Fabrication and near-field characterization of mid-infrared transmission lines

Abstract

During this thesis, we fabricated infrared (IR) antennas and transmission lines (TLs), and characterizedthem by transmission-mode scattering-type scanning near-field optical microscopy (transmission-mode s-SNOM). By means of dipolar antennas we coupled mid-IR light into two-wire TLs and we investigatedpropagation properties such as local field enhancement, field confinement, mode (effective) wavelength,propagation length. In addition, we studied for the first time more complicated antenna structure such asArchimedean spiral antennas, which is a well-know travelling wave broadband antenna for radio-wavetechnology. To that end, we modified the transmission-mode s-SNOM setup available at nanoGUNE tobe able to illuminate the samples with circularly polarized light. In order to support the experimentalobtained near-field distributions, we have performed FDTD and FDFD simulations, which are inexcellent agreement with the experimental data.