Wire grid polarizer with tilted support ribs

Abstract

To improve performance of a wire grid polarizer (WGP), and discover a low-cost method for manufacturing the WGP.SOLUTION: A wire grid polarizer (WGP) can include an array of support-ribs 92 on a substrate. Sides of the support-ribs 92 can be inclined to one side. A wire 132 can be applied onto an upper-side and distal end of each support-rib 92, each wire being separate from wires 132 on adjacent support-ribs 92. The WGP can be made with reduced or no etching.SELECTED DRAWING: Figure 13

Description

[Technical Field]

[0001] This application relates generally to wire grid polarizers. [Background technology]

[0002] A wire grid polarizer (WGP) can split light into two different polarization states. One polarization state can be primarily transmitted through the WGP, while the other polarization state can be primarily absorbed or reflected. The effectiveness or performance of a WGP is based on high transmission of the primarily transmitted polarization (sometimes called Tp) and minimal transmission of the opposite polarization (sometimes called Ts). It can be beneficial to have a high contrast (Tp / Ts). The contrast can be improved by increasing the transmission of the primarily transmitted polarization (e.g., increasing Tp) and decreasing the transmission of the opposite polarization (e.g., decreasing Ts). It would be advantageous to improve the performance of a WGP.

[0003] The ribs of high performance WGPs, especially for visible or ultraviolet polarization of light, and other optical devices can be small and sophisticated, with nanometer-sized pitches, wire widths, and wire heights. Manufacturing such WGPs and other optical devices can be costly. It would be advantageous to find a low-cost method for manufacturing optical devices.

[0004] Patterning and etching can form the wires of a wire grid polarizer. Some desirable materials for wire grid polarizers can be difficult or impractical to etch. It would be beneficial to reduce or eliminate the need for etching to form the wires. Summary of the Invention

[0005] It has been recognized that it would be advantageous to improve the performance of wire grid polarizers (WGPs), to find low-cost methods for manufacturing WGPs, and to reduce or eliminate the need to etch such WGPs. The present invention describes various embodiments of WGPs and methods of making WGPs that meet these needs. Each embodiment may meet one, some, or all of these needs.

[0006] The WGP can include an array of support ribs on a substrate. The sides of the support ribs can be angled to one side. Each support rib can have a wire on its upper side and distal end, each wire separated from the wires of adjacent support ribs. [Brief explanation of the drawings]

[0007] (Drawings may not be drawn to scale.)

[0008] [Figure 1] 1 is a schematic cross-sectional side view illustrating step 10 in a method of making a wire grid polarizer (WGP), which includes providing an uncured layer 12 on a substrate 11, in accordance with one embodiment of the present invention.

[0009] [Figure 2] FIG. 2 is a schematic cross-sectional side view illustrating step 20, which may follow step 10, in a method of making a WGP, including imprinting support ribs 22 in uncured layer 12, in accordance with one embodiment of the present invention.

[0010] [Figure 3] 2 is a schematic cross-sectional side view illustrating step 30, which may follow step 20, in a method of making a WGP, including curing uncured layer 12 to form cured layer 32, in accordance with one embodiment of the present invention.

[0011] [Figure 4]A schematic cross-sectional side view showing step 40, which can follow step 30, in a method of making a WGP, including removing the mold or stamp 13 and leaving support ribs 22 in the hardened layer 32 with channels 41 between adjacent support ribs 22, according to one embodiment of the present invention.

[0012] [Figure 5] A schematic cross-sectional side view showing step 50, which can follow step 40, in a method of making a WGP, including depositing a cap 52 on each support rib 22, each cap 52 extending under side S of the support rib 22, according to one embodiment of the present invention.

[0013] [Figure 6a] A schematic cross-sectional side view showing step 60a, which can follow step 40, in a method of making a WGP, including depositing wires 62 on each support rib 22, each wire 62 extending under side S of the support rib 22, according to one embodiment of the present invention.

[0014] [Figure 6b] A schematic cross-sectional side view showing step 60b, which can follow step 50, in a method of making a WGP, including depositing wires 62 on each cap 52, each wire 62 extending below side S of cap 52, according to one embodiment of the present invention.

[0015] [Figure 7] A schematic cross-sectional side view showing step 70, which can follow steps 60a or 60b, in a method of making a WGP, including depositing a lower rib 72 on each wire 62, each lower rib 72 extending below side S of the wire 62, according to one embodiment of the present invention.

[0016] [Figure 8]1 is a schematic cross-sectional side view showing step 80, which can follow step 70, in a method of making a WGP, including depositing an upper rib 82 on each lower rib 72, each upper rib 82 extending below side S of the lower rib 72, according to one embodiment of the present invention.

[0017] [Figure 9] 1 is a schematic cross-sectional side view of an optical device 90 including an array of parallel, elongated support ribs 92 on a surface 11f of a substrate 11 and sides 92i and 92u of the support ribs 92 that are inclined to one side, according to one embodiment of the present invention.

[0018] [Figure 10] 10 is a schematic perspective view of the optical device 90 of FIG. 9, in accordance with one embodiment of the present invention.

[0019] [Figure 11] 1 is a schematic cross-sectional side view of an optical device 110 similar to optical device 90, except that the outer angles Api and Apu at proximal end 92p of optical device 110 are similar in value to the inner angles Adi and Adu at distal end 92d, respectively, in accordance with one embodiment of the present invention.

[0020] [Figure 12] FIG. 1 is a schematic cross-sectional side view of an optical device 120 similar to other optical devices described herein, in accordance with an embodiment of the present invention, providing guidance as to how angles Api, Apu, Adi, and Adu are defined or interpreted, particularly when sides 92i and 92u are curved, when surface 11f of substrate 11 is rough or curved, when distal end 92d is curved, or combinations thereof.

[0021] [Figure 13] 1 is a schematic cross-sectional side view of an optical device 130, such as a wire grid polarizer (WGP), similar to optical devices 90 and 110, according to one embodiment of the present invention, but further comprising wires 132 on the upper surface 92u and distal end 92d of each support rib 92.

[0022] [Figure 14] 1 is a schematic side cross-sectional view of an optical device 140 similar to optical device 130 according to one embodiment of the present invention, but further comprising several wires 132 of maximum thickness Th132i on the inner surface 92i of the support rib 92 and several wires 132 of maximum thickness Th132s on the surface 11f of the substrate 11 within the channel 93.

