Research progress of topological lasers (Invited)

With the development of topological photonics, topological lasers and semiconductor lasers are promoted by the discovery of the topological edge states and corner states with robustness against defects and perturbations. Firstly, the development history of the topological lasers and the principles of the various kinds of topological lasers was reviewed; Secondly recent realizations of various topological lasers were analyzed and the basic physics about topological edge states and topological corner states was explained. In these experiments, the modes of topological laser were decided by the dielectric structure. The laser was excited by pumping the photonic gain. The analysis show that topological lasers based on topological corner states have higher efficiency and lower threshold than those based on topological edge state, due to the high quality factor and small mode volume of topological corner state, which provides the possibility for future photonic integrated chip. Finally, the challenge and potential applications in the future were outlooked, which was beneficial to explore practical topological laser.