Patent ID: 12253704

DEFINITIONS

The following definitions, including plurals of the same, apply throughout this patent application.

As used herein, the term “conformal layer” means a thin film which conforms to the contours of feature topology. For example, a thickness across the entire conformal layer can have a minimum value ≥1 nm and a maximum value ≤20 nm. As another example, the maximum value divided by the minimum value ≥1 nm of the thickness of the conformal layer can be ≤20, ≤10, ≤5, or ≤3. As another example, the conformal layer at a distal end of each wire can be separate from the conformal layer at a distal end of adjacent wires, the distal end being a farthest end of the wires from the substrate.

As used herein, the term “elongated” means that a length (length of the ribs into the page) is substantially greater than width or thickness (e.g. length can be ≥10 times, ≥100 times, ≥1000 times, or ≥10,000 times larger than width, thickness, or both).

As used herein, the term “nm” means nanometer(s).

As used herein, the term “normal angle deposition” means deposition at an angle of 90°+/−10° with respect to a plane133of a surface on which the material is deposited. SeeFIG.13.

As used herein, the term “on” means located directly on or located above with some other solid material between.

As used herein, the term “parallel” means exactly parallel, parallel within normal manufacturing tolerances, or nearly parallel, such that any deviation from exactly parallel would have negligible effect for ordinary use of the device.

As used herein, the same material composition between different parts of the WGP means exactly the same, the same within normal manufacturing tolerances, or nearly the same, such that any deviation from exactly the same would have negligible effect for ordinary use of the device.

Unless explicitly noted otherwise herein, all temperature-dependent values are such values at 25° C.

Materials used in optical structures can absorb some light, reflect some light, and transmit some light. The following definitions distinguish between materials that are primarily absorptive, primarily reflective, or primarily transparent. Each material can be considered to be absorptive, reflective, or transparent in a wavelength range of intended use, across the ultraviolet spectrum, across the visible spectrum, across the infrared spectrum, or combinations thereof, and can have a different property in a different wavelength range. Materials are divided into absorptive, reflective, and transparent based on reflectance R, the real part of the refractive index n, and the imaginary part of the refractive index/extinction coefficient k. Equation 1 is used to determine the reflectance R of the interface between air and a uniform slab of the material at normal incidence:

R=(n-1)2+k2(n+1)2+k2Equation⁢1
Unless explicitly specified otherwise herein, materials with k≤0.1 in the wavelength range are “transparent” materials, materials with k>0.1 and R≤0.6 in the specified wavelength range are “absorptive” materials, and materials with k>0.1 and R>0.6 in the specified wavelength range are “reflective” materials. If explicitly so stated in the claims, materials with k>0.1 and R≥0.7, R≥0.8, or R≥0.9, in the specified wavelength range, are “reflective” materials.

As used herein, the ultraviolet spectrum means ≥10 nm & <400 nm, the visible spectrum means ≥400 nm & <700 nm, and the infrared spectrum means ≥700 nm & ≤1 mm.

DETAILED DESCRIPTION

Five or six support-ribs22or92are illustrated in the figures and described herein, but there can be many more support-ribs22or92than six, or there can be fewer support-ribs22or92than five, such as for example two or three, particularly if the optical device is a waveguide.

First Method,FIGS.1-8

A first method of making a wire grid polarizer (WGP), illustrated inFIGS.1-8, can comprise some or all of the following steps, which can be performed in the following order or other order if so specified. There may be additional steps not described below. These additional steps may be before, between, or after those described. The WGP can be formed without etching.

The first method can comprise: step10(FIG.1), applying an uncured layer12on a substrate11; step20(FIG.2), imprinting support-ribs22in the uncured layer12with a stamp13; step30(FIG.3), curing the uncured layer12to form a cured layer32; and step40(FIG.4), removing the stamp13, leaving support-ribs22in the cured layer32with channels41between adjacent support-ribs22. Each support-rib22can be connected to adjacent support-ribs22by material of the support-ribs22.

In one embodiment, the uncured layer12can be a liquid with solid inorganic nanoparticles dispersed throughout a continuous phase, and the cured layer32can include a solid, interconnecting network of the inorganic nanoparticles. In another embodiment, the uncured layer12can be a colloidal suspension including a dispersed phase and a continuous phase, and curing the uncured layer12can include removing the continuous phase to form a solid, defining the cured layer32.

