Display device having diffraction gratings with reduced polarization sensitivity

Abstract

Blazed diffraction gratings provide optical elements in head-mounted display systems to, e.g., incouple light into or out-couple light out of a waveguide. These blazed diffraction gratings may be configured to have reduced polarization sensitivity. Such gratings may, for example, incouple or outcouple light of different polarizations with similar level of efficiency. The blazed diffraction gratings and waveguides may be formed in or on a high refractive index substrate such as lithium niobate. In some implementations, the blazed diffraction gratings may include diffractive features having a feature height or feature depth of 40 nm to 120 nm, for example, 80 nm. In some examples, the diffractive features may be etched into the high index substrate, e.g., lithium niobate.