Regensburg 2022 – scientific programme

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O: Fachverband Oberflächenphysik

O 37: Plasmonics and Nanooptics 1

O 37.3: Talk

Wednesday, September 7, 2022, 11:15–11:30, H3

Generation of Rotating Fields via Archimedean Spirals — •Esra Ilke Albar, Heiko Appel, and Franco Bonafe — Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science,22761 Hamburg, Germany

Twisted light (optical vortex), has the distinctive feature that it carries orbital angular momentum. This special type of electromagnetic field promises exciting opportunities for the interaction with matter, and it is expected to enhance spectroscopic techniques. Twisted light already has a vast potential of applications ranging from astronomy and optical tweezers to spintronics. Given this broad spectrum of applications and exciting prospects, it becomes worthwhile to investigate new and efficient methods to generate optical vortices. In this sense, metallic Archimedean spirals in the micro- and nanoscale are good candidates to produce such vortices. We design Archimedean spirals and test their performance in terms of generating field vortices. We perform numerical simulations with the Octopus code which employs the Riemann-Silberstein representation to propagate Maxwell's equations in real-time. Circularly-polarized light is passed through the designed structure, which is modeled both as a non-dispersive linear medium, and as Drude medium. We found that the out-coming field's angular momentum is altered by the structure. By using two different material models the effect of the materials' optical properties and the sole geometrical factors on the angular momentum outcome could be distinguished.