阅读说明：本技术 一种光栅结构、光波导及近眼显示系统 (Grating structure, optical waveguide and near-to-eye display system ) 是由 郭晓明 宋强 黄浩 许恒深 马国斌 于 2020-08-06 设计创作，主要内容包括：本发明实施例涉及光学技术领域,特别涉及一种光栅结构、光波导及近眼显示系统。本发明实施例中提供了一种光栅结构,应用于光波导及近眼显示系统,该光栅结构包括：光栅本体,所述光栅本体内设有通孔,该光栅结构相比于圆柱结构光栅和菱形结构光栅,可调节参数较多、设计自由度高,易于调节光栅的衍射效率,故本发明实施例提供的光栅结构衍射效率较好。(The embodiment of the invention relates to the technical field of optics, in particular to a grating structure, an optical waveguide and a near-to-eye display system. The embodiment of the invention provides a grating structure, which is applied to an optical waveguide and a near-eye display system, and comprises the following components: compared with a cylindrical grating and a rhombic grating, the grating structure has more adjustable parameters, high design freedom and easy adjustment of the diffraction efficiency of the grating, so that the grating structure provided by the embodiment of the invention has better diffraction efficiency.)

1. A grating, comprising:

a grating body;

the grating body is internally provided with a through hole.

2. The grating of claim 1 wherein the grating body is cylindrical.

3. The grating of claim 2, wherein the grating is a hollow annular cylindrical structure; the grating body is cylindrical, and the through hole is a cylindrical hole.

4. The grating of claim 3 wherein the height of the grating body is 10nm to 1 μm, the outer diameter dimension of the grating body is 20nm to 1 μm, and the inner diameter dimension of the grating body is 10nm to 800 nm.

5. The grating of claim 4, wherein the surface of the grating body is provided with a coating layer; the refractive index of the coating layer is higher than that of the grating body, and the thickness of the coating layer is 10nm-200 nm.

6. An optical waveguide, comprising: a waveguide substrate, a coupling-in region, a coupling-out region, and a grating according to any one of claims 1-5 above;

the grating is arranged in the coupling-in area and/or the coupling-out area, the coupling-in area and/or the coupling-out area at least comprises one grating period, and each grating period at least comprises one complete grating.

7. The optical waveguide of claim 6, wherein the long dimension of each grating period is 200nm-2 μm.

8. The optical waveguide of claim 7, wherein the ratio of the long dimension to the short dimension of each grating period is

9. The optical waveguide of claim 8, wherein the gratings of the coupling-in region and/or the coupling-out region exhibit a hexagonal distribution, and wherein a complete grating is distributed at both the vertices and the center of the hexagon.

10. A near-eye display system, comprising: a micro-projector, and an optical waveguide according to any of claims 6-9.

Technical Field

The embodiment of the invention relates to the technical field of optics, in particular to a grating structure, an optical waveguide and a near-to-eye display system.

Background

The augmented reality is a technology of fusing virtual information and a real world, wherein the design of a near-to-eye display system is a key link in the augmented reality technology, and for small-volume augmented reality glasses with better portability, the main scheme in the market is to adopt an optical waveguide as a transmission medium of light, and the optical waveguide is divided into a geometric array waveguide, a diffraction grating waveguide and a volume holographic waveguide, wherein the diffraction grating waveguide is more and more emphasized due to the convenience of nanoimprint processing, and the diffraction grating acts as a thin film in the array waveguide, so that the transmission direction of the light is mainly changed.

At present, in the optical waveguide scheme adopting the two-dimensional diffraction grating, a cylindrical structure or a rhombic structure is generally adopted, the structure is very simple, the adjustable parameters are less, the design freedom is low, the adjustment of the diffraction efficiency is not facilitated, and the diffraction efficiency of the whole diffraction waveguide is poor.

Disclosure of Invention

In view of the foregoing defects in the prior art, an object of the embodiments of the present invention is to provide a grating structure, an optical waveguide and a near-eye display system with better diffraction efficiency.

The purpose of the embodiment of the invention is realized by the following technical scheme:

in order to solve the above technical problem, in a first aspect, an embodiment of the present invention provides a grating, including: the grating comprises a grating body, wherein a through hole is formed in the grating body.

