93‐1: Efficient Large‐Angle Diffraction Using Patterned Chiral Liquid Crystal

Chiral liquid crystals spontaneously arrange into a helical structure of which the pitch depends on the concentration of the chiral dopant. If the effective wavelength inside the liquid crystal matches the period of the helix, Bragg reflection occurs and light is efficiently reflected. A periodic photoalignment pattern at the surface of a substrate can be used to tilt the axis of the helical structure and redirect the reflected light into a desired direction. This principle is used in waveguide-based beam combiners for augmented reality devices and in single component spectrometers.