Design and control of rotating varifocal elliptical airy vortex beams using composite phase metasurfaces

Abstract

In this paper, we propose a novel method for generating tunable elliptical Airy beams (EAVBs) using a bilayer all-dielectric metasurface. The metasurface is designed through the integration and rotation of the phase profiles of elliptical Airy beams and two off-axis Fresnel lenses.The dynamic tuning of the focal length and the beam propagation characteristics is accomplished by taking advantage of the moiré effect, which is generated from the interference between the superimposed phase distributions. The metasurface was theoretically modeled using MATLAB and then verified through Finite-Difference Time-Domain (FDTD) simulations. The results show that it can flexibly control the focal points in the x-y and x-z planes, thereby enabling precise control over the trajectory and focal position of the beam. The high degree of agreement between the theoretical predictions and the simulation results verifies that the proposed metasurface design is effective and versatile. This innovative approach has great application potential in adaptive optics, high-resolution imaging, and optical systems for dynamic beam shaping and focus control.