Diffraction gratings, optical waveguide elements, and display devices

Abstract

The present invention relates to a diffraction grating (10) and an optical waveguide element and display device including the diffraction grating (10). The diffraction grating (10) comprises a substrate (1) and a plurality of microstructure units (2) formed on the substrate (1) so as to be periodically spaced apart in a first dimension (p1) and a second dimension (p2). The pattern formed by the orthogonal projection of the microstructure units (2) onto the substrate (1) includes a first closed pattern (21), the first closed pattern (21) being an asymmetric pattern, where three or more edges are sequentially connected to form a closed boundary, and at least one of the three or more edges is a straight edge that is not parallel to either the first dimension (p1) or the second dimension (p2). Thus, the microstructure units (2) JPEG2026514601000026.jpg11 has many adjustable parameters, offering a high degree of design flexibility and advantages in adjusting light extraction efficiency.

Description

[Technical Field]

[0001] This application belongs to the field of optical displays, and specifically relates to diffraction gratings, optical waveguide elements, and display devices. [Background technology]

[0002] In the fields of augmented reality (AR) and mixed reality (MR), optical waveguide technology is expected to have a wider range of applications than display methods such as bird baths (half-mirror type), worm eyes (off-axis reflection type), and free-form prisms, because it is thinner and has a larger eyebox.

[0003] In optical waveguide systems, diffractive optical waveguides are attracting more attention than array optical waveguides, which partially use semipermeable films, because they have lower production and manufacturing process difficulties and do not produce lattice-like dark fringes when achieving 2D pupil dilation. Currently, there are mainly two types of diffractive optical waveguides: one-dimensional lattice-based and two-dimensional lattice-based. Compared to optical waveguide designs using all one-dimensional lattices, optical waveguide designs based on two-dimensional lattices can achieve 2D pupil dilation without requiring bending regions, thus providing a larger eye box and offering a greater advantage. 。 [Overview of the project]

[0004] the above In response to this problem, this application aims to provide diffraction gratings, optical waveguide elements, and display devices that can improve the design freedom of microstructures and are advantageous for adjusting light extraction efficiency.

[0005] To achieve the above objective, this application provides the following technical solution.

[0006] circuit board and The diffraction grating is provided, comprising microstructure units formed on a substrate so as to be periodically spaced apart in a first dimension and a second dimension, wherein the pattern obtained by orthogonal projection of the microstructure units onto the substrate includes a first closed pattern, the first closed pattern is an asymmetric pattern, and three or more edges are sequentially connected to form a closed boundary, and at least one of the three or more edges is a straight edge that is not parallel to either the first dimension or the second dimension.

[0007] In an alternative embodiment, a straight edge that is not parallel to either the first-dimensional direction or the second-dimensional direction is a transformation edge, and the angle formed by the intersection of the transformation edge with the first-dimensional direction or the second-dimensional direction, and located outside the first closed pattern, is the transformation angle θ. i The conversion angle θ is such that i The angle range is 5° to 175°.

[0008] In an alternative embodiment, the transformation edge in the first closed pattern includes at least one of the first type of straight edge, the second type of straight edge, the third type of straight edge, and the fourth type of straight edge. If we define a reference parallelogram using two pairs of opposite sides, where the maximum ridge width l1 in the first dimension and the maximum ridge width l2 in the second dimension of the first closed pattern are used, The first endpoint of the side of the first type of straight line is located at one vertex of the reference parallelogram, and the second endpoint of the side of the first type of straight line is located at one side of the reference parallelogram or at the other vertex of the reference parallelogram. The first and second endpoints of the sides of the second type of straight line are located on two sides with different directions in the reference parallelogram, The first endpoint of the side of the third type of straight line is located on any side or vertex of the reference parallelogram, and the second endpoint of the side of the third type of straight line is located inside the reference parallelogram. The first and second endpoints of the sides of the fourth type of straight line are both located inside the reference parallelogram.

[0009] In an alternative embodiment, the side length of the side of the first type of straight line is l 10 The distance d between the second endpoint located on one side of 10 and the endpoint closer to the second endpoint on the one side li is JPEG2026514601000056.jpg1042, and the value of l 10 corresponds to l1 or l2, The side length of the side of the second type of straight line is l[[ID=?]] 20 The distance d between the first endpoint located on one side of 20 and the endpoint closer to the first endpoint on the one side 2i is JPEG2026514601000057.jpg1042, and for the side of the second type of straight line where the side length is l 30 The distance d between the second endpoint located on the other side of 30 and the endpoint closer to the second endpoint on the other side 3i is JPEG2026514601000058.jpg1042, and when the value of l 20 corresponds to l1, the value of l 30 corresponds to l2, and when the value of l 20 corresponds to l2, the value of l 30 corresponds to l1, The side length of the side of the third type of straight line is l 40 The distance d between the first endpoint located on one side of 40 and the endpoint closer to the first endpoint on the one side 4i is JPEG2026514601000059.jpg1042, and the value of l 40 corresponds to l1 or l2.

