CN213042024U - Grating, optical waveguide and near-to-eye display system - Google Patents

Grating, optical waveguide and near-to-eye display system Download PDF

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CN213042024U
CN213042024U CN202021626122.9U CN202021626122U CN213042024U CN 213042024 U CN213042024 U CN 213042024U CN 202021626122 U CN202021626122 U CN 202021626122U CN 213042024 U CN213042024 U CN 213042024U
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grating
coupling
optical waveguide
region
display system
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郭晓明
宋强
黄浩
许恒深
马国斌
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Long Optoelectronics Co ltd
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Abstract

The embodiment of the utility model provides a relate to optics technical field, in particular to grating structure, optical waveguide and near-to-eye display system. The embodiment of the utility model provides an in provide a grating, be applied to optical waveguide and near-to-eye display system, this grating includes: the grating body, this internal through-hole that is equipped with of grating, this grating structure compare in cylinder structure grating and rhombus structure grating, but adjustable parameter is more, the design degree of freedom is high, easily adjusts the diffraction efficiency of grating, so the embodiment of the utility model provides a grating diffraction efficiency is better.

Description

Grating, optical waveguide and near-to-eye display system
Technical Field
The embodiment of the utility model provides a relate to optics technical field, in particular to grating, optical waveguide and 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.
SUMMERY OF THE UTILITY MODEL
To the above-mentioned defect of prior art, the embodiment of the utility model provides a grating, optical waveguide and near-to-eye display system that diffraction efficiency is better are provided.
The embodiment of the utility model provides an aim at is realized through following technical scheme:
in order to solve the above technical problem, in a first aspect, the embodiment of the present invention provides a grating, which is characterized in that, include: 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, a second aspect 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
Figure DEST_PATH_GDA0002927219550000021
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, a third aspect of the present invention provides a near-to-eye display system, which comprises: a micro-projector light engine, and an optical waveguide as described in the second aspect.
Compared with the prior art, the beneficial effects of the utility model are that: be different from prior art's condition, the embodiment of the utility model provides a grating is applied to optical waveguide and near-to-eye display system, and this grating includes: the grating body, this internal through-hole that is equipped with of grating, this grating structure compare in cylinder structure grating and rhombus structure grating, but adjustable parameter is more, the design degree of freedom is high, easily adjusts the diffraction efficiency of grating, so the embodiment of the utility model provides a grating diffraction efficiency is better.
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 view 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 according to an embodiment of the present invention;
fig. 3 is a top view of a grating optical structure with one period according to an embodiment of the present invention;
fig. 4 is a graph showing the relationship between the inner radius of a grating structure and the diffraction efficiency according to an embodiment of the present invention;
fig. 5 is an optical schematic diagram 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 the following embodiments. The following examples will assist those skilled in the art in further understanding the present invention, but are not intended to limit the invention in any way. It should be noted that various changes and modifications can be made by one skilled in the art without departing from the spirit of the invention. These all belong to the protection 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, used in the present specification are used for the purpose of indicating the orientation or positional relationship based on the drawings, only for the convenience of 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 operate, 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 can be combined with each other and are 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.
The 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 embodiment of the utility model provides a grating not only can adjust the size of grating body 10, can also adjust through-hole 11's size, but adjustable parameter is more, the design degree of freedom is high, easily adjusts the diffraction efficiency of grating, so this grating diffraction efficiency is better.
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 embodiment of the utility model provides a grating not only can adjust internal diameter, external diameter and height equidimension, can also adjust the coating condition to can effectively adjust the efficiency of each diffraction order, make its optimization be applied to in the optical waveguide.
In practical application, the accessible adopts electron beam/ion beam equipment, utmost point/deep ultraviolet lithography apparatus, perhaps diffraction grating processing equipment such as interference lithography apparatus to process the wafer to use nanometer impression equipment to carry out the impression and duplicate the volume production the embodiment of the utility model discloses a grating structure.
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 application, each grating quantity and distribution in the grating period all can set up according to actual need, need not be restrained with the embodiment of the utility model provides a injecing.
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
Figure DEST_PATH_GDA0002927219550000051
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 grating that carries out the periodicity and arrange can use other cavity gratings or other cavity column gratings, other laws can be presented after the grating structure is arranged through the periodicity to not necessarily present the hexagon and distribute, can carry out the cycle as required in practical application and arrange, need not be held in the utility model discloses the injecion of embodiment. Simultaneously in practical application, the quantity and the distribution of grating all can set up according to actual need in each grating period, need not be restricted to the embodiment of the utility model provides a injecing.
And simultaneously in the embodiment of the utility model provides an in the optical waveguide, the grating that its used is equipped with the through-hole at this internal grating that is equipped with, and other two-dimensional diffraction grating structures such as cylinder structure grating, prism structure grating are compared to this grating structure, and the design degree of freedom is high, diffraction efficiency can design according to actual need, and diffraction efficiency is unanimous basically with the diffraction efficiency of above-mentioned 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.
The first embodiment is as follows: in this embodiment, the gratings used in the optical waveguide are hollow annular cylindrical gratings, each of which has an inner diameter of 90nm, an outer diameter of 300nm and a height of 100nm, and in each grating period, referring to fig. 3, a complete hollow annular cylindrical grating 10 is distributed in the middle, four corners of the grating are respectively distributed with one-fourth hollow annular cylindrical gratings 10, a long side dimension L of each grating period is 200nm to 2 μm, and a ratio of the long side dimension L to the short side dimension W is
