We have developed a metallic double circular grating with sub-wavelength slits which blocks radially polarized light incident from one of its sides and acts as a focusing diffractive element in the other direction. The proposed grating has been optimized for the sub-THz frequency range. Unidirectional transmission through the grating has been demonstrated… (More)
We derive periodic multilayer absorbers with effective uniaxial properties similar to a perfectly matched layer (PML). This approximate representation of a PML is based on effective medium theory, and we call it an effective medium PML (EM-PML). We also show that cylindrical core-shell nanostructures derived from flat multilayers also exhibit very good… (More)
We analyse numerically and experimentally the asymmetric transmission through sub-wavelength double metallic gratings. The possibility of achieving a broadband unidirectional transmission of THz waves through the grating is confirmed. The proposed gratings allow for efficient one-way transmission in the wavelength range from 2.5 to 3.5 mm.
We optimise the transfer function of layered metal-dielectric metamaterials for imaging with sub-wavelength resolution, for high-pass spatial filtering, and for diffraction compensation. A variant of a genetic algorithm is used to optimise the metamaterial. The optimisation criteria include transmission, and reflection coefficients averaged over a range of… (More)
We analyse the transmission of a linearly polarised plane-wave through a diffraction-free layered metamaterial stacked to another photonic crystal. The dispersion relation of the metamaterial at the resonant frequency allows for super-collimation of the incident light, while the photonic crystal introduces transverse momentum to excite a large number of… (More)
We describe layered metal-insulator metamaterials using the model of a linear-shift-invariant system. We present the modelling and optimisation strategy for engineering such metamaterials. A variety of point spread functions may be reached, either for superresolution, or for far-field image processing. The first group includes layered superlenses and… (More)