Optical Janus Skyrmion

Optical skyrmions provide a vital platform for integrating quasiparticle physics, topological theory, and advanced electromagnetic control. Traditionally, the helicity of their topological textures exhibits central symmetry, restricting them to purely Néel or Bloch types. Here, we propose a novel class─optical Janus skyrmions─featuring spatial symmetry breaking of helicity, where Néel and Bloch types spatially coexist in a double-sided heterogeneous configuration. We experimentally generate Janus skyrmions in structured light beams. The texture in the LG scheme gradually degrades during propagation, whereas the BG scheme can preserve the Janus-type helicity modulation within the nondiffracting propagation range zmax. Interestingly, this helicity asymmetry induces a 3D spiral evolution of the structure during propagation. This discovery advances helicity from a static internal feature to a controllable dynamical degree of freedom, thereby enriching the optical skyrmion family and unlocking new dimensions for skyrmion-based information encoding and transmission.