[0010] In an alternative embodiment, the conversion side in the first closed pattern includes two sides of the third type of straight line, and between the two second endpoints of the two sides of the third type of straight line located inside the reference parallelogram, they are connected to each other by one or more of the fourth type of conversion sides and / or one curved side and / or one straight side parallel to the first dimension or the second dimension.

[0011] In an alternative embodiment, at least two of the three or more edges are the transformation edges, and the transformation angles corresponding to two or more of the transformation edges are not equal to each other.

[0012] In an alternative embodiment, the sides of the curve are wave-like, having at least one crest or at least one trough.

[0013] In an alternative embodiment, the pattern obtained by orthogonal projection of the microstructure unit onto the substrate further includes a second closed pattern of any shape.

[0014] In an alternative embodiment, in a parallelogram formed by two sets of opposite sides representing two arrangement periods in the first and second dimensions in which the microstructure units are periodically arranged, the relatively small interior angles are between 30° and 85°.

[0015] In an alternative embodiment, the period of arrangement of the microstructure units in the first dimension and the period of arrangement in the second dimension are both within the range of 150 nm to 2 μm.

[0016] In an alternative embodiment, the period of arrangement of the microstructure units in the first dimension is not equal to the period of arrangement in the second dimension.

[0017] In an alternative embodiment, the diffraction grating is a surface relief type grating or a volume holographic grating, and the thickness of the diffraction grating is in the range of 10 nm to 2 μm.

[0018] In an alternative embodiment, the diffraction grating comprises at least two optical material components having different optical properties, including at least one of refractive index, absorption properties, and birefringence properties.

[0019] In alternative embodiments, in the case of the surface relief type grating, the region of the microstructure unit is formed to be half the thickness of the grating, and in the diffraction grating, the region of the microstructure unit is a high refractive index portion, and the remaining region surrounding the region of the microstructure unit is a low refractive index portion, or in the case of the diffraction grating, the region of the microstructure unit is a low refractive index portion, and the remaining region surrounding the region of the microstructure unit is a high refractive index portion; and in the case of a volume holographic grating in which the refractive index changes in steps, the region of the microstructure unit corresponds to half the thickness of the grating, and the region of the microstructure unit is a portion enclosed by contour lines corresponding to the average refractive index of the optical material.

[0020] This application also, The base and, The base comprises at least one of a light intake grating, a light extraction grating, and an intermediate grating, The present invention provides an optical waveguide element in which at least one of the light intake grating, the light extraction grating, and the intermediate grating employs a diffraction grating as described above in a portion of its region.

[0021] In an alternative embodiment, the diffraction grating has one or more coatings on the side closer to the human eye or on the side farther from the human eye, and the base has one or more coatings on the side without the grating.

[0022] This application further provides a display device including the optical waveguide element described above.

[0023] The diffraction grating, optical waveguide element, and display device provided in the embodiments of this application have an asymmetric structure in the microstructure unit of the two-dimensional diffraction grating, and at least one of the edges constituting the boundary of the microstructure unit of the two-dimensional diffraction grating is a straight edge that is not parallel to any of the periodically arranged two-dimensional directions. As a result, the microstructure unit has many adjustable parameters, offers a high degree of design freedom, is advantageous for adjusting the light extraction efficiency, and can improve diffraction selectivity, diffraction efficiency, and the brightness of images seen by the human eye. [Brief explanation of the drawing]

[0024] [Figure 1] Figure 1 is a schematic diagram showing the structure of one or more diffraction gratings according to one or more embodiments. [Figure 2] Figures 2a to 2g show the boundary shapes of one or more microstructure units according to one or more embodiments. [Figure 3] Figures 3a to 3h show adjustable parameters for one or more microstructure units according to one or more embodiments. [Figure 4] Figures 4a and 4b show the chamfering of one or more microstructure units according to one embodiment. [Figure 5] Figure 5 shows the boundary shape of one or more microstructure units according to the embodiment. [Figure 6] Figures 6a to 6f are schematic diagrams showing the cross-sectional structure of one or more diffraction gratings according to one or more embodiments. [Modes for carrying out the invention]

[0025] To further clarify the purpose, technical solution, and advantages of this application, specific embodiments of this application will be described in detail below with reference to the accompanying drawings. Examples of these preferred embodiments are illustrated in the accompanying drawings. The embodiments shown in the accompanying drawings of this application and the embodiments described in accordance with the accompanying drawings are illustrative only, and this application is not limited to these embodiments.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the field of this application. The terms used herein are for illustrative purposes only and are not intended to limit this application.

[0027] Furthermore, when one component is described as being "installed" on another component, it may be located directly or indirectly within the other component.

[0028] In addition, identical or similar reference numerals in the drawings of embodiments of this application correspond to identical or similar components. In the description of this application, the orientations or positional relationships indicated by terms such as "up," "down," "left," and "right" are orientations or positional relationships based on the drawings and are merely for the purpose of making the description of this application easier and simpler. They do not indicate or suggest that the elements or devices shown have a specific orientation, are configured in a specific orientation, or must be operated in a specific orientation. Therefore, the terms indicating positional relationships described in the drawings are used only as illustrative descriptions and should not be interpreted as limiting this application. A person skilled in the art will be able to understand the specific meaning of these terms depending on the specific circumstances.

