The manipulation of spin angular momentum for binary circular Airy beam during propagation

The Airy beam has attracted great attention since it was proposed in 2007 due to its novel properties, such as non-diffraction, self-healing, and self-acceleration. However, the spin angular momentum (SAM), which is an intrinsic nature of light, has rarely been studied by the Airy beam. Here, we propose a kind of binary circular Airy beam (BCAB) with space-variant polarizations and vortex phases and study the SAM evolution of the BCAB during propagation. We find the effects of appearance and annihilation of SAM during the propagation of BCAB, and the SAM can be further manipulated by adjusting the initial phase and polarization distribution of BCAB. Moreover, the optical tube, optical needle, and optical cage carrying different SAMs are achieved in propagation, which can be applied in various regions, such as optical trapping and manipulation. The BCAB significantly enriches the family of structured light and provides a flexible control scheme of SAM, which can further promote the application of SAM in many fields.