Directional optical waveguide, directional backlight module, and display device

A directional optical waveguide, comprising:

• a time division multiplexing unit, and
• N layers of stacked optical waveguides with a same light-emitting direction, a light-emitting surface of each layer of the optical waveguide being provided with a pixel-type grating, and N being an integer greater than or equal to 2;
• wherein,
• the time division multiplexing unit is configured to control, according to a stacking order of the N layers of optical waveguides within each frame video stream cycle, the N layers of optical waveguides to introduce a source light ray into the corresponding pixel-type grating during a corresponding frame video period, the each frame video stream cycle comprises N frame video periods in a one-to-one correspondence with the N layers of optical waveguides;
• the source light ray that is introduced into the pixel-type grating is diffracted in the pixel-type grating to form a plurality of first-order diffraction light rays in a one-to-one correspondence with display pixels, the plurality of first-order diffraction light rays are incident on an optical waveguide opposite to a light-emitting surface of the optical waveguide in which the pixel-type grating is located;
• and diffraction angles and diffraction azimuth angles of each of the first-order diffraction light rays are different;
• wherein a pixel-type grating corresponding to each layer of optical waveguides comprises k gratings in a one-to-one correspondence with k display pixels;
• gratings corresponding to a same display pixel in adjacent two layers of optical waveguides have a same grating cycle and having different grating phases.