[0029] It should be further explained that, in order to prevent the content of this application from becoming ambiguous due to unnecessary details, the drawings show only structures and / or processing steps that are closely related to the aspects of this application, and other details that are not particularly relevant to this application have been omitted.

[0030] In conventional optical waveguides based on two-dimensional gratings, the two-dimensional diffraction grating is typically composed of multiple microstructure units arranged periodically in the two-dimensional direction. These microstructure units exhibit a columnar structure, and their cross-sections have regular shapes such as circles, ellipses, triangles, or parallelograms. In the process of realizing the embodiments of this application, the inventors discovered that the two-dimensional diffraction gratings relating to the above-mentioned related technologies have problems such as having few adjustable shape parameters for the microstructure units, low design flexibility, and being unfavorable for adjusting the light extraction efficiency.

[0031] An embodiment of this application provides, firstly, a diffraction grating 10 comprising a substrate 1 and a plurality of microstructure units 2 formed on the substrate 1 so as to be periodically arranged in a first-dimensional direction p1 and a second-dimensional direction p2, as shown in Figure 1. Here, the period during which the microstructure units 2 are arranged in the first-dimensional direction p1 is |p1|, and the period during which the microstructure units 2 are arranged in the second-dimensional direction p2 is |p2|. Note that in Figure 1, the microstructure units 2 are shown as dots to illustrate the array arrangement structure of the microstructure units 2 on the substrate 1, and do not indicate that the microstructure units 2 have a circular shape.

[0032] In one or more embodiments, referring to Figure 1, in a parallelogram 3 formed by two sets of opposite sides representing two arrangement periods in a first-dimensional direction p1 and a second-dimensional direction p2 in which the microstructure units 2 are arranged periodically spaced apart, the relatively small interior angle α is between 30° and 85°. This parallelogram 3 is defined as a lattice unit because it is the repeating unit with the smallest area and the smallest side length, and the relatively small interior angle in the repeating lattice unit is between 30° and 85°.

[0033] In one or more embodiments, referring to Figure 1, the period |p1| in which the microstructure units 2 are arranged in the first dimension direction p1 may be 150 nm to 2 μm, and the period |p2| in which the microstructure units 2 are arranged in the second dimension direction p2 may be 150 nm to 2 μm. In a more preferred embodiment, the period |p1| in which the microstructure units 2 are arranged in the first dimension direction p1 and the period |p2| in which they are arranged in the second dimension direction p2 are not equal, i.e., |p1|≠|p2|.

[0034] In the diffraction grating provided in the embodiments of this application, the pattern obtained by orthogonal projection of the microstructure unit 2 onto the substrate 1 includes a first closed pattern. Figures 2a to 2g show the configuration shapes of the microstructure unit 2 in several specific embodiments of this application. As shown in Figures 2a to 2g, the pattern obtained by orthogonal projection of the microstructure unit 2 onto the substrate 1 includes a first closed pattern 21, the first closed pattern being an asymmetric pattern, where three or more edges are sequentially connected to form a closed boundary, and at least one of the three or more edges is a straight edge not parallel to either the first-dimensional direction p1 or the second-dimensional direction p2.

[0035] The following explanation will specifically describe a microstructure unit 2 as shown in Figures 2a to 2g. For example, as shown in the configuration shape of the microstructure unit 2 in Figure 2a, the four sides L1, L2, L3, and L4 are connected sequentially to form a closed boundary of the first closed pattern 21, and the four sides L1, L2, L3, and L4 include straight sides L2 and L4 parallel to the first-dimensional direction p1, a straight side L3 parallel to the second-dimensional direction p2, and a straight side L1 that is not parallel to either the first-dimensional direction p1 or the second-dimensional direction p2.

[0036] For example, as shown in the configuration shape of the microstructure unit 2 in Figure 2b, the four sides L1, L2, L3, and L4 are sequentially connected to form a closed boundary of the first closed pattern 21, and the four sides L1, L2, L3, and L4 include two straight sides L1 and L3 that are not parallel to either the first dimension direction p1 or the second dimension direction p2, in addition to the straight sides L2 and L4 that are parallel to the first dimension direction p1.

[0037] For example, as shown in the configuration shape of the microstructure unit 2 in Figure 2c, the four edges L1, L2, L3, and L4 are sequentially connected to form a closed boundary of the first closed pattern 21, and the four edges L1, L2, L3, and L4 include a straight edge L2 parallel to the first-dimensional direction p1 and a straight edge L3 parallel to the second-dimensional direction p2, as well as two straight edges L1 and L4 that are not parallel to either the first-dimensional direction p1 or the second-dimensional direction p2.

[0038] For example, as shown in the configuration shape of the microstructure unit 2 in Figure 2d, five edges L1, L2, L3, L4, and L5 are sequentially connected to form a closed boundary of the first closed pattern 21, and the five edges L1, L2, L3, L4, and L5 include straight edges L2 and L4 parallel to the first-dimensional direction p1, a straight edge L3 parallel to the second-dimensional direction p2, and two straight edges L1 and L5 that are not parallel to either the first-dimensional direction p1 or the second-dimensional direction p2.