In some embodiments, the grating body is cylindrical.

In some embodiments, the grating structure is a hollow annular cylindrical structure; the grating body is cylindrical, and the through hole is a cylindrical hole.

In some embodiments, the grating body has a height of 10nm to 1 μm, an outer diameter dimension of 20nm to 1 μm, and an inner diameter dimension of 10nm to 800 nm.

In some embodiments, the surface of the grating body is provided with a coating layer, the refractive index of the coating layer is higher than that of the grating body, and the thickness of the coating layer is 10nm-200 nm.

In order to solve the above technical problem, in a second aspect, an embodiment of the present invention provides an optical waveguide, including: a waveguide substrate, an incoupling region, an outcoupling region, and a grating as described in any one of the above; the grating is arranged in the coupling-in area and/or the coupling-out area, the coupling-in area and/or the coupling-out area at least comprises one grating period, and each grating period at least comprises one complete grating.

In some embodiments, the long dimension of each of the grating periods is 200nm-2 μm.

In some embodiments, the ratio of the long side dimension to the short side dimension of each of the grating periods is

In some embodiments, the gratings of the coupling-in region and/or the coupling-out region exhibit a hexagonal distribution with one complete grating distributed at both the vertices and the center of the hexagon.

In order to solve the above technical problem, in a third aspect, an embodiment of the present invention provides a near-eye display system, including: a micro-projector light engine, and an optical waveguide as described in the second aspect.

Compared with the prior art, the invention has the beneficial effects that: in contrast to the prior art, an embodiment of the present invention provides a grating structure applied to an optical waveguide and a near-eye display system, where the grating structure includes: compared with a cylindrical grating and a rhombic grating, the grating structure has more adjustable parameters, high design freedom and easy adjustment of the diffraction efficiency of the grating, so that the grating structure provided by the embodiment of the invention has better diffraction efficiency.

Drawings

One or more embodiments are illustrated by the accompanying figures in the drawings that correspond thereto and are not to be construed as limiting the embodiments, wherein elements/modules and steps having the same reference numerals are represented by like elements/modules and steps, unless otherwise specified, and the drawings are not to scale.

FIG. 1 is a schematic diagram of an optical structure of a grating according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of an optical waveguide provided in an embodiment of the present invention;

FIG. 3 is a top view of a periodic grating optical structure provided by an embodiment of the present invention;

FIG. 4 is a graph of the relationship between the inner radius of a grating structure and the diffraction efficiency provided by an embodiment of the present invention;

fig. 5 is a schematic view of an optical structure of a near-eye display system according to an embodiment of the present invention.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.

In order to facilitate an understanding of the present application, the present application is described in more detail below with reference to the accompanying drawings and specific embodiments. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. Furthermore, the terms "upper", "lower", "left", "right", and the like, as used herein, indicate orientations or positional relationships based on the orientations or positional relationships illustrated in the drawings, are only for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.

It should be noted that, if not conflicted, the various features of the embodiments of the invention may be combined with each other within the scope of protection of the present application. In addition, although the functional blocks are divided in the device diagram, in some cases, the blocks may be divided differently from those in the device. Further, the terms "first," "second," and the like, as used herein, do not limit the data and the execution order, but merely distinguish the same items or similar items having substantially the same functions and actions.

An embodiment of the present invention provides a grating, please refer to fig. 1, including: the grating comprises a grating body 10, wherein a through hole 11 is formed in the grating body 10.

The grating structure provided by the embodiment of the invention can adjust the size of the grating body 10 and the size of the through hole 11, has more adjustable parameters and high design freedom, and is easy to adjust the diffraction efficiency of the grating, so that the grating structure has better diffraction efficiency.

In some embodiments, the grating is a hollow cylindrical structure, the grating body 10 is cylindrical, the through hole 11 may be a prism hole, a taper hole or a cylindrical hole, and the center of the grating body 10 and the center of the through hole 11 may or may not overlap.