[0023] [Figure 15] 1 is a schematic side cross-sectional view of an optical device 150 similar to optical devices 130 and 140 according to one embodiment of the present invention, but further comprising a cap 152 sandwiched between wire 132 and support rib 92 on the upper surface 92u and distal end 92d of each support rib 92.

[0024] [Figure 16] 1 is a schematic cross-sectional side view of an optical device 160 similar to optical device 150, but further comprising several caps 152 on at least a portion of the inner surfaces 92i of the support ribs 92, in accordance with one embodiment of the present invention.

[0025] [Figure 17] 1 is a schematic cross-sectional side view illustrating a step 170 in a method of making an optical device, including providing an uncured layer 172 on a surface 11f of a substrate 11, in accordance with one embodiment of the present invention.

[0026] [Figure 18] A schematic cross-sectional side view showing step 180 in a method of making an optical device, which can follow step 170, including imprinting a pattern of uncured support ribs 182 into uncured layer 172 having sides 182i and 182u of uncured support ribs 92 sloping to one side, according to one embodiment of the present invention.

[0027] [Figure 19]1 is a schematic cross-sectional side view illustrating a step 190 in a method of making an optical device, which may follow step 180, including curing uncured layer 172 to form solid, hardened support ribs 92, in accordance with one embodiment of the present invention.

[0028] [Figure 20] 1 is a schematic cross-sectional side view illustrating a step 200 in a method of making an optical device, which may follow step 190, including removing stamp 171 at an oblique angle A171 relative to surface 11f of substrate 11, according to one embodiment of the present invention.

[0029] [Figure 21] 17 is a schematic cross-sectional side view showing step 210 in a method of making an optical device, which can be followed by step 170, which includes imprinting a pattern of uncured support ribs 182 into an uncured layer 172 having sides 182i and 182u of uncured support ribs 92 sloping to one side (but with stamp ribs 171r of a different shape than that illustrated in FIG. 17), in accordance with one embodiment of the present invention.

[0030] [Figure 22] 2 is a schematic cross-sectional side view illustrating step 220 in a method of making an optical device, which may follow step 210, including curing uncured layer 172 to form solid, hardened support ribs 92, in accordance with one embodiment of the present invention.

[0031] [Figure 23] 2 is a schematic cross-sectional side view illustrating step 230 in a method of making an optical device, which may follow any of steps 190, 200, or 220, including providing a conformal layer 231 on cured support ribs 92, in accordance with one embodiment of the present invention.

[0032] DEFINITIONS The following definitions, including plural equivalents, apply throughout this patent application.

[0033] As used herein, the term "conformal layer" means a thin film that conforms to the contours of a functional topology. For example, the thickness across the entire conformal layer can have a minimum value of 1 nm or more and a maximum value of 20 nm or less. As another example, the maximum value divided by the minimum value of 1 nm or more of the conformal layer thickness can be 20 or less, 10 or less, 5 or less, or 3 or less. As another example, the conformal layer at the distal end of each wire can be separated from the conformal layer at the distal end of an adjacent wire, the distal end being the end of the wire farthest from the substrate.

[0034] As used herein, the term "elongated" means that the length (length of the rib to the surface) is substantially greater than the width or thickness (e.g., the length can be 10 times or more, 100 times or more, 1000 times or more, or 10,000 times or more greater than the width, thickness, or both).

[0035] As used herein, the term "nm" means nanometer(s).

[0036] As used herein, the term "normal angle deposition" means deposition at an angle of 90 degrees ±10 degrees relative to the plane 133 of the surface on which the material is being deposited. See FIG. 13.

[0037] As used herein, the term "on" means placed directly on or above some other solid material.

[0038] As used herein, the term "parallel" means exactly parallel, parallel within standard manufacturing tolerances, or nearly parallel, so that deviations from exact parallelism will have a negligible effect on the normal use of the device.

[0039] As used herein, identical material composition between different portions of a WGP means exactly identical, identical within standard manufacturing tolerances, or nearly identical, whereby deviations from exactly identical will have a negligible effect on the normal use of the device.

[0040] Unless otherwise expressly noted herein, all temperature dependent values ​​are such values ​​at 25°C.

[0041] 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 transmissive. Each material can be considered absorptive, reflective, or transmissive over the wavelength range of its intended use, across the ultraviolet spectrum, the visible spectrum, the infrared spectrum, or a combination thereof, and can have different properties in different wavelength ranges. Materials are classified as absorptive, reflective, and transmissive based on the 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 material at normal incidence:

number

[0042] As used herein, ultraviolet spectrum means from 10 nm to less than 400 nm, visible spectrum means from 400 nm to less than 700 nm, and infrared spectrum means from 700 nm to less than 1 nm. DETAILED DESCRIPTION OF THE INVENTION

[0043] Although five or six support ribs 22 or 92 are illustrated in the drawings and described herein, there may be more than six support ribs 22 or 92, or there may be fewer than five support ribs 22 or 92, such as two or three, particularly when the optical device is a waveguide.

[0044] First method, Figs. 1-8.

[0045] The first method of fabricating a wire grid polarizer (WGP) illustrated in Figures 1-8 can include some or all of the following steps, which can be performed in the following order or in other orders if specified: There can also be additional steps not listed below. These additional steps can occur before, between, or after the steps listed. The WGP can be formed without etching.

[0046] The first method may include step 10 (FIG. 1) of providing an uncured layer 12 on a substrate 11, step 20 (FIG. 2) of imprinting support ribs 22 in the uncured layer 12 using a stamp 13, step 30 (FIG. 3) of curing the uncured layer 12 to form a cured layer 32, and step 40 (FIG. 4) of removing the stamp 13 to leave support ribs 22 in the cured layer 32 with channels 41 between adjacent support ribs 22. Each support rib 22 may be bonded to adjacent support ribs 22 by the material of the support rib 22.

[0047] In one embodiment, uncured layer 12 can be a liquid having solid inorganic nanoparticles dispersed throughout a continuous phase, and cured layer 32 can include a solid interconnected network of inorganic nanoparticles. In another embodiment, uncured layer 12 can be a colloidal suspension including a dispersed phase and a continuous phase, and curing uncured layer 12 can include removing the continuous phase to form a solid that defines cured layer 32.