[0039] For example, as shown in the configuration shape of the microstructure unit 2 in Figure 2e, five edges L1, L2, L3, L4, and L5 are sequentially connected to form a closed boundary of the first closed pattern 21, and the five edges L1, L2, L3, L4, and L5 include straight edges L2 and L4 parallel to the first dimension direction p1, straight edges L1 and L3 parallel to the second dimension direction p2, and a straight edge L5 that is not parallel to either the first dimension direction p1 or the second dimension direction p2.

[0040] For example, as shown in the configuration shape of the microstructure unit 2 in Figure 2f, seven edges L1, L2, L3, L4, L5, L6, and L7 are sequentially connected to form a closed boundary of the first closed pattern 21, and the seven edges L1, L2, L3, L4, L5, L6, and L7 include straight edges L2 and L4 parallel to the first dimension direction p1, straight edges L1, L3, and L5 parallel to the second dimension direction p2, and two straight edges L6 and L7 that are not parallel to either the first dimension direction p1 or the second dimension direction p2.

[0041] For example, as shown in the configuration shape of the microstructure unit 2 in Figure 2g, four sides L1, L2, L3, and L4 are sequentially connected to form a closed boundary of the first closed pattern 21, and the four sides L1, L2, L3, and L4 include a straight side L2 parallel to the first dimension direction p1, a straight side L3 parallel to the second dimension direction p2, as well as one straight side L6 not parallel to either the first dimension direction p1 or the second dimension direction p2, and one curved side L4. In a preferred embodiment, as shown in Figure 2g, the curved side L4 is a wave-like curved side having at least one crest and at least one trough, which can effectively increase the uniformity of pupil expansion in different directions of the diffraction grating.

[0042] In the diffraction grating described above, the microstructure unit of the two-dimensional diffraction grating has an asymmetric structure, and at least one of the edges constituting the boundary of the microstructure unit of the two-dimensional diffraction grating is a straight edge that is not parallel to any of the periodically arranged two-dimensional directions. As a result, this microstructure unit has many adjustable parameters, offers a high degree of design freedom, is advantageous for adjusting the light extraction efficiency, and can improve diffraction selectivity, diffraction efficiency, and the brightness of the image seen by the human eye.

[0043] In one or more embodiments, referring to Figures 3a to 3h, a straight edge that is not parallel to either the first-dimensional direction p1 or the second-dimensional direction p2 is a transformation edge, and the angle formed by intersecting the transformation edge with either the first-dimensional direction p1 or the second-dimensional direction p2, and located outside the first closed pattern 21, is the transformation angle θ. i The transformation angle θ is such that i = 1, 2, 3, 4, ..., i.e., a positive integer. i The angular range is preferably 5° to 175°. For example, in the structures shown in Figures 3a to 3f and 3h, the conversion angle θ i Both are acute angles, and in the structure shown in Figure 3g, one of the transformation angles θ i One is an acute angle (transformation angle θ2 in Figure 3g), and the other transformation angle θ i The angle is obtuse (transformation angle θ1 in Figure 3g). Transformation angle θ i By adjusting the size of the element, the extension direction of the corresponding transformation edge with respect to the first-dimensional direction p1 and the second-dimensional direction p2 can be adjusted.

[0044] In a more preferred embodiment, the transformation angle θ i If the angle is acute, the transformation angle θ i The angle range is more preferably set to 40° to 90°, and the conversion angle θ i If the angle is obtuse, the transformation angle θ i It is preferable to set the angle range to 90° to 140°.

[0045] Furthermore, referring to Figures 3a to 3h, the maximum ridge width in the first dimension direction p1 of the first closed pattern 21 is l1, and the maximum ridge width in the second dimension direction p2 of the first closed pattern 21 is l2. Using the maximum ridge widths l1 and l2 as two pairs of opposite sides, in other words, in the first dimension direction p1 and the second dimension direction p2 in which the microstructure units 2 are periodically spaced apart, a reference parallelogram ABCD, which is the smallest parallelogram that can enclose the first closed pattern 21, is set.

[0046] In one or more embodiments, the transformation edge in the first closed pattern 21 is the edge L of a first type of straight line. 1i and / or side L of a second kind of straight line 2i and / or the side L of a third kind of straight line 3i and / or the side L of a fourth kind of straight line 4i This includes i = 1, 2, 3, 4, ...

[0047] Here, as shown in Figures 3a to 3c, the side L of the first type of straight line 1i The first endpoint is located at one vertex of the reference parallelogram ABCD, and is on side L of the first type of straight line. 1i The second endpoint is located on one side of the reference parallelogram ABCD. Taking Figure 3b as an example, the side L of one of the first type lines. 11 The first endpoint is located at vertex D of the reference parallelogram ABCD, and the second endpoint is located at one side BC of the reference parallelogram ABCD that is not adjacent to vertex D, and the other side L of the first type of straight line. 13 The first endpoint of the first type of straight line is located at vertex B of the reference parallelogram ABCD, and the second endpoint is located at one side AD in the reference parallelogram ABCD that is not adjacent to vertex B. In other possible embodiments, the side L of the first type of straight line 1i The second endpoint is located at the other vertex of the reference parallelogram ABCD, that is, on side L of the first kind of straight line. 1i The two endpoints of the triangle are located at different vertices in the reference parallelogram ABCD.

