Ricerc@Sapienza

Today, nanophotonics still lacks components for modulation that can be easily implementable in existing silicon-on-insulator (SOI) technology. Chalcogenide phase change materials (PCMs) are promising candidates for tuning in the near infrared: at the nanoscale, thin layers can provide enough contrast to control the optical response of a nanostructure. Moreover, all-dielectric metamaterials allow for resonant behavior without having ohmic losses in the telecom range. Here, a novel hybridization of a SOI-based metamaterial with PCM GeTe is experimentally investigated.

We numerically investigated the asymmetric spectral emissivity in the mid- to long-infrared range of
a metamaterial composed by subwavelength oriented air inclusions into a polar (SiC) matrix. The longitudinal
phononic resonance can be excited and tuned as a function of the inclusions content and
orientation, within the application limits of the effective medium homogenization technique. Furthermore,
our numerical results show that it is possible to enhance the emissivity in a given direction

Throughout the 19th and 20th century, chirality has mostly been associated with chemistry. However, while chirality can be very useful for understanding molecules, molecules are not well suited for understanding chirality. Indeed, the size of atoms, the length of molecular bonds and the orientations of orbitals cannot be varied at will. It is therefore difficult to study the emergence and evolution of chirality in molecules, as a function of geometrical parameters. By contrast, chiral metal nanostructures offer an unprecedented flexibility of design.

Phase-transition materials provide exciting opportunities for controlling optical properties of photonic devices dynamically. Here, we systematically investigate the infrared emission from a thin film of vanadium dioxide (VO2). We experimentally demonstrate that such thin films are promising candidates to tune and control the thermal radiation of an underlying hot body with different emissivity features. In particular, we studied two different heat sources with completely different emissivity features, i.e. a black body-like and a mirror-like heated body.

In this paper, we investigate the reflection characteristics of a novel electric–magnetic uniaxial lossy medium, characterized by extreme material properties and having optic axis in a generic direction. The novelty of the medium is specified by particular material parameters: very large transverse and very small axial components of permittivity and permeability with respect to the optic axis of the medium. To study the reflection, we consider an interface between a simple isotropic medium and the uniaxial medium defined by the complex permittivity and permeability tensors.

In this paper, ultra-thin narrow-band, complementary narrow-band, and dual-band metamaterial absorbers (MMAs), exploiting the same electric ring resonator configuration, are investigated at normal and oblique incidence for both transverse electric (TE) and transverse magnetic (TM) polarizations, and with different physical properties in the THz regime. In the analysis of the ultra-thin narrow-band MMA, the limit of applicability of the transmission line model has been overcome with the introduction of a capacitance which considers the z component of the electric field.