High efficiency nonsymmetric waveguide with low transmission color shift

Abstract

A waveguide is provided in embodiments discussed herein. The waveguide further includes a transmission matching layer disposed on the waveguide substrate. The waveguide further includes a first grating material disposed over the transmission matching layer, and a second grating material disposed over the first grating material. The waveguide further includes a grating disposed in the second grating material and the first grating material such that grating structures of the grating include a first layer of the first grating material and a second layer of the second grating material. The second grating material has a second refractive index that is greater than a first refractive index of the first grating material. The waveguide further includes a color shift layer disposed over the grating.

Description

HIGH EFFICIENCY NONSYMMETRIC WAVEGUIDE WITH LOW TRANSMISSIONCOLOR SHIFTFIELD

[0001] Embodiments of the present disclosure generally relate to waveguides of augmented reality displays. More specifically, embodiments described herein provide for waveguides with a transmission matching layer and a color shift layer.BACKGROUND

[0002] Virtual reality is generally considered to be a computer generated simulated environment in which a user has an apparent physical presence. A virtual reality experience can be generated in 3D and viewed with a head-mounted display (HMD), such as glasses or other wearable display devices that have near-eye display panels as lenses to display a virtual reality environment that replaces an actual environment.

[0003] Augmented reality, however, enables an experience in which a user can still see through the display lenses of the glasses or other HMD device to view the surrounding environment, yet also see images of virtual objects that are generated for display and appear as part of the environment. Augmented reality can include any type of input, such as audio and haptic inputs, as well as virtual images, graphics, and video that enhances or augments the environment that the user experiences. As an emerging technology, there are many challenges and design constraints with augmented reality.

[0004] Accordingly, what is needed in the art are waveguides with a transmission matching layer and a color shift layer.SUMMARY

[0005] In one embodiment, a waveguide is provided. The waveguide includes a waveguide substrate. The waveguide further includes a transmission matching layer disposed on the waveguide substrate. The waveguide further includes a first grating material disposed over the transmission matching layer, and a second grating material disposed over the first grating material. The waveguide further includes a grating disposed in the second grating material and the first grating material such that grating structures of the grating include a first layer of the first grating material and a secondlayer of the second grating material. The second grating material has a second refractive index that is greater than a first refractive index of the first grating material. The waveguide further includes a color shift layer disposed over the grating.

[0006] In another embodiments, a waveguide is provided. The waveguide includes a waveguide substrate. The waveguide further includes a transmission matching layer disposed on a first surface opposing a second surface of the waveguide substrate. The waveguide further includes a first grating material disposed over the transmission matching layer, and a second grating material disposed over the first grating material. The waveguide further includes a grating disposed in the second grating material and the first grating material such that grating structures of the grating include a first layer of the first grating material and a second layer of the second grating material. The second grating material have a second refractive index greater than a first refractive index of the first grating material. The waveguide further includes a color shift layer disposed over the grating, and an antireflective layer disposed on the second surface.

[0007] In yet another embodiment, a waveguide is provided. The waveguide includes a waveguide substrate. The waveguide further includes a transmission matching layer disposed on the waveguide substrate. The waveguide further includes a first grating material disposed over the transmission matching layer. The waveguide further includes an incoupler grating disposed on the first grating material. The incoupler grating includes a plurality of blazed device structures. The waveguide further includes a pupil expansion grating disposed in the first grating material, and an outcoupler grating disposed in the first grating material. The outcoupler grating includes a plurality of angled grating structures. The waveguide further includes a color shift layer disposed over the incoupler grating, the pupil expansion grating, and the outcoupler grating.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appendix. It is to be noted, however, that the appendix illustrates only typical embodiments of this disclosure and are therefore not to be consideredlimiting of its scope, for the disclosure may admit to other equally effective embodiments.

[0009] Figure 1 is a sectional, frontal view of a waveguide, according to at least one embodiment.

[0010] Figure 2 is a schematic cross-sectional view of a waveguide, according to at least one embodiment.

[0011] Figure 3 is a schematic cross-sectional view of a waveguide, according to at least one embodiment.

[0012] Figure 4 is a schematic cross-sectional view of an in-coupler grating, according to at least one embodiment.

