Flat spectral response gratings using high index materials

A system comprising:

• a plurality of optical elements in optical communication, the plurality of optical elements being stacked in a first direction, and the plurality of optical elements being configured, during operation, to project an image in a field of view of a user,
• wherein a first optical element of the plurality of optical elements is configured to receive light from a second optical element of the plurality of optical elements;
• wherein the first optical element defines a binary grating at along a periphery of the first optical element, the binary grating comprising:
• a plurality of protrusions extending from a base portion of the first optical element and towards the second optical element in the first direction, the protrusions comprising a first material having a first refractive index for a visible wavelength of light, and each of the protrusions comprising a first surface opposite the base portion of the first optical element;
• and
• a second material disposed between at least some of the plurality of protrusions along the base portion of the first optical element, the second material having a second refractive index for the visible wavelength of light,
• wherein there is an absence of the second material on the first surfaces of the protrusions.