Topological Photonic Crystals in One, Two and Three Dimensions
Open Access
- Author:
- Vaidya, Sachin
- Graduate Program:
- Physics (PHD)
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- January 12, 2023
- Committee Members:
- Mikael Rechtsman, Chair & Dissertation Advisor
Chaoxing Liu, Major Field Member
Eric Hudson, Major Field Member
Noel Giebink, Outside Unit & Field Member
Nitin Samarth, Program Head/Chair - Keywords:
- Topological Photonics
Photonic Crystals
Weyl points
Anderson Localization
Quasicrystals
Bound States in the Continuum
Higher-Order Topological Phases
Chern Insulators - Abstract:
- The recent discovery of topological phases of matter has revolutionized our understanding of condensed matter systems. The information that describes these phases is stored across the entire system, and as a result, some of their properties are protected from local perturbations. These systems exhibit unique phenomena such as transport channels that exist on their boundaries and features that are robust to disorder. Topological phases were first discovered in condensed matter physics but the underlying principles were soon extended to many wave systems such as photonic and acoustic systems. The field of topological photonics aims to both realize novel topological phases in photonic systems and develop applications based on their robust properties. This dissertation aims to further our understanding of topological photonics and lies at the intersection between photonic crystals and topological band theory. In the first two parts of this dissertation, we present two studies that experimentally realize charge-2 Weyl points and observe their splitting in three-dimensional chiral woodpile photonic crystals. This is done at technologically-useful infrared wavelengths by using a state-of-the-art 3D micro-printing technique that employs low loss materials. In the next two parts, we focus on developing a complete topological classification of bands in one- and two-dimensional photonic crystals under crystalline symmetries. Based on this classification, we propose a strategy to diagnose and design a wide variety of topological photonic crystals. We then use this framework to show that Chern insulators can have a meaningful notion of relative polarization whose effects can be seen at the boundary between two Chern insulators with the same Chern number. In the last two parts, we explore miscellaneous topics in photonic crystals. In the first of the two parts, we theoretically predict bound states in the continuum that are localized to point defects in two-dimensional photonic crystals. This allows for the confinement of light in the absence of photonic bandgaps. In the last part, we present the observation of a localization transition in one-dimensional photonic quasicrystals. In addition, we observe a surprising phenomenon that occurs in this system, a second transition of some states to a delocalized regime upon further increasing the quasiperiodic disorder.