27 January 2017 Electromagnetic field confinement in the gap of germanium nanoantennas with plasma wavelength of 4.5 micrometers
Author Affiliations +
Plasmonic nanoantenna designs are quickly evolving in the direction of practical molecular sensing applications hence their wavelength range is being extended from the visible towards the mid-infrared. The problem of obtaining, in the mid-infrared, the same degree of plasmonic confinement obtained with gold in the visible range is related to the perfect conductor behavior of metals at long wavelengths. Here we fabricated bow-tie nanoantennas made of bottom-up assembled “metallic germanium” with free electron density of the order of 1020 cm-3 and therefore short plasma wavelength of 4.5 μm. We demonstrate the existence in the antenna gaps of confined hotspots with radius of the order of 100 nm, which we imaged by near-field photoexpansion microscopy at a wavelength of 5.8 μm in order to provide a clear proof of strong field confinement in the mid-infrared.
Conference Presentation
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Eugenio Calandrini, Eugenio Calandrini, Tommaso Venanzi, Tommaso Venanzi, Felice Appugliese, Felice Appugliese, Michela Badioli, Michela Badioli, Valeria Giliberti, Valeria Giliberti, Leonetta Baldassarre, Leonetta Baldassarre, Paolo Biagioni, Paolo Biagioni, Francesco De Angelis, Francesco De Angelis, Wolfgang M. Klesse, Wolfgang M. Klesse, Giordano Scappucci, Giordano Scappucci, Michele Ortolani, Michele Ortolani, } "Electromagnetic field confinement in the gap of germanium nanoantennas with plasma wavelength of 4.5 micrometers", Proc. SPIE 10111, Quantum Sensing and Nano Electronics and Photonics XIV, 101110F (27 January 2017); doi: 10.1117/12.2253841; https://doi.org/10.1117/12.2253841

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