Reflective wire grid polarizer with transparent cap

Patent metadata

Field	Value
Publication number	US-11513271-B2
Application number	US-202016919513-A
Country	US
Kind code	B2
Filing date	Jul 2, 2020
Priority date	Jul 17, 2019
Publication date	Nov 29, 2022
Grant date	Nov 29, 2022

Abstract

A reflective wire grid polarizer (WGP) can include an array of wires 12 on a face of a substrate 11 , with channels 15 between adjacent wires 12 . The wires 12 can have certain characteristics for WGP performance, such as index of refraction, alternating high/low index continuous thin films, thickness of layer(s), duty cycle, reflective rib shape, a curved side of transparent ribs 21 or 32 , aspect ratio, or combinations thereof.

First claim

What is claimed is:

1. A reflective wire grid polarizer (WGP) comprising:
an array of wires on a face of a substrate, with channels between adjacent wires;
each wire including a reflective rib and a transparent rib, the reflective rib sandwiched between the transparent rib and the substrate;
the transparent rib having a real part of a refractive index ≥1.7 and an extinction coefficient ≤0.1, across a wavelength range from 400 nm through 700 nm:
the reflective rib having a thickness (Th R ), measured perpendicular to the face of the substrate, within the following range: 100 nm≤Th R ≤125 nm;
the transparent rib having a thickness (Th R ), measured perpendicular to the face of the substrate, within the following range: 7 nm≤Th T ≤40 nm;
the array of wires having a duty cycle (DC) within the following range: 0.39≤DC≤0.49, where DC equals wire width divided by pitch of the array of wires, both pitch and width measured at a midpoint between an end of the wires closest to the substrate and an end of the wires farthest from the substrate;
the reflective rib has a flat side facing the transparent rib and parallel to the face of the substrate and the transparent rib has a curved side opposite of the reflective rib; and
the curved side of the transparent rib has a half elliptical shape with a major axis of the half elliptical shape extending perpendicular to the face of the substrate and an eccentricity ≥0.6 and ≤0.9.

2. The WGP of claim 1 , wherein the WGP has the following performance characteristics: Rp ≤0.2% and Rs ≥80% across a wavelength range from 450 nm through 700 nm, where Rp is a percent reflection of a primarily transmitted polarization and Rs is a percent reflection of a primarily reflected polarization.

3. A reflective wire grid polarizer (WGP) comprising:
an array of wires on a face of a substrate, with channels between adjacent wires;
each wire including a reflective rib an a transparent rib, the reflective rib sandwiched between the transparent rib and the substrate;
the transparent rib having a real part of a refractive index ≤1.7 and an extinction coefficient ≤0.1, across a wavelength range from 400 nm through 700 nm;
the reflective rib having a thickness (Th R ), measured perpendicular to the face of the substrate, within the following range: 100 nm ≤Th R ≤125 nm;
the transparent rib having a thickness (Th T ), measured perpendicular to the face of the substrate, within the following range: 7 nm ≤Th T ≤40 nm; and,
the array of wires having a duty cycle (DC) within the following range: 0.39≤DC≤0.49, where DC equals wire width divided by pitch of the array of wires, both pitch and width measured at a midpoint between an end of the wires closest to the substrate and an end of the wires farthest from the substrate;
each reflective rib is wider at a distal end farthest from the substrate than at a proximal end closest to the substrate; and
a taper angle of sidewalls of the reflective rib, relative to a plane perpendicular to the face of a substrate and parallel with the array of wires, is within the following range: 1°≤taper angle 4°.

4. The WGP of claim 3 , further comprising:
a stack of continuous thin films at a distal end of the wires farthest from the substrate;
the stack of continuous thin films including alternating low index layers and high index layers;
the stack of continuous thin films including an odd number of continuous thin films with the low index layers being outermost thin films in the stack;
the stack of continuous thin films including 5 thin films;
the low index layers comprise silicon dioxide and the high index layers comprise niobium pentoxide; and
the high index layers having the following refractive index (n H ) and extinction coefficient (k H ) across the ultraviolet spectrum, across the visible spectrum, or both: n H ≤2.2 and k H ≤0.1.