[0013] Figure 5 is a schematic cross-sectional view of an intermediate coupler grating, according to at least one embodiment.

[0014] Figure 6 is a schematic cross-sectional view of an out-coupler grating, according to at least one embodiment.

[0015] Figure 7 is a frontal, sectional view of the out-coupler grating of a waveguide, according to at least one embodiment.

[0016] Figure 8 is a frontal, sectional view of the out-coupler grating of a waveguide, according to at least one embodiment.

[0017] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.DETAILED DESCRIPTION

[0018] Embodiments of the present disclosure generally relate to waveguide combiners of augmented reality displays. More specifically, embodiments described herein provide for waveguides with a transmission matching layer and a color shift layer. The transmission layer is disposed below the gratings and the color shift layer is disposed above the gratings of the waveguide. The diffraction efficiency of the gratings (e.g., high diffraction efficiency gratings) of a waveguide may cause the waveguide to emit light of various wavelengths when the augmented reality display is not in operation. Without being bound by theory, the transmission matching layer reduces and / or smooths the step transition of light with varying wavelengths which are being transmitted through the out-coupler. Without being bound by theory, thecolor shift layer changes the overall color by adjusting the relative transmission of varying wavelengths in the out-coupler.

[0019] Figure 1 is a sectional, frontal view of a waveguide 100. It is to be understood that the waveguide 100 described herein is an exemplary waveguide and that other waveguides may be used with or modified to accomplish aspects of the present disclosure. The waveguide 100 includes a plurality of grating structures 212. The grating structures 212 may be disposed over the waveguide substrate 101 . The grating structures 212 are nanostructures have a sub-micron critical dimension, e.g., a width less than 1 micrometer. The waveguide 100 includes gratings 104 including at least an in-coupler grating 104a having grating structures 212a and an out-coupler grating 104c having grating structures 212c. In another embodiment, which can be combined with other embodiments described herein, the waveguide 100 further includes an intermediate grating 104b having grating structures 212b of the plurality of grating structures 212. The intermediate grating 104b corresponds to a pupil expansion grating (“pupil expander”) or a fold grating.

[0020] Figure 2 is a schematic cross-sectional view of a waveguide 100. The waveguide 100 of Figure 2 has a bi-layer configuration 200. The waveguide 100 of the bi-layer configuration 200 includes the waveguide substrate 101 , a transmission matching layer 202 disposed over the waveguide substrate 101 , and a first color shift layer 210. In some embodiments, an anti-reflective (AR) coating 214 disposed over the waveguide substrate 101 on the side opposite the transmission matching layer 202. The waveguide 100 further includes a first grating material 204 disposed over the transmission matching layer 202, and a second grating material 206 disposed over the first grating material 204. The first color shift layer 210 is disposed over the second grating material 206.

[0021] The waveguide 100 further includes the in-coupler grating 104a having the grating structures 212a, the intermediate grating 104b having the grating structures 212b, and the out-coupler grating 104c having grating structures 212c. The grating structures 212a of the in-coupler grating 104a are disposed in the first grating material 204 and the second grating material 206. The grating structures 212a of the in-coupler grating 104a of the bi-layer configuration 200 include a first layer of the first grating material 204 and a second layer of the second grating material 206. Thegrating structures 212b of the intermediate grating 104b and the grating structures 212c of the out-coupler grating 104c are disposed in the second grating material 206.

[0022] The transmission matching layer 202 has a thickness of about 10 nm to about 60 nm, such as about 20 nm to about 50 nm, such as about 30 nm to about 40 nm, alternatively about 10 nm to about 20 nm, alternatively about 20 nm to about 30 nm, alternatively about 40 nm to about 50 nm, alternatively about 50 nm to about 60 nm. The transmission matching layer 202 has a refractive index (Rl) of about 2.2 to about 2.7, such as about 2.3 to about 2.6, such as about 2.4 to about 2.5, alternatively about 2.2 to about 2.3, alternatively about 2.3 to about 2.4, alternatively about 2.5 to about 2.6, alternatively about 2.6 to about 2.7. Without being bound by theory, the transmission matching layer reduces and / or smooths the step transition of light with varying wavelengths which are being transmitted through the out-coupler.