[0048] Furthermore, referring to Figures 3a to 3c, the side L of the first type of straight line 1i The side length in is l 10 The distance d between the second endpoint located on one side and the endpoint on the same side that is closer to the second endpoint. li Preferably The file is JPEG2026514601000060.jpg1042, and l 10 The value corresponds to l1 or l2. Taking Figure 3c as an example, the side L of one of the first type lines. 11 The second endpoint of is located on side BC, and the side length of side BC is l1, therefore l 10 The value corresponds to l1, and in this case, it is the side L of the first kind of straight line. 1i The distance d between the second endpoint and the endpoint C on side BC that is closer to the second endpoint. 11 Preferably The image is JPEG2026514601000061.jpg1038. The other side L of the first type of straight line. 14 The second endpoint of the reference parallelogram ABCD is located on one side AB, and the side length of side AB is l², therefore l 10 The value corresponds to l2, and in this case, it is the side L of the first kind of straight line. 14 The distance d between the second endpoint and the endpoint A on side AB that is closer to the second endpoint. 14 Preferably The image is JPEG2026514601000062.jpg1038. In a more preferred embodiment, the distance d li teeth The filename is JPEG2026514601000063.jpg1038. Note that side L of the first type of straight line. 1i If the two endpoints of are located at different vertices of the reference parallelogram ABCD, then d 1i = 0.

[0049] Here, as shown in Figures 3d to 3e, the side L of the second type of straight line 2i The first and second endpoints are located on two sides of the aforementioned reference parallelogram ABCD that are in different directions. Taking Figure 3d as an example, the side L of the second type of straight line... 21The first endpoint is located on one side BC of the reference parallelogram ABCD, the second endpoint is located on the other side CD of the reference parallelogram ABCD, and the second endpoint is located on side L of the second type of straight line. 22 The first endpoint is located on one side AD of the reference parallelogram ABCD, and the second endpoint is located on the other side CD of the reference parallelogram ABCD.

[0050] Furthermore, referring to Figures 3d and 3e, the side L of the second type of straight line 2i The side length in is l 20 The distance d between a first endpoint located on one side and the endpoint on the same side that is closer to the first endpoint. 2i Preferably The image is JPEG2026514601000064.jpg1042, and the side L of the second type of straight line. 2i The side length in is l 30 The distance d between the second endpoint located on the other side and the endpoint on the first side that is closer to the second endpoint. 3i Preferably The file is JPEG2026514601000065.jpg1042, and l 20 If the value of corresponds to l1, then l 30 The value of l corresponds to l2, while l 20 If the value of l corresponds to l2, then l 30 The value corresponds to l1. Taking Figure 3e as an example, the side L of the second type of straight line. 21 The first endpoint of the side is located on one side AD, the second endpoint is located on the other side CD, and the length of side AD is l1, therefore, l 20 The value corresponds to l1, and the side length of side CD is l2, therefore, l 30 The value corresponds to l2, and in this case, it is the side L of the second type of straight line. 21 The distance d between the first endpoint and the endpoint D on side AD that is closer to the first endpoint. 21 Preferably The image is JPEG2026514601000066.jpg1038, and it represents the side L of a straight line of type 2. 21 The distance d between the second endpoint of and the endpoint D on side CD that is closer to the second endpoint. 31 Preferably The image is JPEG2026514601000067.jpg1038. Note that in Figure 3d, the sides (L) of the two Type 2 straight lines are shown. 21 and L 22 Since the second endpoint of ) coincides, the distance (d 31 and d 32 ) are the same, and therefore in Figure 3d, d 31 Only is shown. In a more preferred embodiment, distance d 2i teeth Let the file be named JPEG2026514601000068.jpg1038, and the distance d 3i teeth Let's call it JPEG2026514601000069.jpg1038.

[0051] Here, as shown in Figures 3f to 3h, the side L of the third type of straight line 3i The first endpoint is located on any side or vertex of the reference parallelogram ABCD, and the side L of the third type of straight line 3i The second endpoint of the third type of straight line L is located inside the aforementioned reference parallelogram ABCD. Taking Figure 3f as an example, the side L of the third type of straight line L 31 The first endpoint is located on one side CD of the reference parallelogram ABCD, and the second endpoint is located inside the reference parallelogram ABCD, on side L of the third kind of straight line. 32 The first endpoint of the plane is located on one side CD of the reference parallelogram ABCD, and the second endpoint is located inside the reference parallelogram ABCD.

