Scientific Results

Cold and Hot Spots: From Inhibition to Enhancement by Nanoscale Phase Tuning of Optical Nanoantennas

Year: 2020

Authors: Blascetta NP., Lombardi P., Toninelli C., van Hulst NF.

Autors Affiliation: Barcelona Inst Sci & Technol, Inst Ciences Foton, ICFO, Barcelona 08860, Spain; European Lab Nonlinear Spect, CNR INO, I-50019 Florence, Italy; European Lab Nonlinear Spect, LENS, I-50019 Florence, Italy;‎ Inst Catalana Recerca & Estudis Avancats, ICREA, Barcelona 08010, Spain

Abstract: Optical nanoantennas are well-known for the confinement of light into nanoscale hot spots, suitable for emission enhancement and sensing applications. Here, we show how control of the antenna dimensions allows tuning the local optical phase, hence turning a hot spot into a cold spot. We manipulate the local intensity exploiting the interference between driving and scattered field. Using single molecules as local detectors, we experimentally show the creation of subwavelength pockets with full suppression of the driving field. Remarkably, together with the cold excitation spots, we observe inhibition of emission by the phase-tuned nanoantenna. The fluorescence lifetime of a molecule scanned in such volumes becomes longer, showing slow down of spontaneous decay. In conclusion, the spatial phase of a nanoantenna is a powerful knob to tune between enhancement and inhibition in a 3-dimensional subwavelength volume.

Journal/Review: NANO LETTERS (PRINT)

Volume: 20 (9)      Pages from: 6756  to: 6762

KeyWords: local phase; near field interference; hot spot – cold spot; antenna enhancement; inhibition of emission; local density of states; superresolution; nanoantenna; plasmonics; single molecule
DOI: 10.1021/acs.nanolett.0c02607

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