[0023] The waveguide substrate 101 has a substrate refractive index of about 2.0 to about 2.6, such as about 2.1 to about 2.5, such as about 2.2 to about 2.4, alternatively about 2.0 to about 2.1 , alternatively about 2.1 to about 2.2, alternatively about 2.2 to about 2.3, alternatively about 2.3 to about 2.4, alternatively about 2.4 to about 2.5, alternatively about 2.5 to about 2.6. The waveguide substrate 101 may be formed from any suitable material, provided that the waveguide substrate 101 can adequately transmit light in a selected wavelength or wavelength range and can serve as an adequate support for the waveguide 100 described herein. Substrate selection may include substrates of any suitable material, including amorphous dielectrics, non- amorphous dielectrics, crystalline dielectrics, silicon oxide, polymers, and combinations thereof. In some embodiments, which may be combined with other embodiments described herein, the waveguide substrate 101 includes glass, quartz, sapphire (AI2O3), silicon carbide (SiC), lithium niobate (LiNbOs), indium tin oxide (ITO), or combinations thereof. In other embodiments, which may be combined with other embodiments described herein, the waveguide substrate 101 includes high-refractive- index glass. The high Rl glass includes greater than 2 percent by weight of lanthanide (Ln), titanium (Ti), tantalum (Ta), or combination thereof.

[0024] In some embodiments, the transmission matching layer 202 has a Rl of about 2.2 to about 2.7, such as about 2.3 to about 2.6, such as about 2.4 to about 2.5, alternatively about 2.2 to about 2.3, alternatively about 2.3 to about 2.4, alternatively about 2.5 to about 2.6, alternatively about 2.6 to about 2.7. The transmission matching layer 202 may include one or more of silicon oxycarbide (SiOC), titanium dioxide(TiC>2), silicon dioxide (SiC ), vanadium (IV) oxide (VOx), aluminum oxide (AI2O3), aluminum-doped zinc oxide (AZO), indium tin oxide (ITO), tin dioxide (SnO2), zinc oxide (ZnO), tantalum pentoxide (Ta2Os), silicon nitride (SislS ), zirconium dioxide (ZrO2), niobium oxide (Nb20s), cadmium stannate (Cd2SnO4), titanium silicon oxide (TiSiOx) or silicon carbon-nitride (SiCN) containing materials.

[0025] The first grating material 204 has a first Rl of about 2.0 to about 2.5, such as about 2.1 to about 2.4, such as about 2.2 to about 2.3, alternatively about 2.0 to about 2.1 , alternatively about 2.1 to about 2.2, alternatively about 2.3 to about 2.4, alternatively about 2.4 to about 2.5. The second grating material 206 has a second Rl of about 2.0 to about 2.5, such as about 2.1 to about 2.4, such as about 2.2 to about 2.3, alternatively about 2.0 to about 2.1 , alternatively about 2.1 to about 2.2, alternatively about 2.3 to about 2.4, alternatively about 2.4 to about 2.5. The second Rl of the second grating material 206 is greater than or the same as the first Rl of the first grating material 204 in the bi-layer configuration 200. In some embodiments, the difference between the first Rl of the first grating material 204 and the second Rl of the second grating material 206 is about 0.1 to about 0.5, such as about 0.2 to about 0.4, such as about 0.25 to about 0.35, alternatively about 0.1 to about 0.2, alternatively about 0.2 to about 0.25, alternatively about 0.35 to about 0.4, alternatively about 0.4 to about 0.5.

[0026] The first grating material 204 and the second grating material 206 may independently include one or more of SiOC, TiO2, S iC>2, VOx, AI2O3, AZO, ITO, SnO2, ZnO, Ta2Os, SisN4, ZrO2, Nb2Os, Cd2SnO4, TiSiOx, or SiCN containing materials. In some embodiments, the transmission matching layer 202 and at least one of the first grating material 204 and / or the second grating material 206 are the same, resulting in the same Rl values. In some embodiments, the transmission matching layer 202 and at least one of the first grating material 204 or the second grating material 206 are different, resulting in differing Rl values. In other embodiments, each of the transmission matching layer 202, the first grating material 204, and the second grating material 206 each include a different material composition.

