Waveguides having reflective layers formed by reflective flowable materials
In some embodiments, compositions and methods comprising reflective flowable materials, e.g., reflective liquids including reflective inks and/or liquid metals, are described. In some embodiments, a surface is contacted with a reflective flowable material, thereby forming a reflective layer on the surface. In some embodiments, the surface is a surface of a waveguide, for example a waveguide for a display device, and the flowable material coats surfaces of protrusions on the surface to form reflective diffractive optical elements. Some embodiments include a display device comprising a reflective layer of reflective flowable material.
1. An optical device comprising:
an optical waveguide structure comprising:
a light redirecting element comprising:
a plurality of protrusions on an area of a surface of a waveguide; and
a reflective material disposed on the area and forming a layer on surfaces of the plurality of protrusions, the layer having at least one parameter that varies across the area,
wherein a reflectivity of the light redirecting element varies with the at least one parameter of the layer across the area; and
at least one additional waveguide, wherein the waveguide and the at least one additional waveguide form a waveguide stack.
2. The optical device of claim 1 , wherein the at least one parameter is a thickness of the layer across the area.
3. The optical device of claim 2 , wherein the thickness of the layer varies by 25% or more across the area.
4. The optical device of claim 1 , wherein the at least one parameter is a composition of the layer across the area.
5. The optical device of claim 1 , wherein the at least one parameter is coverage of the layer across the area, and wherein the layer covers less than an entirety of the area.
6. The optical device of claim 1 , wherein the layer comprises metal.
7. The optical device of claim 6 , wherein the metal is a liquid metal.
8. The optical device of claim 7 , wherein the liquid metal is selected from the group consisting of: gallium; indium; mercury; gallium-indium eutectic; gallium-indium alloy; gallium indium tin alloy; Ga, In, Sn and Zn alloy; Ga, In, and Sn alloy; sodium-potassium alloy; gallium, indium and stannum; gallium-indium-zinc-copper metallic; and silver indium gallium.
9. The optical device of claim 1 , wherein the area is delineated by walls or barriers on the surface of the optical waveguide structure, wherein the walls or barriers extend vertically to a height above the plurality of protrusions, and wherein the walls or barriers are configured to function as spacers to provide a gap between the waveguide and the at least one additional waveguide in the optical waveguide structure.
10. The optical device of claim 1 , wherein the waveguide stack is optically coupled to a spatial light modulator, wherein the spatial light modulator is configured to inject light containing image information into the waveguide stack.
11. The optical device of claim 1 , wherein the first waveguide and the at least one additional waveguide each comprise associated outcoupling optical elements, wherein the respective associated outcoupling optical elements are configured to redirect light out of the first waveguide and the at least one additional waveguide with different amounts of wavefront divergence.
12. The optical device of claim 1 , wherein the optical device is an augmented reality display, wherein the first waveguide and the at least one additional waveguide are configured to transmit light from an ambient environment.
13. The optical device of claim 1 , wherein each waveguide of the stack of waveguides comprises an incoupling grating, wherein, in a top-down view, incoupling gratings of different waveguides are laterally offset from one another.
14. The optical device of claim 13 , wherein the light redirecting element comprises the incoupling grating.
15. The optical device of claim 14 , wherein the reflectivity of the incoupling grating of the first waveguide is different from the reflectivity of the incoupling grating of the at least one additional waveguide.
16. The optical device of claim 15 , wherein the incoupling grating of the first waveguide selectively redirects light of a first wavelength into the first waveguide, and wherein the incoupling grating of the at least one additional waveguide selectively redirects light of a second wavelength into the at least one additional waveguide, wherein the first wavelength is different from the second wavelength.