In another embodiment, the uncured layer12can be a solution including molecules in a solvent. The solvent can include water and an organic liquid. The molecules can include metal atoms bonded to reactive groups. Each reactive-group can be —Cl, —OR1, —OCOR1, or —N(R1)2. Each R1can be an alkyl group, such as for example —CH3, —CH2CH3, or —CH2CH2CH3. Curing the uncured layer12can include reacting the molecules to form a solid of the metal atoms interconnected with each other, defining the cured layer32.

The first method can further comprise depositing an upper rib53, or a stack of upper ribs53, on the distal end D of each of the support-ribs22(see steps50,60aor60b,70,80, or combinations thereof inFIGS.5-8). Example combinations of these steps, following steps10,20,30, and40, include: step50; steps50then60b; steps50,60b, then70; steps50,60b,70, then80; step60a; steps60athen70; steps60a,70, then80.

Step50can include depositing a cap52on each support-rib22at a distal end D of each support-rib22farthest from the substrate11. The cap52can be sputter deposited. The cap52can be transparent (e.g. across the ultraviolet spectrum, across the visible spectrum, across the infrared spectrum, or combinations thereof).

The cap52can be wider than the support-rib22at or near the distal end D in order to block part or all of the channels41, and thus minimize or prevent later-deposited upper ribs53from being deposited in the channels41. For example, 1.1≤WC/WSR, 1.2≤WC/WSR, 1.4≤WC/WSR, 1.6≤WC/WSR, 1.8≤WC/WSR, or 1.9≤WC/WSR; and WC/WSR≤2.1, WC/WSR≤2.4, WC/WSR≤2.8, WC/WSR≤3.5, WC/WSR≤4, or WC/WSR≤6, where WCis a width of the cap52measured at the distal end D of the support-rib22, and WSRis a width of the support-rib22measured at 20% of a distance from the distal end D of the support-rib22towards a proximal end P of the support-rib22closest to the substrate11.

Step60acan follow step40and can include depositing a wire62on each support-rib22at a distal end D of each support-rib22farthest from the substrate11. Step60bcan follow step50and can include depositing a wire62on each cap52. Example deposition methods of the wire62include sputter deposition or evaporation deposition. The wire62can be reflective (e.g. across the ultraviolet spectrum, across the visible spectrum, across the infrared spectrum, or combinations thereof). Steps60aand60bcan be performed before or after the following steps70and80.

Step70can follow step60aor step60band can include depositing a lower rib72on each wire62. The lower rib72can have a real part of a refractive index nL≤1.6, nL≤1.5, nL≤1.4, nL≤1.3, or nL≤1.2 and an extinction coefficient kL≤0.1, kL≤0.01, or kL≤0.001. Step80can follow step70and can include depositing a top rib82on each lower rib72. The top rib82can have a real part of a refractive index nT≥1.6, nT≥1.7, nT≥1.9, nT≥2.1, or nT≥2.3 and an extinction coefficient kT≤0.1, kT≤0.01, or kT≤0.001. The refractive indices and extinction coefficients of this paragraph can be such values across the ultraviolet spectrum, across the visible spectrum, across the infrared spectrum, or combinations thereof.

Depositing the stack of upper ribs53can include depositing the upper ribs53such that one, some, or all of the upper ribs53are separate from associated upper ribs53on adjacent support-ribs22. A bottom41bof the channels41can be free of material of the upper ribs53. The bottom41bof the channels41can be free of material of the caps52, the wires62, the lower ribs72, the top ribs82, or combinations thereof. Depositing the caps52can include depositing each cap52such that it is separate from caps52on adjacent support-ribs22. Depositing the wires62can include depositing each wire62such that it is separate from wires62on adjacent support-ribs22. Depositing the lower ribs72can include depositing each lower rib72such that it is separate from lower ribs72on adjacent support-ribs22. Depositing the top ribs82can include depositing each top rib82such that it is separate from top ribs82on adjacent support-ribs22. Deposition of any of the upper ribs53with separation from associated upper ribs53on adjacent support-ribs22can be achieved as described in the “FIRST AND SECOND METHODS, WIRE SEPARATION” section below.

The support-ribs22, the upper ribs53, the caps52, the wires62, the lower ribs72, the top ribs82, or combinations thereof, can have a curved cross-sectional shape at a distal end D farthest from the substrate11. This curved cross-sectional shape can be a parabolic or half-elliptical cross-sectional shape. The curved cross-sectional shape can improve WGP performance, such as by increasing transmission of a predominantly-transmitted polarization.

The cap52can extend down sides S of the support-rib22, the wire62can extend down sides S of the cap52, the lower rib72can extend down sides S of the wire62, the top ribs82can extend down sides S of the lower ribs72, or combinations thereof. The curved cross-sectional shape combined with the upper ribs53extending down sides of the lower, adjacent rib in the stack can improve manufacturing throughput because this shape can allow a thinner layer to achieve the same polarization effect.

