Author(s): Zengping Su, Wei Li, Jue Li, Haoye Qin, Yongkang Wang, Wenjing Lv, Mengyao Li, Bo Li, and Qinghua Song Topologically protected, continuous ring of unidirectional guided resonances that locks vortex laser emission into a single direction is constructed by engineering isotropic interband coupling in a bilayer photonic crystal. [Phys. Rev. Lett. 137, 016201] Published Wed Jul 01, 2026