Broadband Dual‐Space Vortex Multiplexing Through Disorder‐Empowered Topological Metasurfaces

ABSTRACT The co‐manipulation of orbital angular momentum (OAM) in real and momentum spaces presents challenges in electromagnetic wave engineering, primarily due to the counteraction between topological defects and disorder, particularly in overcoming the intrinsic bandwidth limitations of topological photonic systems. Recent advancements have shown the generation of real‐momentum space vortices through bound states in the continuum in topological photonic crystals (PhCs), but these implementations face critical trade‐offs between spatial disorder tolerance and operating bandwidth. Here, we present a disorder‐empowered metasurface architecture that breaks this paradigm through geometric‐phase engineering combined with topological PhC design. Our platform achieves simultaneous broadband OAM generation in both real and momentum spaces, notably demonstrating a 40% fractional bandwidth in the momentum domain—far surpassing previous records. Experimental results break the prevailing notion that real‐space disorder inevitably degrades momentum‐space performance, demonstrating instead that engineered disorder actively stabilizes dual‐space broadband characteristics over an ultra‐wide frequency range. This phenomenon originates from geometrically locked Pancharatnam‐Berry phase robustness and self‐compensated momentum‐space topology, enabling wavelength‐independent vortex generation with preserved charge orthogonality across domains. This dual‐broadband capability expands the information‐carrying potential of topological photonic devices, paving the way for high‐capacity communication systems that leverage disorder as a beneficial design feature rather than a limiting factor.