[0052] Furthermore, referring to Figures 3f and 3g, the side L of the third type of straight line 3i The side length in is l 40 The distance d between a first endpoint located on one side and the endpoint on the same side that is closer to the first endpoint. 4i Preferably The file is JPEG2026514601000070.jpg1042, and l 40 The value corresponds to l1 or l2. Taking Figure 3f as an example, the side L of the third type of straight line. 31 The first endpoint of is located on one side CD, and the side length of side CD is l², therefore, l 40 The value corresponds to l2, and in this case, it is the side L of the third kind of straight line.31 The distance d between the first endpoint of 31 and the endpoint C of side CD that is closer to the first endpoint 41 is preferably JPEG2026514601000071.jpg1038, and for the third type of straight side L 32 since the first endpoint of 32 is also located on side CD, similarly, l 40 the value of l corresponds to l2, and in this case, for the third type of straight side L 32 the distance d between the first endpoint of 32 and the endpoint D of side CD that is closer to the first endpoint 42 is preferably JPEG2026514601000072.jpg1038. In a more preferred embodiment, the distance d 4i is JPEG2026514601000073.jpg1038. Note that for the two third - type straight sides L 3i that exist, and when the first endpoints of the two third - type straight sides L 3i are located on the same side, the distance d 3i corresponding to the two third - type straight sides L 4i is not simultaneously half of the length of the corresponding side. When the first endpoint of the third - type straight side L 3i is located at the vertex of the reference parallelogram ABCD, d 4i = 0.

[0053] In some embodiments, referring to FIGS. 3a to 3f, the conversion angle θ i is an acute angle. In some other embodiments, referring to FIG. 3g, the conversion angle θ2 is an acute angle while the conversion angle θ1 is an obtuse angle.

[0054] Here, as shown in FIG. 3h, for the fourth - type straight side L 4i both the first endpoint and the second endpoint are located inside the reference parallelogram ABCD, for example, like the fourth - type straight side L 41 in FIG. 3h. <##

[0055] In the configurations shown in FIGS. 3a to 3h, for the conversion sides in the first closed pattern 21 shown in FIGS.1i Including only the first closed pattern 21 shown in Figures 3d and 3e, the transforming edge is the second type of straight edge L. 2i Including only the first closed pattern 21 shown in Figures 3f and 3g, the transformation edge is the third type of straight edge L. 3i Including only the first closed pattern 21 shown in Figure 3h, the transformation edge is the third type of straight edge L. 3i and the side L of the fourth type of straight line 4i Includes.

[0056] From the above configuration patterns, the following shape changes can be easily conceived. For example, side AB in Figure 3d corresponds to side L of the first type of straight line in the structure of Figure 3b. 13 Therefore, the transformation edge in the first closed pattern 21 is the edge L of a straight line of the first kind. 1i and the side L of the second type of straight line 2i This includes, for example, side AB in Figure 3f and side L of the first type of straight line in the structure of Figure 3b. 13 Therefore, the transformation edge in the first closed pattern 21 is the edge L of the first kind of straight line. 1i and the side L of the third type of straight line 3i This includes, for example, side AB in Figure 3h and side L of the first type of straight line in the structure of Figure 3b. 13 Therefore, the transformation edge in the first closed pattern 21 is the edge L of the first type of straight line. 1i , side L of a third type of straight line 3i and the side L of the fourth type of straight line 4i Includes.

[0057] In one or more embodiments, as shown in Figure 3h, the transformation edge in the first closed pattern 21 is an edge L of two third-kind straight lines. 31 , L 32 Including two sides L of the aforementioned third type of straight line 31 , L 32 Between the two second endpoints located inside the aforementioned reference parallelogram ABCD is one side L of the fourth type of straight line. 41 They are connected to each other by a side L of the three kinds of straight lines. In some other embodiments, two sides L of the three kinds of straight lines are connected to each other by a side L. 31 , L 32Between the two second endpoints of the , there are one or more fourth-kind transformation edges L 4i They may be connected to each other by curved edges and / or straight edges parallel to the first-dimensional direction p1 or the second-dimensional direction p2.

[0058] Referring to Figures 3a to 3h, in the diffraction grating provided in the embodiment of this application, the adjustable parameters of the microstructure unit 2 are: (1) the duty cycles l1|p1| and l2|p2| in the two-dimensional directions in which the microstructure unit 2 is periodically arranged; (2) the number of edges that are not parallel to either the first-dimensional direction p1 or the second-dimensional direction p2; and (3) the transformation angle θ of the transformation edges. i (4) the size of the transformation edge (position of the two endpoints); (5) the combination of different types of transformation edges and curved edges. Thus, the microstructure unit 2 has many adjustable parameters and offers a great deal of design freedom.

[0059] In a more preferred embodiment, taking the microstructure unit 2 shown in Figure 3c as an example, if there are two or more of the transformation edges, the transformation angles θ corresponding to the two or more of the transformation edges are as follows. i They are not equal to each other.

[0060] In a preferred embodiment, referring to Figures 4a and 4b, the first closed pattern 21 has vertices 23 formed by straight chamfers (shown in Figure 4a) or arc chamfers (shown in Figure 4b). By providing straight chamfers or arc chamfers, the number of small internal angles to be processed in the microstructure can be reduced, thereby lowering the difficulty of process processing, increasing yield, reducing scattering, and improving image contrast. Here, the length of the side of the straight chamfer is less than or equal to half the length of the shortest straight side among the three or more sides, and is usually in the range of 1 nm to 500 nm, and the radius of curvature of the arc chamfer is less than or equal to half the length of the shortest straight side among the three or more sides, and is usually in the range of 1 nm to 500 nm.

