Experimental demonstration of optical transport, sorting and self-arrangement using a ‘tractor beam’


  • A Corrigendum to this article was published on 27 February 2013


Following the Keplerian idea of optical forces, one would intuitively expect that an object illuminated by sunlight radiation or a laser beam will be accelerated along the direction of photon flow. Recent theoretical studies1,2,3,4,5 have shown that small particles can be pulled by light beams against the photon stream, even in beams with uniform optical intensity along the propagation axis. Here, we present a geometry to generate such a ‘tractor beam’, and experimentally demonstrate its functionality using spherical microparticles of various sizes, as well as its enhancement with optically self-arranged structures of microparticles. In addition to the pulling of the particles, we also demonstrate that their two-dimensional motion and one-dimensional sorting may be controlled conveniently by rotation of the polarization of the linearly polarized incident beam. The relative simplicity of this geometry could serve to encourage its widespread application, and ongoing investigations will broaden the understanding of the light–matter interaction through studies combining more interacting micro-objects with various properties.

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Figure 1: Pulling and pushing forces along a fringe (z-axis) in the geometry of two interfering plane waves.
Figure 2: Experimental arrangement and results.
Figure 3: Examples of particle sorting by polarization-switching of the ‘tractor beam’.
Figure 4: Optically self-arranged structures and their different behaviour in the ‘tractor beam’.

Change history

  • 06 February 2013

    In this version of this Letter originally published, the surname of the first author of ref. 26 should have been “Zhang” and the reference should have read: 26. Zhang, L. & Marston, P. L. Geometrical interpretation of negative radiation forces of acoustical Bessel beams on spheres. Phys. Rev. E 84, 035601 (2011). This has now been corrected in the HTML and PDF versions of the Letter.


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The authors acknowledge the comments of H.I.C. Dalgarno and support from the USTAN and the following projects: CSF (GA202/09/0348, GPP205/11/P294), MEYS CR (LH12018), ISI (RVO:68081731), COST-STSM-MP0604-04235 and EC (ALISI CZ.1.05/2.1.00/01.0017).

Author information

O.B., T.Č. and P.Z. developed the presented method, supervised the project and wrote the manuscript. O.B. performed all the experiments and subsequent data analysis. O.B., V.K., M.Š. and L.C. performed computer simulations.

Correspondence to P. Zemánek.

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The authors declare no competing financial interests.

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Brzobohatý, O., Karásek, V., Šiler, M. et al. Experimental demonstration of optical transport, sorting and self-arrangement using a ‘tractor beam’. Nature Photon 7, 123–127 (2013). https://doi.org/10.1038/nphoton.2012.332

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