[0048] In another embodiment, the uncured layer 12 can be a solution containing molecules in a solvent. The solvent can include water and organic liquids. The molecules can include metal atoms bonded to reactive groups. Each reactive group can be a group such as -Cl, -OR, or -O. 1 ,-OCOR 1 , or -N(R 1 )2. Each R 1 can be, for example, an alkyl group such as —CH, —CHCH, or —CHCHCH. Curing the uncured layer 12 can include reacting the molecules to form a solid of interconnected metal atoms that define the cured layer 32.

[0049] The first method can further comprise depositing an upper rib 53, or a stack of upper ribs 53, on the distal end D of each of the support ribs 22 (see steps 50, 60a or 60b, 70, 80, or combinations thereof in FIGS. 5-8 ). Following steps 10, 20, 30, and 40, exemplary combinations of these steps include step 50, step 50 then 60b, step 50, 60b then 70, step 50, 60b, 70 then 80, step 60a, step 60a then 70, step 60a, 70 then 80.

[0050] Step 50 may include depositing a cap 52 on each support rib 22 at a distal end D of each support rib 22 that is furthest from the substrate 11. The cap 52 may be sputter deposited. The cap 52 may be transparent (e.g., across the ultraviolet spectrum, across the visible spectrum, across the infrared spectrum, or a combination thereof).

[0051] The cap 52 may be wider than the support rib 22 at or proximal to the distal end D to block some or all of the channel 41, thus minimizing or preventing deposition of the subsequently deposited upper rib 53 within the channel 41. For example, 1.1≦W C / W SR , 1.2≦W C / W SR , 1.4≦W C / W SR , 1.6≦W C / W SR , 1.8≦W C / W SR , or 1.9≦W C / W SR and W C / W SR ≦2.1, W C / W SR ≦2.4, W C / W SR ≦2.8, W C / W SR ≦3.5,W C / W SR ≦4, or W C / W SR ≦6, and W C is the width of the cap 52 measured at the distal end D of the support rib 22, and W SR is the width of the support rib 22 measured at 20% of the distance from the distal end D of the support rib 22 toward the proximal end P of the support rib 22 closest to the substrate 11.

[0052] Step 60a may follow step 40 and may include depositing a wire 62 on each support rib 22 at a distal end D of each support rib 22 farthest from substrate 11. Step 60b may follow step 50 and may include depositing a wire 62 on each cap 52. Exemplary deposition methods for wire 62 include sputter deposition or evaporative deposition. Wire 62 may be reflective (e.g., across the ultraviolet spectrum, across the visible spectrum, across the infrared spectrum, or a combination thereof). Steps 60a and 60b may be performed before or after subsequent steps 70 and 80.

[0053] Step 70 may follow step 60a or step 60b and may include depositing a lower rib 72 on each wire 62. The lower rib 72 has a real part of the refractive index n L ≦1.6, n L ≦1.5, n L ≦1.4, n L ≦1.3, or n L ≦1.2 and extinction coefficient k L ≦0.1, k L ≦0.01, or k L ≦0.001. Step 80 may follow step 70 and may include depositing an upper rib 82 on each lower rib 72. The upper rib 82 may have a real part of the refractive index n T ≥ 1.6, n T ≥ 1.7, n T ≥ 1.9, n T ≧2.1, or n T ≧2.3 and extinction coefficient k T ≦0.1, k T ≦0.01, or k T The refractive index and extinction coefficient in this paragraph can have such values ​​across the ultraviolet spectrum, across the visible spectrum, across the infrared spectrum, or for a combination thereof.

[0054] Depositing the stack of upper ribs 53 can include depositing the upper ribs 53 such that one, some, or all of the upper ribs 53 are separated from associated upper ribs 53 on adjacent support ribs 22. b The lower end 41 of the channel 41 may be free of material from the upper rib 53. b The deposition method may not include the material of the caps 52, wires 62, lower ribs 72, upper ribs 82, or combinations thereof. Depositing the caps 52 may include depositing each cap 52, thereby separating it from the caps 52 on adjacent support ribs 22. Depositing the wires 62 may include depositing each wire 62, thereby separating it from the wires 62 on adjacent support ribs 22. Depositing the lower ribs 72 may include depositing each lower rib 72, thereby separating it from the lower ribs 72 on adjacent support ribs 22. Depositing the upper ribs 82 may include depositing each upper rib 82, thereby separating it from the upper ribs 82 on adjacent support ribs 22. Depositing any of the upper ribs 53 with separation from the associated upper ribs 53 on adjacent support ribs 22 may be achieved as described in the section "First and Second Methods, Wire Separation" below.

[0055] The support ribs 22, the upper ribs 53, the caps 52, the wires 62, the lower ribs 72, the upper ribs 82, or a combination thereof, can have a curved cross-sectional shape at the distal ends D furthest from the substrate 11. This curved cross-sectional shape can be a parabolic or semi-elliptical cross-sectional shape. The curved cross-sectional shape can improve WGP performance, such as by increasing the transmittance of the primarily transmitted polarization.

[0056] The cap 52 can extend under the side S of the support rib 22, the wire 62 can extend under the side S of the cap 52, the lower rib 72 can extend under the side S of the wire 62, the upper rib 82 can extend under the side S of the lower rib 72, or a combination thereof. The curved cross-sectional shape combined with the upper rib 53 extending under the side of an adjacent rib lower in the stack can improve manufacturing throughput, as this shape can allow for the same polarizing effect to be achieved in thinner layers.

[0057] The support ribs 22 are provided for improved optical performance, especially at low wavelengths, e.g., n 22 ≦1.4, n 22 ≦1.3, n 22 ≦1.2, or n 22 Low refractive index (n 22 ) of the support rib 22. 22 ) is the refractive index (n 11 ) and the refractive index (n 52 ) or both.

[0058] One way to achieve this low refractive index is to include small voids or cavities within the cured layer 32. These small, air-filled voids lower the overall refractive index of the cured layer 32. For example, the cured layer 32 can include silicon dioxide, which has a refractive index of approximately 1.4-1.5, but with the voids, the overall refractive index can be less than 1.4. These voids can be created by using a solvent within the uncured layer 12 with large molecules. For example, the solvent chemical within the uncured layer 12 can have a molecular weight of 70 g / mol or greater, 80 g / mol or greater, 90 g / mol or greater, 100 g / mol or greater, or 110 g / mol or greater. As another example, the solvent chemical can have a large number of atoms, such as 15 or more atoms, 20 or more atoms, or 25 or more atoms, within each molecule. It can be useful for the solvent chemical not to have an excessively high molecular weight so that it can be sufficiently volatile. Thus, all chemicals in the solvent can have a molecular weight of 125 g / mol or less, 150 g / mol or less, 175 g / mol or less, 200 g / mol or less, or 300 g / mol or less. All molecules in the solvent can contain 30 atoms or less, 50 atoms or less, or 75 atoms or less. Furthermore, the solvent can contain large-space structures such as aryl molecules or molecules with double bonds. For example, the uncured layer 12 can contain benzene or xylene. Thus, the support rib 22 can contain organic moieties. For example, 0.1% or more, 1% or more, or 10% or more and 15% or less, 25% or less, or 50% or less of the atoms in the support rib 22 can be part of organic moieties.

