Single mode full color waveguide combiner using asymmetric transmissive and reflective diffraction gratings

A waveguide display comprising an image generator and an optical system, the optical system comprising:

• a waveguide substrate;
• a diffractive coupler associated with the waveguide substrate, the diffractive coupler comprising at least two diffraction gratings;
• wherein each of the diffraction gratings includes a first layer of grating elements and a second layer of grating elements, the first and second layers of grating elements being arranged in different planes, the first and second layers of grating elements having a same grating period associated with the respective diffraction grating, and the grating elements of the second layer having a lateral offset with respect to the grating elements of the first layer.

A method comprising generating an image and coupling the image into a waveguide, the waveguide comprising:

• a waveguide substrate;
• a diffractive coupler associated with the waveguide substrate, the diffractive coupler comprising at least two diffraction gratings;
• wherein each of the diffraction gratings includes a first layer of grating elements and a second layer of grating elements, the first and second layers of grating elements being arranged in different planes, the first and second layers of grating elements having a same grating period associated with the respective diffraction grating, and the grating elements of the second layer having a lateral offset with respect to the grating elements of the first layer.