Spin‐orbit interactions (SOIs) of light in tight focusing systems have gained much attention due to the potential applications in optical trapping and microscopy. SOI effects strongly affect the distributions and properties of focal fields, which are determined by the polarization and spatial degrees of freedom of incoming light. Remarkably, structured light fields exhibit SOI phenomena with complex behaviors. Here the SOIs in the tightly focused higher‐order Poincaré sphere beams that simultaneously contain vortex phase front and higher polarization orders are theoretically studied. The interplay between spin and orbital angular momenta in the focused field is revealed, and the amount of spin‐orbit conversion is found to be determined by the angular momentum of the incident field and the focusing system. In particular, based on the superposition of two circular polarization vortex bases, a general description of the interplay between spin and orbital parties is provided, paving a way to arbitrarily controlling the SOIs in nonparaxial fields. The findings are expected to deepen the understanding of SOIs that play a critical role in classical and quantum optics.

中文翻译：

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紧密聚焦的高阶庞加莱球面光束中自旋和轨道角莫曼塔之间的相互作用

紧密聚焦系统中的光的自旋轨道相互作用（SOI）由于在光学陷波和显微镜中的潜在应用而备受关注。SOI效应强烈影响焦点场的分布和特性，焦点场的分布和特性由入射光的偏振和空间自由度决定。值得注意的是，结构化光场表现出具有复杂行为的SOI现象。在理论上研究了紧聚焦的高阶庞加莱球面光束中同时包含涡旋相位前相和较高偏振阶的SOI。揭示了聚焦场中自旋和轨道角动量之间的相互作用，发现自旋轨道转换的量由入射场和聚焦系统的角动量决定。尤其是，基于两个圆极化涡旋基的叠加，提供了对自旋和轨道方之间相互作用的一般描述，为在非傍轴场中任意控制SOI提供了一种方法。这些发现有望加深对在经典光学和量子光学中起关键作用的SOI的理解。