Purcell effect and lasing from quantum dots in a topological photonic crystal nanocavity

We report on Purcell enhancement of single quantum dot and a low-threshold topological nanolaser in 2D topological photonic crystal nanocavity based on the second-order corner state. In the fabricated cavities with a low density of quantum dots, we demonstrate the Purcell enhancement of single quantum dot. In the cavities with a high density, a topological laser is observed with a low threshold of about 1μW.