Broadband adaptive lens assembly with variable optical power for augmented reality display

A display device comprising:

• a waveguide configured to guide light in a lateral direction parallel to an output surface of the waveguide, the waveguide further configured to outcouple the guided light through the output surface;
• and
• a broadband adaptive lens assembly configured to incouple and to diffract therethrough the outcoupled light from the waveguide, the broadband adaptive lens assembly comprising a first waveplate lens comprising a liquid crystal (LC) layer arranged such that the first waveplate lens has birefringence (Δn) that varies in a radially outward direction from a central region of the first waveplate lens, and configured to diffract the outcoupled light at a diffraction efficiency greater than 90% within a wavelength range including at least 450 nm to 630 nm,
• wherein a radial arrangement of the Δn of the first waveplate lens, resulting from liquid crystal molecules of the LC layer at a given radius from a central axis of the first waveplate lens having substantially the same angle of rotation, is such that the first waveplate lens radially converges light having a first polarization while radially diverging light having a second polarization opposite the first polarization, and
• wherein the broadband adaptive lens assembly is configured to be selectively switched between a plurality of states having different optical powers.