The support-ribs22can have a low index of refraction (n22) for improved optical performance, especially at low wavelengths, such as for example: n22≤1.4, n22≤1.3, n22≤1.2, or n22≤1.1. Furthermore, the index of refraction (n22) of the support-ribs22can be less than an index of refraction (n11) of the substrate11, less than an index of refraction (n52) of the cap52, or both.

One way of achieving this low index of refraction is to include small voids or cavities in the cured layer32. These small voids, filled with air, lower the overall index of refraction of the cured layer32. For example, the cured layer32can include silicon dioxide, with an index of refraction of around 1.4-1.5, but with the voids, the overall index of refraction can be <1.4. These voids can be formed by use of a solvent in the uncured layer12which has larger molecules. For example, a chemical in a solvent in the uncured layer12can have a molecular weight of ≥70 g/mol, ≥80 g/mol, ≥90 g/mol, ≥100 g/mol, or ≥110 g/mol. As another example, a chemical in this solvent can have a large number of atoms in each molecule, such as for example ≥15 atoms, ≥20 atoms, or ≥25 atoms. It can be useful for chemicals in this solvent to not have too high of a molecular weight so that it can be sufficiently volatile. Therefore, all chemicals this solvent can have a molecular weight of ≤125 g/mol, ≤150 g/mol, ≤175 g/mol, ≤200 g/mol, or ≤300 g/mol. All molecules in this solvent can include ≤30 atoms, ≤50 atoms, or ≤75 atoms. Further, this solvent can have a structure which occupies larger space, such as an aryl molecule or otherwise a molecule with double bonds. For example, the uncured layer12can include benzene or xylene. Thus, the support-ribs22can include organic moieties. For example, ≥0.1%, ≥1%, or ≥10% and ≤15%, ≤25%, or ≤50% of atoms in the support-ribs22can be part of organic moieties.

The support-ribs22and the caps52can have the same or similar material composition. For example, ≥60%, ≥75%, ≥85%, or ≥90%; and ≤92%, ≤95%, or ≤99%; of a material composition of the support-ribs22can be the same as a material composition of the caps52. An inorganic portion of the support-ribs22can be the same as an inorganic portion of the caps52. Thus, a difference in the material composition between the support-ribs22and the caps52can be added organic moieties in the support-ribs22.

First Optical Device,FIGS.5-8

A wire grid polarizer (WGP) can be formed by the first method described above, and consequently can include a broader variety of materials (even those difficult to etch) and thus potentially improved performance, durability, or both. The WGP can also be made at a lower cost due to avoidance or reduction of etch. The WGP, and components of the WGP, can have properties as described above.

As illustrated inFIGS.5-8, the WGP can include an array of support-ribs22on a substrate11, and an upper rib53or a stack of upper ribs53on the distal end D of each of the support-ribs22. The support-ribs22and the stack of upper ribs53can be parallel and elongated, with a length extending into the pages of the drawings. Alternatively, the support-ribs22and the stack of upper ribs53can extend in variable directions, like a metamaterial polarizer for example.

The upper rib53or a stack of upper ribs53can include one upper rib53(FIGS.5and6a), two upper ribs53(FIG.6b), three upper ribs53(FIG.7), four upper ribs53(FIG.8), or >four upper ribs53. In one embodiment, the stack of upper ribs53can include the following upper ribs53in the following order moving outwards from the support-ribs22: the cap52, the wire62, the lower rib72, and then the top rib82. In another embodiment, the stack of upper ribs53can include the following upper ribs53in the following order moving outwards from the support-ribs22: the wire62, the lower rib72, and then the top rib82. In another embodiment, the upper rib53can include the wire62.

Second Optical Device, with Slanted Support-Ribs92

As illustrated inFIGS.9-16and23, optical devices90,110,120,130,140,150,160, and230are shown comprising an array of parallel, elongated support-ribs92on a face11fof a substrate11with channels93between adjacent support-ribs92. Each support-rib92can have a cross-sectional profile with a proximal end92pclosest to the substrate11and a distal end92dopposite of the proximal end92p. The distal end92dcan be farthest from the substrate11. Each support-rib92can also have sides92iand92ufacing the channels93and extending from the proximal end92pto the distal end92d. The channels93can include an air-filled region extending along a length of the channels93, the length of the channels93being a longest dimension of the channels.

