Topological spin textures, among which skyrmions and merons are typical examples, have with their swirling vectorial structures triggered enormous interest in physical systems including elementary particles and magnetic materials. Manipulating their symmetry and topology is important for understanding the mechanisms that underlie their topological phase transformation as well as offering tunable degrees of freedom to encode information, which has already been demonstrated in magnetic materials. Recently, the photonic counterparts of skyrmions and merons were constructed in a 2D wave system with deep-subwavelength features promising for optical sensing, imaging, and information decoding. However, their experimental realization relied on stringent excitation conditions that only support a single spin texture type on a specific structure. Here, we demonstrate for the first time the transformation between photonic skyrmion and meron spin lattices on the same metallic meta-surface having a well-designed structural period. We show experimentally the wavelength-tuned symmetry transformation of the photonic spin lattices, which are also found to be robust against disorder in the structure to a certain degree. This work provides new insights into controlling the electromagnetic field symmetry and topology, as well as in developing applications in spin optics and topological photonics.

中文翻译：

---

光子斯格明子和梅伦自旋纹理之间的波长调谐转换

拓扑自旋纹理（其中斯格明子和半子是典型的例子）以其旋转的矢量结构引发了人们对包括基本粒子和磁性材料在内的物理系统的巨大兴趣。操纵它们的对称性和拓扑对于理解其拓扑相变的机制以及提供可调自由度来编码信息非常重要，这已经在磁性材料中得到了证明。最近，在具有深亚波长特征的二维波系统中构建了斯格明子和半子的光子对应物，有望用于光学传感、成像和信息解码。然而，他们的实验实现依赖于严格的激发条件，仅支持特定结构上的单一自旋纹理类型。在这里，我们首次证明了具有精心设计的结构周期的同一金属超表面上的光子斯格明子和半子自旋晶格之间的转变。我们通过实验展示了光子自旋晶格的波长调谐对称变换，还发现这种变换在一定程度上对结构中的无序具有鲁棒性。这项工作为控制电磁场对称性和拓扑以及开发自旋光学和拓扑光子学应用提供了新的见解。