Investigations of Photonic Topological Structures Based on Metallic and All-Dielectric Metamaterials
Abstract
In this proposal titled ÒInvestigations of Photonic Topological Structures Based on Metallic and All-Dielectric MetamaterialsÓ I propose to investigate a new class of photonic structures: photonic topological metamaterials (PTMs). These photonic structures exhibit highly unusual properties, such as topologically protected transport of edge states; wave propagation that is mathematically equivalent to particle motion in a magnetic field; long-term localization inside chaotic topologically protected optical cavities; ÒperfectÓ coupling of strongly-confined guided modes into vacuum; unidirectional emission of point dipoles, and many others. The key to these exotic and potentially disruptive properties lies in the topological aspect of wave motion in such structures which is still poorly understood in the context of photonics. Even less developed are the experimental tools that can be utilized for measuring such topology-related quantities as Berry curvature and Chern index, which determine wave propagation in PTMs. While many ideas in this area originally come from topological electron phases in condensed matter physics, optical topological structures have many unique properties and challenges that set them apart from their solid-state counterparts. For example, the spin degree of freedom that electrons naturally possess can only be emulated in optics using a special class of spin-degenerate metamaterials and meta-waveguides that were recently invented in our group. Moreover, photonic structures are inherently three-dimensional, which further complicates the measurement (and even proper definition) of topology-related quantities that naturally arise in two-dimensional topological states of electronic matter. Many other phenomena, such as far-field coupling of topological waves to incident laser beams, are simply outside of the realm of condensed matter physics. Interfacing heterogeneous topological phases of matter, such as quantum Hall and quantum valley Hall, is also outside of the experimental realm, yet our preliminary simulations indicate that such interfaces can be emulated and utilized in optics. Thus, with complexity of PTMs come the opportunities that we are going to explore as part of the proposed research scope using first-principles electromagnetic simulations, simplified analytic theory, and optical/microwave experiments. The specific objectives and deliverables of this project are: ÀÀ To explore the spin degree of freedom of electromagnetic waves and to experimentally emulate a quantum spin Hall photonic topological metamaterial across the EM spectrum. This synthetic degree of freedom increases the number of optologically protected edge states and enables the realization of positive and negative index waves because the effective global Chern index is doubled. Previous microwave designs are too complex to be scalable to optical frequencies. ÀÀ To explore the new concept of photonic valleytronics. We will emulate quantum valley Hall PTMs that possess an additional (valley) degree of freedom and measure the local Chern index associated with it. Both all-Si and metallic PTMs will be experimentally explored using far and near-field techniques. ÀÀ To realize scattering-free edge states between heterogeneous PTMs and disordered topological cavities. We will create interfaces between quantum spin and valley Hall PTMs and demonstrate reflections-free light propagation with long time delay through topologically protected photonic cavities imbedded inside such heterogeneous photonic structures.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Sep 11, 2018
- Source ID
- W911NF1710479
Entities
People
- Gennady Shvets
Organizations
- Army Contracting Command
- Cornell University
- United States Army