Topological Singularity in a Non‐Interleaved Bidirectional Transmissive Metasurface Consisting of Weakly Coupled Resonators

ABSTRACT Exceptional points (EPs), marked by eigenvalue‐eigenstate coalescence, exhibit a robust topologically protected 2π phase upon encirclement, thereby supplying an additional phase‐engineering mechanism that enables intriguing asymmetric wave manipulation. Here, based on a framework of two weakly coupled resonators, a novel mechanism is proposed for localizing the topological singularity in a two‐dimensional parameter space, which establishes a deterministic geometry‐EP mapping and provides an efficient, closed‐form design route. By invoking reciprocity and synthesizing the topological exceptional (ET) phase with the Pancharatnam‐Berry (PB) phase, asymmetric responses are engineered in the bidirectional circular‐polarization conversion channels. As a proof of concept, we demonstrate two λ/14‐thick non‐interleaved metasurfaces in the microwave regime for near‐field holographic manipulation and far‐field beam steering, respectively. Both numerical simulations and experimental measurements confirm that each metasurface exhibits asymmetric wave manipulation under bidirectional right‐circularly polarized wave (RCP) illumination: the meta‐hologram generates distinct holographic patterns, while the far‐field metasurface demonstrates asymmetric beam deflection angles. Our findings provide new routes to localize topological singularities and substantially expand the bidirectional wave‐control capacities of topological metasurfaces, paving the way for geometry‐programmable EP control in compact duplex communication, polarization‐multiplexed holography, and secure information encoding.