Study of room temperature coupling of colloidal quantum dots to plasmonic arrays and metamaterials: from single quantum dot to quantum dot assemblies

Abstract

There is much current interest in coupling emitters, such as fluorescing dye molecules and semiconductor quantum dots to plasmonic systems. Controlling the electromagnetic interactions between quantum emitters and the plasmonic system in the weak, intermediate, and strong coupling regimes has focused on an intense research effort in recent years. The weak and intermediate coupling regimes are associated with enhancement of the emission and absorption rates of nearby resonant emitters, while the strong coupling regime allows for coherent energy transfer between emitters and plasmonic system. Interest in this topic is motivated by the ability of plasmonic system to confine light to sub diffraction-limited mode volumes, which can drive coherence effects in collective quantum emitter systems, leading to applications in coherent light generation, photochemistry, quantum information processing, and quantum photonic fluids. In the first part of my thesis, I will discuss the experimental and theoretical study of room-temperature tunable coupling of single-photon emitting colloidal quantum dots(CQDs) to localised and delocalised modes in plasmonic nanocavity arrays using second-order photon correlation and time-resolved photoluminescence measurement. We will also discuss experimental evidence of indirect excitation of remote CQDs mediated by both the modes in the plasmonic arrays and propose a model to explain these observations. The second part of my thesis focuses on room temperature strong coupling between excitons in CQD assembly and surface lattice resonances in Plasmonic lattices and the emergence of the additional polaritonic peak in photoluminescence spectra of strongly coupled CQD-plasmonic lattice hybrid templates. In the third work, we will discuss the experimental and theoretical study of long-range optical energy propagation due to strongly coupled CQD-plasmonic lattice devices.The last part of my thesis focuses on the observation of photonic spin momentum locking in achiral CQD coupled to a special class of plasmonic metamaterial with hyperbolic isofrequency, known as hyperbolic metamaterial(HMM). We provide a theoretical explanation for the emergence of spin momentum locking through rigorous modeling based on photon Green’s function where pseudo spin of light arises from coupling of CQDs to evanescent modes of HMM.