Photonic spin-dependent wave shaping with metasurfaces: applications in edge detection

The task of spatial light modulation is to control the amplitude, wavefront, and polarization state of an incident beam. It is commonly achieved by using diffractive optical elements through dynamic phase delay, where a local optical path difference is created by varying the height of a material over a thickness of many wavelengths. Unlike the dynamic phase, the accumulation of the Pancharatnam-Berry (PB) phase does not rely on the thickness of the material but arises from the conversion of the polarization state during propagation. Metasurfaces based on the PB phase mechanism are a type of artificial electromagnetic arrays composed of subwavelength anisotropic nanostructures which enable space-variant polarization control and hence, space-variant phase modulation of the light field. Because of the strong interaction between nanostructures and light, the PB phase metasurface typically has a constant height profile, which is beneficial to micro-/nano-optics efficiency and fabrication. Thanks to the spin selectivity, PB phase metasurface offers a number of advantages, including easy fabrication (robust to fabrication error), compact form factor, lightweight property, and unique frequency dependency. Recently, the field of PB phase metasurfaces has made rapid progress as a platform for excessive potential applications. There are several representative demonstrations of PB phase metasurface-based devices such as ultrathin optical metalens, high-efficiency hologram, polarization imaging, nonlinear wavefront manipulation, augmented reality, and virtual reality. This chapter summarizes some of our recent studies by using PB phase metasurface on spin-dependent wave shaping, edge detection, and the extended tunable spin-dependent manipulation and quantum edge detection.