Observation of multitype topological textures in a subwavelength acoustic Mie resonator

Topological textures, which refer to nontrivial vector field configurations with topological protection in real space, have aroused great interest in various physical branches. However, conventional topological textures are achieved under stringent excitation conditions that solely hosted a single symmetry configuration in a designed metastructure. Here, we propose a subwavelength acoustic Mie resonator to support localized skyrmion and meron lattice modes for velocity field vectors on structure surface simultaneously depending on the excited location of the point source. We theoretically analyze and numerically calculate the near-field distribution of Mie resonating modes, and find that the higher-order monopole modes correspond to N\'eel type skyrmion modes, while the multipolar resonating modes belong to meron lattice modes consisting of symmetrically distributed merons and antimerons on the structure surface along the azimuthal direction. We also experimentally observe the near-field distribution of velocity vectors to verify the skyrmions and merons on the structure surface, and the topologically protected property is demonstrated by introducing the structure defects. Multitype topological textures can be simultaneously excited on a subwavelength Mie resonator without strict excitation conditions, which may be a versatile platform for encoding information in versatile topological textures.