Tunable Optical Vortex Knots Governed by a Quasi-Spin-Decoupled Liquid Crystal Pancharatnam–Berry Phase Element

Three-dimensional topologies of knots have played fundamental roles across multiple physics disciplines. In structured light, the stable knotted wave occurs in the form of knotted vortex loops. Although static laboratory generation of these structures has been achieved by various optical devices, the continuous and dynamically tunable modulation remains largely unexplored. Here, we present experimental demonstrations of the continuous deformation of optical vortex knots and links by developing an optical system incorporating a Pancharatnam–Berry phase element (PBPE). The generated optical vortex knots can be spatially stretched, compressed, and rotated via a single liquid crystal PBPE and conventional optical wave plates. Our method offers general approaches for the topological evolution and control of optical knots and potential applications to other physical fields.