In various embodiments, a waveguide assembly includes first and second waveguide slabs. The first waveguide slab is to receive image-bearing light and enlarge a pupil size of the light parallel to a first axis. The first waveguide slab includes a first input-coupling device to couple image-bearing light into the first waveguide slab under total internal reflection (TIR), and a first out-coupling region to decouple image-bearing light out of the first waveguide slab by reflection. The second waveguide slab is to couple at least a portion of the out-coupled image-bearing light from the first waveguide slab into the second waveguide slab and enlarge the pupil size parallel to a second axis, which is substantially orthogonal to the first axis. The second waveguide slab includes a diffractive in-coupling region and a transmissive diffractive out-coupling region, through which a user can view real world imagery and the out-coupled image-bearing light simultaneously.