Waveguide comprising a bragg polarization grating

A method comprising:

• producing light corresponding to an image;
• coupling the light corresponding to the image into an optical waveguide comprising an input-coupler, an intermediate-component, and an output-coupler;
• after the light corresponding to the image has been coupled into the optical waveguide, and has traveled within at least a portion of the optical waveguide by way of total internal reflection (TIR), diffracting the light corresponding to the image into a zero-order beam having one of right handed circular polarization or left handed circular polarization, and a first-order beam having the other one of right handed circular polarization or left handed circular polarization;
• after the light corresponding to the image has been diffracted into the zero-order beam having the one of right handed circular polarization or left handed circular polarization, and the first-order beam having the other one of right handed circular polarization or left handed circular polarization, coupling at least a portion of the light corresponding to the image out of the optical waveguide;
• and
• implementing the intermediate-component using a stack of birefringent layers that is configured to:
• diffract the light corresponding to the image that is incident thereon into the zero-order beam having the one of right handed circular polarization or left handed circular polarization, and the first-order beam having the other one of right handed circular polarization or left handed circular polarization;
• have a relatively high diffractive efficiency for light within an angle of incidence range having one of right handed circular polarization or left handed circular polarization;
• and
• have a relatively low diffractive efficiency for light within the angle of incidence range having the other one of right handed circular polarization or left handed circular polarization.

A system comprising:

• an optical waveguide comprising an input-coupler, an intermediate-component, and an output-coupler;
• and
• a display engine configured to produce an image and to direct light corresponding to the image towards the input-coupler of the optical waveguide, wherein:
• the input-coupler is configured to couple light corresponding to the image, that is incident on the input-coupler, into the optical waveguide and towards the intermediate-component;
• the intermediate-component is configured to perform pupil expansion and direct the light corresponding to the image towards the output-coupler;
• the output-coupler is configured to couple, out of the optical waveguide, the light corresponding to the image that travels in the optical waveguide from the input-coupler to the output-coupler via the intermediate-component by way of total internal reflection (TIR);
• and
• the intermediate-component comprises a Bragg polarization grating configured to:
• diffract the light corresponding to the image that is incident thereon into a zero-order beam having one of right handed circular polarization or left handed circular polarization, and a first-order beam having the other one of right handed circular polarization or left handed circular polarization;
• have a relatively high diffractive efficiency for light within an angle of incidence range having one of right handed circular polarization or left handed circular polarization;
• and
• have a relatively low diffractive efficiency for light within the angle of incidence range having the other one of right handed circular polarization or left handed circular polarization.