Controlled transportation of mesoscopic particles by enhanced spin orbit interaction of light in an optical trap

Abstract

We study the effects of the spin orbit interaction (SOI) of light in an optical trap and show that the propagation of the tightly focused trapping beam in a stratified medium can lead to significantly enhanced SOI. For a plane polarized incident beam the SOI manifests itself by giving rise to a strong anisotropic linear diattenuation effect which produces polarization-dependent off-axis high intensity side lobes near the focal plane of the trap. Single micron-sized asymmetric particles can be trapped in the side lobes, and transported over circular paths by a rotation of the plane of input polarization. We demonstrate such controlled motion on single pea-pod shaped single soft oxometalate (SOM) particles of dimension around $1\times 0.5\mu$m over lengths up to $\sim$15 $\mu$m . The observed effects are supported by calculations of the intensity profiles based on a variation of the Debye-Wolf approach. The enhanced SOI could thus be used as a generic means of transporting mesoscopic asymmetric particles in an optical trap without the use of complex optical beams or changing the alignment of the beam into the trap.

9 pages, 7 figures

References in corpus (11)

• Optical spin-to-orbital angular momentum conversion in inhomogeneous anisotropic media
• Hall Effect of Light
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• Geometrodynamics of Spinning Light
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Cited by in corpus (4)

• Angular Momentum Transfer in Interaction of Laguerre-Gaussian Beams with Atoms and Molecules
• Manipulating the transverse spin angular momentum and Belinfante momentum of spin-polarized light by a tilted stratified medium in optical tweezers
• Observation of Larmor-like precession of a single birefringent particle due to spin-dependent forces in tilted optical tweezers
• 'Complementarity' in paraxial and non-paraxial optical beams