Optical waveguide device and display device

An optical waveguide device, comprising:

• a waveguide substrate having a first surface with a coupling-in region and an opposite second surface with a reflecting region, and further having a coupling-out region;
• a coupling-in grating disposed in the coupling-in region of the first surface of the waveguide substrate and configured to receive input light within a predetermined field of view, diffract at least a portion of the input light to form positive first-order diffraction light and zero-order diffraction light, and couple the light into the waveguide substrate, such that the light can propagate within the waveguide substrate through total reflection, wherein a light spot of the zero-order diffraction light first projected onto the second surface has a first profile, and the first profile is at least partially located in the reflection region;
• a coupling-out grating disposed in the coupling-out region of the waveguide substrate and configured to couple at least a portion of the light propagating into the coupling-out grating out of the waveguide substrate through diffraction;
• a reflection grating disposed in the reflection region of the second surface and configured such that a portion of the zero-order diffraction light forms positive first-order reflection light through diffraction and the positive first-order reflection light is propagated to the coupling-out grating through total reflection in the waveguide substrate;
• wherein a projection of the reflection region on the first surface at least partially overlaps with the coupling-in region, and a ratio of an area of an overlapping portion to an area of the coupling-in region is less than or equal to 40%.