Figure DEST_PATH_GDA0002927219550000061
Meanwhile, as for the simulation of the grating shown in this embodiment, referring to fig. 2, the grating is periodically arranged in the coupling-in region 2 and the coupling-out region 3 of the optical waveguide, and the refractive index of the grating layer is 1.8, the diffraction efficiency of the forward order is 62.53%, the diffraction efficiency of the extended order is 8.35%, and the diffraction efficiency of the coupling-out order is 1.04%, so that the grating refractive index and the diffraction efficiency can meet the application requirements in the optical waveguide.
Example two: in order to observe the variation of the diffraction efficiency of the hollow annular cylindrical grating under different inner diameter sizes, please refer to fig. 4, we also provide a graph of the relationship between the inner radius of the grating structure and the diffraction efficiency. In the present embodiment, the same grating structure as that shown in the first embodiment is that the outer diameter of each hollow annular cylindrical grating is 300nm, the height is 100nm, and in each grating period, please refer to fig. 3, a complete hollow annular cylindrical grating 10 is distributed in the middle, quarter hollow annular cylindrical gratings 10 are distributed at four corners, the long side dimension L of each grating period is 200nm-2 μm, and the ratio of the long side dimension L to the short side dimension W is
Figure DEST_PATH_GDA0002927219550000062
Different from the grating structure shown in the first embodiment, in the present embodiment, the inner diameter value of the hollow annular cylindrical grating is optimized differently, and it is observed that the diffraction efficiency of the hollow annular cylindrical grating changes with the change of the inner diameter. In this embodiment, the hollow portions are respectively alignedThe inner diameter value of the annular cylindrical grating is simulated from 60nm to 200nm, please refer to fig. 2 and fig. 3, the gratings with different inner diameters are respectively and sequentially arranged according to the grating period, and then are respectively and sequentially arranged in the coupling-in area 2 and the coupling-out area 3 of the optical waveguide for the grating period with different inner diameters. It should be noted that the abscissa in fig. 4 is the inner radius value of the hollow annular cylindrical grating, and it can be seen from fig. 4 that the hollow annular cylindrical grating in this embodiment can well control the forward efficiency, the extension efficiency, and the outcoupling efficiency, and thus it can be seen that the grating can also be applied to optical waveguides.
In other embodiments, the grating may be other hollow gratings or other hollow cylindrical gratings, and in practical applications, the size, period and direction of the grating in the optical waveguide may be set according to practical needs, and need not be limited by the above embodiments.
Therefore, the embodiment of the present invention provides a grating having many adjusting parameters, high design freedom and better diffraction efficiency, and being applied to the optical waveguide to achieve better imaging effect. The grating may be arranged in the coupling-in region of the diffractive optical waveguide for coupling in light, or the grating may be arranged in the coupling-out region of the diffractive optical waveguide for expanding the pupil and coupling out light.
In order to further improve the diffraction efficiency of the optical waveguide, in other embodiments, a coating layer may also be disposed on the surface of the waveguide substrate 1, and similarly, the coating layer is made of a material with a high refractive index, so that the refractive index of the coating layer is higher than that of the grating layer, and the thickness of the coating layer is also 10nm to 200 nm.
In practical applications, the shape of the waveguide substrate 1 is not limited to the rectangle shown in the figure, and may be other polygonal shapes or irregular shapes; the shape of the coupling-in area 2 is not limited to the circular shape shown in the drawing, and may be a polygon or an irregular shape; the shape of coupling-out region 3 is also not limited to the quadrangle shown in the figure, and can be other polygons or irregular shapes, and the shapes of waveguide substrate 1, coupling-in region 2 and coupling-out region 3 can all be set according to actual need, need not be restricted to the embodiment of the present invention.
In other embodiments, the coupling-in area 2 and the coupling-out area 3 may not be provided with the grating structure as described in any of the above embodiments, but may also be provided with a super-surface structure, a resonant grating structure, a volume holographic structure, a two-dimensional grating structure, or a one-dimensional grating structure such as an inclined grating, a trapezoidal grating, a blazed grating, and a rectangular grating, specifically, the grating structures of the coupling-in area 2 and the coupling-out area 3 may be provided according to actual needs, for example, the grating structures as described in any of the above embodiments may be used for both the coupling-in area 2 and the coupling-out area 3, or the grating structure as described in any of the above embodiments may be used for only the coupling-in area 2 or the coupling-out area 3, or the coupling-in area 2 or the coupling-out area 3 that does not use the grating structure as described in any of the above embodiments, or may be provided according to actual, need not be in the limit of the embodiment of the utility model.
The embodiment of the utility model provides a near-to-eye display system is still provided, include: the micro-projector 4 and the optical waveguide according to any of the above embodiments are referred to for details of the optical waveguide, and details are not repeated herein, wherein an image source in the micro-projector 4 may be one of LCOS, DMD, OLED, and MEMS, and is configured to emit light for imaging.
In the embodiment of the present invention, the light emitted from the micro-projector 4 is coupled into the waveguide substrate 1 through the coupling-in region 2, and the light coupled into the waveguide substrate 1 can propagate in the waveguide substrate 1 by total reflection, and when the light propagates to the coupling-out region 3, the light can be coupled out of the waveguide substrate 1 through the coupling-out region 3, so as to be able to propagate to the human eye 5 for imaging.
The embodiment of the utility model provides an in provide a grating, be applied to optical waveguide and near-to-eye display system, this grating includes: the grating body, this internal through-hole that is equipped with of grating, this grating structure compare in cylinder structure grating and rhombus structure grating, but adjustable parameter is more, the design degree of freedom is high, easily adjusts the diffraction efficiency of grating, so the embodiment of the utility model provides a grating structure diffraction efficiency is better.
It should be noted that the above-described device embodiments are merely illustrative, where the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit it; within the idea of the invention, also technical features in the above embodiments or in different embodiments can be combined, steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention.

