Prabath Hewageegana

Enhanced mid-infrared transmission through a metallic diffraction grating

We study theoretically an enhancement of the intensity of mid-infrared light transmitted through a metallic diffraction grating. We show that for s-polarized light the enhancement of the transmitted light is much stronger than for p-polarized light. By tuning the parameters of the diffraction grating, the enhancement of the transmitted light can be increased by a few orders of magnitude. The spatial distribution of the transmitted light is highly nonuniform with very sharp peaks, which have spatial widths of about 10 nm.

Optical transitions in topological insulator quantum dots

We study the optical properties of quantum dots in topological insulator nanofilm. The quantum dots have cylindrical shape and are realized as a region of larger thickness of the nanofilm. The energy spectra of quantum dots depend on their size and the thickness of nanofilm. There are two types of optical transitions in topological insulator quantum dots: interband and intraband transitions with corresponding energies around 400 meV and 50 meV for quantum dot of radius ≈ 10 nm (for Ti2Se3 topological insulator). The intensities of intraband transitions are almost an order of magnitude larger than the intensities of interband transitions.