Orbital-to-spin angular momentum conversion employing local helicity
| Autor: | Peter Banzer, Jörg S. Eismann, Gerd Leuchs, Sergey Nechayev |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Physics
Angular momentum FOS: Physical sciences 02 engineering and technology Input field 021001 nanoscience & nanotechnology Polarization (waves) 01 natural sciences Helicity Quantum electrodynamics 0103 physical sciences 010306 general physics 0210 nano-technology Spin (physics) Nanoscopic scale Circular polarization Optics (physics.optics) Physics - Optics |
| Zdroj: | Physical Review B |
| ISSN: | 2469-9969 2469-9950 |
| DOI: | 10.1103/physrevb.99.075155 |
| Popis: | Spin-orbit interactions in optics traditionally describe an influence of the polarization degree of freedom of light on its spatial properties. The most prominent example is the generation of a spin-dependent optical vortex upon focusing or scattering of a circularly polarized plane-wave by a nanoparticle, converting spin to orbital angular momentum of light. Here, we present a mechanism of conversion of orbital-to-spin angular momentum of light upon scattering of a linearly polarized vortex beam by a spherical silicon nanoparticle. We show that focused linearly polarized Laguerre-Gaussian beams of first order ($\ell = \pm 1$) exhibit an $\ell$-dependent spatial distribution of helicity density in the focal volume. By using a dipolar scatterer the helicity density can be manipulated locally, while influencing globally the spin and orbital angular momentum of the beam. Specifically, the scattered light can be purely circularly polarized with the handedness depending on the orbital angular momentum of the incident beam. We corroborate our findings with theoretical calculations and an experimental demonstration. Our work sheds new light on the global and local properties of helicity conservation laws in electromagnetism. 8 pages, 6 figures, 1 table |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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