Broadband computer-generated holography (CGH)-based Bessel beam generation

In the recent era of development, metasurfaces have provided a new way to develop ultra-compact multifunctional optical devices by overcoming the bottlenecks of traditional bulky optics. Due to phase singularities, metasurface-enabled Bessel beams of higher orders can carry orbital angular momentum (OAM) which makes them a potential candidate for high-capacity communication and data transmission systems. Herein this manuscript, Bessel beams of distinct order are designed using the technology of computer-generated holography for the visible spectrum. For full-range phase coverage, geometric phase modulation is applied along with a spin decoupling strategy to incorporate multifunctionality. The designed metasurface can transform the incident circular polarization component into its orthogonal one and can produce different-order beams. For proof of the broadband optical operation, the response of the designed metasurface is demonstrated at three wavelengths i.e., 488nm, 532nm, and 633nm. Moreover, a highly indexed lossless material zinc selenide (ZnSe) is introduced for the visible spectrum for a highly efficient optical response. The proposed design strategy can be extensively applied in optical communication, photography, optical data storage, and tomography techniques.