Use of Dielectric Metasurfaces to Generate Deep-Subwavelength Nondiffractive Bessel-Like Beams with Arbitrary Trajectories and Ultralarge Deflection

For decades, accelerating beams have attracted considerable interest in fundamental physics and in various emerging applications. However, not only are conventional accelerating beam generators (such as spatial light modulators) bulky and diffraction-inefficient, they also have a poorly resolved ability of phase manipulation that limits the accelerating beam's minimum size and maximum degree of curvature. In this study, a dielectric metasurface is used to generate highly focused nondiffractive Bessel-like accelerating beams with predefined arbitrary trajectories within a broadband spectral range of 550–710 nm. In particular, a similar metasurface with a combined phase profile allows the generation of a Bessel-like vortex beam with an ultrahigh numerical aperture of 0.79, resulting in a subwavelength beamwidth of 234 nm (≈0.43λ) down to the diffraction limit. In addition, various accelerating Bessel-like beams and beam arrays with different predefined trajectories and characteristic beam parameters that are not otherwise achievable with conventional spatial light modulators are demonstrated with synthetic-phase metasurfaces. This study promotes the diversity of Bessel-like accelerating beams for practical applications in fields such as optical manipulation, optical storage, biomedical imaging, and material processing.