Polarization-Insensitive Grating Waveguide for Augmented Reality Display

Transverse electric (TE) polarized light and transverse magnetic (TM) polarized light cannot be used for the display in the general grating waveguide head-mounted display system owing to polarization sensitivity. To solve this problem, a design method for polarization-insensitive grating is proposed, based on a genetic algorithm and rigorous coupled-wave analysis. The method's optical design is based on a wavelength of 532 nm. The average diffraction efficiencies of the in-coupling grating in TE polarized, TM polarized, and non-polarized light increase from 6. 1% to 21.0%, 13. 7% to 40. 5%, and 9. 9% to 30. 7%, respectively. The average diffraction efficiencies of the out-coupling grating in TE polarized, TM polarized, and non-polarized light increase from 3.1% to 12.1%, 0.8% to 10. 7% , and 1.9% to 11. 4%, respectively. A prototype of the display system is built, and the test shows that the display is clear and bright. A large field of view of 30 degrees X 22 degrees is achieved , revealing the usability of the polarization-insensitive grating waveguide design method and the non-polarization image source in the field of augmented reality. The proposed method can be useful in the research and development of waveguide augmented reality systems.