Holographic Plastics with Liquid Crystals

Holography via laser interference is a powerful technique for precise processing of plastics by creating ultrafine structures down to the nanometer level. As all of the information from the laser can be reconstructed in these ultrafine structures by periodic refractive index modulation, the produced holographic plastics have been recognized to be indispensable for flexible and lightweight three-dimensional displays, augmented/virtual reality, high-density data storage, advanced anticounterfeiting, etc. Particularly, the marriage of liquid crystals (LCs) with holographic plastics not only is profitable for facile holographic processing but also can impart versatile stimuli-response functions. However, despite extensive research on this interdisciplinary field, several fundamental questions are still unclear. (1) Is there any simple form to illustrate how the refractive index modulation manipulates light propagation? (2) Does the refractive index modulation work in the same way for different types of holograms? (3) What are the big challenges for future practical applications? With these questions in mind, this perspective presents several important equations for both transmission and reflection holograms, summarizes updated advances in the field, and finally calls for endeavors to meet the urgent needs in rapidly growing information technology.