As illustrated inFIGS.13-16, optical devices130,140,150, and160can each be a wire grid polarizer (WGP) with a wire132on the upper-side92uand the distal end92dof each support-rib92. The wires132can be parallel and elongated. To facilitate polarization, each wire132can be separate from wires132on adjacent support-ribs92. The following discussion of the shape of the support-ribs92and the added cap152can be helpful for ensuring or improving separation of wires132on separate support-ribs92, even with wire132deposition from normal incidence (seeFIG.13).

The sides of the support-ribs92can include an inner-side92iwhich leans towards and faces the substrate11, and an upper-side92u, opposite of the inner-side92iand not facing the substrate11or facing away from the substrate11. This leaning or slanting of the support-ribs92can facilitate deposition of wires132(particularly by normal-angle deposition) on the upper-side92u, on the distal end92d, or both, with each wire132being separate from wires132on adjacent support-ribs92. In one embodiment, all support-ribs92can lean in a single direction.

The lean or slant of the support-ribs92can be quantified by angles A92, Api, and Apu. Angle A92is a smallest angle between a plane95(FIGS.9-12) and the face11fof the substrate11. The plane95extends along a length L (FIG.10) of each support-rib92through a center of the support-rib92from the proximal end92pto the distal end92d. Example values for A92include 5°≤A92, 15°≤A92, 25°≤A92, 40°≤A92, or 60°≤A92; and A92≤45°, A92≤60°, A92≤75°, or A92≤85°. Apiis an external angle between the inner-side92iand the face11fof the substrate11. Example values for Apiinclude 5°≤Api, 15°≤Api, 25°≤Api, 35°≤Api, 45°≥Api, 55°≤Api, or 65°≤Api; and Api≤45°, Api≤55°, Api≤65°, Api≤75°, or Api≤85°. Apuis an external angle between the upper-side92uand the face11fof the substrate11. Example values for Apuinclude 95°≤Apu, 105°≤Apu, 115°≤Apu, 130°≤Apu, or 150°≤Apu; and Apu≤135°, Apu≤150°, Apu≤165°, or Apu≤175°. Api−Apucan be related as follows: |180°−Api−Apu|≤2°, |180°−Api−Apu|≤5°, |180°−Api−Apu|≤10°, |180°−Api−Apu|≤20°, or |180°−Api−Apu|≤30°.

If the optical device is a wire grid polarizer (WGP) with wires132, then angles A92, Api, and Apucan be selected, along with size and spacing between the support-ribs92, to keep each wire132separate from wires132on adjacent support-ribs92. In the following equation, Lc(FIG.9) is a straight-line distance, from one support-rib92to an adjacent support-rib92in the channel, parallel to the face11fof the substrate11, and Li(FIG.9) is a straight-line distance of the inner-side92ifrom the proximal end92pto the distal end92d. Typically, Lcis selected based on needed WGP performance (e.g. balance of Tp and Ts), and Liis selected based on needed support-rib92structural strength. Angle A92can then be calculated from the following equation:

A9⁢2=cos-1(LcLi).
This value of A92can result in the support-ribs92blocking the face11fof the substrate11in the channels11from normal angle deposition of the wires132. It might not be needed or desirable to achieve the exact A92value noted above. Variation from such angle can be quantified by the equation

A9⁢2=cos-1(X*LcLi).
Values of “X” for different circumstances are described in the following two paragraphs.

Partial blocking of the channels11might be acceptable, if some deposition of the wires132in the channels93is allowed in the specific WGP design, or if deposition is performed at an oblique angle with deposition target facing the upper-side92u. Example ranges of X, for use in the equation

A9⁢2=cos-1(X*LcLi),
include X≤0.95, X≤0.9, X≤0.8, X≤0.7, X≤0.6, X≤0.5, X≤0.4, or X≤0.2.

For some designs, particularly for high transmission of the predominantly-transmitted polarization (e.g. high Tp), partial coverage of the upper-side92u, the distal end92d, or both with the wires132can be helpful. This can be achieved by increasing X to decrease A92. Example ranges of X, for use in the equation

A9⁢2=cos-1(X*LcLi),
include X≥1.03, X≥1.05, X≥1.1, X≥1.15, or X≥1.2.

Angles Adiand Aduat the distal end92dof the support-rib92can be selected, and formed by shape of the stamp171described below, for desired blocking of the channels93during deposition, WGP durability, and reduced manufacturing cost. Adiis an internal angle between the inner-side92iand the distal end92d. Aduis an internal angle between the upper-side92uand the distal end92d.

