Detuned electrical dipoles for plasmonic sensing.
We demonstrate that a pair of electrical dipolar scatterers resonating at different frequencies, i.e., detuned electrical dipoles, can be advantageously employed for plasmonic sensing of the environment, both as an individual subwavelength-sized sensor and as a unit cell of a periodic array. It is shown that the usage of the ratio between the powers of light scattered into opposite directions (or into different diffraction orders), which peaks at the intermediate frequency, allows one to reach a sensitivity of ≈ 400 nm/RIU with record high levels of figure of merit exceeding 200. Qualitative considerations are supported with detailed simulations and proof-of-principle experiments using lithographically fabricated gold nanorods with resonances at 800 nm.
Evlyukhin
Andrey B
AB
Institute of Sensors, Signals and Electrotechnics (SENSE), University of Southern Denmark, Niels Bohrs All 1E, DK-5230 Odense M, Denmark.
Bozhevolnyi
Sergey I
SI
Pors
Anders
A
Nielsen
Michael G
MG
Radko
Ilya P
IP
Willatzen
Morten
M
Albrektsen
Ole
O
D003198:Computer Simulation; D004574:Electromagnetic Fields; D006046:Gold / Q000737:chemistry*; D008027:Light; D008956:Models, Chemical; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D012542:Scattering, Radiation; D020349:Surface Plasmon Resonance / Q000379:methods*
D006046:Gold