[0059] The support ribs 22 and the cap 52 can have the same or similar material composition. For example, 60% or more, 75% or more, 85% or more, or 90% or more and 92% or less, 95% or less, or 99% or less of the material composition of the support ribs 22 can be the same as the material composition of the cap 52. The inorganic portion of the support ribs 22 can be the same as the inorganic portion of the cap 52. Thus, the difference in material composition between the support ribs 22 and the cap 52 can be the organic portion added within the support ribs 22.

[0060] First optical device, Figs.

[0061] Wire grid polarizers (WGPs) can be formed by the first method described above and, as a result, can include a wide variety of materials (even those that are difficult to etch), potentially improving performance, durability, or both. Due to the avoidance or reduction of etching, WGPs can also be made at low cost. WGPs and WGP components can have the properties described above.

[0062] 5-8, the WGP can include an array of support ribs 22 on a substrate 11 and an upper rib 53 or stack of upper ribs 53 on the distal end D of each of the support ribs 22. The support ribs 22 and stack of upper ribs 53 can be parallel and elongated, with a length extending into the plane of the drawing. Alternatively, the support ribs 22 and stack of upper ribs 53 can extend in various directions, such as in a metamaterial polarizer.

[0063] The upper rib 53 or stack of upper ribs 53 can include one upper rib 53 ( FIGS. 5 and 6 a), two upper ribs 53 ( FIG. 6 b), three upper ribs 53 ( FIG. 7), four upper ribs 53 ( FIG. 8), or more than four upper ribs 53. In one embodiment, the stack of upper ribs 53 can include the following upper ribs 53 in the following order moving outward from the support rib 22: cap 52, wire 62, lower rib 72, and then upper rib 82. In another embodiment, the stack of upper ribs 53 can include the following upper ribs 53 in the following order moving outward from the support rib 22: wire 62, lower rib 72, and then upper rib 82. In another embodiment, the upper rib 53 can include the wire 62.

[0064] A second optical device 92 with angled support ribs.

[0065] As illustrated in FIGS. 9-16 and 23, the surface 11 of the substrate 11 has channels 93 between adjacent support ribs 92. f Optical devices 90, 110, 120, 130, 140, 150, 160, and 230 are shown having an array of parallel, elongated support ribs 92 thereon. Each support rib 92 has a proximal end 92 closest to the substrate 11. p and proximal end 92 p the opposite distal end 92 of d The distal end 92 may have a cross-sectional profile having a d The support rib 92 may be furthest from the substrate 11. Each support rib 92 has a proximal end 92 facing the channel 93. p to distal end 92 d Side 92 extending to i and 92 u The channel 93 may include an air-filled region that extends along the length of the channel 93, the length of the channel 93 being the longest dimension of the channel.

[0066] As illustrated in FIGS. 13 to 16, the optical devices 130, 140, 150, and 160 are respectively attached to the upper surface 92 of each support rib 92. u and distal end 92d The support rib 92 may be a wire grid polarizer (WGP) having wires 132 thereon. The wires 132 may be parallel and elongated. To facilitate polarization, each wire 132 may be separated from the wires 132 on adjacent support ribs 92. The following description of the shape of the support ribs 92 and added caps 152 may be useful to ensure or improve separation of the wires 132 on separate support ribs 92, even with deposition of the wires 132 from normal incidence (see FIG. 13 ).

[0067] The sides of the support ribs 92 are inclined toward the substrate 11, with the inner surfaces 92 facing it. i and inner surface 92 i an upper surface 92 that faces away from or does not face the substrate 11, u This leaning or tilting of the support ribs 92 can include a sloping or tilting edge on the upper surface 92, with each wire 132 separating from the wire 132 on the adjacent support rib 92. u Upper, distal end 92 d This can facilitate deposition of wire 132 onto, above, or both (particularly with perpendicular angle deposition). In one embodiment, all of the support ribs 92 can lean in a single direction.

[0068] The leaning or inclination of the support rib 92 is at an angle A 92 , A pi , and A pu The angle A can be quantified by 92 9 to 12) and the surface 11 of the substrate 11. f The surface 95 extends along the length L (FIG. 10) of each support rib 92, through the center of the support rib 92, and to the proximal end 92. p to distal end 92 d A 92 An example value for is 5 o ≦A 92 , 15 o ≦A 92 ,twenty five o ≦A 92 , 40 o ≦A 92, or 60 o ≦A 92 and A 92 ≦45 o , A 92 ≦60 o , A 92 ≦75 o , or A 92 ≦85 o Includes: A pi is the inner surface 92 i and the surface 11 of the substrate 11 f It is an exterior angle between A pi An example value for is 5 o ≦A pi , 15 o ≦A pi ,twenty five o ≦A pi , 35 o ≦A pi , 45 o ≦A pi , 55 o ≦A pi , or 65 o ≦A pi and A pi ≦45 o , A pi ≦55 o , A pi ≦65 o , A pi ≦75 o , or A pi ≦85 o It can include: A pu is the upper surface 92 u and the surface 11 of the substrate 11 f It is an exterior angle between A pu An example value for is 95 o ≦A pu , 105 o ≦A pu , 115 o ≦A pu , 130 o ≦A pu , or 150 o ≦A pu and A pu ≦135 o , A pu ≦150 o , A pu ≦165 o , or A pu≦175 o Includes: A pi -A pu can be related as follows: |180 o -A pi -A pu |≦2 o , |180 o -A pi -A pu |≦5 o , |180 o -A pi -A pu |≦10 o , |180 o -A pi -A pu |≦20 o , or |180 o -A pi -A pu |≦30 o .