For example, Adiand Aducan be close to 90° as shown inFIGS.9-10. This design can improve support-rib92durability and can reduce stamp171cost. Alternatively, as illustrated inFIG.11, Adican be <90° (e.g. Adi<90°, Adi≤80°, Adi≤70°, Adi≤60°, or Adi≤50°; and Adi≥10°); and Aducan be >90° (e.g. Adu>90°, Adu≥100°, Adu≥110°, Adu≥120°, Adu≥130°; and Adu≤180°), thus extending the inner-side92iat the distal end92dover the channel93. This design can improve blocking of the face11fof the substrate11during deposition of the wires132.

Channel angle Acis illustrated inFIGS.9and11. The channel angle Acis an angle between sides92iand92uof the support-ribs92and the face11fof the substrate11in the channels93. As illustrated inFIG.9, in each channel93, one channel angle Accan be <90° and the other channel angle Ac, on an opposite side of the channel, can be >90°. Alternatively, as illustrated inFIG.11, in each channel93, both channel angles Accan be ≈90°, such as for example 90°+/−5°, 90°+/−10°, 90°+/−15°, or 90°+/−20°. The embodiment ofFIG.11, with both channel angles Ac≈90°, may be preferred due to increased performance resulting from increased channel93depth.

The following further describes how the aforementioned angles are defined or interpreted. Any angle described as an “external angle” is measured external to the support-rib92. As illustrated inFIG.12, if the sides92iand92uare curved, then side-line121is used to determine angles Apiand Apu. Side-lines121are aligned with a narrowest dimension of the side92ior92uand at an angle to align with an average direction of the side92ior92u. If angles Ap, and Apucannot be precisely and repeatedly determined across the optical device, such as due to curvature of the substrate or roughness of the face11fof the substrate11, then these angles Apiand Apuare measured at a substrate-line123extending through a core of the substrate11. The substrate-line123has a direction that is an average of the face11fof the substrate11, or an average of a side11sof the substrate11opposite of the face11f, whichever has the smoothest surface. If the distal end92dis curved, then distal-line122is used to determine angles Adiand Adu. Distal-line122extends between locations where the two side-lines121exit the distal end92d.

In summary, distance Lc, distance Li, angle A92, value X in the equation

A9⁢2=cos-1(X*LcLi),
and angles Adiand Aduat the distal end92d, can be selected for partial or complete blocking of the face11fof the substrate11in the channels93by the support-ribs92as viewed from perpendicular to the face11fof the substrate11. See line94inFIG.9, indicating this complete blocking. Complete blocking of the channels93, as viewed from perpendicular to the face11fof the substrate11, can result in negligible or no wires132on the inner-side92iof each support-rib92, on the substrate11in the channels93, or both, as illustrated inFIG.13.

Alternatively, as illustrated inFIG.14, the wires132can enter the channels93and cover part of the inner-side92iof each support-rib92, part of the substrate11in the channels93, or both. For example, ≥50%, ≥75%, or ≥90% of the inner-side92iof each support-rib92, the substrate11in the channels93, or both can be free of material of the wires132, and the other portion can be coated with the wire132.

If the wire132does cover part of the inner-side92i, part of the substrate11in the channels93, or both, it can cover it with a small thickness due to blocking effect of the slanted support-ribs92. For example, Th132i≤10 nm, Th132i≤20 nm, or Th132i≤50 nm, where Th132iis a maximum thickness of the wires132on the inner-sides92i, measured perpendicular to the inner-side92i. As another example, Th132u/Th132i≥2, Th132u/Th132i≥5, Th132u/Th132i≥10, Th132u/Th132i≥20, where Th132uis a maximum thickness of the wire132on the upper-side92u, measured perpendicular to the upper-side. As another example, Th132u/Th132s≥2, Th132u/Th132s≥5, Th132u/Th132s≥10, or Th132u/Th132s≥20, where Th132sis a maximum thickness of the wire132on the face11fof the substrate11in a channel93adjacent to the support-rib92, measured perpendicular to the face11fof the substrate11.

As illustrated inFIGS.15-16, the WGP150and160can further comprise a cap152sandwiched at least partly between each wire132and each support-rib92. A purpose of the cap152is to further close off the channel during deposition of the wire132. Thus, the cap152can help to compensate for manufacturing limitations of support-rib92length Liand angle Api. For example, there can be limited wicking of the uncured layer172into the stamp171, thus limiting a depth of stamp-channels173(FIGS.17-18). This limitation can be compensated for by use of the cap152. Another benefit of the longer support-rib92plus cap152combination is that this can increase channel93length and thus provide a larger region with a reduced effective index of refraction as described in U.S. Pat. No. 6,122,103. It can be helpful for the cap152on each support-rib92to be separate from (i.e. not touch) the caps152on adjacent support-ribs92. This separation can facilitate deposition of separate wires132.