[0027] In some embodiments, which can be combined with other embodiments described herein, the first color shift layer 210 of the waveguide 100 with the bi-layer configuration 200 is at least partially disposed over at least one of the second grating material 206, the one or more grating structures 212a of the in-coupler grating 104a, the one or more grating structures 212b of the intermediate grating 104b, or the oneor more grating structures 212c of the out-coupler grating. In at least one embodiment, the first color shift layer 210 of the waveguide is substantially disposed over each of the second grating material 206 of the waveguide 100 with the bi-layer configuration 200, the one or more grating structures 212a of the in-coupler grating 104a, the one or more grating structures 212b of the intermediate grating 104b, and the one or more grating structures 212c of the out-coupler grating.

[0028] In some embodiments, which can be combined with other embodiments described herein, the first color shift layer 210 is substantially disposed over a surface of the waveguide 100 with the bi-layer configuration 200. The first color shift layer 210, in this embodiment, has a thickness is disposed over the surface of the in-coupler grating 104a, the surface of the intermediate grating 104b, and the surface of the out- coupler grating 104c. That is to say that in such instances, the first color shift layer 210 may have a variable thickness depending on the location and corresponding topology of the surface of the waveguide 100 with the bi-layer configuration, wherein the first color shift layer 210 is disposed.

[0029] In some embodiments, which can be combined with other embodiments described herein, the first color shift layer 210 has an Rl of about 1.3 to about 1.8, such as about 1 .4 to about 1 .7, such as about 1 .5 to about 1 .6, alternatively about 1 .3 to about 1 .4, alternatively about 1 .4 to about 1 .5, alternatively about 1 .6 to about 1 .7, alternatively about 1 .7 to about 1 .8. The first color shift layer 210 includes, but is not limited to, photoresist material, SiC>2, Si3N4 or combinations thereof. Without being bound by theory, the color shift changes the overall color by adjusting the relative transmission of varying wavelengths in the out-coupler.

[0030] Figure 3 is a schematic cross-sectional view of a waveguide 100 with a blazed configuration 300. In at least one embodiment, which can be combined with other embodiments described herein, the waveguide 100 with the blazed configuration 300 includes a waveguide substrate 101 , a transmission matching layer 202 disposed over the waveguide substrate 101 , and an AR coating 214 disposed over the waveguide substrate 101 on the side opposite the transmission matching layer 202. The waveguide 100 with the blazed configuration further includes a first grating material 204 disposed over the transmission matching layer 202. The waveguide 100 with the blazed configuration 300 further includes a first color shift layer 210 disposed over the first grating material 204.

[0031] In some embodiments, which can be combined with other embodiments, described herein, the transmission matching layer 202 can include can include a thickness of about 10 nm to about 60 nm, such as about 20 nm to about 50 nm, such as about 30 nm to about 40 nm, alternatively about 10 nm to about 20 nm, alternatively about 20 nm to about 30 nm, alternatively about 40 nm to about 50 nm, alternatively about 50 nm to about 60 nm. In some embodiments, the first grating material 204 can include can include a thickness of about 50 nm to about 300 nm, such as about 100 nm to about 250 nm, such as about 150 nm to about 200 nm, alternatively about 50 nm to about to about 100 nm, alternatively about 100 nm to about 150 nm, alternatively about 200 nm to about 250 nm, alternatively about 250 nm to about 300 nm.

[0032] In one embodiment, which can be combined with other embodiments described herein, the waveguide 100 with the blazed configuration 300 further includes an in-coupler grating 104a having a plurality of grating structures 212a, an intermediate grating 104b having a plurality of grating structures 212b, and an out- coupler grating 104c with a plurality of grating structures 212c. The grating structures 212a of the in-coupler grating 104a may be disposed over the first grating material 204. The grating structures 212b of the intermediate grating 104b and / or the grating structures 212c of the out-coupler grating 104c may be disposed in the first grating material 204.