[0061] Figure 5 shows the configuration shape of the microstructure unit 2 in some other specific embodiments of the present application. In some other specific embodiments, the pattern of the microstructure unit 2 projected onto the substrate 1 may include a second closed pattern 22 in addition to the first closed pattern 21 described above. The boundary of the second closed pattern 22 may be a pattern of any shape, and may be a pattern enclosed by one or more straight lines and / or one or more curved lines. For example, it may be circular, elliptical, sector, ring, polygon, etc. Typically, the area of ​​the second closed pattern 22 is smaller than the area of ​​the first closed pattern 21. As shown in Figure 5, the second closed pattern 22 is rectangular.

[0062] In the embodiments of this application, the diffraction grating 10 described above can be realized as a surface relief grating or as a volume holographic grating. Specifically, the grating thickness is in the range of 10 nm to 2 μm. Figures 6a to 6f show cross-sectional views of diffraction gratings in some specific embodiments of this application. Here, Figure 6a is a structural diagram of a relief grating enveloped by straight grooves, Figure 6b is a structural diagram of a relief grating enveloped by helical grooves, Figure 6c is a structural diagram of a relief grating enveloped by sawtooth grooves, Figure 6d is a structural diagram of a relief grating enveloped by stepped grooves, Figure 6e is a structural diagram of a relief grating enveloped by curved surfaces, and Figure 6f is a configuration diagram of a volume holographic grating.

[0063] In the embodiments of this application, the diffraction grating 10 consists of at least two optical material components having different optical properties, including refractive index and / or absorption properties and / or birefringence properties. Therefore, when the grating is placed in air, air is also considered one of the optical materials. For non-birefringent materials, the optical properties of the material can be comprehensively described by refractive index and absorption properties. If the two optical materials differ mainly in their refractive index, the grating can be divided into a high refractive index portion and a low refractive index portion. Referring to Figures 6 to 6f, the diffraction grating 10 includes a high refractive index portion 101 and a low refractive index portion 102, but it should be noted that these drawings can also be used to distinguish between two optical materials having different absorption properties and / or birefringence properties.

[0064] In the case of the surface relief type grating, it is preferable that the region of the microstructure unit 2 is formed to be half the thickness of the grating. In one specific embodiment, in the diffraction grating 10, the region of the microstructure unit 2 is the high refractive index portion 101, and the remaining region surrounding the region of the microstructure unit 2 is the low refractive index portion 102, with the refractive index of the high refractive index portion 101 being in the range of 1.5 to 3.0 and the refractive index of the low refractive index portion 102 being in the range of 1.0 to 1.5. In some other specific embodiments, in the diffraction grating 10, the region of the microstructure unit 2 is the low refractive index portion 102, and the remaining region surrounding the region of the microstructure unit 2 is the high refractive index portion 101.

[0065] In the case of a volumetric holographic grating in which the refractive index changes in steps, the region of the microstructure unit 2 preferably corresponds to half the thickness of the grating, and the portion where the refractive index is greater than the average refractive index is defined as the high refractive index region, and the portion where the refractive index is less than the average refractive index is defined as the low refractive index region, with the contour line corresponding to the average refractive index of the optical material as the boundary. Here, the region of the microstructure unit 2 is the portion enclosed by the contour line corresponding to the average refractive index of the optical material, and may be either the high refractive index region or the low refractive index region.

[0066] Embodiments of this application further provide an optical waveguide element based on the diffraction grating provided in the above embodiments, the optical waveguide element comprising a base, an optical intake grating and an optical extraction grating provided on the base, the optical intake grating being used to take in an external light beam into the base, and the optical extraction grating being used to extract a light beam from the base. In further embodiments, the optical waveguide element may further comprise an intermediate grating. Here, the optical intake grating and / or the optical extraction grating and / or the intermediate grating employ the diffraction grating provided in the embodiments of this application in some or all areas. When the diffraction grating provided in the embodiments of this application is applied to an optical waveguide element, the base of the optical waveguide element may be directly multiplexed as the substrate of the diffraction grating, that is, the base of the optical waveguide element and the substrate of the diffraction grating may be integrated.

[0067] In an alternative embodiment, in the optical waveguide element, the diffraction grating has one or more coatings on the side closer to the human eye and / or on the side farther from the human eye, and / or the base has one or more coatings on the side without the grating. Furthermore, the base may have a multilayer structure, and the diffraction grating may have a multilayer structure.

[0068] This application further provides a display device, such as an augmented reality (AR) display device or a mixed reality (MR) display device. The display device comprises a projection device and an optical waveguide element provided in the above embodiments of this application, wherein the projection device generates image light (light carrying image information), the image light is taken in by an optical intake grating to a base, transmitted through the base to an optical extraction grating, further extracted from the base by the optical extraction grating, and transmitted to a human eye, thereby enabling the human eye to observe the corresponding image information.

[0069] As is clear from the above, the diffraction grating, optical waveguide element, and display device provided in the above embodiments of this application have an asymmetric structure in the microstructure unit of the two-dimensional diffraction grating, and at least one of the edges constituting the boundary of the microstructure unit of the two-dimensional diffraction grating is a straight edge that is not parallel to any of the periodically arranged two-dimensional directions. As a result, this microstructure unit has many adjustable parameters, offers a great degree of design freedom, is advantageous for adjusting the light extraction efficiency, and can improve diffraction selectivity, diffraction efficiency, and the brightness of images seen by the human eye.

