2, Stanford University, Stanford, California, United States
We illustrate the applications of magnetic phenomena at optical frequencies sustained by semiconductor and metal nanostructures for improving nanophotonic technologies, ranging from increased efficiency and performance in lightning and displays to the modification of the intrinsic optoelectronic properties of materials.
In this context, high-refractive index optical antennas have emerged as promising tools for the control of light at the nanoscale, benefitting from mature fabrication technologies and potential integration with on-chip optoelectronic systems. In this presentation, we exploit two of the advantages offered by silicon nanostructures. First, thanks to the narrow Mie resonances of silicon nanobeams, we demonstrate strong coupling to a molecular J-aggregate, with a Rabi frequency of 150 meV. Both hybrid polariton branches are visible in photocurrent measurements, therefore tailoring the optoelectronic response of both materials. Second, thanks to the coexistence of magnetic and electric dipole response in silicon nanowires, we demonstrate directional emission from an atomically thin MoS2 monolayer. Compared to the so-called Kerker condition for plane wave scattering based on the interference of electric and magnetic dipoles, we show that there are two possible mechanisms to direct the emission of a source dipole with a nanowire.
Additionally, we demonstrate that a nanostructured metallic mirror with high impedance can be used as an electrode with desirable optical properties. Metallic contacts normally show radiative losses as surface plasmon polaritons, which limit the efficiency of light-emitting devices. We demonstrate that our approach reduces these losses by studying the emission enhancement and photoluminescence lifetime for a dye emitter layer deposited on the electrodes. Our design behaves like a magnetic mirror with a maximum of electric field at the mirror surface, yielding enhanced light emission.