Switchable flat optical elements with patterned cholesteric liquid crystal for augmented reality displays

Abstract

Switchable polarization volume hologram gratings and lenses have been developed. The diffraction efficiency can be modulated by a vertical electric field. A small amount of liquid crystal monomer is doped into cholesteric liquid crystal to form a stabilized polymer network to make the unwinding process reversible. The fabricated devices exhibit submillisecond response time, a large range of diffraction efficiency modulation, and high see-through quality. Some potential applications are demonstrated, including a significantly suppressed rainbow effect, enhanced light efficiency for a waveguide-based augmented reality display, and a Maxwellian-view type waveguide with pupil expansion. The unique properties and benefits of these switchable reflective gratings and lenses open a new door for near-eye displays, especially novel optical systems for augmented reality waveguide displays.