Patent Description:
This invention relates to waveguide displays, and multi-waveguide optical structures.

Diffraction gratings are optical components with periodic structures that can split and diffract light into several beams travelling into different directions. The directions of these beams depend on the spacing of the grating and the wavelength of the light. In some examples, a diffraction grating is made up of a set of slots with a spacing wider than the wavelength of the light to cause diffraction. After the light interacts with the grating, the diffracted light is composed of the sum of interfering waves emanating from each slot in the grating. Depths of the slots affect the path length of the waves to each slot, which accordingly affect the phases of the waves from each of the slots and thus the diffractive efficiencies of the slots. If the slots have a uniform depth, the slots in the grating may have a uniform diffractive efficiency. If the slots have non-uniform depths, the slots in the grating may have non-uniform diffractive efficiencies.

<CIT> discloses a multi-waveguide optical structure with each waveguide having a substrate, a patterned layer, and an adhesive layer.

Innovative aspects of the subject matter described in this specification may include a multi-waveguide optical structure, as claimed in independent claim <NUM>, including multiple waveguides stacked to intercept light passing sequentially through each waveguide, each waveguide associated with a differing color and a differing depth of plane, each waveguide including a first adhesive layer, a substrate having a first index of refraction, and a patterned layer positioned such that the first adhesive layer is between the patterned layer and the substrate, the first adhesive layer providing adhesion between the patterned layer and the substrate, the patterned layer having a second index of refraction less than the first index of refraction, the patterned layer defining a diffraction grating, wherein a field of view associated with the waveguide is based on the first and the second indices of refraction.

These and other embodiments may each optionally include one or more of the following features. Each waveguide further comprises a second adhesive layer positioned such that the substrate is between the first adhesive layer and the second adhesive layer. A waveguide support connecting and positioning each of the multiple waveguides, with at least one of the first and second adhesive layers of each waveguide adhering to the waveguide support. Each waveguide further comprises an anti-reflective layer positioned between the substrate and the second adhesive layer. Each waveguide further comprises an additional patterned layer positioned such that the second adhesive layer is positioned between the substrate and the additional patterned layer. The substrate is made of glass or sapphire. The field of view of each waveguide is at least <NUM> degrees. The first index of refraction is approximately <NUM> and the second index of refraction is at least <NUM>. The patterned layer includes a residual layer thickness of less than <NUM> nanometers.

Innovative aspects of the subject matter described in this specification may include a multi-waveguide optical structure, including multiple waveguides stacked to intercept light passing sequentially through each waveguide, each waveguide associated with a differing color and a differing depth of plane, each waveguide including a first adhesive layer, an anti-reflective layer, a substrate positioned between the first adhesive layer and the anti-reflective layer, the substrate having a first index of refraction, a first patterned layer positioned such that the first adhesive layer is between the first patterned layer and the substrate, the first adhesive layer providing adhesion between the first patterned layer and the substrate, the first patterned layer having a second index of refraction less than the first index of refraction, the first patterned layer defining a diffraction grating, wherein a field of view associated with the waveguide is based on the first and the second indices of refraction, a second adhesive layer, and a second patterned layer positioned such that the second adhesive layer is positioned between the anti-reflective layer and the second patterned layer, the second adhesive layer providing adhesion between the second patterned layer and the anti-reflective layer.

Innovative aspects of the subject matter described in this specification may include multiple waveguides stacked to intercept light passing sequentially through each waveguide, each waveguide associated with a differing color and a differing depth of plane, each waveguide including a first adhesive layer, an anti-reflective layer, a substrate positioned between the first adhesive layer and the anti-reflective layer, the substrate having a first index of refraction, a patterned layer positioned such that the first adhesive layer is between the patterned layer and the substrate, the first adhesive layer providing adhesion between the patterned layer and the substrate, the patterned layer having a second index of refraction less than the first index of refraction, the patterned layer defining a diffraction grating, wherein a field of view associated with the waveguide is based on the first and the second indices of refraction, and a second adhesive layer positioned such that the anti-reflective layer is positioned between the second adhesive layer and the substrate; and a waveguide support connecting and positioning each of the multiple waveguides, with at least one of the first and second adhesive layers of each waveguide adhering to the waveguide support.

