Optical eyepiece using single-sided patterning of grating couplers
An eyepiece includes a substrate and an in-coupling grating patterned on a single side of the substrate. A first grating coupler is patterned on the single side of the substrate and has a first grating pattern. The first grating coupler is optically coupled to the in-coupling grating. A second grating coupler is patterned on the single side of the substrate adjacent to the first grating coupler. The second grating coupler has a second grating pattern different from the first grating pattern. The second grating coupler is optically coupled to the in-coupling grating.
1 . An eyepiece comprising:
a substrate;
an in-coupling grating imprinted on a single side of the substrate; and
a grating coupler imprinted on the single side of the substrate and optically coupled to the in-coupling grating, wherein the grating coupler comprises a plurality of tiles defining an exit pupil expander (EPE) of the eyepiece,
wherein each tile of the plurality of tiles comprises a plurality of protrusions.
2 . The eyepiece of claim 1 , wherein each tile of the plurality of tiles comprises a first grating pattern, wherein a grating region is interspersed among the plurality of tiles, and comprises a second grating pattern that is different from the first grating pattern.
3 . The eyepiece of claim 2 , wherein the grating region defines an orthogonal pupil expander (OPE) of the eyepiece.
4 . The eyepiece of claim 2 , wherein the in-coupling grating comprises a first set of parallel ridges, and the grating region comprises a second set of parallel ridges orthogonal to the first set of parallel ridges.
5 . The eyepiece of claim 1 , wherein the grating coupler is configured to receive light diffracted by the in-coupling grating and reduce a brightness of light emitted by a center region of the grating coupler.
6 . The eyepiece of claim 1 , wherein the grating coupler is configured to receive light diffracted by the in-coupling grating and diffuse light emitted by a center region of the grating coupler.
7 . The eyepiece of claim 1 , wherein each protrusion of the plurality of protrusions has one or more sidewalls.
8 . The eyepiece of claim 7 , wherein each sidewall of the one or more sidewalls is oriented at a different angle to the substrate.
9 . The eyepiece of claim 1 , wherein each protrusion of the plurality of protrusions includes two intersecting ridges oriented in two different directions.
10 . The eyepiece of claim 1 , wherein each protrusion of the plurality of protrusions has a cylindrical or ellipsoidal shape.
11 . The eyepiece of claim 1 , wherein each protrusion of the plurality of protrusions has at least one rectangular, circular, triangular, or polygonal surface.
12 . The eyepiece of claim 1 , wherein each tile of the plurality of tiles comprises a plurality of cuboids.
13 . The eyepiece of claim 12 , wherein each cuboid of the plurality of cuboids has a different height.
14 . The eyepiece of claim 1 , wherein an area of each tile of the plurality of tiles decreases as a position of the tile changes from a center of the grating coupler to a boundary of the grating coupler.
15 . The eyepiece of claim 1 , wherein an area of each tile of the plurality of tiles increases as a position of the tile changes from a first boundary of the grating coupler to a second boundary of the grating coupler.
16 . The eyepiece of claim 1 , wherein each tile of the plurality of tiles has at least one of a rectangular shape, a circular shape, an elliptical shape, a polygonal shape, or a hexagonal shape.
17 . The eyepiece of claim 1 , wherein each tile of the plurality of tiles comprises a plurality of recesses.
18 . The eyepiece of claim 17 , wherein the plurality of recesses have a refractive index greater than 1.4.
19 . The eyepiece of claim 17 , wherein at least one of a width or a length of each recess of the plurality of recesses is in a range from 5 nm to 800 nm.
20 . The eyepiece of claim 17 , wherein a cross-section of each recess of the plurality of recesses has a triangular, sawtooth, or staircase shape.
21 . An eyepiece comprising:
a substrate;
an in-coupling grating imprinted on a single side of the substrate; and
a grating coupler imprinted on the single side of the substrate and optically coupled to the in-coupling grating, wherein the grating coupler comprises a plurality of tiles defining an exit pupil expander (EPE) of the eyepiece,
wherein each tile of the plurality of tiles comprises a plurality of cuboids.
