An achromatic metasurface waveguide for augmented reality displays

Augmented reality (AR) displays are emerging as the next generation of interactive platform, providing deeper human-digital interactions and immersive experiences beyond traditional flat-panel displays. Diffractive waveguide is a promising optical combiner technology for AR owing to its potential for the slimmest geometry and lightest weight. However, severe chromatic aberration of diffractive coupler has constrained widespread adoption of diffractive waveguide. Wavelength-dependent light deflection, caused by dispersion in both in-coupling and out-coupling processes, results in limited full-color field of view (FOV) and nonuniform optical responses in color and angular domains. Here we introduce an innovative full-color AR system that overcomes this long-standing challenge of chromatic aberration using a combination of inverse-designed metasurface couplers and a high refractive index waveguide. The optimized metasurface couplers demonstrate true achromatic behavior across the maximum FOV supported by the waveguide (exceeding 45°). Our AR prototype based on the designed metasurface waveguide, exhibits superior color accuracy and uniformity. This unique achromatic metasurface waveguide technology is expected to advance the development of visually compelling experience in compact AR display systems.