Tunable Skyrmion, Meron, and Skyrmion Bag Textures in Surface Phonon Polariton Lattices.

Surface phonon polaritons (SPhPs) enable nanoscale manipulation of mid-infrared light via deeply subwavelength topological vector textures, such as skyrmions. Achieving dynamic, real-time control over these topological features remains challenging. Here, we theoretically propose and numerically demonstrate an actively tunable platform on a silicon carbide membrane that creates lattices of diverse topological textures, including skyrmions, merons, and skyrmion bags. By exploiting the sublinear SPhP dispersion, we dynamically adjust the excitation wavelength to tune the topological character of these lattices. This enables tunability between bubble-type and Néel-type configurations, controlling field confinement and topology for topological textures in the electric field and the spin angular momentum. Furthermore, we identify a novel singularity-type meron arising from the interplay of electric and magnetic spin components. This texture exhibits topological charge conservation in moiré superlattices and a spatially confined spin reversal with tunable lateral sizes as low as λ SPhP / 29 and skyrmion number density confinements as low as λ SPhP / 64 . These findings provide a versatile framework for on-chip, reconfigurable topological photonic devices with potential applications in high-resolution imaging and precision metrology in the mid-infrared. The results can be readily extended to other topological systems, where similar dispersion relations hold.