In an optical near eye display system, a monolithic three-dimensional optical microstructure is formed by a waveguide substrate with at least one DOE having grating regions that integrate the functions of in-coupling of incident light into the waveguide, exit pupil expansion in one or two directions, and out-coupling of light from the waveguide within a single optical element. An in-coupling region of the DOE couples the incident light into the waveguide and to a beam steering and out-coupling region. The beam steering and out-coupling region provides exit pupil expansion and couples light out of the waveguide. The beam steering and out-coupling region of the DOE can be configured with a two-dimensional (2D) grating that is periodic in two directions.