22 . The eyepiece of claim 21 , wherein each cuboid of the plurality of cuboids has a different height.
23 . An eyepiece comprising:
a substrate;
an in-coupling grating imprinted on a single side of the substrate; and
a grating coupler imprinted on the single side of the substrate and optically coupled to the in-coupling grating, wherein the grating coupler comprises a plurality of tiles defining an exit pupil expander (EPE) of the eyepiece,
wherein the grating coupler is configured to receive light diffracted by the in-coupling grating and diffuse light emitted by a center region of the grating coupler.
24 . The eyepiece of claim 23 , wherein each tile of the plurality of tiles comprises a plurality of recesses.
25 . The eyepiece of claim 23 , wherein an area of each tile of the plurality of tiles increases or decreases as a position of the tile changes from a first location of the grating coupler to a second location of the grating coupler.
26 . An eyepiece comprising:
a substrate;
an in-coupling grating imprinted on a single side of the substrate; and
a grating coupler imprinted on the single side of the substrate and optically coupled to the in-coupling grating, wherein the grating coupler comprises a plurality of tiles defining an exit pupil expander (EPE) of the eyepiece,
wherein the grating coupler is configured to receive light diffracted by the in-coupling grating and diffuse light emitted by a center region of the grating coupler,
wherein each tile of the plurality of tiles comprises a first grating pattern, wherein a grating region is interspersed among the plurality of tiles, and comprises a second grating pattern that is different from the first grating pattern,
wherein the in-coupling grating comprises a first set of parallel ridges, and the grating region comprises a second set of parallel ridges orthogonal to the first set of parallel ridges.
27 . The eyepiece of claim 26 , wherein each tile of the plurality of tiles comprises a plurality of recesses.
28 . The eyepiece of claim 26 , wherein an area of each tile of the plurality of tiles increases or decreases as a position of the tile changes from a first location of the grating coupler to a second location of the grating coupler.
29 . An eyepiece comprising:
a substrate;
an in-coupling grating imprinted on a single side of the substrate; and
a grating coupler imprinted on the single side of the substrate and optically coupled to the in-coupling grating, wherein the grating coupler comprises a plurality of tiles defining an exit pupil expander (EPE) of the eyepiece,
wherein an area of each tile of the plurality of tiles decreases as a position of the tile changes from a center of the grating coupler to a boundary of the grating coupler.
30 . The eyepiece of claim 29 , wherein each tile of the plurality of tiles comprises a plurality of recesses.
31 . The eyepiece of claim 29 , wherein each tile of the plurality of tiles comprises a plurality of cuboids.
32 . An eyepiece comprising:
a substrate;
an in-coupling grating imprinted on a single side of the substrate; and
a grating coupler imprinted on the single side of the substrate and optically coupled to the in-coupling grating, wherein the grating coupler comprises a plurality of tiles defining an exit pupil expander (EPE) of the eyepiece,
wherein an area of each tile of the plurality of tiles increases as a position of the tile changes from a first boundary of the grating coupler to a second boundary of the grating coupler.
33 . The eyepiece of claim 32 , wherein each tile of the plurality of tiles comprises a plurality of recesses.
34 . The eyepiece of claim 32 , wherein each tile of the plurality of tiles comprises a plurality of cuboids.
35 . An eyepiece comprising:
a substrate;
an in-coupling grating imprinted on a single side of the substrate; and
a grating coupler imprinted on the single side of the substrate and optically coupled to the in-coupling grating, wherein the grating coupler comprises a plurality of tiles defining an exit pupil expander (EPE) of the eyepiece,
wherein each tile of the plurality of tiles comprises a plurality of recesses.
36 . The eyepiece of claim 35 , wherein the plurality of recesses have a refractive index greater than 1.4.
37 . The eyepiece of claim 35 , wherein an area of each tile of the plurality of tiles increases or decreases as a position of the tile changes from a first location of the grating coupler to a second location of the grating coupler.