Particular implementations of the subject matter described in this specification can be implemented so as to realize one or more of the following advantages. Implementations of the present disclosure may abrogate the need for etching of a glass (or sapphire) substrate to form diffraction gratings. By such abrogation, the present disclosure enables simpler, higher volume processing of highly efficient diffraction waveguide displays that also exhibit enhanced environmental stability and benefits for building multi-waveguide light field displays while lowering manufacturing costs. Furthermore, the present disclosure provides formation of a composite material structure of the waveguide that is both optically efficient and lower cost versus traditional methods of formation.

Other potential features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims.

This document describes a multi-waveguide optical structure. Specifically, the multi-waveguide optical structure includes multiple waveguides stacked to intercept light passing sequentially through each waveguide. Each waveguide is associated with a differing color and a differing depth of plane. Furthermore, each waveguide is associated with a first adhesive layer, a substrate having a first index of refraction, and a patterned layer positioned such that the first adhesive layer is between the patterned layer and the substrate. The first adhesive layer provides adhesion between the patterned layer and the substrate. The patterned layer has a second index of refraction less than the first index of refraction and defines a diffraction grating. A field of view associated with the waveguide is based on the first and the second indices of refraction.

<FIG> illustrates an imprint lithography system <NUM> that forms a relief pattern on a substrate <NUM>. The substrate <NUM> may be coupled to a substrate chuck <NUM>. In some examples, the substrate chuck <NUM> can include a vacuum chuck, a pin-type chuck, a groove-type chuck, an electromagnetic chuck, and/or the like. In some examples, the substrate <NUM> and the substrate chuck <NUM> may be further positioned on an air bearing <NUM>. The air bearing <NUM> provides motion about the x-, y-, and/or z-axes. In some examples, the substrate <NUM> and the substrate chuck <NUM> are positioned on a stage. The air bearing <NUM>, the substrate <NUM>, and the substrate chuck <NUM> may also be positioned on a base <NUM>. In some examples, a robotic system <NUM> positions the substrate <NUM> on the substrate chuck <NUM>.

The imprint lithography system <NUM> further includes an imprint lithography flexible template <NUM> that is coupled to one or more rollers <NUM>, depending on design considerations. The rollers <NUM> provide movement of a least a portion of the flexible template <NUM>. Such movement may selectively provide different portions of the flexible template <NUM> in superimposition with the substrate <NUM>. In some examples, the flexible template <NUM> includes a patterning surface that includes a plurality of features, e.g., spaced-apart recesses and protrusions. However, in some examples, other configurations of features are possible. The patterning surface may define any original pattern that forms the basis of a pattern to be formed on substrate <NUM>. In some examples, the flexible template <NUM> may be coupled to a template chuck, e.g., a vacuum chuck, a pin-type chuck, a groove-type chuck, an electromagnetic chuck, and/or the like.

The imprint lithography system <NUM> may further comprise a fluid dispense system <NUM>. The fluid dispense system <NUM> may be used to deposit a polymerizable material on the substrate <NUM>. The polymerizable material may be positioned upon the substrate <NUM> using techniques such as drop dispense, spin-coating, dip coating, chemical vapor deposition (CVD), physical vapor deposition (PVD), thin film deposition, thick film deposition, and/or the like. In some examples, the polymerizable material is positioned upon the substrate <NUM> as a plurality of droplets.

Referring to <FIG> and <FIG>, the imprint lithography system <NUM> may further comprise an energy source <NUM> coupled to direct energy towards the substrate <NUM>. In some examples, the rollers <NUM> and the air bearing <NUM> are configured to position a desired portion of the flexible template <NUM> and the substrate <NUM> in a desired positioning. The imprint lithography system <NUM> may be regulated by a processor in communication with the air bearing <NUM>, the rollers <NUM>, the fluid dispense system <NUM>, and/or the energy source <NUM>, and may operate on a computer readable program stored in a memory.

In some examples, the rollers <NUM>, the air bearing <NUM>, or both, vary a distance between the flexible template <NUM> and the substrate <NUM> to define a desired volume therebetween that is filled by the polymerizable material. For example, the flexible template <NUM> contacts the polymerizable material. After the desired volume is filled by the polymerizable material, the energy source <NUM> produces energy, e.g., broadband ultraviolet radiation, causing the polymerizable material to solidify and/or cross-link conforming to shape of a surface of the substrate <NUM> and a portion of the patterning surface of the flexible template <NUM>, defining a patterned layer <NUM> on the substrate <NUM>. In some examples, the patterned layer <NUM> may comprise a residual layer <NUM> and a plurality of features shown as protrusions <NUM> and recessions <NUM>.

