Nanophotonics has the ability to revolutionise how matter (molecules) interacts with photonics. In nanophotonics one normally employs metallic or dielectric nanostructures to enhance the near-field and therefore the coupling between photons and molecules. In this project two such structures are presented: (i) a nanoplasmonic system that can successfully model single molecular coupling and (ii) a dielectric system using one or more anapoles for which directional and controlled lasing is achieved on the nanoscale.
By bringing two nano-metallic structures close together (even just a few nanometers), the plasmon modes from each structure couple (hybridise) to produce an extremely high field enhancement in the gap [1]. Upon placing a molecule or quantum emitter (QE) in the gap strong coupling (SC) may take place between the QE and photonic mode, which involves the coherent exchange of energy between the plasmonic field and the QE [2]. The strong coupling leads to a splitting of the excited plasmonic mode into two hybrid modes [2] and may be observed as a peak splitting in the far-field scattering cross section. It was possible to achieve the aim of conclusively demonstrating strong coupling for a single emitter at ambient temparature, with a Rabi splitting of 21THz corresponding to a Rabi energy of 87 meV.
The second part of this thesis investigated whether an anapole-based nanolaser could be constructed. This exploited the property that the electromagnetic energy is confined to the bulk of the disk at the anapole wavelength [3]. A density of quantum emitters was embedded in an indium phosphide disk supporting the anapole, in air (monomer, dimer and trimer) and on a glass substrate (monomer and dimer). Directional lasing was shown to have been achieved by plotting the fields and occupation densities at points in the disk(s), and the preferred scattering angles to the far field.