Abstract
Abstract A strategy is proposed to achieve wideband tunable perfect plasmonic absorption in graphene nanoribbons by employing attenuated total refraction (ATR) in Otto prism configuration. In this configuration, the Otto prism with a deep-subwavelength dielectric spacer is used to generate tunneling evanescent waves to excite localized plasmons in graphene nanoribbons. The influence of the configuration parameters on the absorption spectra of graphene plasmons is studied systematically, and the key finding is that perfect absorption can be achieved by actively controlling the incident angle of light under ATR conditions, which provides an effective degree of freedom to tune the absorption properties of graphene plasmons. Based on this result, it is further demonstrated that by simultaneously tuning the incident angle and the graphene Fermi energy, the tunable absorption waveband can be significantly enlarged, which is about 3 times wider than the conventional cavity-enhanced configuration. Our proposed strategy to achieve wideband, tunable graphene plasmons could be useful in various infrared plasmonic devices.
Highlights
Graphene, the truly two-dimensional crystal consisting of carbon atoms in a honeycomb lattice, has received extensive research interest due to its excellent optoelectronic properties and potential applications [1, 2]
This is because the resonant wavelength of localized graphene plasmons is mainly determined by the geometric parameters of graphene nanoribbons and the Fermi energy
A clear dividing line can be observed at the incident angle of 30° in the three figures, corresponding to the critical angle of attenuated total refraction (ATR) occurring at the spacer/air interface
Summary
The truly two-dimensional crystal consisting of carbon atoms in a honeycomb lattice, has received extensive research interest due to its excellent optoelectronic properties and potential applications [1, 2]. These unique properties make graphene a promising one-atom-thick platform for the realization of highly integrated active plasmonic devices, such as infrared biosensors [18,19,20,21,22], plasmonic modulators [23], plasmonic infrared photodetectors [24,25,26], plasmonic thermal emitters [27], and so forth Despite these exciting potentials, the relatively low excitation efficiency of graphene plasmons is a major obstacle for graphenebased optoelectronics, due to the inherent one-atom thinness of graphene as well as the large wave vector mismatch between graphene plasmons and free-space photons [28]. It is demonstrated that by simultaneously adjusting the incident angle and the Fermi energy of graphene, the tunable wavelength region with high plasmonic absorption can be much wider than that of the conventional Fabry-Pérot cavity-based configuration
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