Topological insulator quantum cascade laser in synthetic space: towards a realization

Abstract

When optical nonlinearities are introduced to photonic topological insulators, the system starts separating from its original solid-state roots, and creating fertile ground to completely new inventions, one of which is the topological insulator laser [1]. This type of laser provides single mode lasing of semiconductor laser arrays through robust injection locking from one laser to the next despite inevitable variations and defects in semiconductor processing. Since the concept was first demonstrated [2], [3], it was far and wide applied in many systems [4]–[6], and now it seems that topological insulator lasers are currently the most auspicious application of topological photonics.