Topological phase transitions in photonic hybrid metasurfaces

Abstract

Topological photonics is a rapidly developing field that studies the application of topological concepts to devices that manipulate light. Topological photonic devices promise a pathway towards robust quantum computers and 6G technology. Photonic topological insulators (PTIs) are engineered materials that have a band gap in their spectra and can support edge states protected by the band structure topology. These edge states propagate around the system boundary and are immune to detrimental backscattering, with proposed applications in areas from signal transport to quantum computation. This thesis explores the potential for interaction-induced topological phase transitions in photonic systems. I review the basic concepts of PTIs and discuss the Bernevig-Hughes-Zhang model of a $\mathcal{Z}_2$ PTI. I then discuss the composition of this model with a simple material excitation that interacts with the BHZ model near the band gap. I show that this interaction induces topological phase transitions in certain circumstances. I apply this concept to a hexagonal-pattern hybrid metasurface, demonstrating the hybrid edge states associated with the interaction-induced topology. Finally, I delineate the potential avenues for experimental implementation of the system studied.