Independent control of both amplitude and phase for orthogonal circularly polarized electromagnetic waves through polarization conversions

Spin-selective multi-functional integrated metasurfaces have attracted much research attention due to its promising application prospects. However, the goal of independent and arbitrary control of both amplitude and phase for orthogonal circularly polarized (CP) waves still has not been achieved fully. This is because it requires mirror asymmetric structure to achieve such a goal but there is no apparent physical relation between the unit cell structure and the spin-selective properties. A simple method with clear physical pictures is proposed in this paper to achieve the goal of arbitrary spin-selective manipulations. The idea is to convert the incident orthogonal CP waves to orthogonal linearly polarized (LP) waves first, then manipulate the LP waves with matured techniques, and finally convert the LP waves back to the corresponding CP waves. Simulations and experiments have been carried out to validate the method. Using this idea, spin-selective focusing, spin-selective deflection and spin-selective orbital angular momentum vortex beam have been demonstrated.