Light-matter interaction in photonic cavities

Abstract

In this thesis, light‒matter interaction in several novel photonic platforms are investigated by time-resolved fluorescence lifetime measurements along with their theoretical and numerical analyses. Firstly, a simple leaky-mode wedge-type photonic nanocavity is proposed for the inhibition of spontaneous light emission of the CdTe/CdS quantum dots (QDs) by enforcing the suppression of optical modes under the weak coupling regime. Thus, for the first time, the inhibited spontaneous emission rate is achieved using a low Q-factor photonic structure. Secondly, a fluorescence lifetime imaging technique is employed to investigate the spontaneous transition rate of the BODIPY dye molecules, which are doped in a single PEG nanofiber. The spontaneous emission rate of the confined dye molecules is observed to inhibit and enhance periodically upon swelling of the nanofiber through its exposure to relative humidity, suggesting an efficient optical switch mechanism. In the third photonic platform, the critical role of the confined hybrid mode in a CdTe QDs-doped single nanofiber, which is partially decorated by gold nanoparticles, on the modification of the spontaneous emission dynamics of the fluorescent emitters in a low Q-factor photonic-plasmonic nanocavity is explored for the first time. This is followed by chemically growing hollow cylindrical nanocavities on the surface of a single polymer microfiber, which is uniformly doped with perovskite nanowires; the assembly is employed for the localization of light to meaningfully alter the emission rate of the fluorescent nanowires; due to interaction of the electromagnetic field of the whispering gallery modes, supported by the microfiber, with the boundaries of the cylindrical hollow nanocavities. Finally, a quasi-optical cavity, originating from the transverse Anderson localization of the light waves in an entirely three-dimensional disordered medium, formed by polymer medium with randomly positioned air bubbles, is realized as an alternative to conventional photonic cavities for the intense light localization to strongly enhance the spontaneous emission rate of the fluorescent emitters.