Claims (7)

1. A grating, comprising:
a grating body;
a through hole is formed in the grating body;
the grating is of a hollow annular columnar structure; the grating body is cylindrical, the through hole is a cylindrical hole, the height of the grating body is 10nm-1 mu m, the outer diameter of the grating body is 20nm-1 mu m, and the inner diameter of the grating body is 10nm-800 nm.
2. The grating of claim 1, 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.
3. An optical waveguide, comprising: a waveguide substrate, a coupling-in region, a coupling-out region, and a grating according to any one of claims 1-2 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.
4. The optical waveguide of claim 3, wherein the long dimension of each grating period is 200nm-2 μm.
5. The optical waveguide of claim 4, wherein the ratio of the long dimension to the short dimension of each grating period is
Figure DEST_PATH_FDA0002927219540000011
6. The optical waveguide of claim 5, 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.
7. A near-eye display system, comprising: a micro-projector, and an optical waveguide according to any of claims 3-6.
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111812760A (en) * 2020-08-06 2020-10-23 深圳珑璟光电技术有限公司 Grating structure, optical waveguide and near-to-eye display system
CN114527537A (en) * 2022-03-07 2022-05-24 深圳珑璟光电科技有限公司 Two-dimensional grating and forming method thereof, optical waveguide and near-to-eye display equipment

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111812760A (en) * 2020-08-06 2020-10-23 深圳珑璟光电技术有限公司 Grating structure, optical waveguide and near-to-eye display system
CN111812760B (en) * 2020-08-06 2024-01-30 深圳珑璟光电技术有限公司 Grating structure, optical waveguide and near-to-eye display system
CN114527537A (en) * 2022-03-07 2022-05-24 深圳珑璟光电科技有限公司 Two-dimensional grating and forming method thereof, optical waveguide and near-to-eye display equipment
CN114527537B (en) * 2022-03-07 2024-01-30 深圳珑璟光电科技有限公司 Two-dimensional grating, forming method thereof, optical waveguide and near-to-eye display device

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