[0069] If the optical device is a wire grid polarizer (WGP) with wires 132, then angle A 92 , A pi , and A pu can be selected to keep each wire 132 separated from the wires 132 on adjacent support ribs 92, along with the size and spacing between the support ribs 92. In the following equation, L c (FIG. 9) shows the surface 11 of the substrate 11 from one support rib 92 in the channel to the adjacent support rib 92. f is the straight line distance parallel to L i (Figure 9) is the proximal end 92 p to distal end 92 d Inner surface up to 92 i Generally, L c is selected based on the desired WGP performance (e.g., balance of Tp and Ts), and L i is selected based on the desired structural strength of the support rib 92. 92 is expressed by the following formula A 92 =cos -1 (L c / L i ) can be calculated from A 92This value of is determined by the surface 11 of the substrate 11 within the channel 11. f This can provide support ribs 92 that block the vertical deposition of wires 132. 92 It may not be necessary or desirable to achieve such an angle. 92 =cos -1 (X×L c / L i ) The values ​​of "X" for different situations are described in the next two paragraphs.

[0070] Partial blocking of the channel 11 may occur if some deposition of the wire 132 within the channel 93 is acceptable in a particular WGP design, or if deposition is present on the upper surface 92 u This may be acceptable if performed at an oblique angle with the deposition target facing 92 =cos -1 (X×L c / L i ), exemplary ranges of X 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.

[0071] For some designs, especially for high transmission of the primarily transmitted polarization (e.g., high Tp), the upper surface 92 with the wires 132 u , distal end 92 d Partial coverage of A, B, C, D, E ... 92 This can be achieved by reducing the formula A. 92 =cos -1 (X×L c / L i ), exemplary ranges of X include X≧1.03, X≧1.05, X≧1.1, X≧1.15, or X≧1.2.

[0072] Distal end 92 of support rib 92 d Angle A at di and A ducan be selected and formed by the shape of the stamp 171 described below to achieve the desired blocking of the channel 93 during deposition, durability of the WGP, and reduced manufacturing costs. di is the inner surface 92 i and distal end 92 d It is an interior angle between A du is the upper surface 92 u and distal end 92 d is the interior angle between

[0073] For example, A di and A du can be closer to 90 degrees, as shown in FIGS. 9-10. This design can improve the durability of the support rib 92 and reduce the cost of the stamp 171. Alternatively, as illustrated in FIG. di is less than 90 degrees (e.g., A di <90 o , A di ≦80 o , A di ≦70 o , A di ≦60 o , or A di ≦50 o and A di ≧10 o ), and A du is greater than 90 degrees (for example, A du >90 o , A du ≧100 o , A du ≧110 o , A du ≧120 o , A du ≧130 o , and A du ≦180 o ) and thus distal end 92 d Inner surface 92 i Extending above the channel 93. This design allows the surface 111 of the substrate 11 to be f Blocking can be improved.

[0074] Channel Angle A c 9 and 11. The channel angle A c The side 92 of the support rib 92 i and 92 u and the surface 11 of the substrate 11 in the channel 93 f As illustrated in FIG. 9, in each channel 93, one channel angle A c is the other channel angle A on the opposite side of the channel that can be less than 90 degrees c can be greater than 90 degrees. Alternatively, as illustrated in FIG. 11, in each channel 93, both channel angles A c For example, 90 o ±5 o , 90 o ±10 o , 90 o ±15 o , or 90 o ±20 o The angle between the two channels can be set to approximately 90 degrees. c ~90 o 11 may be preferred due to the increased performance resulting from the increased channel 93 depth.

[0075] The following further describes how the aforementioned angles are defined or interpreted. Any angle described as an "external angle" is measured on the exterior of the support rib 92. As illustrated in FIG. 12, the side 92 i and 92 u is curved, then side line 121 is used to determine angle A pi and A pu The side line 121 is determined by the side 92 i or 92 u The narrowest dimension and side 92 i or 92 u The angle A is aligned with the average direction of the pi and A pu However, the curvature of the substrate or the surface 11 of the substrate 11 fIf these angles A cannot be precisely and repeatedly determined across the optical device due to roughness, then pi and A pu is measured at a substrate line 123 that extends through the center of the substrate 11. The substrate line 123 is f average or surface 11 f the opposite side 11 of the substrate 11 s The direction of the average of the distal end 92 has the smoothest surface. d If the angle A is curved, then the distal line 122 is at an angle A di and A du The distal line 122 is used to determine the distance between the two side lines 121 and the distal end 92. d The perimeter extends between the locations where the perimeter exits the

[0076] In summary, Equation A 92 =cos -1 (X×L c / L i ) distance L c , distance L i , angle A 92 , value X, and distal end 92 d Angle A at di and A du However, the surface 11 of the substrate 11 f As viewed perpendicular to the surface 11 of the substrate 11, the support ribs 92 allow the surface 11 of the substrate 11 to be supported within the channels 93. f 9. The surface 11 of the substrate 11 can be selectively blocked partially or completely. See line 94 in FIG. 9, which shows this complete blocking. f As viewed perpendicular to the channel 93, complete blocking of the channel 93 occurs when the inner surface 92 of each support rib 92 is i The wires 132 can be negligible or absent on the top, on the substrate 11 within the channel 93, or both.

[0077] Instead, as illustrated in FIG. 14, the wire 132 enters the channel 93 and is secured to the inner surface 92 of each support rib 92. iThe inner surface 92 of each support rib 92 may cover a portion of the substrate 11 within the channel 93, a portion of the substrate 11 within the channel 93, or both. i , 50% or more, 75% or more, or 90% or more of the substrate 11 within the channel 93, or both, may be free of wire 132 material, and other portions may be coated with wire 132.

[0078] The wire 132 is connected to the inner surface 92 i If the part of the substrate 11 in the channel 93, or both, is not covered, it can be covered with a small thickness due to the blocking effect of the angled support ribs 92. For example, 132i ≦10nm, Th 132i ≦20 nm, or Th 132i ≦50 nm, Th 132i is the inner surface 92 i Inner surface 92 measured perpendicular to i The maximum thickness of the wire 132 is shown in Fig. 1. 132u / Th 132i ≧2, Th 132u / Th 132i ≧5, Th 132u / Th 132i ≧10, Th 132u / Th 132i ≧20, and Th 132u is the upper surface 92 mm measured perpendicular to the upper surface u The maximum thickness of the wire 132 is shown in Fig. 1. 132u / Th 132s ≧2, Th 132u / Th 132s ≧5, Th 132u / Th 132s ≧10, or Th 132u / Th 132s ≧20, and Th 132s is the surface 11 of the substrate 11 f The surface 11 of the substrate 11 within the channel 93 adjacent to the support rib 92 measured perpendicular to the f This is the maximum thickness of the upper wire 132.

