Optical waveguide structure and display device

An optical waveguide structure, comprising:

• at least two layers of optical waveguides laminated one on another and having a same refractive index, the optical waveguides comprising a bottom-layer optical waveguide and a top-layer optical waveguide in a lamination direction, the bottom-layer optical waveguide comprising a first surface away from the top-layer optical waveguide, and the top-layer optical waveguide comprising a second surface away from the bottom-layer optical waveguide;
• a coupling-in grating provided on the first surface or the second surface and configured to allow received parallel light beams to enter the optical waveguides, and the parallel light beams being propagated in the optical waveguides in a total-reflection manner at a first propagation step;
• a beam splitting structure arranged between two adjacent layers of the optical waveguides, and configured to allow a first part of light beams in the light beams propagated in a corresponding optical waveguide to be reflected in such a manner that the first part of light beams are propagated at a second propagation step, and allow a second part of light beams in the light beams propagated in a corresponding optical waveguide to be transmitted in such a manner that the second part of light beams are propagated at the first propagation step, the second propagation step being different from the first propagation step;
• and
• a coupling-out grating arranged on the first surface or the second surface and configured to extract the light beams propagated in total-reflection manner in the at least two layers of optical waveguides;
• wherein the beam splitting structure comprises at least two light splitting members arranged sequentially in a propagation direction of the light beams within the optical waveguides, and for the at least two light splitting members, ratios of intensity of the first part of light beams to intensity of the second part of light beams are different;
• and
• for the at least two light splitting members, the ratios of the intensity of the first part of light beams to the intensity of the second part of light beams gradually increase or gradually decrease in the propagation direction of the light beams within the optical waveguides;
• wherein change in splitting ratios of the at least two light splitting members is set in accordance with the space arrangement of the coupling-in grating and the coupling-out grating;
• wherein an orthogonal projection of the beam splitting structure onto the first surface is located within a first region of the first surface such that light beams from the beam splitting structure are directly transmitted toward the coupling-out grating, there is a gap between the first region and an orthogonal projection of the coupling-in grating onto the first surface and the first region is arranged to partially overlap an orthogonal projection of the coupling-out grating onto the first surface.