# US 12,111,474 B2 · Grating structure, diffraction optical waveguide, and display device

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- Number: US 12,111,474 B2
- Document ID: US12111474B2
- Status: Granted
- Kind: B2
- Application number: 18/350,683
- Filed: 2023-07-11
- Published: 2024-03-07
- Granted: 2024-10-08
- Earliest claimed: 2022-09-07
- Assignees: Jiaxing Uphoton Optoelectronics Technology Co., Ltd.
- Applicants: Jiaxing Uphoton Optoelectronics Technology Co., Ltd.
- Inventors: Peng Chen; Guofang Sun; Lei Sui; Kehan Tian
- Web page: https://patentgrep.com/patent/US12111474B2

## CPC

- G02B 27/0172: {characterised by optical features}
- G02B 6/0016: {Grooves, prisms, gratings, scattering particles or rough surfaces}
- G02B 6/124: Geodesic lenses or integrated gratings
- G02B 27/0081: {with means for altering, e.g. enlarging, the entrance or exit pupil}
- G02B 27/0101: {characterised by optical features (G02B27/0172 takes precedence)}
- G02B 27/4227: {in image scanning systems}
- G02B 6/0026: {Wavelength selective element, sheet or layer, e.g. filter or grating}
- G02B 6/34: utilising prism or grating {(G02B6/293 takes precedence)}
- G02B 2027/0125: {Field-of-view increase by wavefront division}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A grating structure, a diffraction optical waveguide, and a display device are disclosed. The grating line of the grating structure has a cross-sectional profile with a narrow top and a wide bottom, wherein the cross-sectional profile comprises six feature points, and the six feature points respectively have coordinates (0, 0), (L2, H2), (L3, H3), (L4, H4), (L5, H5) and (L6, 0) in a cross section, and satisfy following relationships: Hdrop=min(H4,H5)−max(H3,H2)>50 nm; 0.1<(L5−L4)/(L3−L2); L3>0.34T; and 0.05T<L5−L4<0.32T. By controlling the parameters of these feature points, the cross-sectional profile can be adjusted, and thus significantly improving the optical effect (comprising diffraction efficiency and uniformity) that the grating structure can achieve, and at the same time increasing degrees of freedom in grating design and optical effect regulation.

## Claims

### Claim 1

A grating structure, comprising a plurality of grating lines arranged in a plane, the plurality of grating lines being arranged with a period of T along a first direction in the plane and extending along a second direction perpendicular to the first direction, wherein,
each of at least part of the plurality of grating lines has a cross-sectional profile with a narrow top and a wide bottom in a cross section perpendicular to the second direction, the cross-sectional profile comprises six feature points being in sequence along the first direction, which are a first feature point, a second feature point, a third feature point, a fourth feature point, a fifth feature point and a sixth feature point, and the feature points are maximum-curvature points of the cross-sectional profile; and
in a coordinate system with the first feature point as an origin, the first direction as a first coordinate axis L, and a direction perpendicular to the plane as a second coordinate axis H, the first feature point, the second feature point, the third feature point, the fourth feature point, the fifth feature point, and the sixth feature point respectively have coordinates (0, 0), (L2, H2), (L3, H3), (L4, H4), (L5, H5) and (L6, 0), and satisfy following relationships, so that both diffraction efficiency and uniformity are well-maintained:
Hdrop=min(H4,H5)−max(H3,H2)>50 nm;
0.1<(L5−L4)/(L3−L2);
L3>0.34T; and
0.05T<L5−L4<0.32T.

### Claim 2 (depends on 1)

The grating structure of claim 1, wherein 0.025T<L3−L2<0.65T.

### Claim 3 (depends on 1)

The grating structure of claim 1, wherein the six feature points further satisfy at least one of following relationships:
140 nm<Hdrop<200 nm
0.13T<L5−L4<0.25T;
L3>0.59T; and
0.05T<L3−L2<0.3T.

### Claim 4 (depends on 1)

The grating structure of claim 1, wherein,
min(H4, H5)>200 nm; and
min(H2, H3)>50 nm.

