Experimental Realization of Highly Efficient Beam Combination and Steering via Topological Multimode

Abstract Topology multimode provides a promising avenue for developing multi‐channel robust photonic devices and optical power manipulation. Particularly, the backscattering‐immune property of topological multimode holds potential for ideally lossless optical beam combination. In this work, the combination of topological multimode in topologically non‐trivial photonic crystals, is experimentally observed achieving a beam combination efficiency of up to 93%. The near‐perfect combination can be explained by the power orthogonal excitation principle of topological multimode. Furthermore, controllable beam steering is successfully achieved by incorporating topological one‐way large‐area waveguide states into the output spatial channel with tunable excitation. The work paves the way for the application of topological photonics in the directional manipulation of high‐power electromagnetic radiation.