Fig. 16
From: Waveguide-based augmented reality displays: perspectives and challenges
(a, b Are redrawn from [113] and c, d are redrawn from [114])
Methodology of expanding angular bandwidth for VHGs and PVGs. a Spatial invariant (traditional) in-coupler design and its diffraction property. b Rolled \(k\)-vector in-coupler design and its corresponding diffraction property. c Two-layer structure of PVGs. d Diffraction properties for single-layer PVGs with slanted angle \(26.7^\circ\), \(24.2^\circ\) and two-layer PVG at horizontal period \(450\,\text{nm}\)