All-Dielectric Structured Materials as Enablers of Chiral and Topological Photonic Phenomena
October 24th, 2019 AITZOL GARCÍA-ETXARRI Donostia International Physics Center

High refractive index nanoantennas and periodically structured dielectric materials such as metasurfaces and photonic crystals are enabling an unprecedented control of light in the recent past. These all-dielectric optical devices present two instrumental features. On the one hand, they are usually free of ohmic optical losses. On the other hand, in contrast with plasmonic systems, they can sustain both electric and magnetic optical resonances. This additional magnetic dipolar character adds an additional degree of freedom to their capabilities for manipulating light and facilitates new opportunities for the development of novel experimental applications. In this talk, we will explore two of these emergent opportunities.

First, we will analyze how single dielectric nanostructures supporting combinations of electric and magnetic resonances can augment the interaction of circularly polarized light with chiral molecules [2]. Specifically, we will show how Silicon nanoparticle arrays can greatly enhance the sensitivity of chiral spectroscopic techniques such as circular dichroism spectroscopy and we will see how this augmented chiral interaction can also be used for the separation of chiral molecular enantiomers by optical means with high efficiencies.

On the other hand, we will see how all-dielectric photonic crystals can mimic many topological effects happening in solid-state electronic systems. Specifically, we will see learn how to apply the method of Topological Quantum Chemistry (TQC) to the propagation of light in Photonic crystals. This tool allows to predict the emergence of topological phases on periodic systems based exclusively on Elementary Band Representations, a very well know mathematical tool n in the field of crystallography. In this work, we applied TQC to Photonic crystals; surprisingly, we discovered that certain paradigms in the design of Photonic Topological insulators are not strictly truthful. Moreover, the versatility of the method allowed us to design novel topological photonic systems with unprecedented physical properties. In particular, we will introduce the first instance of fragile topology in a physical system.

Seminar, October 24, 2019, 12:00. ICFO’s Seminar Room

Hosted by Prof. Romain Quidant