As illustrated inFIG.15, the cap152can cover part or all of the upper-side92u, part or all of the distal end92d, or both. As illustrated inFIG.16, the cap152can cover at least part of the inner-side92iof each support-rib92. For example, ≥50%, ≥75%, or ≥90% of the inner-side92iof each support-rib92can be free of material of the cap152, and the other portion can be coated with the cap152.

Example maximum thicknesses Th152iof the cap152on the inner-sides92i, measured perpendicular to the inner-side92i, include Th152i≤5 nm, Th152i≤10 nm, or Th152i≤20 nm. As another example, Th152u/Th152i≥2, Th152u/Th152i≥5, Th152u/Th152i≥10, Th152u/Th152i≥20, where Th152uis a maximum thickness of the cap152on the upper-side92u, measured perpendicular to the upper-side92u.

Second Method,FIGS.9-23

A second method of making an optical device, such as a wire grid polarizer (WGP), can comprise some or all of the following steps, which are illustrated inFIGS.17-23. The second method can be performed in the following order or other order if so specified. Some of the steps can be performed simultaneously unless explicitly noted otherwise in the claims. There may be additional steps not described below. These additional steps may be before, between, or after those described. Components of the optical device, and the optical device itself, can have properties as described above. Any additional description of properties of the optical device in the below second method, not described above, can be applicable to the above described optical device.

The second method can comprise some or all of the following: (a) step170, applying an uncured layer172on a face11fof a substrate11(FIG.17); (b) step180or210, imprinting a pattern of uncured support-ribs182in the uncured layer172(FIGS.18&21); (c) step190or220, curing the uncured layer (FIGS.19&22); (d) depositing a cap152on the upper-side92uand the distal end92dof each support-rib92(FIGS.15&16); and (e) depositing a wire132on the upper-side92uof each support-rib92, on the distal end92dof each support-rib92, or both (FIGS.13-16).

(b) & (c): Imprinting the pattern of support-ribs92in the uncured layer172can be performed, such as for example with the stamp171as described below, to produce leaning support-ribs92, which can have angles as described above.

As illustrated inFIGS.18and21, imprinting can include pressing a stamp171into the uncured layer172. The stamp171can include stamp-ribs171rmating with the channels93and stamp-channels173mating with the support-ribs92.

Due to the leaning shape of the support-ribs92, it can be difficult to remove the stamp171from the support-ribs92without damaging them. One methods for removing the stamp171from the optical device without damaging the support-ribs92is removing the stamp171at an angle A171(seeFIG.20), which can be close to A92(seeFIGS.9-12). For example, A171can be within 2°, 5°, 10°, 20°, or 30° of A92.

Other methods for removing the stamp171from the optical device without damaging the support-ribs92are using a stamp171that is flexible, using support-ribs92that are flexible, or both. The stamp171can include an elastic material. The stamp-ribs171r, a base171bof the stamp171attached to the stamp-ribs171r, or both can be elastic. The stamp-ribs171r, a base171bof the stamp171attached to the stamp-ribs171r, or both can comprise polyimide, polydimethylsiloxane, or both. The stamp-ribs171r, a base171bof the stamp171attached to the stamp-ribs171r, the support-ribs92when the stamp171is removed from the support-ribs92, or combinations thereof can have a modulus of elasticity ≤6 GPa, ≤3 GPa, ≤1 GPa, or ≤0.1 GPa; and can be ≥0.1 GPa, ≥0.01 GPa, ≥0.005 GPa, ≥0.001 GPa, or ≥0.0001 GPa. The support-ribs92can be flexible by partially curing the uncured layer172, removing the stamp171, then finalizing the cure. The partially-cured support-ribs92can flex as the stamp171is removed.

(c) Curing the uncured layer172can including curing the uncured support-ribs182into support-ribs92that are solid and cured. In one embodiment, the uncured layer172can be a liquid with solid inorganic nanoparticles dispersed throughout a continuous phase, the solid inorganic nanoparticles including metal atoms bonded to reactive groups, where each reactive-group is independently —Cl, —OR2, —OCOR2, or —N(R2)2, and R2is an alkyl group; and curing can include reacting the molecules to form a solid of the metal atoms interconnected with each other. In another embodiment, the uncured layer172can be a liquid with solid inorganic nanoparticles dispersed throughout a continuous phase; and curing can include forming a solid, interconnecting network of the inorganic nanoparticles. In another embodiment, the uncured layer172can be a colloidal suspension including a dispersed phase and a continuous phase; and curing the uncured layer172can include removing the continuous phase.

