Spin‐Orbit Modal Optical Vortex Beam Shaping from Dielectric Metasurfaces

Abstract

works in the 1960s on optical resonators the emergence of optical vortex modes associated with on-axis optical phase singularities and ensuing doughnut shaped intensity patterns. [1] The underlying helical-shaped equiphase surfaces for the light field remained barely studied for almost three decades, though the fabrication of helical phase plates [2] and the interferometric assessment of beams with helical phase profile [3] date back to the 1970s. Optical waves rotating around a phase singularity has only been articulated in the late 1980s. [4] Soon after, within a paraxial wave optics framework, Laguerre-Gauss beams have been recognized as a basis made out of optical vortex modes carrying an integer multiple of ℏ of optical orbital angular momentum per photon, [5] which kick-started a wealth of fundamental and technological developments that are still ongoing. The generation of Laguerre-Gauss beams involves the shaping of azimuthal and radial degrees of freedom (respectively labeled by the indices l ∈ Z and p ∈ N )-according to the paraxial expression of the electric field in the cylindrical coordinate system (r, φ, z