Nanophotonics of Plasmonic and Two-Dimensional Metamaterials

Abstract

Various nanostructured materials display unique and interesting optical properties. Specific nanoscale objects discussed in an experimental perspective in this dissertation include optical metamaterials, surface plasmon sensors, and two-dimensional materials. These nanoscale objects were fabricated, investigated optically, and their applications are assessed. First, one-dimensional magnetic gratings were studied, followed by their two-dimensional analog, the so-called "fishnet." Both were fabricated, characterized, and their properties, such as waveguiding modes, are examined. Interestingly, these devices can exhibit optical magnetism and even negative refraction; however, their general characterization at oblique incidence is challenging due to diffraction. Here, a new method of optical characterization of metamaterials which takes into account diffraction is presented. Next, surface plasmon resonance (SPR) was experimentally used in two schemes, for the first time, to determine the transition layer characteristics between a metal and dielectric. The physics of interfaces, namely the singularity of electric permittivity and how it can be electrically shifted, becomes clearer owing to the extreme sensitivity of SPR detection mechanisms. Finally, ultra-thin two-dimensional semiconducting materials had their radiative lifetime analyzed. Their lifetimes are tuned both by number of atomic layers and applied voltage biasing across the surface, and the changes in lifetime are suspected to be due to quenching or enhancement of non-radiative process rates.