The dual focus property of focused circularly polarized ring Airy beam (RAB) under the action of tightly focused lens is demonstrated in this paper. The radiation forces at two foci of tightly focused RAB are calculated, the numerical results show that the particle could be longitudinally and transversely trapped at the two foci. By varying corresponding parameters, we could control the property of two traps. The trapping force increases with NA and the scaling parameter w; and an appropriate initial radius r(0) is necessary for the enhancement of either trap. The two traps could move closer as w increases or r(0) decreases. To realize the dual optical trap, we should choose a smaller decaying parameter a and a larger NA, or the dual optical trap would degenerate into a single optical trap. Moreover, because of the influence of the Brownian motion and the scattering force, the size of the particle should be in a special range. (C) 2020 Elsevier Ltd. All rights reserved.
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