Reducing eye glow in augmented reality waveguide through topological metagrating design

Eye glow remains a challenging issue for diffractive augmented reality (AR) waveguides with conventional binary gratings. This work introduces topological metagratings, optimized via adjoint design techniques, to mitigate eye glow while enhancing display performance. The proposed metagrating, designed with 300 nm-thick silicon nitride on a 0.7 mm-thick glass substrate (refractive index: 1.51) and a 424 nm pitch, achieves a 50% outcoupling efficiency and reduces eye glow diffraction to 17%, surpassing binary gratings with 30% outcoupling and 20% eye glow loss. The integrated metagrating into an AR waveguide also improves outcoupling conversion efficiency by 60% and brightness by 8%, while reducing eye glow brightness by 40%. This study demonstrates the promise of topological metagratings in addressing eye glow and advancing AR waveguide performance, paving the way for enhanced user experience in AR systems.