Topological photonics in synthetic dimensions

Topological photonics is a new and rapidly growing field that deals with topological phases and topological insulators for light. Recently, the scope of these systems was expanded dramatically by incorporating non-spatial degrees of freedom. These synthetic dimensions can range from a discrete ladder of cavity modes or Bloch modes of an array of waveguides to a time-bin division (discrete time steps) in a pulsed system or even to parameters such as lattice constants. Combining spatial and synthetic dimensions offers the possibility to observe fundamental and exotic phenomena such as dynamics in four dimensions or higher, long-range interaction with disorder, high-dimensional nonlinear effects, and more. Here, we review the latest developments in using non-spatial dimensions as a means to enhance fundamental features of photonic topological systems, and we attempt to identify the next challenges. (C) 2021 Optical Society of America

Automated summary

Topological photonics is a rapidly growing field that has expanded its scope by incorporating non-spatial degrees of freedom. This offers the possibility to observe fundamental and exotic phenomena, with the next challenge being identified as enhancing the fundamental features of photonic topological systems.