Photonic Metamaterials

Abstract

In this chapter, we provide a study of the plasmonic properties of photonic metamaterials. We start with a description of the properties of metamaterial heterostructures. The extensive research on layered materials has revealed that it is possible to obtain a new degree of freedom for tuning the dispersion properties. Based on this concept, researchers have investigated hyperbolic metamaterials (HMMs). Recently, several kinds of photonic crystals have been proposed as classical counterparts of the layered materials. However, the observation of nanostructured metamaterials from the perspective of metamaterial structural design properties has remained difficult until now. Thus, we consider the propagation of surface plasmon polaritons (SPPs) at the boundary of geometrically different metamaterials. We consider two-layered and multilayered composites. All the heterostructures under consideration are made of alternating graphene and dielectric sheets. We analytically estimate the dispersion properties, absorption and propagation lengths of SPPs. The variation of graphene dielectric functions is described by the Drude model. Next, we analytically identify the key factors influencing the propagation length along with the absorption enhancement – the feature highly desirable in terahertz photoconductive antennas – and consider analytical variations aiming to tune the dispersion relations. We proceed by reporting on a highly non-local metamaterial formed by means of a plasmonic nanorod composite. An analytical characterization of the non-local optical response of plasmonic nanowire metamaterials is presented. The former enables negative refraction, sub-wavelength light guiding and emission lifetime engineering. We analyze the dispersion of optical waves propagating in a nanowire composite. Finally, we study and characterize the hyperbolic THz regime of the studied active HMMs. A broadband slow-wave propagation regime takes place if the graphene-based HMM system is periodically patterned. This occurs due to the hyperbolic dispersion. By doing so, reconfigurable amplification of THz waves in a broad-spectrum region is attained. This might be engineered by tuning the quasi-Fermi level of graphene. Moreover, the mechanisms leading to the enhancement of the frequency region of the bound surface wave have been proposed in the frame of this study.