Waveguide element and waveguide stack for display applications

A waveguide display element comprising:

• a waveguide body,
• an in-coupling grating arranged to the waveguide body,
• two first exit pupil expander gratings on different sides of the in-coupling grating corresponding to said separate directions,
• two second exit pupil expander gratings at least partly on different sides of the out-coupling grating that are adapted to receive light from the two exit pupil expander gratings, respectively, and
• a single out-coupling grating adapted to receive light from at least one of the second exit pupil expander gratings,
• wherein:
• the in-coupling grating is configured to couple incoming light into the waveguide body into two separate directions using opposite diffraction orders for splitting the field of view of the incoming light,
• the grating is further configured such that said coupling takes place only at wavelengths below a threshold wavelength residing in the visible wavelength range,
• the in-coupling grating has a period, which is short enough to prevent coupling of wavelengths above said threshold wavelength into the waveguide body, and
• at least part of the light is adapted to travel from the first exit pupil expander gratings to the second exit pupil expander gratings via a region of the waveguide layer on which the out-coupling grating is located, and further back to the out-coupling grating.