<FIG> illustrates a waveguide <NUM> that may be formed utilizing the imprint lithography system <NUM>. In short, the waveguide <NUM> intercepts light passing therethrough, e.g., from a source of light (light beam), and provides total internal refraction of the light. In some examples, the waveguide <NUM> facilitates the generation of a virtual content display. The waveguide <NUM> is a multi-layered structure that includes a patterned layer <NUM>, a first adhesive layer <NUM>, a substrate <NUM>, an anti-reflective layer <NUM>, and a second adhesive layer <NUM>.

The substrate <NUM> is positioned between the first adhesive layer <NUM> and the anti-reflective layer <NUM>. The substrate <NUM> is associated with a first index of refraction, and in some examples, is made of glass or sapphire. In some examples, the first index of refraction is at least <NUM> or greater. The first adhesive layer <NUM> provides adhesion between the patterned layer <NUM> and the substrate <NUM>. The first adhesive layer <NUM> can be made of such materials as acrylated resin.

The patterned layer <NUM> is positioned such that the first adhesive layer <NUM> is between the patterned layer <NUM> and the substrate <NUM>. The patterned layer <NUM> can include a photo-cured acrylic polymer layer. The patterned layer <NUM> is associated with a second index of refraction. In some examples, the first index of refraction is greater than the second index of refraction. In some examples, the second index of refraction is approximately <NUM>. The patterned layer <NUM> further includes diffraction gratings <NUM> and a residual layer <NUM>. In some examples, the residual layer <NUM> has a thickness less than <NUM> nanometers, and further, in some examples, less than <NUM> nanometers. The diffraction gratings <NUM> can be formed by such methods including imprint lithography, and can include a critical dimension of approximately <NUM> nanometers.

To that end, as a result of the waveguide <NUM> including the residual layer <NUM> positioned between the substrate <NUM> and the diffraction gratings <NUM>, the waveguide <NUM> can define a diffraction-based waveguide display. In particular, the combination of the patterned layer <NUM> and the substrate <NUM>, and specifically, the combination of the patterned layer <NUM> associated with the second index of refraction (e.g., approximately <NUM>) and the substrate <NUM> associated with the first index of refraction (e.g., greater than <NUM>) provides the diffraction-based waveguide display. Moreover, the diffraction-based waveguide display is provided without forming diffraction gratings in the substrate <NUM> as a result of forming the diffraction-based waveguide display based on the combination of the patterned layer <NUM> associated with the second index of refraction (e.g., approximately <NUM>) and the substrate <NUM> associated with the first index of refraction (e.g., greater than <NUM>). Thus, the need to dry etch the substrate <NUM> (e.g., dry etch high-index glass or sapphire) is abrogated. However, in some examples, the substrate <NUM> can be partially etched (e.g., a plasma process under atmospheric or low pressure conditions) to remove the residual layer <NUM> and/or transfer the pattern into the substrate <NUM>, while maintaining a portion of the residual layer <NUM> on a surface of the substrate <NUM>.

In some examples, as a result of the residual layer <NUM> having a thickness less than <NUM> nanometers, or less than <NUM> nanometers, refractive index matching between the patterned layer <NUM> and the substrate <NUM> is reduced, or minimized.

The waveguide <NUM> is associated with a field of view based on the first and the second indices of refraction. That is, the field of view of the waveguide <NUM> is based on the combination of the second index of refraction associated with the patterned layer <NUM> and the first index of refraction associated with the substrate <NUM>. In some examples, the field of view of the waveguide <NUM> is at least <NUM> degrees. That is, when the second index of refraction associated with the patterned layer <NUM> is approximately <NUM>, and the first index of refraction associated with the substrate <NUM> is greater than <NUM>, the field of view associated with the waveguide <NUM> is at least <NUM> degrees.