In some embodiments, the grating is a hollow annular cylindrical structure, and is a hollow annular cylindrical grating, the grating body 10 is cylindrical, the through hole 11 is a cylindrical hole, and the center of the grating body 10 overlaps the center of the through hole 11. In some embodiments, the height of the grating body 10 is 10nm to 1 μm, the outer diameter is 20nm to 1 μm, and the inner diameter is 10nm to 800nm, so that the grating has many adjustable parameters, such as the height, the outer diameter, and the inner diameter of the hollow annular cylindrical grating, and the like, and has high design freedom and good diffraction efficiency.

Meanwhile, in order to further improve the diffraction rate of the grating, a coating layer can be further arranged on the surface of the grating body 10, and the refractive index of the coating layer is higher than that of the grating body 10. The coating layer is made of a high refractive index material, for example, titanium dioxide or the like. In some of these embodiments, the thickness of the coating layer is 10nm to 200 nm. The grating provided by the embodiment of the invention can adjust the sizes of the inner diameter, the outer diameter, the height and the like, and can also adjust the film coating condition, so that the efficiency of each diffraction order can be effectively adjusted, and the grating is optimally applied to the optical waveguide.

In practical applications, the wafer can be processed by using diffraction grating processing equipment such as electron beam/ion beam equipment, extreme/deep ultraviolet lithography equipment, or interference lithography equipment, and the grating structure according to the embodiment of the invention can be produced by imprinting and duplicating through nano-imprinting equipment.

An embodiment of the present invention further provides an optical waveguide, referring to fig. 2, the optical waveguide includes a waveguide substrate 1, a coupling-in region 2, a coupling-out region 3, and a grating as described in any of the above embodiments. The coupling-in region 2 and the coupling-out region 3 are arranged on the waveguide substrate 1, the grating is arranged in the coupling-in region 2 and/or the coupling-out region 3, at least one grating period is included in the coupling-in region and/or the coupling-out region 3, and each grating period at least includes one complete grating. For details of the grating, please refer to the above embodiments, which are not described herein.

In other embodiments, referring to fig. 3, in order to further improve the diffraction efficiency, in each of the grating periods, a complete grating 10 is disposed in the middle, and quarter gratings 10 are disposed at four corners, respectively. In practical applications, the number and distribution of the gratings in each grating period can be set according to actual needs, and the limitation of the embodiments of the present invention is not required.

In some embodiments, referring to fig. 3 again, the long dimension L of each grating period is 200nm-2 μm, and the ratio of the long dimension L to the short dimension W is

In some embodiments, after the gratings are periodically arranged in the coupling-in region 2 and/or the coupling-out region 3, the gratings are distributed in a hexagonal shape, and a complete grating is distributed at the vertex and the center of the hexagonal shape. For example, referring to fig. 1 and 3, in one grating period shown in fig. 3, a complete hollow annular cylindrical grating 10 is disposed in the middle, and four corners of the grating are respectively disposed with one quarter of the hollow annular cylindrical gratings 10, and then, after the periodic arrangement of one grating period shown in fig. 3, the structure shown in fig. 1 can be obtained, in fig. 1, the gratings are distributed in a hexagonal shape, as shown by a dotted line C, a complete hollow annular cylindrical grating is uniformly distributed at the vertex and the center of the hexagonal shape, and it should be noted that the dotted line C is only a reference line and does not really exist in the grating structure. In other embodiments, the gratings that are periodically arranged may use other hollow gratings or other hollow cylindrical gratings, the grating structures may exhibit other rules after being periodically arranged, and may not necessarily exhibit hexagonal distribution, and may be periodically arranged as needed in practical applications, without being limited by the embodiments of the present invention. Meanwhile, in practical application, the number and distribution of the gratings in each grating period can be set according to actual needs, and the limitation of the embodiment of the invention is not required.

Meanwhile, in the optical waveguide provided by the embodiment of the invention, the used grating is provided with the through hole in the grating body, compared with other two-dimensional diffraction grating structures such as a cylindrical structure grating and a prism structure grating, the grating structure has high design freedom degree, the diffraction efficiency can be designed according to actual needs, and the diffraction efficiency is basically consistent with that of the other diffraction grating structures. The diffraction efficiency of the grating applied in the optical waveguide is described below with reference to the drawings and the specific embodiments.