[0079] 15-16, WGPs 150 and 160 may further comprise a cap 152 at least partially sandwiched between each wire 132 and each support rib 92. The purpose of cap 152 is also to close the channel during deposition of wire 132. Thus, cap 152 may extend over the length L of support rib 92. i and angle A pi This can help compensate for manufacturing limitations of the stamp 171. For example, wicking of the uncured layer 172 into the stamp 171 can be limited, thus limiting the depth of the stamp-channel 173 (FIGS. 17-18). This limitation can be compensated for by the use of caps 152. Another advantage of the combination of long support ribs 92 and caps 152 is that it can increase the length of the channel 93, thus providing a large region with a reduced effective refractive index, as described in U.S. Pat. No. 6,122,103. It can be useful for the caps 152 on each support rib 92 to be separated (i.e., not touching) from the caps 152 on adjacent support ribs 92. This separation can facilitate deposition of the separation wires 132.

[0080] As illustrated in FIG. 15, the cap 152 is u Part or all of the distal end 92 d As illustrated in FIG. 16 , the cap 152 may cover some, all, or both of the inner surface 92 of each support rib 92. i For example, the inner surface 92 of each support rib 92 may cover at least a portion of the inner surface 92 of the support rib 92. i 50% or more, 75% or more, or 90% or more of the surface may be free of cap 152 material, and the other portions may be coated with cap 152.

[0081] Inner surface 92 i Inner surface 92 measured perpendicular to i An exemplary maximum thickness Th of the upper cap 152 152i Th 152i ≦5nm, Th 152i≦10 nm, or Th 152i ≦20 nm. As another example, Th 152u / Th 152i ≧2, Th 152u / Th 152i ≧5, Th 152u / Th 152i ≧10, Th 152u / Th 152i ≧20, and Th 152u is the upper surface 92 u Upper surface 92 measured perpendicular to u This is the maximum thickness of the upper cap 152.

[0082] Second method, Figs. 9-23.

[0083] A second method for making an optical device such as a wire grid polarizer (WGP) can include some or all of the following steps illustrated in FIGS. 17-23. The second method can be performed in the following order, or in other orders if specified. Some steps can be performed simultaneously, unless otherwise specified in the claims. There can also be additional steps not listed below. These additional steps can occur before, between, or after the steps listed. The optical device and components of the optical device itself can have properties as described above. Additional descriptions of properties of the optical device in the second method below not listed above can be applicable to the optical device described above.

[0084] The second method may comprise some or all of the following: (a) depositing a surface 11 of a substrate 11; f (b) providing an upper uncured layer 172, step 170 (FIG. 17); (c) imprinting a pattern of uncured support ribs 182 into the uncured layer 172, step 180 or 210 (FIGS. 18 and 21); (d) curing the uncured layer, step 190 or 220 (FIGS. 19 and 22); and (e) applying a coating of the upper surface 92 of each support rib 92 to the upper surface 92 of each support rib 92. u and distal end 92 d (e) The upper surface 92 of each support rib 92 is covered with a cap 152 (FIGS. 15 and 16). u, the distal end 92 of each support rib 92 d , or both of them, and a wire 132 is deposited thereon (FIGS. 13 to 16).

[0085] (b) and (c) Imprinting a pattern of support ribs 92 into the uncured layer 172 can be performed, for example, using a stamp 171 as described below, thereby generating leaning support ribs 92 that can have angles as described above.

[0086] 18 and 21, imprinting can include pressing a stamp 171 into the uncured layer 172. The stamp 171 includes stamp ribs 171 that mate with the channels 93. r and stamped channels 173 that mate with support ribs 92.

[0087] Due to the leaning shape of the support ribs 92, it can be difficult to remove the stamp 171 from the support ribs 92 without damaging them. One method for removing the stamp 171 from the optical device without damaging the support ribs 92 is to 92 (See Figures 9 to 12) 171 (See FIG. 20) to remove the stamp 171. For example, 171 is A 92 The angle can be within 2, 5, 10, 20, or 30 degrees of the angle.

[0088] Another method for removing the stamp 171 from the optical device without damaging the support ribs 92 is to use a flexible stamp 171, a flexible support rib 92, or both. The stamp 171 may comprise an elastic material. The stamp ribs 171 r or a stamp rib 171 of a stamp 171 connected to both r , base 171 b The stamp rib 171 can be elastic. r Stamp rib 171 of stamp 171 connected to r, base 171 b Or both may comprise polyimide, polydimethylsiloxane, or both. r , Stamp Rib 171 r The base 171 of the stamp 171 is connected to b , the support ribs 92 when the stamp 171 is removed from the support ribs 92, or combinations thereof, can have a modulus of elasticity that can be 6 GPa or less, 3 GPa or less, 1 GPa or less, or 0.1 GPa or less, and 0.1 GPa or more, 0.01 GPa or more, 0.005 GPa or more, 0.001 GPa or more, or 0.0001 GPa or more. The support ribs 92 can be made flexible by partially curing the uncured layer 172, removing the stamp 171, and then completing the curing. The partially cured support ribs 92 can bend when the stamp 171 is removed.

[0089] (c) curing the uncured layer 172 can include curing the uncured support ribs 182 into solid, cured support ribs 92. In one embodiment, the uncured layer 172 can be a liquid having solid inorganic nanoparticles dispersed throughout a continuous phase, the solid inorganic nanoparticles including metal atoms bonded to reactive groups, each reactive group independently selected from -Cl, -OR ... 2 , -OCOR 2 , or -N(R 2 )2 and R 2 is an alkyl group, and curing can include reacting the molecules to form a solid of interconnected metal atoms. In another embodiment, uncured layer 172 can be a liquid having solid inorganic nanoparticles dispersed throughout a continuous phase, and curing can include forming a solid interconnected network of inorganic nanoparticles. In another embodiment, uncured layer 172 can be a colloidal suspension including a dispersed phase and a continuous phase, and curing uncured layer 172 can include removing the continuous phase.