(d) & (e): The cap152, the wires132, or both can be deposited by sputter deposition, which can facilitate deposition of separation of the caps152, the wires132, or both on separate support-ribs92. The separation of the caps152, the wires132, or both on separate support-ribs92can improve WGP performance, such as for example increased transmission of the desired polarization (e.g. increase Tp) and reduced transmission of the opposite polarization (e.g. decrease Ts). Sputter deposition of the cap152can also result in the cap152having a linear profile152Lfacing the support-rib92and a curved profile152Cfacing the wire132, which can improve WGP performance. This linear profile152L/curved profile152Ccan also can improve WPG performance.

Deposition of the cap152, the wires132, or both can include normal angle deposition, or can even be performed solely by normal angle deposition. Some manufacturing facilities lack equipment for oblique angle deposition, thus such normal angle deposition can allow reduced cost manufacture of WGPs due to avoidance of purchase of additional equipment.

(b) to (e): As illustrated inFIGS.11and18-20, adjacent support-ribs22and92can be connected at the proximal end92pby material111of the support-ribs92. This can be accomplished by not pressing the stamp171all the way to the substrate. This connection of the support-ribs92by material111of the support-ribs92can increase strength of the support-ribs92, which can be particularly helpful in the embodiments described herein with inclined or leaning support-ribs92. Although the support-ribs92might be connected at the proximal end92p, each support-rib92can be separate from (i.e. not touch) adjacent support-ribs92at the distal end92dand at the sides92iand92u. This separation can facilitate deposition of separate cap152, separate wires132, or both.

The uncured layer172, the support-ribs92, the cap152, or combinations thereof can have a low index of refraction for improved optical performance, such as for example ≤1.1, ≤1.2, ≤1.3, or ≤1.4. In one embodiment, such index of refraction can be ≥1.0.

One way of achieving this low index of refraction is to include small voids or cavities in the uncured layer172, which can remain in the support-ribs92. These small voids, filled with air, can lower the overall index of refraction. For example, the support-ribs92can include silicon dioxide, with an index of refraction of around 1.4-1.5, but with the voids, the overall index of refraction can be <1.4. These voids can be formed by use of a solvent in the uncured layer172which has larger molecules. For example, a solvent in the uncured layer172can have a molecular weight of ≥70 g/mol, ≥80 g/mol, ≥90 g/mol, ≥100 g/mol, or ≥110 g/mol. As another example, a chemical in this solvent can have a large number of atoms, such as for example ≥15 atoms, ≥20 atoms, or ≥25 atoms. It can be helpful for this solvent to not have too high of a molecular weight so that it can be sufficiently volatile. Therefore, this solvent can have a molecular weight of ≤125 g/mol, ≤150 g/mol, ≤175 g/mol, ≤200 g/mol, or ≤300 g/mol. This solvent can also have ≤30 atoms, ≤50 atoms, or ≤75 atoms. Further, this solvent can have a structure which occupies larger space, such as an aryl molecule or otherwise a molecule with double bonds. For example, the uncured layer172can include benzene or xylene.

The support-ribs have a real part of a refractive index nS≥1.7 or nS≥2.0 and an extinction coefficient kS≤0.1, across the ultraviolet spectrum, across the visible spectrum, across the infrared spectrum, or combinations thereof. Example materials of the support-ribs92include an oxide of hafnium, lead, niobium, tantalum, titanium, tungsten, zirconium, silicon or combinations thereof.

The support-ribs92can include organic moieties to facilitate manufacturing, to affect WGP performance, or combinations thereof. These organic moieties can be part of the material composition of the uncured layer172, and can remain after the uncured layer172is cured to form the support-ribs92. For example, ≥0.1%, ≥1% and ≥25%, ≤50% of atoms in the support-ribs92can be part of organic moieties. As another example, a mass percent of the organic moieties in the support-ribs can be ≥0.1% and ≤20%. The organic moieties can include —CH3, —CH2CH3, or both. As another example, all organic moieties can include ≤3 carbon atoms.

The cap152can have the same or a different material composition as/than the support-rib92. In one embodiment, the caps152and the support-ribs92can comprise silicon dioxide. In one embodiment, the support-ribs92and not the caps152can include organic moieties due to different methods of deposition/formation of each (e.g. support-ribs92typically formed by spin-on then imprint and the caps152typically formed by sputter).

