Abstract
The backscattering spectra of a 500 nm thick gold film, which was excited near the 525 nm transverse localized plasmon resonance of its constituent, self-organized, vertically-aligned nanorods by normally incident 515 nm, 300 fs laser pulses with linear, radial, azimuthal and circular polarizations, revealed a few-percent conversion into Stokes and anti-Stokes side-band peaks. The investigation of these spectral features based on the nanoscale characterization of the oligomeric structure and numerical simulations of its backscattering response indicated nonlinear Fano-like plasmonic interactions, particularly the partially degenerate four-wave mixing comprised by the visible-range transverse plasmon resonance of the individual nanorods and an IR-range collective mode of the oligomeric structure. Such oligomeric structures in plasmonic films may greatly enhance inner nonlinear electromagnetic interactions and inner near-IR hotspots, paving the way for their engineered IR tunability for broad applications in chemosensing and biosensing.
Original language | English |
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Article number | 59 |
Number of pages | 9 |
Journal | Sensors |
Volume | 21 |
Issue number | 1 |
DOIs | |
Publication status | Published - 1 Jan 2021 |
Externally published | Yes |
Keywords
- Four-wave mixing
- Gold nanorods
- Laguerre–Gaussian beams
- Plasmonic sensors
- Resonance structures