Experimental Demonstration of Multidimensional and Multifunctional Metalenses Based on Photonic Spin Hall Effect

Metalens is one kind of two-dimensional ultrathin lenses with subwavelength artificial structures that can focus light in a compact, flexible way. However, most strategies for designing metalenses only work on one specific spin state of light (i.e., either right- or left-circularly polarized light), hindering simultaneous control of both spins. Utilizing both the Pancharatnam-Berry phase and the propagation phase, we can rationally control the phase for each spin state of light. As proof-of-concept demonstrations, here we numerically and experimentally realize the independent focusing and manipulation of both spins of light by V-antenna metasurfaces, which can be regarded as the demonstration of the photonic spin Hall effect. Our multidimensional metalens is able to focus light of different spins at designated positions along both transverse and longitudinal directions. It can be used as a polarization analyzer to distinguish the polarization state of incident light. In addition, our multifunctional metalens can act either as a convex lens or an axicon, depending on the spin of light. The demonstrated multidimensional and multifunctional metalens has versatile potentials in spin-dependent nanophotonics, ranging from optical imaging and micro/nano-object manipulation to optical sensing.