Flexible design of multifocal metalenses based on autofocused Airy beams

Abstract

Extreme miniaturization of on-demand optical devices such as ultrathin lenses is currently leading to significant advancements in manufacturing novel materials and nanotechnologies. Flexibility and tunability of engineered layouts enable efficient integration of complex photonic modules. In this regard, here we propose an autofocused Airy (AFA)-based metalens that operates, depending on the molded phase profile, as a multifocal focusing lens, which to the best of our knowledge has not been reported before. To do this, we call attention to the fact that the two conjugate focal points of an AFA beam can be brought into real space by applying a proper convex lens phase profile. Considering full control of the phase and amplitude of the incident light with dielectric C-shaped meta-atoms, we conceived that both generations of the AFA beam and their focusing with a convex lens could be carried out by a compact wavelength-scale metasurface. In addition, hybrid AFA focusing and phase-only lensing are demonstrated as a versatile method to be implemented in designing multifocal setups.