Progress of two-dimensional photonic topological insulators

Inspired by the exciting discovery of topological insulators in condensed-state physics, some topo-logical physics phenomena, such as integer quantum Hall effect, quantum spin Hall effect, topological semi-metals and higher order topological insulators, have successively realized in photonic system. Thanks to the clean energy band, simple design and accurate production of samples, the optical system has gradually become an important platform for studying physical topological models and novel topological phenomena. Topological photonics provides new methods to manipulate light fields and photons. The topological protected edge states can realize the propagation of photons which immune to material defects and impurity. Such ideal transport states are unprecedented in traditional optics, which may lead to radical changes in novel integrated optical devices. In this review, based on the two-dimensional optical system, we briefly introduce the exciting developments of topological photonics, such as photonic integer quantum Hall effect, photonic quantum spin Hall effect, photonic Floquet topological insulators, topological Anderson insulators and photonic higher order topological insulators. We focus on the topological insulators mentioned above and its topological model and novel topological phenomena. Finally, we conclude with the novel topological effects in optics and their applications in novel optical device.