US Patent 11036109 Variable-focus virtual image devices based on polarization conversion

Example display devices include a waveguide configured to propagate visible light under total internal reflection in a direction parallel to a major surface of the waveguide. The waveguide has formed thereon an outcoupling element configured to outcouple a portion of the visible light in a direction normal to the major surface of the waveguide. The example display devices additionally include a polarization-selective notch reflector disposed on a first side of the waveguide and configured to reflect visible light having a first polarization while transmitting the portion of the visible light having a second polarization. The example display devices further include a polarization-independent notch reflector disposed on a second side of the waveguide and configured to reflect visible light having the first polarization and the second polarization, where the polarization-independent notch reflector is configured to convert a polarization of visible light reflecting therefrom.