Topological Photonics (Brief Review)

Topological insulators, originally discovered in the context of condensed matter physics, have provided a powerful source of inspiration for the design of novel types of photonic crystals and waveguides. It was unveiled that the quantized global characteristics of the band structure and eigenfunctions in the reciprocal space underpin exotic properties of topological materials, such as their abilities to support scattering-resistant wave transport along the edges or boundary surfaces and host robust confined states at corners or hinges. The topological physics brought to the realm of photonics is enriched by non-Hermitian and nonlinear effects and holds special promise for disorder-immune device applications. We review the recent progress in implementing topological states of light in a plethora of platforms, including metacrystals, arrays of microring resonators and optical waveguide lattices, that furthermore bridges to advances in quantum optics and nonlinear nanophotonics.