Thursday, June 13, 2013

Separation of spin angular momentum in space-variant linearly polarized beam

Hao Chen, Zhongliang Yu, Jingjing Hao, Zhaozhong Chen, Ji Xu, Jianping Ding, Hui-Tian Wang

We show that the spin angular momentum (SAM) flux in a space-variant linearly polarized beam can be separated in the focal plane. Such a beam carries only orbital angular momentum (OAM) and develops a net SAM flux upon focusing. The radial splitting of the SAM flux density is mediated by the phase vortex (or OAM) and can be controlled by the topological charge of the phase vortex. Optical trapping experiments verify the separation of the SAM flux density. The proposed approach enriches the manipulation of the angular momentum of light fields and inspires more designs of focus engineering, which would benefit optical micromanipulation of microscopic particles.
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