[0033] In some embodiments, which can be combined with other embodiments described herein, the first color shift layer 210 is substantially disposed over a surface of the waveguide 100 with the blazed configuration such that a layer of uniform thickness is disposed over the plurality of grating structures 212a of the in-coupler grating 104a, the plurality of grating structures 212b of the intermediate grating 104b, and the plurality of grating structures 212c of the out-coupler grating 104c. As such, the surface of the first color shift layer 210 is not planar. The first color shift layer 210 comprises a uniform thickness perpendicular to the surface of which it is disposed of about 0 nm to about 200 nm, such as about 10 nm to about 150 nm, such as about 50 nm to about 100 nm, alternatively about 10 nm to about 50 nm, alternatively about 50 nm to about 75 nm, alternatively about 75 nm to about 100 nm, alternatively about 100 nm to about 150 nm, alternatively about 150 nm to about 200 nm. In some embodiments, the first color shift layer 210 is non-uniformly disposed on the surface of the waveguide 100 with the blazed configuration 300 such that the surface of the first color shift layer 210 is smooth and / or planar. That is to say that in such instances,the first color shift layer 210 may have a variable thickness depending on the location and corresponding topology of the surface of the waveguide 100 with the blazed configuration 300 wherein the first color shift layer 210 is disposed.

[0034] In some embodiments, which can be combined with other embodiments described herein, at least one of the grating structures 212a of the in-coupler grating 104a may be slanted with a flat bottom. In another embodiment, which can be combined with other embodiments described herein, at least one of the grating structures 212a of the in-coupler grating 104a may be slanted with a tilted bottom. In another embodiment, which can be combined with other embodiments described herein, at least one of the grating structures 212a of the in-coupler grating 104a may be blazed. The blazed structures can include sidewalls that are slanted relative to the top surface of the first grating material 204.

[0035] Figure 4 is a schematic, cross-sectional view of an in-coupler grating 104a having a plurality grating structures 212a. The plurality of grating structures 212a of the in-coupler grating 104a are blazed structures 402, wherein each of the blazed structures 402 includes a blazed surface 404, a sidewall 406, a depth 422, and a linewidth 424.

[0036] The each of the blazed structures 402 independently include a blazed surface 404 having a trim width 410 that is defined as the length of the blazed surface 404. The trim width 410 is less than half of the total width of the blazed structures 402, e.g., less than 50%. The top width 412 is defined by the total width of the top surface. The top width 412 is greater than 50% of the width of the blazed structure 402.

[0037] The blazed surface 404 has a blaze angle y. The blaze angle y is the angle between the blazed surface 404 and the surface parallel p of the first grating material 204. The depth 422 corresponds to the height of the sidewall 406 and the linewidth 424 corresponds to the distances between sidewalls 406 of adjacent blazed structures 402.

[0038] The blaze angle y of two or more blazed structures 402 can be different. The blaze angle y of two or more blazed structures 402 can be the same. The depth 422 of two or more blazed structures 402 can be different. The depth 422 of two or more blazed structures 402 can be the same. The linewidth 424 of two or more blazed structures 402 can be different. The linewidths 424 of one or more blazed structures 402 can be the same.

[0039] In one embodiment, which can be combined with other embodiments described herein, each of the grating structures 212a of the in-coupler grating 104a are blazed structures 402 independently including a depth 422, a linewidth 424, and a blaze angle y. In at least one embodiment, the plurality of grating structures 212a of the in-coupler grating 104a independently include a depth 422 of about 50 nm to about 100 nm, such as about 60 nm to about 90 nm, such as about 70 nm to about 80 nm, alternatively about 50 nm to about 60 nm, alternatively about 60 nm to about 70 nm, alternatively about 80 nm to about 90 nm, alternatively about 90 nm to about 100 nm. In at least one embodiment, the plurality of grating structures 212a of the incoupler grating 104a independently include a linewidth 424 of about 300 nm to about 500 nm, such as about 350 nm to about 450 nm, such as about 375 nm to about 425 nm, alternatively about 300 nm to about 350 nm, alternatively about 350 nm to about 375 nm, alternatively about 375 nm to about 400 nm, alternatively about 400 nm to about 425 nm, alternatively about 425 nm to about 450 nm, alternatively about 450 nm to about 500 nm. In at least one embodiment, the plurality of grating structures 212a of the in-coupler grating 104a independently include a blaze angle y of about 25° to about 45°, such as about 30° to about 40°, such as about 32.5° to about 37.5°, alternatively about 25° to about 30°, alternatively about 30° to about 32.5°, alternatively about 32.5° to about 35°, alternatively about 35° to about 37.5°, alternatively about 37.5° to about 40°, alternatively about 40° to about 45°. In at least one embodiment, the plurality of grating structures 212a of the in-coupler grating 104a independently include an Rl of about 1 .5 to about 2.6, such as about 1 .7 to about 2.4, such as about 1 .9 to about 2.2, such as about 2.0 to about 2.1 , alternatively about 1 .5 to about 1 .7, alternatively about 1 .7 to about 1 .9, alternatively about 1 .9 to about 2.0, alternatively about 2.1 to about 2.2, alternatively about 2.2 to about 2.4, alternatively about 2.4 to about 2.6.

