Browsing by Author "Hanson, G. W."

Now showing 1 - 3 of 3

Open Access
Anisotropic absorber and tunable source of MIR radiation based on a black phosphorus-SiC metasurface
(Elsevier BV, 2022-03-28) Hajian, Hodjat; Rukhlenko, I. D.; Hanson, G. W.; Özbay, Ekmel
We propose a black phosphorus-silicon carbide (BP-SiC) metasurface with in-plane structural symmetry that can act as both a nearly perfect anisotropic absorber and tunable polarized source of mid-infrared (MIR) radiation. The metasurface is a periodic array of square SiC patches integrated with a BP flake at the top and separated from a bottom reflector by a BaF2 spacer. We first use analytical calculations and numerical simulations to study the hybridization of the anisotropic plasmons of BP with isotropic phonons of SiC. We also analyze the in-plane characteristics of the resulting hybrid modes of the BP/SiC heterostructure and the BP-SiC metasurface. It is then demonstrated that the proposed metasurface can serve as a nearly perfect anisotropic absorber of MIR radiation with highly selective and omnidirectional features. It is also shown that the metasurface can be used as a polarized MIR source with tunable temperature, which is determined by the thermal equilibrium between the matter and radiation. The suggested design holds promise for artificial coatings that can tune the blackbody thermal signatures, MIR sensing, and highly directional in-plane transportation of the MIR energy.
Open Access
Hybrid surface plasmon polaritons in graphene coupled anisotropic van der Waals material waveguides
(Institute of Physics Publishing Ltd., 2021-08-23) Hajian, Hodjat; Rukhlenko, I. D.; Hanson, G. W.; Özbay, Ekmel
Polaritons in anisotropic van der Waals materials (AvdWMs), with either hyperbolic or elliptical topologies, have garnered significant attention due to their ability of field confinement and many useful applications in in-plane polariton nanophotonics, including directional guiding, canalization, and hyperlensing. Here, we obtain the dispersion relation of hybrid surface plasmon polaritons (SPPs) supported by a parallel-plate waveguide composed of an AvdWM, as an example tungsten ditelluride, that is coupled with a graphene layer. Through analytical calculations and numerical simulations, we first investigate the impact of losses on the modal characteristics of SPPs supported by the AvdWM. We then show that the coupling of the anisotropic layer to a graphene sheet in a parallel-plate waveguide heterostructure allows one to control the in-plane propagation and dispersion topology of the hybrid SPPs by changing the spacer thickness and the graphene chemical potential. Moreover, it is found that owing to the different coupling regimes, this anisotropic-isotropic SPPs hybridization can enhance the propagation length and spatial localization of the guided modes. We believe this approach can lead to the realization of vdW heterostructures with improved functionalities for in-plane and out-of-plane infrared nanophotonics.
Open Access
Tunable plasmon-phonon polaritons in anisotropic 2D materials on hexagonal boron nitride
(De Gruyter Open, 2020) Hajian, Hodjat; Rukhlenko, I. D.; Hanson, G. W.; Low, T.; Bütün, Bayram; Özbay, Ekmel
Mid-infrared (MIR) plasmon-phonon features of heterostructures composing of a plasmonic anisotropic two-dimensional material (A2DM) on a hexagonal boron nitride (hBN) film are analyzed. We derive the exact dispersion relations of plasmon-phonons supported by the heterostructures and demonstrate the possibility of topological transitions of these modes within the second Reststrahlen band of hBN. The topological transitions lead to enhanced local density of plasmon-phonon states, which intensifies the spontaneous emission rate, if the thickness of the hBN layer is appropriately chosen. We also investigate a lateral junction formed by A2DM/hBN and A2DM, demonstrating that one can realize asymmetric guiding, beaming, and unidirectionality of the hybrid guided modes. Our findings demonstrate potential capabilities of the A2DM/hBN heterostructures for active tunable light–matter interactions and asymmetric in-plane polariton nanophotonics in the MIR range.