GeSn Topological Photonic Crystal Laser

We present a topological photonic crystal nanocavity laser based on group-IV GeSn and integrated on silicon. We engineer the interface between one-dimensional photonic crystal nanobeams with different topological phases to deterministically induce a zero-dimensional topological mode. The resulting cavity allows for robust lasing with tight optical confinement, which is made possible by edge state topological protection. Our design demonstrates the feasibility of CMOS-compatible, topologically engineered nanolasers based on GeSn, which advances scalable photonic integration and mid-infrared optoelectronics. This work opens up new possibilities for compact, thermally stable light sources on silicon.