[0040] In one embodiment, which can be combined with other embodiments described herein, each of the grating structures 212a of the in-coupler grating 104a independently include any suitable material, such as SiOC, TiO2, SiC>2, VOx, AI2O3, AZO, ITO, SnO2, ZnO, Ta20s, Si3N4, ZrO2, Nb2Os, Cd2SnO4, TiSiOx, or SiCN containing materials.

[0041] FIG. 5 is a schematic, cross-sectional view of a plurality of grating structures 212b of the intermediate grating 104b. In some embodiments, which can be combined with other embodiments described herein, the intermediate grating 104bcan include a plurality of grating structures 212b disposed in the first grating material 204. In at least one embodiment, the plurality of grating structures 212b includes one or more grating structures 502 having a depth 504 and a width 506.

[0042] In some embodiments, which can be combined with other embodiments described herein, the intermediate grating 104b can include a plurality of grating structures 212b disposed in the first grating material 204. The grating structures 212b of the intermediate grating 104b can each independently include a binary structure having a depth 504 and a width 506. In at least one embodiment, the plurality of grating structures 212b of the intermediate grating 104b independently include a depth 504 of about 10 nm to about 100 nm, such as about 25 nm to about 75 nm, such as about 40 nm to about 60 nm, alternatively about 10 nm to about 25 nm, alternatively about 25 nm to about 40 nm, alternatively about 60 nm to about 74 nm, alternatively about 75 nm to about 100 nm. In at least one embodiment, the plurality of grating structures 212b of the intermediate grating 104b independently include a width 506 of about 50 nm to about 300 nm, such as about 100 nm to about 250 nm, such as about 150 nm to about 200 nm, alternatively about 50 nm to about to about 100 nm, alternatively about 100 nm to about 150 nm, alternatively about 200 nm to about 250 nm, alternatively about 250 nm to about 300 nm. In at least one embodiment, the plurality of grating structures 212b of the intermediate grating 104b independently include a Rl of about 1 .5 to about 2.6, such as about 1 .7 to about 2.4, such as about 1.9 to about 2.2, such as about 2.0 to about 2.1 , alternatively about 1.5 to about 1.7, alternatively about 1.7 to about 1.9, alternatively about 1.9 to about 2.0, alternatively about 2.1 to about 2.2, alternatively about 2.2 to about 2.4, alternatively about 2.4 to about 2.6.

[0043] In one embodiment, which can be combined with other embodiments described herein, each of the grating structures 212b of the intermediate grating 104b independently include, but are not limited to, SiOC, TiO2, SiO2, VOx, AI2O3, AZO, ITO, SnO2, ZnO, Ta20s, SisN4, ZrO2, Nb2Os, Cd2SnO4, TiSiOx, or SiCN containing materials.

[0044] FIG. 6 s a schematic, cross-sectional view of the out-coupler grating 104c. The out-coupler grating 104c includes a plurality of grating structures 212c disposed in the first grating material 204. The grating structures 212c of the embodiments of FIG. 6 are a slanted grating structure 602. The slanted grating structure 602 includes a depth 604 which corresponds to the height of the of the structure, a top width 606awhich corresponds to the width of the top of the structure, and a structure width 606b which corresponds to the total width of the structure along the horizontal axis. The slanted grating structure 602 includes a slant angle o, which can be defined as the angle between the perpendicular axis 608 relative to the first grating material 204 and the exterior surface of the slanted grating structure 602.