[0090] (d) and (e), the cap 152, the wire 132, or both, can be deposited by sputter deposition, which can facilitate separate deposition of the cap 152, the wire 132, or both, on separate support ribs 92. Separate deposition of the cap 152, the wire 132, or both, on separate support ribs 92 can improve WGP performance, such as increased transmittance of a desired polarization (e.g., increased Tp) and decreased transmittance of the opposite polarization (e.g., decreased Ts). Sputter deposition of the cap 152 can facilitate the deposition of a linear profile 152 facing the support ribs 92. L and a curved profile 152 facing the wire 132 C This linear profile 152 can also result in a cap 152 having a L / Curved Profile 152 C can also improve WPG performance.

[0091] The deposition of the cap 152, the wire 132, or both, can include or even be performed solely by vertical angle deposition. Because some manufacturing facilities lack equipment for angle deposition, such vertical angle deposition can reduce the manufacturing costs of the WGP due to avoiding the purchase of additional equipment.

[0092] As illustrated in (b) through (e), FIGS. 11 and 18-20, adjacent support ribs 22 and 92 are secured to the proximal end 92 by the material 111 of support rib 92. p This can be achieved by not pressing all of the stamp 171 into the substrate. This connection of the support ribs 92 with the material 111 of the support ribs 92 can increase the strength of the support ribs 92. This can be particularly useful in the embodiments described herein with angled or leaning support ribs 92. The support ribs 92 have a proximal end 92 p , each support rib 92 may be joined at a distal end 92 d and side 92 i and 92u 132. The separator cap 152 may be separated from (i.e., not touching) adjacent support ribs 92 at 152. This separation may facilitate deposition of the separator cap 152, the separator wire 132, or both.

[0093] The uncured layer 172, the support ribs 92, the cap 152, or a combination thereof can have a low refractive index for improved optical performance, for example, 1.1 or less, 1.2 or less, 1.3 or less, or 1.4 or less. In one embodiment, such a refractive index can be 1.0 or greater.

[0094] One way to achieve this low refractive index is to include small voids or cavities in the uncured layer 172, which can remain within the support ribs 92. These small, air-filled voids can lower the overall refractive index. For example, the support ribs 92 can include silicon dioxide, which has a refractive index of approximately 1.4-1.5, but with the voids, the overall refractive index can be less than 1.4. These voids can be created by using a solvent in the uncured layer 172 with large molecules. For example, the solvent in the uncured layer 172 can have a molecular weight of 70 g / mol or more, 80 g / mol or more, 90 g / mol or more, 100 g / mol or more, or 110 g / mol or more. As another example, the chemical in the solvent can have a large number of atoms, such as 15 or more atoms, 20 or more atoms, or 25 or more atoms. It can be useful for the solvent not to have an excessively high molecular weight, thereby making it sufficiently volatile. Thus, the solvent can have a molecular weight of 125 g / mol or less, 150 g / mol or less, 175 g / mol or less, 200 g / mol or less, or 300 g / mol or less. The solvent can also have 30 atoms or less, 50 atoms or less, or 75 atoms or less. Additionally, the solvent can have large occupying structures such as aryl molecules or molecules with other double bonds. For example, the uncured layer 172 can include benzene or xylene.

[0095] The support rib has a refractive index of less than the real part n across the ultraviolet spectrum, across the visible spectrum, across the infrared spectrum, or a combination thereof. S ≧1.7 or n S ≧2.0 and extinction coefficient k S ≦0.1. Exemplary materials for the support ribs 92 include oxides of hafnium, lead, niobium, tantalum, titanium, tungsten, zirconium, silicon, or combinations thereof.

[0096] The support ribs 92 can include organic moieties that facilitate manufacturing, affect the performance of the WGP, or a combination thereof. These organic moieties can be part of the material composition of the uncured layer 172 and can remain after the uncured layer 172 is cured to form the support ribs 92. For example, 0.1% or more, 1% or more, and 25% or less, 50% or less of the atoms in the support ribs 92 can be organic moieties. As another example, the weight percent of the organic moieties in the support ribs can be 0.1% or more, 20% or less. The organic moieties can include —CH3, —CH2CH3, or both. As another example, all organic moieties can contain 3 or fewer carbon atoms.

[0097] The caps 152 can have the same or different material composition as the support ribs 92. In one embodiment, the caps 152 and the support ribs 92 can comprise silicon dioxide. In one embodiment, the support ribs 92 but not the caps 152 can include organic moieties due to the different methods of their respective deposition / formation (e.g., the support ribs 92 are typically formed by spin-on followed by imprinting, while the caps 152 are typically formed by sputtering).

[0098] The support ribs 92, substrate 11, and cap 152 can have the same or similar material compositions. For example, 70% or more, 80% or more, 90% or more, or 95% or more of the material compositions of the support ribs 92, substrate 11, and cap 152 can be the same. The support ribs 92, substrate 11, cap 152, or a combination thereof can be transparent across the ultraviolet, visible, or infrared spectrum, or a combination thereof. The wire 132 can be reflective across the ultraviolet, visible, or infrared spectrum, or a combination thereof.

[0099] As illustrated in FIG. 23 , the second method may further include step 230, which includes providing a conformal layer 231 on the cured support ribs 92, forming an optical device 232. Step 230 may follow any of steps 190, 200, or 220. The conformal layer 231 may be provided by atomic layer deposition. The conformal layer 231 may be provided by adjusting the refractive index (n 92 ) higher refractive index (n 231 ) Exemplary values ​​for these refractive indices are n 92 ≥ 1.3, n 92 ≧1.5, or n 92 ≥ 1.7, n 92 ≦1.6, n 92 ≦1.8, or n 92 ≦1.99, n 231 ≧2.0 or n 231 ≧2.2, and n 231 ≦3.0 or n 92 These refractive indices n 231 and n 92 The values ​​and relationships can be across the ultraviolet spectrum, the visible spectrum, the infrared spectrum, or a combination thereof. When the optical device is a waveguide, the addition of conformal layer 231 can be used to achieve a specific wavelength or wavelength range of interest. 231 >n 92 In this case, the performance of the waveguide can be improved.

[0100] First and second methods, wire separation.

[0101] It can be useful for the wires 62 or 132 to be separated from the wires 62 or 132 on adjacent support ribs 22 or 92. The following paragraphs describe how this is accomplished in both the first and second methods.

[0102] In the first method, the preferred method of deposition is sputtering. The pressure in the chamber can be ramped up for low-directional deposition, resulting in deposition of wire 62 from all angles and selective deposition of wire 62 at distal end D of support rib 22. However, excessively high deposition pressure can result in excessively slow deposition rates. A pressure of 5 mTorr is suggested to (a) disperse deposition of wire 62 from all angles due to high pressure; and (b) lower pressure improves deposition rate.

