Pancharatnam–Berry optical elements for head-up and near-eye displays [Invited]
In this invited article, Tao Zhan et al. review the status of liquid crystal diffractive elements and their application as optical combiners. Because of the use of the liquid crystal, these diffractive elements present functionalities that are not found with other materials. These functionalities are a strong polarization dependence, the capability to be switched on and off with an applied electric field, and a large birefringence dispersion. After reviewing the device fabrication, the authors list the recent advancements in the field of display applications where liquid crystal diffractive elements are used— namely, the increased pixel density by temporal multiplexing, multiplane display, and see-through optical combiner. The authors also give a short overview about the simulation methods, such as matrix solvers, FDTD, FDFD, and rigorous coupled wave analysis.