TALK: Linear and nonlinear photonic metasurfaces by Professor Guixin Li

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 both the spin and orbital angular momentum of light. It was demonstrated that the spin dependent metasurface can be applied to design highly efficient optical holograms, which have important applications in many areas, including holographic displays, beam shaping, data storage, optical trapping, and optical tweezers.

In nonlinear optical regime, we applied the concept of nonlinear geometrical Berry phase for designing nonlinear photonic metasurfaces. For example, in a second- and third- harmonic generation processes, the plasmonic meta-atoms, with certain rotational symmetries, can acquire a nonlinear geometric Berry phase of 3θ, 4θ, where θ is the in-plane orientation angle of the meta-atoms. This nonlinear phase can be continuously tuned by from zero to 2π by simply varying θ. Several interesting applications such as nonlinear image encryption and nonlinear spin-orbit interaction will be discussed.