Achromatic single-layer waveguide for wide-view augmented reality displays

Waveguide technology stands as the cornerstone of augmented reality (AR) displays. The polarization volume grating (PVG), with strong refractive index modulation and distinctive polarization selectivity, has exhibited great potential to achieve the two core prerequisites [full-color vision and wide field of view (FOV)] of current waveguide-based AR displays. However, the development of single-layer full-color PVG waveguides remains stagnant, primarily hindered by severe chromatic dispersion. To address this, this study proposes a novel achromatic design for a single-layer, full-color PVG-based waveguide for AR displays. In this structure, PVGs serve as the coupling grating of the waveguide, while two polarization gratings are positioned on the opposite side, aligned with the PVGs region. The additional polarization grating is specially designed to compensate for the red-light diffraction angle, which broadens the red-light transmission range within the waveguide, thereby enhancing the overall full-color FOV. Experimental results well validate the design’s effectiveness, showing that the proposed design achieves an 18.4° horizontal full-color FOV in a waveguide with a refractive index n g =1.51—which is 2.6-fold higher than the 5.1° of conventional solutions. When silicon carbide (SiC) with a refractive index of 2.6 is used as the waveguide material, the proposed full-color design will achieve an impressive 84° horizontal full-color FOV. This study offers a new pathway for advancing color display technology in single-layer diffractive optical waveguides.