Flat miniaturized surfaces to structure light to Hermite-Gaussian beams

Conventional wireless communication systems are primarily dependent on the radio frequency spectrum, which will gradually become congested and bandwidth-limited due to increasing global internet traffic. Optical wireless communication, coupled with structured light, is the key to providing tariff-free, high-speed internet. Orbital angular momentum in structured light beams can facilitate multiplexing of spatial modes. Optical vortex beams have been widely studied for communication, but they suffer from beam divergence, sensitivity to turbulence, and constraints on receiver aperture. Hermite-Gaussian (HG) beams are a compelling alternative, featuring orthogonality, lower crosstalk, and compact beam profiles in low-order modes, making them ideal for efficient optical wireless communication. However, conventional optics for HG beam generation introduce bulkiness and system complexity, limiting their integration in photonic systems. A single-cell-driven, broadband metasurface platform is numerically studied to generate HG beams in the visible wavelength range (488−633 nm), addressing the aforementioned issues. The proposed metasurfaces, made of rectangular-shaped zinc sulfide unit cells, achieve an average transmission efficiency of 80% across the visible spectrum. These advancements could enhance optical trapping, tweezers, and non-invasive handling, while also innovating free-space optical communication, multiplexed communication, and structured illumination in biomedical imaging.