S-shaped waveguide-induced asymmetry between counter-propagating modes in a racetrack resonator

Ongoing progress in photonic integrated circuits necessitates the integration of semiconductor ring lasers (SRLs) with high performance and predictable behavior, which can be achieved when the symmetry of the SRL, which supports both clockwise and counterclockwise beam propagation, is unbalanced through loss mechanisms inside the resonator. In this work, numerical simulations were carried out on the symmetric layout of the racetrack resonator equipped with an asymmetric S-shaped internal waveguide. The simulations results were compared with the ones of analogue structures without internal waveguide showing the benefit induced by this additional element in term of the unidirectionality of the SRL