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. A method of making an optical waveguide structure, the method comprising:
forming a reflective optical element for a waveguide, wherein forming the reflective optical element comprises:
providing a pattern of protrusions on a first surface of the waveguide; and
depositing a reflective ink to form a reflective ink layer on surfaces of the protrusions, the reflective ink layer having at least one parameter that varies across an area occupied by the pattern of protrusions, and
wherein a reflectivity of the reflective optical element varies with the at least one parameter of the reflective ink across the area occupied by the pattern of protrusions.
2. The method of claim 1 , wherein the reflective ink is selectively deposited on a predetermined region of the first surface of the waveguide.
3. The method of claim 2 , wherein the first surface comprises a vertically-extending wall that defines at least a portion of the predetermined region onto which the reflective ink is selectively deposited, wherein the wall restricts lateral movement of the reflective ink.
4. The method of claim 2 , wherein the depositing comprises administering the reflective ink from an inkjet, a microdispenser, or an applicator rod.
5. The method of claim 1 , further comprising:
forming an additional reflective optical element on an additional waveguide by depositing the reflective ink on a pattern of protrusions on a surface of the additional optical waveguide, wherein the additional reflective optical element is configured to reflect incident electromagnetic radiation; and
attaching at least the additional waveguide to a surface of the waveguide,
thereby producing a stack of waveguides.
6. The method of claim 1 , wherein the reflective ink comprises a particle-free ink.
7. The method of claim 1 , wherein the reflective ink comprises aluminum, silver, or a combination thereof.
8. The method of claim 1 , wherein the reflective ink further comprises a binder, and wherein the binder is present in the reflective optical element.
9. The method claim 1 , wherein the reflective optical element further comprises a surface accumulation.
10. The method of claim 1 , wherein the protrusions of the first surface comprise photoresist.
11. The method of claim 10 , wherein the wall comprises a mechanical spacer configured to maintain space between the waveguide and an overlying additional waveguide.
12. The method of claim 1 , wherein the protrusions of the first surface are part of a grating, and wherein at least a portion of the reflective ink is disposed non-conformally on the grating, and wherein an interface between the reflective ink and the first surface is substantially free of gaps.
13. The method of claim 1 , wherein the reflective optical element is a diffractive optical element configured to redirect incident light at angles such that the light propagates through the waveguide by total internal reflection.
14. The method of claim 1 , wherein the reflective optical element is configured to reflect incident electromagnetic radiation with a reflectivity of at least 60%.
15. The method of claim 1 , wherein the reflective optical element is part of a light incoupling optical element or a light distributing element configured to reflect electromagnetic radiation into the first waveguide.
16. The method of claim 1 , wherein the at least one parameter is a thickness of the reflective ink layer across the area occupied by the pattern of protrusions.
17. The method of claim 16 , wherein the thickness of the reflective ink layer varies by 25% or more across the area occupied by the pattern of protrusions.
18. The method of claim 1 , wherein the at least one parameter is a composition of the reflective ink layer across the area occupied by the pattern of protrusions.
19. The method of claim 1 , wherein the at least one parameter is a coverage of the reflective ink layer across the area occupied by the pattern of protrusions.
20. The method of claim 19 , wherein the reflective ink layer covers less than an entirety of the area occupied by the pattern of protrusions.
21. A method of making a display device, the method comprising:
forming a reflective layer of reflective ink on a first surface of an optical waveguide, wherein the first surface comprises protrusions that form a grating,
wherein at least one parameter of the reflective layer varies across an area occupied by the protrusions,
wherein the reflective layer is disposed on the first surface, thereby making a reflective optical element, and
wherein a reflectivity of the reflective optical element varies with the at least one parameter of the reflective layer across the area occupied by the protrusions; and
disposing the reflective optical element in a display device.
22. The method of claim 21 , wherein the reflective layer of reflective ink is disposed non-conformally on the first surface, and wherein an interface between the reflective layer and first surface is substantially free of gaps.
23. The method of claim 21 , wherein the reflective layer and protrusions form a diffractive optical element.
24. The method of claim 21 , wherein the at least one parameter is a thickness of the reflective layer across the area occupied by the protrusions.
25. The method of claim 24 , wherein the thickness of the reflective layer varies by 25% or more across the area occupied by the protrusions.
26. The method of claim 21 , wherein the at least one parameter is a composition of the reflective layer across the area occupied by the plurality of surface protrusions.
27. The method of claim 21 , wherein the at least one parameter is a coverage of the reflective layer across the area occupied by the protrusions.
28. The method of claim 27 , wherein the reflective layer covers less than an entirety of the area occupied by the protrusions.
29. A method of making an optical device, the method comprising:
providing a waveguide comprising a plurality of surface protrusions; and
forming a reflective layer on the plurality of surface protrusions, the reflective layer having at least one parameter that varies across an area occupied by the plurality of surface protrusions, wherein the reflective layer is formed by depositing a reflective flowable material on the plurality of surface protrusions,
wherein a reflectivity of the reflective layer varies with the at least one parameter of the reflective layer across the area occupied by the plurality of surface protrusions, and
wherein the plurality of surface protrusions and the reflective layer form a reflective diffractive optical element.
30. The method of claim 29 , further comprising providing a spatial light modulator, wherein the spatial light modulator is positioned to output light onto the reflective diffractive optical element.
31. The method of claim 29 , wherein the flowable material comprises a reflective ink.
32. The method of claim 29 , wherein the flowable material comprises a liquid metal.
33. The method of claim 29 , wherein the at least one parameter is a thickness of the reflective layer across the area occupied by the plurality of surface protrusions.
34. The method of claim 33 , wherein the thickness of the reflective layer varies by 25% or more across the area occupied by the plurality of surface protrusions.
35. The method of claim 29 , wherein the at least one parameter is a composition of the reflective layer across the area occupied by the plurality of surface protrusions.
36. The method of claim 29 , wherein the at least one parameter is a coverage of the reflective layer across the area occupied by the plurality of surface protrusions.
37. The method of claim 36 , wherein the reflective layer covers less than an entirety of the area occupied by the plurality of surface protrusions.