Liquid-crystal-based polarization volume grating applied for full-color waveguide displays

Opt Lett. 2018 Dec 1;43(23):5773-5776. doi: 10.1364/OL.43.005773.

Abstract

In this Letter, we demonstrate polarization volume grating (PVG)-based couplers for a double-layer waveguide display to realize a full-color near-eye display. The polarized interference exposure with photo-alignment methods was employed to generate a birefringent spiral configuration with two-dimensional periodicity in a chiral-dopant reactive mesogen material. Such a structure presents a unique highly efficient single-order Bragg diffraction with polarized selectivity. The prepared PVG couplers exhibited over 80% diffraction efficiency with large diffraction angles at spectra of blue (457 nm), green (532 nm), and red (630 nm). The demonstrated waveguide prototype showed a full-color display with a diagonal field of view of around 35°. The overall optical efficiency was measured as high as 118.3 cd/m2 per lumen with a transparency of 72% for ambient light.