Broadband integrated metalens for creating super-oscillation 3D hollow spot by independent control of azimuthally and radially polarized waves

Three-dimensional hollow spots have attracted significant interest for a wide variety of optical applications including optical trapping, simulated emission depletion microscopy, and optical tweezers. In this paper, an integrated superoscillatory metalens is proposed based on all-dielectric metasurfaces for independent control of azimuthally and radially polarized waves for broadband operation. The reported metalens integrates the functions of two independent lenses on single substrate, whose phase profiles are overlapped on the same plane and are optimized for independent modulation of azimuthal and radial components in vector cylindrically polarized waves. The independent manipulation of the two orthogonal polarizations allows for significantly reducing the transverse size of the 3D hollow spot. Numerical simulation shows the formation of a 3D hollow spot with inner sizes of 0.33 λ and 1.32 λ in the transverse and axial directions respectively. More importantly, the broadband performance of the proposed superoscillatory lens was also demonstrated with a bandwidth of 40 nm (from 612.8 nm to 652.8 nm). Such a superoscillatory lens is promising for applications of optical trapping, optical tweezers, and super-resolution microscopy. (paper)