Airy Beam Generation: Approaching Ideal Efficiency and Ultra Wideband with Reflective and Transmissive Metasurfaces

Airy beams are essential for photonic applications, owing to their intriguing diffraction-free, self-accelerating, and self-healing properties. Recently, 2D metasurfaces have offered great opportunities for generating Airy beams within subwavelength thickness. However, they suffer from the bottlenecks of low efficiency and narrow bandwidth, which may limit their applications in practice. In this study, a strategy is proposed to design amplitude- and phase-controllable metasurfaces that can generate desirable high-efficiency and ultra wideband Airy beams, based on the Jones matrix analysis. Two exemplary prototypes of Airy beam generators operating in reflection and transmission geometries are demonstrated in the microwave region, achieving high efficiency approaching the theoretical limitation in an ultrawide bandwidth (fractal bandwidth of 84% for reflective prototype and 118% for transmissive). The results show a significant advantage of the bandwidth and total efficiency over low-thickness metasurfaces. The proposed strategy and metasurface generators may trigger great interest in ultra wideband and high-efficiency wave manipulations, with small thickness and flat profile compatible with integrated systems, which hold promise for structured light, metaoptics, beam shaping, and advanced holography.