Weak Measurement Enhanced Spin Hall Effect of Light for Particle Displacement Sensing.

Neugebauer, Martin; Nechayev, Sergey; Vorndran, Martin; Leuchs, Gerd; Banzer, Peter · Nano Lett · 2019

basic_science · Level V

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Abstract

A spherical nanoparticle can scatter tightly focused optical beams in a spin-segmented manner, meaning that the far field of the scattered light exhibits laterally separated left- and right-handed circularly polarized components. This effect, commonly referred to as giant spin Hall effect of light, strongly depends on the position of the scatterer in the focal volume. Here, a scheme that utilizes an optical weak measurement in a cylindrical polarization basis is put forward to drastically enhance the spin-segmentation and, therefore, the sensitivity to small displacements of a scatterer. In particular, we experimentally achieve a change of the spin-splitting signal of 5% per nanometer displacement.