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Physics Seminar

The marriage of bandstructure modes and experimental observables in photonic materials

Speaker: Matthias Saba (University of Fribourg)
Date: Wednesday 25 May 2022
Time: 15:00
Venue: Zoom

Nano-structuring matter on a periodic lattice is an old idea that paves the way towards new functional optical materials. Such materials range from so-called photonic crystals made of bio-molecules found in nature to bespoke metallic arrays, also known as metamaterials. Particularly in the photonic crystals community, a Bloch wave formalism with an associated photonic bandstructure picture has been adopted from the solid state physics community, and has led to both deep physical insight on the material behavior and important design principles. Concurrently, in contrast to electrons in a conventional crystal, Bloch modes in a photonic material are usually strongly coupled to vacuum radiation outside the material. Most experiments and applications indeed rely on understanding this interplay between internal and external fields to characterize and exploit the inherently finite material. I will here show how an analytical extension of the Bloch picture leads to a full solution set in a finite photonic material (with boundaries). This allows defining a scattering problem for a rigorous quantitative connection between the modal picture and optical experiments.

Bio: Matthias Saba received a Ph.D. degree in Physics in 2015 from the University of Erlangen-Nuremberg (Germany) for his work on chiral biomimetic photonic crystals. He joined the Condensed Matter Theory Group at Imperial College London from 2015 to 2019, where he studied 3D photonic topological materials and metamaterials. His current research interest as a group leader in the Soft Matter Physics Group at the Adolphe Merkle Institute (Switzerland) focusses on the design and understanding of 3D light-emitting plasmonic crystals, and single and multi-net metamaterials.