Propagation of Chiral Whispering Gallery Modes in Microrings Enabled by Tilted Angular Gratings

Whispering gallery mode (WGM) microcavities are extensively studied as ultra-low-threshold microlasers. However, their rotational symmetry confines light within the cavity, resulting in isotropic emission, limiting their use in optical communication, where directional control is essential for data manipulation. Previous studies have integrated gratings into microring lasers to emit orbital angular momentum (OAM) beams, with chiral WGMs generating OAM beams in opposite directions. However, these approaches often rely on gain-loss modulation using non-Hermitian physics [1], which poses significant fabrication challenges. Considering research that introduced S-shaped structures to break spatial symmetry in microrings [2] to realize the chiral WGM propagation, this study proposes incorporating spatial asymmetry into grating-integrated microrings for chiral WGM propagation as the groundwork for the chiral propagation of OAM fields.