Enhanced Light-Matter Interactions in Complex Photonic Systems
Mentor: Andrea Alù
Abstract
Interactions between light and matter are fundamental to breakthroughs in lasers, sensing, imaging, spectroscopy, energy harvesting, and quantum information processing. As a result, significant recent efforts have been geared towards enhancing and controlling light-matter interactions to advance these applications and technologies. Complex engineered photonic systems, often involving nanoscale designs of photonic components, have provided fertile grounds to manipulate light unprecedentedly, achieving extreme control over interactions among photons and between light and matter. In this dissertation, we exploit four types of complexity to enhance light-matter and light-light interactions in various photonic platforms.
First, we start by tailoring the spatial complexity in photonic designs, which can stimulate unusual light interactions with plasmonic materials. In a one-dimensional metamaterial, i.e., an artificially engineered periodic structure, we show that perturbing the discrete translational symmetry can induce a topological knot in reciprocal space. It enables strong nonlocal coupling between a dark mode and a brighter surface mode, which offers new opportunities for efficient sensing and Raman scattering.
Introducing complexity in the material constituents together with deliberate spatial designs, we further explore how nonlinearities in metamaterials unleash novel forms of controlling light emission, leveraging strongly enhanced interactions with light. Besides, blending different types of materials can also push the limits of complex photonic designs. We design an ultrasmall nanocavity hybridizing two distinct materials — a high-index dielectric encapsulated by the low-loss metal, demonstrating record-high Purcell enhancement. The proposed hybridized nanocavity is expected to enhance quantum emission and strong coupling substantially.
As another degree of freedom, complexity can be introduced in the temporal dimension. Time variations in material properties provide a new knob for complex photonic designs. Among them, time-interfaces, realized by switching the properties of the entire medium in time, introduce striking complexity in wave dynamics. In a transmission-line metamaterial, we have observed time reflections at a photonic time interface and associated broadband and ultrafast frequency translation for the first time. Combining multiple time interfaces in the same platform, we realize a passive photonic time crystal, which holds the prospect of extreme interaction with light with zero energy cost, inaccessible in either time-invariant or conventional time-varying systems.
Finally, we harness the complexity in the frequency domain. Complex spectral responses and modal patterns can arise in wave-chaotic systems. In this context, we realize coherent control over photon-photon interactions in a chaotic photonic microcavity involving over a thousand optical modes. Efficient control of its radiation is further demonstrated via reflectionless scattering modes, paving the way for efficient energy harvesting, routing, and conversion.
Zoom Meeting ID: 722 951 7086 Passcode: 2024
Members of the doctoral faculty are invited to attend.