Topological Photonics with Synthetic Gauge Fields

Jhih-Sheng Wu^1*

¹Department of Photonics, National Yang Ming Chiao Tung University, Hsinchu, Taiwan

* Presenter:Jhih-Sheng Wu, email:jwu@nycu.edu.tw

I will briefly introduce topological photonics. Compared to electrons, photonic systems lack continuous interactions, such as magnetic fields and spin-orbit couplings, which play an important role in creating non-trivial bands. It is until recently that a clever idea with all dielectric materials was proposed to make topological photonic crystals. Such an idea utilizes parity-symmetries of the unit cells of photonic crystals to design effective spin-orbit coupling in photonic crystals. However, parity-type interaction requires the abrupt changes of a unit cell, which could lead to scatterings and other problems at the boundary. We propose a continuous approach where continuous deformation of the unit cells serves as effective gauge fields in the reciprocal space and gives rise to pseudomagnetic fields. We show that these pseudomagnetic fields can create Landau levels in photonic bands and hence makes topological photonic crystals. Indeed, these interactions belong to the time-symmetry type.
Such an approach benefits from preserving local symmetries of a unit cell. The boundary of these topological photonic crystals hosts robust edge states, which are free of scattering due to continuous deformation. Our approach has a great potential in broad bandwidth applications.

Keywords: topological photonics, synthetical gauge fields, strain-engineering, photonic crystals, Landau levels