Dynamic Control of Polarization Singularities in Momentum Space by a Hybrid Photonic System

ABSTRACT Dynamic control of polarization singularities, including bound states in the continuum (BICs) and circularly polarized points ( C points), provides significant potential for engineering far‐field polarization textures and chiral light‐matter interactions. However, dynamic manipulation of these singularities typically requires reconfigurable structures or tunable materials, posing substantial challenges for practical applications. Here, we propose a hybrid photonic system (HPS) comprising a photonic crystal (PhC) slab and a perfect electric conductor (PEC) layer. By simply adjusting the vertical distance between the PEC and the PhC slab, one can dynamically manipulate polarization singularities in momentum space, without altering the PhC slab's geometry or material composition. Specifically, this mechanism enables robust manipulation of singularity trajectories, including the generation and annihilation of general BICs (GBICs) located off high‐symmetry lines; charge inversion of the symmetry‐protected BIC (SPBIC) and band transition accompanied by topological phase transition; and the recovery of BIC from a pair of C points, even under broken in‐plane inversion ( C 2 ) symmetry. This dynamic control of polarization singularities in momentum space offers a versatile and fabrication‐tolerant scheme for post‐fabrication control of momentum‐space singularities, paving the way toward compact, reconfigurable photonic devices for chiral optics, topological photonics, and dynamic beam shaping.