### Claim 5 (depends on 4)

The grating structure of claim 4, wherein,
min(H4,H5)>400 nm; and/or
min(H2,H3)>150 nm.

### Claim 6 (depends on 1)

The grating structure of claim 1, wherein the cross-sectional profile comprises at least a curve which is formed between two adjacent feature points among the first feature point, the second feature point, the third feature point, the fourth feature point, the fifth feature point, and the sixth feature point.

### Claim 7 (depends on 6)

The grating structure of claim 6, wherein the cross-sectional profile comprises at least a straight line which is formed between two adjacent feature points among the first feature point, the second feature point, the third feature point, the fourth feature point, the fifth feature point, and the sixth feature point.

### Claim 8 (depends on 1)

The grating structure of claim 1, wherein the cross-sectional profile comprises five straight lines each of which is formed between two adjacent feature points among the first feature point, the second feature point, the third feature point, the fourth feature point, the fifth feature point, and the sixth feature point.

### Claim 9 (depends on 1)

The grating structure of claim 1, wherein the cross-sectional profile comprises five straight lines each of which is formed between two adjacent feature points among the first feature point, the second feature point, the third feature point, the fourth feature point, the fifth feature point, and the sixth feature point,
the cross-sectional profile is a stepped profile, wherein L2=0, H2=H3, L3=L4, H4=H5, and L5=L6; and following relationships are satisfied:
0.3T<L3−L2<0.7T;
0.1T<L5−L4<0.4T;
0.15<(L5−L4)/(L3−L2)<0.8; and
0.65T<L3−L2+L5−L4<0.9T.

### Claim 10 (depends on 9)

The grating structure of claim 9, wherein 160 nm<H3<420 nm, 320 nm<H5<600 nm.

### Claim 11 (depends on 9)

The grating structure of claim 9, wherein the six feature points further satisfy at least one of following relationships:
0.4T<L3−L2<0.66T;
0.2<(L5−L4)/(L3−L2)<0.78;
0.71T<L3−L2+L5−L4<0.85T;
185 nm<H3<340 nm; and

### Claim 12 (depends on 9)

The grating structure of claim 9, wherein the six feature points further satisfy at least one of following relationships:
0.4T<L3−L2<0.66T;
0.2<(L5−L4)/(L3−L2)<0.78;
0.71T<L3−L2+L5−L4<0.85T;
350 nm<H5<590 nm.

### Claim 13 (depends on 1)

The grating structure of claim 1, wherein H2/H3, and/or H4H5.

### Claim 14 (depends on 13)

The grating structure of claim 13, wherein H2>H3, and/or H4>H5.

### Claim 15 (depends on 13)

The grating structure of claim 13, wherein |H4-H5|<100 nm, and/or |H2−H3|<100 nm.

### Claim 16 (depends on 1)

A diffraction optical waveguide for display, comprising a waveguide substrate and a coupling-in grating arranged on the waveguide substrate, wherein the coupling-in grating comprises the grating structure of claim 1, which is configured to couple a light beam into the waveguide substrate, enabling the light beam to propagate within the waveguide substrate through total internal reflection.

### Claim 17 (depends on 16)

The diffraction optical waveguide of claim 16, further comprising a coupling-out grating arranged on the waveguide substrate, wherein the coupling-out grating is configured to couple at least a portion of the light beam within the waveguide substrate propagating thereinto through total internal reflection substantially along a coupling-in direction out of the waveguide substrate by diffraction, the first direction being substantially consistent with the coupling-in direction.

### Claim 18 (depends on 16)

A display device comprising the diffraction optical waveguide of claim 16.

### Claim 19 (depends on 18)

The display device of claim 18, wherein the display device is a near-eye display device and comprises a lens and a frame for holding the lens close to the eye, the lens comprising the diffraction optical waveguide.

### Claim 20 (depends on 18)

The display device of claim 18, wherein the display device is an augmented reality display device or a virtual reality display device.