Diffraction grating with a variable refractive index using multiple resins
An inkjet is used to fabricate an optical device having a varying refractive index. The inkjet deposits a first material having a first refractive index and a second material having a second refractive index in a pattern on a substrate. The first material and/or the second material are processed to form an optical device having a refractive index that varies in one or two dimensions. The optical device is used in a virtual-reality system or augmented-reality system to provide angular selectivity from display to a user's eye.
1. A method of creating an optical device having a variable index of refraction, the method comprising:
receiving a first material having a first refractive index;
receiving a second material having a second refractive index, wherein the first refractive index is less than the second refractive index;
depositing the first material and the second material in a pattern on a structure, wherein the structure has a varying refractive index that varies laterally to provide angular selectivity; and
processing the first material and/or the second material to create a layer on the structure having a variable refractive index based on the pattern.
2. The method of claim 1 , wherein an inkjet is used for depositing drops of the first material and/or for depositing drops of the second material on the structure.
3. The method of claim 1 , wherein the processing is mixing the first material with the second material.
4. The method of claim 3 , further comprising imprinting the layer to form an optical grating in the layer.
5. The method of claim 1 , wherein the structure is a grating and the layer is an overcoat to the grating.
6. The method of claim 1 , wherein processing is exposing the first material and the second material to an energy gradient.
7. The method of claim 1 , wherein:
the layer has a first direction of increasing refractive index;
the structure has a second direction of increasing refractive index; and
the first direction is opposite the second direction.
8. The method of claim 1 , further comprising designing the pattern to reduce a residual layer.
9. The method of claim 1 , further comprising generating the first material and/or the second material by doping a resin with a sol-gel precursor, a monomer containing a reactive functional group, and/or nanoparticles.
10. The method of claim 9 , wherein the sol-gel precursor is titanium butoxide.
11. The method of claim 9 , wherein:
the monomer is acrylic acid, and/or
the nanoparticles are TiO 2 , GaP, and/or HfO 2 .
12. The method of claim 1 , wherein drops of the first material and/or drops of the second material have a diameter equal to or greater than 10 μm and equal to or less than 80 μm.
13. An optical device used in a virtual reality and/or an augmented-reality system, the optical device comprising:
a substrate;
a grating on the substrate; and
an overcoat on the grating, wherein:
the grating is made of a material with a varying refractive index, wherein refractive index varies laterally to provide angular selectivity; and
the overcoat is made of a material with a varying refractive index.
14. The optical device of claim 13 , wherein a maximum refractive index of the material minus a minimum refractive index of the material is equal to or greater than 0.5 and/or equal to or less than 1.5.
15. The optical device of claim 13 , wherein the grating and/or the overcoat comprise a cured butyl-acrylate based resin.
16. The optical device of claim 13 , wherein:
the overcoat has a first direction of increasing refractive index;
the grating has a second direction of increasing refractive index; and
the first direction is opposite the second direction.
17. The optical device of claim 13 , wherein the material with the varying refractive index has an index of refraction that varies in two dimensions.
18. The optical device of claim 13 , wherein the material with the varying refractive index comprises acrylic acid, TiO 2 , GaP, and/or HfO 2 .
19. A system used in a virtual reality and/or an augmented-reality system, the system comprising:
an optical source;
a waveguide;
an optical coupler configured to couple light from the optical source into the waveguide; and
an output coupler configured to couple light out of the waveguide, the output coupler comprising:
a grating having a varying refractive index, wherein the refractive index varies laterally to provide angular selectivity, and
an overcoat of the grating made of a material with a varying refractive index.
20. The system as recited in claim 19 , the output coupler further comprising a substrate, wherein the grating is disposed on the substrate.