Probing the backscattering of TiO2 particles with vortex beams

Xavier Zambrana-Puyalto; Xavier Vidal; Gabriel Molina-Terriza

doi:10.1117/12.2555460

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1 April 2020 Probing the backscattering of TiO₂ particles with vortex beams

Xavier Zambrana-Puyalto, Xavier Vidal, Gabriel Molina-Terriza

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Proceedings Volume 11345, Nanophotonics VIII; 1134507 (2020) https://doi.org/10.1117/12.2555460
Event: SPIE Photonics Europe, 2020, Online Only

Abstract

We present a set of experiments in which the backscattering spectra of 4 μm single TiO₂ particles are probed with circularly polarized vortex beams. The experiment is carried out with a tunable laser at λ = 760 - 810nm. We observe that the use of vortex beams enables us to tailor the backscattering in different ways. Given a certain backscattering of a particle (induced by a Gaussian beam or a plane wave), we observe that vortex beams can tune it and sharpen it. Moreover, we also observe that the level of conservation of helicty can be increased thanks to the use of vortex beams. We explain the mechanisms that give rise to these effects using Mie Theory. Our method of backscattering control can be experimentally implemented in most of microscopy set-ups. In addition, if brought to its limits, the method can be used to excite single multipolar modes from spheres. We believe that our method could find application in the levitation of particles or the excitation of whispering gallery modes.

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Xavier Zambrana-Puyalto, Xavier Vidal, and Gabriel Molina-Terriza "Probing the backscattering of TiO₂ particles with vortex beams", Proc. SPIE 11345, Nanophotonics VIII, 1134507 (1 April 2020); https://doi.org/10.1117/12.2555460

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