Generation of Non-Diffracting Circular Airy OAM Beams using Single Layer Metamaterial Structure

We present the design of a single-layer metamaterial structure to generate the non-diffracting circular Airy orbital angular momentum (OAM) beam at millimeter-wave frequencies. Our work is supported by the full-wave 3D Electromagnetic simulations using CST Microwave Studio. The metamaterial structure design consists of eight distinct unit cells by creating metallic patterns on either side of the dielectric substrate to provide full control to generate 0° to 360° phase variation. Arrangement of these unit cells in the metamaterial structure is such that to transform the incident Gaussian beam to the circular Airy OAM beam of order <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\ell=1$</tex>. This simulation based study demonstrates the autofocusing property in the generated circular Airy OAM beam up to a certain distance. An additional lens made up of the same unit cells is placed beyond this auto-focusing zone to further reduce the divergence of the circular airy OAM beam.