TY - JOUR

T1 - Multiband Plasmonic Sierpinski Carpet Fractal Antennas

AU - De Nicola, Francesco

AU - Purayil, Nikhil Santh Puthiya

AU - Spirito, Davide

AU - Miscuglio, Mario

AU - Tantussi, Francesco

AU - Tomadin, Andrea

AU - De Angelis, Francesco

AU - Polini, Marco

AU - Krahne, Roman

AU - Pellegrini, Vittorio

PY - 2018/6/20

Y1 - 2018/6/20

N2 - Deterministic fractal antennas are employed to realize multimodal plasmonic devices. Such structures show strongly enhanced localized electromagnetic fields typically in the infrared range with a hierarchical spatial distribution. Realization of engineered fractal antennas operating in the optical regime would enable nanoplasmonic platforms for applications, such as energy harvesting, light sensing, and bio-/chemical detection. Here, we introduce a novel plasmonic multiband metamaterial based on the Sierpinski carpet (SC) space-filling fractal, having a tunable and polarization-independent optical response, which exhibits multiple resonances from the visible to mid-infrared range. We investigate gold SCs fabricated by electron-beam lithography on CaF2 and Si/SiO2 substrates. Furthermore, we demonstrate that such resonances originate from diffraction-mediated localized surface plasmons, which can be tailored in deterministic fashion by tuning the shape, size, and position of the fractal elements. Moreover, our findings illustrate that SCs with high order of complexity present a strong and hierarchically distributed electromagnetic near-field of the plasmonic modes. Therefore, engineered plasmonic SCs provide an efficient strategy for the realization of compact active devices with a strong and broadband spectral response in the visible/mid-infrared range. We take advantage of such a technology by carrying out surface enhanced Raman spectroscopy (SERS) on Brilliant Cresyl Blue molecules deposited onto plasmonic SCs. We achieve a broadband SERS enhancement factor up to 104, thereby providing a proof-of-concept application for chemical diagnostics.

AB - Deterministic fractal antennas are employed to realize multimodal plasmonic devices. Such structures show strongly enhanced localized electromagnetic fields typically in the infrared range with a hierarchical spatial distribution. Realization of engineered fractal antennas operating in the optical regime would enable nanoplasmonic platforms for applications, such as energy harvesting, light sensing, and bio-/chemical detection. Here, we introduce a novel plasmonic multiband metamaterial based on the Sierpinski carpet (SC) space-filling fractal, having a tunable and polarization-independent optical response, which exhibits multiple resonances from the visible to mid-infrared range. We investigate gold SCs fabricated by electron-beam lithography on CaF2 and Si/SiO2 substrates. Furthermore, we demonstrate that such resonances originate from diffraction-mediated localized surface plasmons, which can be tailored in deterministic fashion by tuning the shape, size, and position of the fractal elements. Moreover, our findings illustrate that SCs with high order of complexity present a strong and hierarchically distributed electromagnetic near-field of the plasmonic modes. Therefore, engineered plasmonic SCs provide an efficient strategy for the realization of compact active devices with a strong and broadband spectral response in the visible/mid-infrared range. We take advantage of such a technology by carrying out surface enhanced Raman spectroscopy (SERS) on Brilliant Cresyl Blue molecules deposited onto plasmonic SCs. We achieve a broadband SERS enhancement factor up to 104, thereby providing a proof-of-concept application for chemical diagnostics.

KW - antenna metamaterial

KW - Au Sierpinski carpet fractal

KW - chemical sensor

KW - localized surface plasmon

KW - quasi-periodic photonic crystal

KW - surface enhanced Raman spectroscopy

U2 - 10.1021/acsphotonics.8b00186

DO - 10.1021/acsphotonics.8b00186

M3 - Journal article

VL - 5

SP - 2418

EP - 2425

JO - ACS Photonics

JF - ACS Photonics

SN - 2330-4022

IS - 6

ER -