[0103] In the second method, preferred deposition methods include evaporation or low pressure sputtering, both of which deposit a layer of metal on the upper surface 92 of each support rib 92. u and distal end 92 d This results in directional deposition of wire 132 on adjacent support ribs 92. With evaporation or low-pressure sputtering, the pressure can be reduced as much as possible while still maintaining a plasma. In a second method, using angled support ribs 92, directional deposition such as with evaporation or low-pressure sputtering can facilitate separation of wire 62 on adjacent support ribs 92.

[0104] In a first manner, the channel 41 can be partially blocked by the cap 52 described above, facilitating separation of the wires 62 on adjacent support ribs 22. In a second manner, the channel 93 can be partially blocked by the cap 152 described above, facilitating separation of the wires 132 on adjacent support ribs 92.

[0105] The shape of the support ribs 22 or 92 can help facilitate separation of the wires 62 or 132. The support ribs 22 in FIGS. 2-8 are illustrated with curved distal ends D, which facilitates manufacturing, but can make it more difficult to hold the wires 62 apart from one another. The distal ends 92 of the support ribs 92 in the second method illustrated in FIGS. 9-10 and 13-16 d The distal end 92 of the support rib 92 in the second method illustrated in FIGS. 11 and 19-20 has a rectangular shape that can be more difficult to manufacture, but can help keep the wires 132 separated from one another. d has a trapezoidal shape which can further help to keep the wires 132 separated from each other. The rectangular shapes of Figures 9-10 and 13-16 and the trapezoidal shapes of Figures 11 and 19-20 above can be applied to a first method. The stamp 13 in the first method can be replaced by the stamp 171 of Figures 17-22.

[0106] A high aspect ratio (AR) of the support ribs 22 or 92 can help facilitate separation of the wires 62 or 132, where AR=Th 22 / P or AR=Th 92 / P and Th 22 is the thickness of the support rib 22, and Th 92 is the thickness of the support rib 92 and P is the pitch of the support rib 22 or 92.

[0107] If the above methods are insufficient to keep the wires 62 or 132 separated, and if the wires 62 or 132 are made from aluminum, then a small amount of the aluminum in the channels 41 or 93 can be oxidized to form aluminum oxide, thus separating the pure aluminum wires 62 or 132 from each other. Aluminum was used as an example. Oxidation can be used with other suitable materials. Isotropic etching may also be used to remove a small amount of the wires 62 or 132 in the channels 41 or 93.

[0108] 92 third optical device with angled support ribs.

[0109] 23, optical device 232 can include a conformal layer 231 on support ribs 92. Support ribs 92 of optical device 232 are illustrated with a shape similar to support ribs 92 of optical device 110, although these support ribs 92 can have other shapes as described herein. Conformal layer 231 and support ribs 92 can have refractive index values ​​as described above. If the optical device is a waveguide, the addition of conformal layer 231 can improve the refractive index, particularly at or over a wavelength range of interest. 231 >n 92 The performance of the waveguide can be improved if the optical device 232 can be formed into the WGP, for example, by adding a wire 132 as described herein.

Claims

1. A wire grid polarizer (WGP), comprising: an array of parallel elongated support ribs on a surface of a substrate having channels between adjacent support ribs; each support rib has a cross-sectional profile with a proximal end disposed closest to the substrate and a distal end disposed farthest from the substrate, a side facing the channel and extending from the proximal end to the distal end; The side surfaces of the support rib are two side surfaces each inclined to one side, and include an inner side surface inclined toward and facing the surface of the substrate, and an upper side surface opposite the inner side surface and facing away from the surface of the substrate, 15°≦A ９２ ≦75°, and A ９２ is the minimum angle between a plane and the surface of the substrate, the plane extending along the length of each support rib from the proximal end to the distal end through the center of the support rib; a wire on the upper surface and the distal end of each support rib, each wire being separate from the wire of an adjacent support rib; the support ribs and the substrate are transmissive and the wire is reflective across the ultraviolet, visible, or infrared spectrum, or a combination thereof; WGP.

2. a cap on the upper surface and the distal end of each support rib, the cap being at least partially sandwiched between each wire and each support rib; the cap has a different material composition than the support rib; the cap is transparent across the visible spectrum; the cap has a linear profile facing the support rib and a curved profile facing the wire; The WGP of claim 1.

3. The WGP of claim 2 , wherein the cap on each support rib is separated from the cap on an adjacent support rib.

4. 45°≦A ｐｉ ≦65° and 115°≦A ｐｕ ≦135°, and A ｐｉ is the exterior angle between the inner surface and the surface of the substrate, and A ｐｕ 4. The WGP of claim 1, wherein ∇ is the external angle between the upper surface and the surface of the substrate.

5. |A ｐｉ -A ｄｉ |≦20° and |180°-A ｐｕ -A ｄｕ |≦20°, and A ｐｉ is the exterior angle between the inner surface and the surface of the substrate, and A ｄｉ is the interior angle between the interior surface and the distal end, and A ｐｕ is the exterior angle between the upper surface and the surface of the substrate, and A ｄｕ 5. The WGP of claim 1, wherein is the interior angle between the upper surface and the distal end.

6. A ９２ = cos －１ (X x L ｃ / L ｉ ), where X≦0.95 or X≧1.03, and L ｃ is the linear distance from one support rib to an adjacent support rib in the channel parallel to the surface of the substrate, and L ｉ 6. The WGP of claim 1, wherein ∑ is the linear distance of the inner surface from the proximal end to the distal end.

7. The support rib has a real part of the refractive index n Ｓ 7. The WGP of claim 1 having a ρ of ≦1.

4.

8. The support rib has a refractive index that is greater than or equal to the real part n across the ultraviolet spectrum, across the visible spectrum, across the infrared spectrum, or a combination thereof. Ｓ ≧1.7 and extinction coefficient k Ｓ 7. The WGP of claim 1, having a ρ of ≦0.

1.

9. The support ribs have a refractive index that is smaller than the real part n across the visible spectrum. Ｓ 7. The WGP of claim 1 having a .gtoreq.2.

0.

10. 10. The WGP of claim 1, wherein between 0.1% and 50% of the atoms in the support rib are part of an organic moiety.

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