The support-ribs92, the substrate11, and the cap152can have the same or similar material composition. For example, ≥70%, ≥80%, ≥90%, or ≥95% of a material composition of the support-ribs92, the substrate11, and the cap152can be the same. The support-ribs92, the substrate11, the cap152, or combinations thereof can be transparent across the ultraviolet spectrum, the visible spectrum, the infrared spectrum, or combinations thereof. The wire132can be reflective, across the ultraviolet spectrum, the visible spectrum, the infrared spectrum, or combinations thereof.

As illustrated inFIG.23, the second method can further comprise step230, including applying a conformal layer231on cured support-ribs92, forming optical device232. Step230can follow any of steps190,200, or220. The conformal layer231can be applied by atomic layer deposition. The conformal layer231can have a refractive index (n231) that is higher than a refractive index (n92) of the support-ribs92. Example values of these refractive indices include: n92≥1.3, n92≥1.5, or n92≥1.7; n92≤1.6, n92≤1.8, or n92≤1.99; n231≥2.0 or n231≥2.2; and n231≤3.0 or n92≤4.0. These refractive index n231and n92values and relationships can be such values and relationships across the ultraviolet spectrum, visible spectrum, infrared spectrum, or combinations thereof. If the optical device is a waveguide, addition of the conformal layer231can improve waveguide performance, especially if n231>n92at a wavelength or across a wavelength range of intended use.

First and Second Methods, Wire Separation

It can be useful for the wires62or132to be separate from wires62or132on adjacent support-ribs22or92. The following paragraphs describe how to achieve this in both the first method and the second method.

In the first method, a preferred method of deposition is sputter. Pressure in the chamber can be raised for less directional deposition, resulting in deposition of the wire62from all angles and preferential deposition of the wire62at a distal end D of the support-ribs22. A deposition pressure that is too high, however, can result in too slow of a deposition rate. A pressure of five millitorr is suggest for balancing (a) deposition of the wire62from all angles by high pressure; with (b) lower pressure to improve deposition rate.

In the second method, preferred deposition methods include evaporation or low pressure sputter, either resulting in directional deposition of the wire132on the upper-side92uand the distal end92dof each support-rib92. In evaporation or low pressure sputter, pressure can be lowered as far as possible while still maintaining a plasma. In the second method, with slanted support-ribs92, directional deposition, such as by evaporation or low pressure sputter, can facilitate separation of wires62on adjacent support-ribs92.

In the first method, the channels41can be partially blocked, by the cap52described above, to facilitate separation of wires62on adjacent support-ribs22. In the second method, the channels93can be partially blocked, by the cap152described above, to facilitate separation of wires132on adjacent support-ribs92.

A shape of support-ribs22or92can help facilitate separation of wires62or132. The support-ribs22inFIGS.2-8are illustrated with a curved distal end D, which facilitates manufacturing, but can make it more difficult to keep the wires62separate from each other. The distal end92dof support-ribs92in the second method, and illustrated inFIGS.9-10and13-16, have a rectangular shape, which can be more difficult to manufacture, but can help keep wires132separate from each other. The distal end92dof support-ribs92in the second method, and illustrated inFIGS.11and19-20, have a trapezoid shape, which can further assist in keeping wires132separate from each other. The rectangular shape ofFIGS.9-10and13-16and the trapezoid shape ofFIGS.11and19-20, and described above, can be applied in the first method. The stamp13in the first method can be replaced by the stamp171ofFIGS.17-22.

A high aspect ratio (AR) of the support-ribs22or92can help facilitate separation of wires62or132, where AR=Th22/P or AR=Th92/P, Th22is a thickness of support-ribs22, Th92is a thickness of support-ribs92, and P is a pitch of the support-ribs22or92.

If the above methods are insufficient for keeping the wires62or132separate, and if the wires62or132are made of aluminum, then any small amount of aluminum in the channels41or93can be oxidized to form aluminum oxide, thus separating pure aluminum wires62or132from each other. Aluminum was used as an example—oxidation can be used with other suitable materials. An isotropic etch may also be used to remove any small amount of wires62or132in the channels41or93.

Third Optical Device, with Slanted Support-Ribs92

As illustrated inFIG.23, optical device232can include a conformal layer231on support-ribs92. The support-ribs92of optical device232are illustrated with a shape similar to the support-ribs92of optical device110, but these support-ribs92can have other shapes as described herein. The conformal layer231and the support-ribs92can have refractive index values as described above. If the optical device is a waveguide, addition of the conformal layer231can improve waveguide performance, especially if n231>n92at a wavelength or across a wavelength range of intended use. Optical device232can be formed into a WGP, such as for example with addition of a wire132as described herein.