[0045] In some embodiments, which can be combined with other embodiments, the plurality of grating structures 212c of the out-coupler grating 104c can each independently include a slanted grating structure 602 having a depth 604, top width 606a, and a slant angle o. In at least one embodiment, the plurality of grating structures 214c of the out-coupler grating 104c independently include a depth 604 of about 50 nm to about 300 nm, such as about 100 nm to about 250 nm, such as about 150 nm to about 200 nm, alternatively about 50 nm to about to about 100 nm, alternatively about 100 nm to about 150 nm, alternatively about 200 nm to about 250 nm, alternatively about 250 nm to about 300 nm. In at least one embodiment, the plurality of grating structures 212c of the out-coupler grating 104c independently include a top width 606a of about 50 nm to about 300 nm, such as about 100 nm to about 250 nm, such as about 150 nm to about 200 nm, alternatively about 50 nm to about to about 100 nm, alternatively about 100 nm to about 150 nm, alternatively about 200 nm to about 250 nm, alternatively about 250 nm to about 300 nm. In at least one embodiment, the plurality of grating structures 212c of the out-coupler grating 104c independently include a slant angle o of about 25° to about 45°, such as about 30° to about 40°, such as about 32.5° to about 37.5°, alternatively about 25° to about 30°, alternatively about 30° to about 32.5°, alternatively about 32.5° to about 35°, alternatively about 35° to about 37.5°, alternatively about 37.5° to about 40°, alternatively about 40° to about 45°. In at least one embodiment, the plurality of grating structures 212c of the out-coupler 104c independently include a Rl of about 1 .5 to about 2.6, such as about 1 .7 to about 2.4, such as about 1 .9 to about 2.2, such as about 2.0 to about 2.1 , alternatively about 1 .5 to about 1 .7, alternatively about 1 .7 to about 1 .9, alternatively about 1 .9 to about 2.0, alternatively about 2.1 to about 2.2, alternatively about 2.2 to about 2.4, alternatively about 2.4 to about 2.6.

[0046] In one embodiment, which can be combined with other embodiments described herein, each of the grating structures 212c of the out-coupler grating 104c independently include any suitable material, such as SiOC, TiO2, SiC>2, VOx, AI2O3,AZO, ITO, SnO2, ZnO, Ta2Os, SisN4, ZrO2, Nb20s, Cd2SnO4, TiSiOx, or SiCN containing materials.

[0047] In some embodiments, which can be combined with other embodiments, the plurality of grating structures 212c of the out-coupler grating 104c can each independently include a blazed grating structure. In at least one embodiment, plurality of grating structures 212c of the out-coupler grating 104c include a blazed grating structure that is similar to and / or identical to the blazed grating structure plurality grating structures 212a of the an in-coupler grating 104a, as depicted in Figure 4.

[0048] Figure 7 is a frontal, sectional view of the out-coupler grating 104c of a waveguide 100. The out-coupler grating 104c of Figure 7 does not have the transmission matching layer 202 or a first color shift layer 210. The waveguide 100 can cause a transmission color shift 702 to be produced from the out-coupler grating 104c of waveguide 100. The diffraction efficiency of the plurality of grating structures 212c of out-coupler grating 104c may cause the waveguide 100 to transmit light of various wavelengths with different transmission coefficients when the augmented reality display is not in operation, i.e. , displaying an image. Thus the waveguide 100 with the bi-layer configuration 200 and the blazed configuration 300 include at least the transmission matching layer 202 and first color shift layer 210. Without being bound by theory, the transmission matching layer reduces and / or smooths the step transition of light with varying wavelengths which are being transmitted through the out-coupler. Without being bound by theory, the color shift layer changes the overall color by adjusting the relative transmission of varying wavelengths in out-coupler.

[0049] Figure 8 is a frontal, sectional view of the out-coupler grating 104c of a waveguide 100 having a transmission matching layer 202 and a first color shift layer 210. The out-coupler grating 104c includes a plurality of grating structures 212c. The waveguide 100 further includes a transmission matching layer 202 and a first color shift layer 210. Including both the transmission matching layer 202 and the first color shift layer 210 reduces and / or mitigates the transmission color shift 702 which can be produced from wearing the augmented reality display.

