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

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.