By designing an ultrathin metasurface, which consists of spatially variant plasmonic structures with engineered geometric Berry phase, it is shown that spin-orbit coupling of light can be utilized to manipulate the SAM dependent focusing of light or the optical vortex beam and rotate the orbital angular momentum of light. More recently, we also demonstrated that the spin dependent metasurface can be applied to design highly efficient optical holograms The metasurface hologram offers the unique opportunity of creating high quality holographic optical patterns with high spatial resolution and broad angle of view, which have important impact in the areas including holographic displays, beam shaping, data storage, optical trapping, optical tweezers and so on.
In nonlinear optical regime, we also provided proof for the first time of the existence of nonlinear geometrical Berry phase in a third harmonic generation process by using a plasmonic nanocross with spatially variant orientation angle. The nonlinear geometric Berry phase is 4θ, where θ is the orientation angle of the nanocross with respect to the x-axis. This nonlinear phase can be continuously tuned by from zero to 2π by simply rotating the in plane orientation angle of the meta-atom.