Plasmonic Bi-Cavity Nanostructure for Efficient Light Collection and Localization
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| Main Authors: | , , , , , , , |
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| Format: | Preprint |
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2026
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| author | Monken, Vitor Correa, Raul Miranda, Hudson Rabelo, Cassiano Nadas, Rafael Vasconcelos, Thiago L. Cancado, Luiz Gustavo Jorio, Ado |
| author_facet | Monken, Vitor Correa, Raul Miranda, Hudson Rabelo, Cassiano Nadas, Rafael Vasconcelos, Thiago L. Cancado, Luiz Gustavo Jorio, Ado |
| contents | Tip-enhanced Raman spectroscopy (TERS) typically relies on high-NA excitation to generate a strong axial field at the tip apex, which shortens the working distance and constrains sample geometries. We show that a plasmonic bi-cavity tip, the plasmon-tunable tip pyramid (PTTP), co-tuned in nanopyramid length L and plateau length W, supports a hybrid antenna-cavity mode that funnels energy to the apex under radially polarized, on-axis excitation, even with a dry objective of NA = 0.75. Finite-element simulations identify W as a design-critical parameter that sets an in-plane surface-plasmon-polariton (SPP) Fabry-Pérot-like resonance; co-tuning (L,W) yields a periodic series of maximal apex |E|^2. Experiments on monolayer graphene confirm near-field enhancement and reproduce the characteristic annular TERS point spread function (PSF) with NA = 0.75. Relaxing the NA requirement increases working distance and compatibility with constrained environments, pointing to practical, deployment-ready nano-Raman instrumentation. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2601_11870 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Plasmonic Bi-Cavity Nanostructure for Efficient Light Collection and Localization Monken, Vitor Correa, Raul Miranda, Hudson Rabelo, Cassiano Nadas, Rafael Vasconcelos, Thiago L. Cancado, Luiz Gustavo Jorio, Ado Optics Tip-enhanced Raman spectroscopy (TERS) typically relies on high-NA excitation to generate a strong axial field at the tip apex, which shortens the working distance and constrains sample geometries. We show that a plasmonic bi-cavity tip, the plasmon-tunable tip pyramid (PTTP), co-tuned in nanopyramid length L and plateau length W, supports a hybrid antenna-cavity mode that funnels energy to the apex under radially polarized, on-axis excitation, even with a dry objective of NA = 0.75. Finite-element simulations identify W as a design-critical parameter that sets an in-plane surface-plasmon-polariton (SPP) Fabry-Pérot-like resonance; co-tuning (L,W) yields a periodic series of maximal apex |E|^2. Experiments on monolayer graphene confirm near-field enhancement and reproduce the characteristic annular TERS point spread function (PSF) with NA = 0.75. Relaxing the NA requirement increases working distance and compatibility with constrained environments, pointing to practical, deployment-ready nano-Raman instrumentation. |
| title | Plasmonic Bi-Cavity Nanostructure for Efficient Light Collection and Localization |
| topic | Optics |
| url | https://arxiv.org/abs/2601.11870 |