The anti-reflective layer <NUM> is positioned between the substrate <NUM> and the second adhesive layer <NUM>. In some examples, the anti-reflective layer <NUM> is inorganic. The anti-reflective layer <NUM> and/or the patterned layer <NUM> provide environment protection/stability to the substrate <NUM>. Specifically, when the substrate <NUM> includes glass (or sapphire) with a high-index (e.g., greater than <NUM>), the substrate <NUM>, when exposed to the environment, can form precipitants at a surface of the substrate <NUM>. As a result, a haze contamination layer can form, (e.g., on the surface of the substrate <NUM>), corrosion of the substrate <NUM> can form, and/or scattered light associated with the waveguide <NUM> can increase. To that end, the anti-reflective layer <NUM> and/or the patterned layer <NUM> isolate the ionic surface of the substrate <NUM> (e.g., ionic surface of glass substrate), providing the environmental protection/stability of the substrate <NUM>.

The second adhesion layer <NUM> provides adhesion between the anti-reflective layer <NUM> and the substrate <NUM>. In some examples, the second adhesion layer <NUM> is vapor deposited and bonded to the substrate <NUM> (e.g., glass). The second adhesive layer <NUM> can be made of such materials as acrylated resin.

<FIG> illustrates a multi-waveguide optical structure <NUM> including multiple waveguides 402a, 402b, 402c (collectively referred to as waveguides <NUM>) stacked to intercept light passing sequentially through each waveguide <NUM>. Each of the waveguides <NUM> can be similar to the waveguide <NUM> of <FIG>. In some examples, each of the waveguides <NUM> is associated with a differing color and a differing depth of plane. That is, as light passes through each of the waveguides <NUM>, each of the waveguides <NUM> interacts with the light differently, and each exiting light of the waveguide <NUM> is based on a differing color and a differing depth of plane associated with the virtual content display. In some examples, the multi-waveguide optical structure <NUM> includes greater than three waveguides <NUM>, including six or nine waveguides <NUM>. In some examples, each of the waveguides <NUM> of the multi-waveguide optical structure <NUM> is separated by air.

The multi-waveguide optical structure <NUM> includes waveguide supports 404a, 404b (collectively referred to as waveguide supports <NUM>). The waveguide supports <NUM> connect and position the multiple waveguides <NUM> within the multi-waveguide optical structure <NUM>. To that end, the first adhesive layer <NUM> and the second adhesive layer <NUM> of each of the waveguides <NUM> provide adhesion between the respective waveguide <NUM> and the waveguide supports <NUM>. The waveguide supports <NUM> can be made of such materials as acrylated resin or epoxy resin. In some examples, the patterned layer <NUM> provides additional bonding between the respective waveguide <NUM> and the waveguide supports <NUM>.

<FIG> illustrates a waveguide <NUM> including an additional patterned layer. Specifically, the waveguide <NUM> includes a first patterned layer <NUM>, a first adhesive layer <NUM>, a substrate <NUM>, an anti-reflective layer <NUM>, a second adhesive layer <NUM>, and a second patterned layer <NUM>. The first patterned layer <NUM>, the first adhesive layer <NUM>, the substrate <NUM>, the anti-reflective layer <NUM>, and the second adhesive layer <NUM> are substantially similar as the patterned layer <NUM>, the first adhesive layer <NUM>, the substrate <NUM>, the anti-reflective layer <NUM>, and the second adhesive layer <NUM> of the waveguide <NUM> of <FIG>.

Furthermore, the second patterned layer <NUM> is positioned such that the second adhesive layer <NUM> is positioned between the anti-reflective layer <NUM> and the second patterned layer <NUM>. The second adhesive layer <NUM> provides adhesion between the second patterned layer <NUM> and the substrate <NUM>. In some examples not forming part of the claimed invention, as shown in <FIG>, a waveguide <NUM>' is absent the anti-reflective layer <NUM>, and thus, includes the second patterned layer <NUM> such that second adhesive layer <NUM> is positioned between the substrate <NUM> and the second patterned layer <NUM>.

The second patterned layer <NUM> is substantially similar to the patterned layer <NUM> of <FIG>. Specifically, the second patterned layer <NUM> is associated with a third index of refraction. In some examples, the first index of refraction associated with the substrate <NUM> is greater than the third index of refraction associated with the second patterned layer <NUM>. In some examples, the third index of refraction is approximately <NUM>. The second patterned layer <NUM> further includes diffraction gratings <NUM> and a residual layer <NUM> having a thickness less than <NUM> nanometers. The diffraction gratings <NUM> can be formed by such methods including imprint lithography, and can include a critical dimension of approximately <NUM> nanometers.

