Diffractive optical waveguide and display device

Abstract

The present application provides a diffractive optical waveguide for optical pupil expansion and a display device. The diffractive optical waveguide for optical pupil expansion comprises a waveguide substrate; a coupling-out grating disposed on or in the waveguide substrate and configured to couple input light out of the waveguide substrate by diffraction, wherein the coupling-out grating comprises a plurality of grating lines with widths; the plurality of grating lines are spaced in a cycle of a first predetermined period along a first direction and are spaced in a cycle of a second predetermined period along a second direction; each of the grating lines comprises a plurality of periodic structures in continuous and connected arrangement. Each of the periodic structures comprises a first edge and a second edge spaced in the first direction. The first predetermined period is defined as the distance between the first edge and the second edge in the first direction. The width of the first edge is equal to that of the second edge. The distance between the center of the first edge and the center of the second edge in the second direction is defined 0.5 times the second predetermined period. At least one of the first side edge and the second side edge of each periodic structure is a non-linear side edge.