Polarization-multiplexed metalens via spin-independent manipulation of spin–orbit interactions

Metasurfaces have demonstrated revolutionary capabilities in manipulating the polarization, phase, and amplitude of light. Pancharatnam–Berry (P–B) phase metasurfaces can operate over a broad spectrum and robust phase distributions against fabrication tolerance. However, the conjugated characteristic of the modulated phases for different spin photons introduces an obstacle for multifunctional photonics applications. This problem seriously hinders the development of P–B phase metasurfaces. We proposed a method through symmetry breaking of photonic spin–orbit interactions and achieving spin-independent manipulation of spin–orbit interactions. As a proof-of-principle demonstration, we realized polarization-multiplexed multifunctional metalenses at visible and infrared wavelengths with high numerical aperture, and the focal lengths of different foci can be adjusted independently. The proposed metalens has potential applications in imaging, optical communications and optical trapping, and also the approach of independent manipulation of spin–orbit interactions can facilitate the development of P–B phase metasurfaces toward spin-controlled multifunctional photonics. (paper)