[0050] The present disclosure provides waveguide configurations that reduce and / or eliminate transmission color shift during use within an optical device. Waveguide configurations disclosed herein incorporate a waveguide substrate, a transmission matching layer disposed over the waveguide substrate, and an AR coating disposed over a surface of the waveguide substrate opposite the transmissionmatching layer. Waveguides of the present disclosure further include one or more grating materials disposed over the transmission matching layer, and one or more color shift layers disposed over the grating materials. Furthermore, waveguides of the present disclosure include an in-coupler grating, an intermediate grating, and an out- coupler grating that can be disposed on or in the grating materials. Waveguides of the present disclosure offer a unique route to addressing issues commonly associated with color shift transmission.

[0051] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

What is claimed is:

1. A waveguide, comprising: a waveguide substrate; a transmission matching layer disposed on the waveguide substrate; a first grating material disposed over the transmission matching layer; a second grating material disposed over the first grating material; a grating disposed in the second grating material and the first grating material such that grating structures of the grating include a first layer of the first grating material and a second layer of the second grating material, the second grating material having a second refractive index that is greater than a first refractive index of the first grating material; and a color shift layer disposed over the grating.

2. The waveguide of claim 1 , wherein the first refractive index is about 2.0 to about 2.5.

3. The waveguide of claim 1 , wherein a difference between the first refractive index and the second refractive index is about 0.1 to about 0.5.

4. The waveguide of claim 1 , wherein the the transmission matching layer has a refractive index of 2.2 to 2.7.

5. The waveguide of claim 1 , wherein the waveguide further comprises an intermediate grating disposed in the second grating material.

6. The waveguide of claim 1 , wherein the color shift layer comprises a thickness of about 0 nm to about 200 nm.

7. The waveguide of claim 1 , wherein the waveguide further comprises an out- coupler grating disposed in the second grating material.

8. The waveguide of claim 1 , wherein the color shift layer has a third refractive index of about 1 .3 to about 1 .8.

9. A waveguide, comprising: a waveguide substrate; a transmission matching layer disposed on a first surface opposing a second surface of the waveguide substrate; a first grating material disposed over the transmission matching layer; a second grating material disposed over the first grating material; a grating disposed in the second grating material and the first grating material such that grating structures of the grating include a first layer of the first grating material and a second layer of the second grating material, the second grating material have a second refractive index greater than a first refractive index of the first grating material; a color shift layer disposed over the grating; and an antireflective layer disposed on the second surface.

10. The waveguide of claim 9, wherein the first refractive index is about 2.0 to about 2.5.11 . The waveguide of claim 9, wherein a difference between the first refractive index and the second refractive index is about 0.1 to about 0.5.

12. The waveguide of claim 9, wherein the transmission matching layer has a refractive index of 2.2 to 2.7.

13. The waveguide of claim 9, wherein the waveguide further comprises an intermediate grating disposed in the second grating material.

14. The waveguide of claim 9, wherein the color shift layer comprises a thickness of about 0 nm to about 200 nm.

15. The waveguide of claim 9, wherein the waveguide further comprises an out- coupler grating disposed in the second grating material.

16. The waveguide of claim 9, wherein the color shift layer has a third refractive index of about 1 .3 to about 1 .8.

17. A waveguide, comprising: a waveguide substrate; a transmission matching layer disposed on the waveguide substrate; a first grating material disposed over the transmission matching layer; an incoupler grating disposed on the first grating material, the incoupler grating comprising a plurality of blazed device structures; a pupil expansion grating disposed in the first grating material; an outcoupler grating disposed in the first grating material, the outcoupler grating comprising a plurality of angled grating structures; and a color shift layer disposed over the incoupler grating, the pupil expansion grating, and the outcoupler grating.

18. The waveguide of claim 17, wherein the first grating material comprises a first refractive index of about 2.0 to about 2.5.

19. The waveguide of claim 17, wherein the first grating material comprises a second thickness of about 50 nm to about 300 nm.

20. The waveguide of claim 17, wherein the transmission matching layer has a refractive index of 2.2 to 2.7.

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