Topology and Light
From Electrons to Photons
Topological effects are universal! The mathematical principles of topology can be applied not only to electrons, but also to many other physical systems. For example, optical micro-resonators were arranged like carbon atoms in a graphene layer. Optical micro-resonators are small lasers that here are connected to each other in a lattice. Through a combination of special optical properties and material characteristics, light (instead of electrons) is transmitted backscatter-free along the edge of a structure.
Send the Light Around the Corner!
In this model of an optical topological insulator, light can move around corners! You can see a honeycomb structure of optical resonators. The light is generated in the red quantum films by a laser and surrounded by black and white mirrors. The diameter of the turrets is actually only about two micrometers, much less than that of a human hair. The center is insulating so that light cannot spread there. It instead spreads out along the edge.
In the Lead!
In 2018, a group of researchers from the Technical Physics Chair in Würzburg designed for the first time a topological insulator for a special optical excitation – the exciton-polariton, a hybrid of light and matter.