Low-threshold topological nanolasers based on the second-order corner state

Topological lasers are immune to imperfections and disorder, which are mostly at microscale. The topological nanolaser with small footprint, low threshold and high energy-efficiency has yet to be explored. Scientists in China demonstrated a topological nanolaser utilizing the second-order corner state in 2D photonic crystal slab with a low threshold of about 1 μW and a high spontaneous emission coupling factor of 0.25. This result shows a great potential for topological nanophotonic circuitry.