Planar hyperlens based on a modulated graphene monolayer

Abstract

The canalization of terahertz surface plasmon polaritons using a modulated graphene monolayer is investigated for subwavelength imaging. An anisotropic surface conductivity formed by a set of parallel nanoribbons with alternating positive and negative imaginary conductivities is used to realize the canalization regime required for hyperlensing. The ribbons are narrow compared to the wavelength, and are created electronically by gating a graphene layer over a corrugated ground plane. Good quality canalization of surface plasmon polaritons is shown in the terahertz even in the presence of realistic loss in graphene, with relevant implications for subwavelength imaging applications.

Self-biased reconfigurable graphene stacks for terahertz plasmonics

“…In a different context, the large range of imaginary conductivity values provided by the stacks can easily be exploited in planar hyperlenses. Currently, graphene-based hyperlenses 52 are based on achieving large contrast of conductivities within the surface by using non-uniform metallic gates located very close to graphene. However, these gates are difficult to fabricate and impair the performance of the lenses.…”

Directive Surface Plasmons on Tunable Two-Dimensional Hyperbolic Metasurfaces and Black Phosphorus: Green’s Function and Complex Plane Analysis

“…In the non-hyperbolic (purely anisotropic) case (σ xx , σ zz > 0), (14) is the equation for an ellipse in q-space with the axis oriented along q x and q z . The length of the ellipse's principal axes along q x and q z is proportional to σ zz and σ xx , respectively.…”

“…Both natural materials and metasurfaces can be isotropic or anisotropic, and, e.g., isotropic graphene can be employed to form an effective anisotropic metasurface by modulating its conductivity [3], [14]. And, both natural materials and metasurfaces may exhibit a hyperbolic regime.…”

Tunable plasmonic metasurface for perfect absorption

“…Here, l and s are the chemical potential and the scattering time for electrons, respectively, with s ¼ ml=ev 2 F (m is the mobility and v F % 10 6 m/s the Fermi velocity). In this work, we use the parameters a = 76 GHz/X and c g = 1.5 THz, which correspond to l = 0.65 eV and m = 10 4 cm 2 /V s. The conductivity grating established via periodic doping allows for free space radiation to couple into the surface plasmons sustained by the graphene layer, which have much shorter wavelength [24][25][26][27][28][29][30][31][32][33][34]. Hence, the modulation period needs to be much smaller than the wavelength of incident radiation (k 0 ) 2pc).…”