Pancharatnam–Berry optical elements for head-up and near-eye displays Invited

Liquid-crystal-based Pancharatnam–Berry phase optical elements (PBOEs), also known as diffractive wave plates (DWPs), geometric phase optics (GPO), or geometric phase holograms (GPHs), are functional planar structures with patterned orientation of anisotropy axis. Several scientifically interesting yet practically useful electro-optical effects, such as focusing, beam splitting, waveguide coupling, and wavelength filtering, have been realized with PBOEs. Because of the high degree of optical tunability, polarization selectivity, nearly 100% diffraction efficiency, and simple fabrication process, PBOEs have found widespread applications in emerging display systems, particularly virtual/augmented/mixed reality displays and head-up displays. In this review, we will describe the basic operation principles, present device fabrication procedures, discuss numerical modeling methods, and address applications of PBOEs in emerging display systems.