Abstract
In this paper we show that graphene surface plasmons can be excited when an electromagnetic wave packet impinges on a single metal slit covered with graphene. The excitation of the plasmons localized over the slit is revealed by characteristic peaks in the absorption spectrum. It is shown that the position of the peaks can be tuned either by the graphene doping level or by the dielectric function of the material filling the slit. The whole system forms the basis for a plasmonic sensor when the slit is filled with an analyte.
Highlights
The diffraction of electromagnetic (EM) waves on metallic structures gives rise to a series of interesting phenomena, such as the Wood and Rayleigh anomalies [1, 2] and the extraordinary optical transmission [3]. Theoretical models for these phenomena have been elaborated by modelling the metal as perfect electric conductor (PEC), as in Refs. [4,5,6]
Screening of graphene surface plasmon-polaritons (SPPs) by a perfect [25,26,27] or dispersive (Drude) [28] metal adjacent to it leads to the formation of acoustic SPPs with linear spectrum
We demonstrate that the electromagnetic wave, when diffracted by the slit edges, excites a standing wave of SPPs in graphene at a series of resonant frequencies, which are determined by the graphene doping
Summary
The diffraction of electromagnetic (EM) waves on metallic structures gives rise to a series of interesting phenomena, such as the Wood and Rayleigh anomalies [1, 2] and the extraordinary optical transmission [3]. Screening of graphene SPPs by a perfect [25,26,27] or dispersive (Drude) [28] metal adjacent to it leads to the formation of acoustic SPPs with linear spectrum In such kind of structures SPP’s group velocity is quite low compared to polaritons in graphene on a thick dielectric substrate since high wavevectors correspond to relatively low frequencies in the SPP dispersion relation. The latter means that graphene’s conductivity exhibits its nonlocal properties in the THz frequency range and, gives rise to the nonlocal SPPs [29,30,31,32]. Excitation of the polaritons yields a series of absorption peaks in the spectrum and these resonant frequencies turn out to be very sensitive to the dielectric constant of the dielectric material filling the slit, as it will be demostrated by our calculated results
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