5. The WGP of claim 3 , wherein the WGP has the following performance characteristics: Rp ≤0.2% and Rs ≥80% across a wavelength range from 450 nm through 700 nm, where Rp is a percent reflection of a primarily transmitted polarization and Rs is a percent reflection of a primarily reflected polarization.

6. A reflective wire grid polarizer (WGP) comprising:
an array of wires on a face of a substrate, with channels between adjacent wires;
each wire including a reflective rib and a transparent rib, the reflective rib sandwiched between the transparent rib and the substrate;
the transparent rib having a real part of a refractive index ≥1.7 and an extinction coefficient ≤0.1, across a wavelength range from 400 nm through 700 nm;
the reflective rib having a thickness (Th R ), measured perpendicular to the face of the substrate, within the following range: 100 nm ≤Th R ≤25 nm;
the transparent rib having a thickness (Th T ), measured perpendicular to the face of the substrate, within the following range: 7 nm ≤Th T ≤40 nm; and
the array of wires having a duty cycle (DC) within the following range: 0.39≤DC≤0.49, where DC equals wire width divided by pitch of the array of wires, both pitch and width measured at a midpoint between an end of the wires closest to the substrate and an end of the wires farthest from the substrates; and
the WGP has the following performance characteristics: Rp ≤0.2% and Rs ≥80% across a wavelength range from 450 nm through 700 nm, where Rp is a percent reflection of a primarily transmitted polarization and Rs is a percent reflection of a primarily reflected polarization.

7. The WGP of claim 6 , wherein the reflective rib has a flat side facing the transparent rib and parallel to the face of the substrate and the transparent rib has a curved side opposite of the reflective rib.

8. The WGP of claim 6 , wherein the real part of the refractive index is ≥2.0 and the extinction coefficient is ≤0.01.

9. The WGP of claim 6 , wherein the transparent rib comprises titanium dioxide.

10. The WGP of claim 6 , wherein:
107 nm≤Th R ≤117 nm;
11 nm≤Th T ≤17 nm; and
0.42≤DC≤0.46.

11. The WGP of claim 6 , wherein the reflective rib adjoins the transparent rib and the substrate.

12. The WGP of claim 6 , wherein each wire consists essentially of the reflective rib and the transparent rib.

13. The WGP of claim 6 , wherein a surface of the transparent rib not facing the reflective rib is exposed to air, is covered by a material having a thickness of ≤15 nm, or both.

14. The WGP of claim 6 , wherein the reflective rib has multiple widths, including a narrow section and a wide section.

15. The WGP of claim 6 , wherein the array of wires have an aspect ratio (AR) of ≥1.8, where AR=Th R /P, Th R is a thickness of the wires measured perpendicular to the face of the substrate, and P is a pitch of the array of wires.

16. The WGP of claim 6 , further comprising:
a stack of continuous thin films at a distal end of the wires farthest from the substrate;
the stack of continuous thin films including alternating low index layers and high index layers;
the stack of continuous thin films including an odd number of continuous thin films with the low index layers being outermost thin films in the stack;
the stack of continuous thin films including 5 thin films;
the low index layers comprise silicon dioxide and the high index layers comprise niobium pentoxide; and
the high index layers having the following refractive index (n H ) and extinction coefficient (k H ) across the ultraviolet spectrum, across the visible spectrum, or both: n H ≥2.2 and k H ≤0.1.

17. A reflective wire grid polarizer (WGP) comprising:
an array of wires on a face of a substrate, with channels between adjacent

Assignees

• Moxtek Inc

Inventors

• Bacon-Brown Daniel
• Black Michael
• Nielson R Stewart
• Williams Bradley R
• Downard Benjamin
• Rice Jeffrey H
• Pierce Jim

Classifications

• G02B5/3058 Primary

  comprising electrically conductive elements, e.g. wire grids, conductive particles · CPC title

• G02B5/3075

  for use in the UV (G02B5/3066 takes precedence) · CPC title