To that end, as a result of the waveguide <NUM> including the residual layer <NUM> positioned between the substrate <NUM> and the diffraction gratings <NUM>, the waveguide <NUM> can define a diffraction-based waveguide display. In particular, the combination of the second patterned layer <NUM> and the substrate <NUM>, and specifically, the combination of the second patterned layer <NUM> associated with the third index of refraction (e.g., approximately <NUM>) and the substrate <NUM> associated with the first index of refraction (e.g., greater than <NUM>) provides a diffraction-based waveguide display. Moreover, the diffraction-based waveguide display is provided without forming diffraction gratings in the substrate <NUM> as a result of forming the diffraction-based waveguide display based on the combination of the second patterned layer <NUM> associated with the third index of refraction (e.g., approximately <NUM>) and the substrate <NUM> associated with the first index of refraction (e.g., greater than <NUM>). Thus, the need to dry etch the substrate <NUM> (e.g., dry etch high-index glass or sapphire) is abrogated.

In some examples, the combination of the first patterned layer <NUM>, the second patterned layer <NUM>, and the substrate <NUM>, and specifically, the combination of the first patterned layer <NUM> associated with the first index of refraction (e.g., approximately <NUM>), the second patterned layer <NUM> associated with the third index of refraction (e.g., approximately <NUM>), and the substrate <NUM> associated with the first index of refraction (e.g., greater than <NUM>) provides the diffraction-based waveguide display.

The waveguide <NUM> is associated with a field of view based on the first and the third indices of refraction. That is, the field of view of the waveguide <NUM> is based on the combination of the third index of refraction associated with the second patterned layer <NUM> and the first index of refraction associated with the substrate <NUM>. In some examples, the field of view of the waveguide <NUM> is at least <NUM> degrees. That is, when the third index of refraction associated with the second patterned layer <NUM> is approximately <NUM>, and the first index of refraction associated with the substrate <NUM> is greater than <NUM>, the field of view associated with the waveguide <NUM> is at least <NUM> degrees. In some examples, the field of view of the waveguide <NUM> is based on the combination of the second index of refraction associated with the first patterned layer <NUM>, the third index of refraction associated with the second patterned layer <NUM> and the first index of refraction associated with the substrate <NUM>.

In some examples, each of the waveguides <NUM> of the multi-waveguide optical structure <NUM> of <FIG> can be similar to the waveguide <NUM> of <FIG> and/or the waveguide <NUM>' of <FIG>. In some examples, the waveguides <NUM> of the multi-waveguide optical structure <NUM> can be similar to any combination of the waveguide <NUM> of <FIG>, the waveguide <NUM> of <FIG>, and the waveguide <NUM>' of <FIG>.

Claim 1:
A multi-waveguide optical structure (<NUM>), comprising:
multiple waveguides (<NUM>, 402a, 402b, 402c, <NUM>) stacked to intercept light passing sequentially through each waveguide (<NUM>, 402a, 402b, 402c, <NUM>), each waveguide (<NUM>, 402a, 402b, 402c, <NUM>) associated with a differing color and a differing depth of plane, each waveguide (<NUM>, 402a, 402b, 402c, <NUM>) comprising:
a first adhesive layer (<NUM>, <NUM>),
a substrate (<NUM>, <NUM>, <NUM>) having a first index of refraction,
a first patterned layer (<NUM>, <NUM>, <NUM>) positioned such that the first adhesive layer (<NUM>, <NUM>) is between the first patterned layer (<NUM>, <NUM>, <NUM>) and the substrate (<NUM>, <NUM>, <NUM>), the first adhesive layer (<NUM>, <NUM>) providing adhesion between the first patterned layer (<NUM>, <NUM>, <NUM>) and the substrate (<NUM>, <NUM>, <NUM>), the first patterned layer (<NUM>, <NUM>, <NUM>) having a second index of refraction less than the first index of refraction, the first patterned layer (<NUM>, <NUM>, <NUM>) defining a diffraction grating, wherein a field of view associated with the waveguide (<NUM>, 402a, 402b, 402c, <NUM>) is based on the first and the second indices of refraction,
a second adhesive layer (<NUM>, <NUM>) positioned such that the substrate (<NUM>, <NUM>, <NUM>) is between the first adhesive layer (<NUM>, <NUM>) and the second adhesive layer (<NUM>, <NUM>), and
an anti-reflective layer (<NUM>, <NUM>) positioned between the substrate (<NUM>, <NUM>, <NUM>) and the second adhesive layer (<NUM>, <NUM>).