxiv_org_abs_2412_04804
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Quantum-hydrodynamic modal perspective on plasmonic gap structures
Zhang, Pu
Tserkezis, Christos
Mortensen, N. Asger
Mesoscale and Nanoscale Physics
Optics
Quantum Physics
Plasmonic gap structures are among the few configurations capable of generating extreme light confinement, finding applications in surface-enhanced spectroscopy, ultrasensitive detection, photocatalysis and more. Their plasmonic response undergoes a dramatic, quantum effect-driven transition as the gap size approaches zero. Modal analysis can reveal insights into the mechanisms governing this process, which are otherwise obscured by nonlocal damping effects. Here, we offer a fresh modal perspective on the transition of the plasmonic response using quantum hydrodynamic theory (QHT)-based quasinormal mode (QNM) analysis. Focusing on the bonding dipolar and charge-transfer plasmons of a nanosphere dimer, we examine the detailed mode transition through the touching regime as well as the asymptotic behavior compared with the classical results as the constituent nanoparticles either separate or overlap. The complex eigenfrequency particularly provides accurate information on the linewidth and quality factor of the plasmon modes. We introduce an index to characterize charge-transfer efficiency, especially for the charge-transfer plasmon. The significant role of nonlocal damping in the mode evolution is elucidated by our mode-resolved QHT-QNM analysis. The insights from our theoretical study provide an integrated understanding of mode evolution in plasmonic gap structures, which can further advance gap structure-based applications.
title Quantum-hydrodynamic modal perspective on plasmonic gap structures
topic Mesoscale and Nanoscale Physics
Optics
Quantum Physics
url https://arxiv.org/abs/2412.04804