Super‐Robust Telecommunications Enabled by Topological Half‐Supermodes

ABSTRACT Topological photonics offer transformative potential for robust integrated waveguide devices due to their backscattering‐immune properties. However, their integration faces two fundamental challenges: mode symmetry mismatch with conventional waveguides and prohibitive dimensions. We successfully overcome these two critical challenges by introducing a novel valley‐ridge gap waveguide based on topological half‐supermode engineering. By strategically hybridizing ridge waveguide modes and valley kink states, we create an exotic odd‐symmetric supermode enabling robust propagation and ultra‐compact operation. The further implementation of a perfect electric conductor boundary halves the lateral dimensions while eliminating radiation loss. Crucially, our proposed valley–ridge interface achieves direct transverse electric mode matching with standard waveguides without transition structures, enabling seamless integration. Experimental results demonstrate reflection losses lower than −15 dB in realistic telecommunication scenarios with super‐robust signal propagation through sharp bends. This work innovatively conceptualizes topological half‐supermodes and pioneers their practical applications for integrated waveguide devices, establishing a completely new waveguide class that uniquely combines robust backscattering immunity with deep subwavelength compactness.