Teardrop Reflector-Assisted Unidirectional Hybrid Silicon Microring Lasers

We study directional bistability in hybrid silicon microring lasers and demonstrate a unidirectional laser. Unidirectional emission is achieved by integrating a passive reflector that feeds laser emission back into the laser cavity to introduce an extra unidirectional gain. We show that the length of the passive reflector is a critical parameter in determining the lasing behavior.