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Enhanced optical trapping via structured scattering


Interferometry can completely redirect light, providing the potential for strong and controllable optical forces. However, small particles do not naturally act like interferometric beamsplitters and the optical scattering from them is not generally thought to allow efficient interference. Instead, optical trapping is typically achieved via deflection of the incident field. Here, we show that a suitably structured incident field can achieve beamsplitter-like interactions with scattering particles. The resulting trap offers order-of-magnitude higher stiffness than the usual Gaussian trap in one axis, even when constrained to phase-only structuring. We demonstrate trapping of 3.5–10.0 μm silica spheres, achieving a stiffness up to 27.5 ± 4.1 times higher than was possible using Gaussian traps as well as a two-orders-of-magnitude higher measured signal-to-noise ratio. These results are highly relevant to many applications, including cellular manipulation1,2, fluid dynamics3,4, micro-robotics5 and tests of fundamental physics6,7.

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Figure 1: Trapping via Mie interference.
Figure 2: Trap stiffness of ENTRAPS.
Figure 3: Layout of experiment.


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This work was supported by the Australian Research Council Discovery Project (contract no. DP140100734) and by the Air Force Office of Scientific Research (grant no. FA2386-14-1-4046). W.P.B. acknowledges support through the Australian Research Council Future Fellowship scheme FF140100650.

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Authors and Affiliations



M.A.T. and W.P.B. conceived and led the project. M.A.T. developed the theoretical concepts and performed the calculations and analysis. A.B.S. and H.R.D. developed the experimental apparatus. M.W. and M.A.T. performed the experiments, with assistance from A.B.S. M.A.T. and W.P.B. wrote the paper with input from all co-authors.

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Correspondence to Michael A. Taylor.

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The authors declare no competing financial interests.

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Taylor, M., Waleed, M., Stilgoe, A. et al. Enhanced optical trapping via structured scattering. Nature Photon 9, 669–673 (2015).

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