[0070] Although this application has been described above with reference to specific embodiments, those skilled in the art will understand that various modifications can be made to its form and details without departing from the spirit and scope of this application as defined by the claims and equivalents.

Claims

1. circuit board and The substrate comprises microstructure units formed on the substrate so as to be periodically spaced apart in a first dimension and a second dimension, wherein the pattern obtained by orthogonal projection of the microstructure units onto the substrate includes a first closed pattern. A diffraction grating wherein the first closed pattern is an asymmetric pattern, and three or more edges are sequentially connected to form a boundary of the first closed pattern, and at least one of the three or more edges is a straight edge that is not parallel to either the first dimension or the second dimension.

2. A straight edge that is not parallel to either the first-dimensional direction or the second-dimensional direction is a transformation edge, and the angle formed by the intersection of the transformation edge with either the first-dimensional direction or the second-dimensional direction, and located outside the first closed pattern, is the transformation angle θ. ｉ The conversion angle θ is such that ｉ The diffraction grating according to claim 1, wherein the angular range is 5° to 175°.

3. The transformation edge in the first closed pattern includes at least one of the following: a straight edge of type 1, a straight edge of type 2, a straight edge of type 3, and a straight edge of type 4. The maximum ridge width l in the first dimension of the first closed pattern １ And the maximum ridge width l in the aforementioned second dimension ２ If we define a reference parallelogram with and as two pairs of opposite sides, The first endpoint of the side of the first type of straight line is located at one vertex of the reference parallelogram, and the second endpoint of the side of the first type of straight line is located at one side of the reference parallelogram that is not adjacent to the first endpoint, or at the other vertex of the reference parallelogram that is not adjacent to the first endpoint. The first and second endpoints of the sides of the second type of straight line are located on two sides with different directions in the reference parallelogram, The first endpoint of the side of the third type of straight line is located on any side or vertex of the reference parallelogram, and the second endpoint of the side of the third type of straight line is located inside the reference parallelogram. The diffraction grating according to claim 2, wherein the first and second endpoints of the sides of the fourth type of straight line are both located inside the reference parallelogram.

4. The side length of the side of the first type of straight line is l １０ The distance d between the second endpoint located on one side and the endpoint on the same side that is closer to the second endpoint. ｌｉ teeth and l １０ has a value of l １ or l ２ corresponds to, The side length of the side of the second type of straight line is l ２０ The distance d between the first endpoint located on one side and the endpoint on the same side that is closer to the first endpoint. ２ｉ teeth The side length of the side of the second type of straight line is l ３０ The distance d between the second endpoint located on the other side and the endpoint on the other side that is closer to the second endpoint. ３ｉ teeth and l ２０ The value of l １ If it corresponds to l ３０ The value of l ２ Corresponding to, l ２０ The value of l ２ If it corresponds to l ３０ The value of l １ In response to, The side length of the third type of straight line is l ４０ The distance d between the first endpoint located on one side and the endpoint on the same side that is closer to the first endpoint. ４ｉ teeth and l ４０ The value of l １ or l ２ A diffraction grating according to claim 3, corresponding to the present invention.

5. The diffraction grating according to claim 3, wherein the transformation edge in the first closed pattern includes two sides of the third type of straight line, and the two second endpoints of the two sides of the third type of straight line that are located inside the reference parallelogram are connected to each other by at least one of one or more transformation edges of the fourth type, one curved edge, and one straight line parallel to the first or second dimension.

6. The diffraction grating according to claim 2, wherein at least two of the three or more sides are the transformation sides, and the transformation angles corresponding to two or more of the transformation sides are not equal to each other.

7. The diffraction grating according to claim 1, wherein the first closed pattern has at least one curved edge.

8. The diffraction grating according to claim 1, wherein the pattern obtained by orthogonal projection of the microstructure unit onto the substrate further includes a second closed pattern of any shape.

9. A diffraction grating according to any one of claims 1 to 8, wherein in a parallelogram formed by two sets of opposite sides representing two arrangement periods in the first and second dimensions in which the microstructure units are periodically arranged, the relatively small interior angles are between 30° and 85°.

10. The diffraction grating according to claim 1, wherein the period of the arrangement of the microstructure units in the first dimension and the period of the arrangement in the second dimension are both within the range of 150 nm to 2 μm.

11. The diffraction grating according to claim 10, wherein the period of the arrangement of the microstructure units in the first dimension is not equal to the period of the arrangement in the second dimension.

12. The diffraction grating according to claim 1, wherein the diffraction grating is a surface relief type grating or a volume type holographic grating, and the thickness of the diffraction grating is in the range of 10 nm to 2 μm.

13. The diffraction grating according to claim 12, wherein the diffraction grating comprises at least two optical material components having different optical properties, including at least one of refractive index, absorption properties, and birefringence properties.

14. In the case of the surface relief type lattice, the microstructure unit region is formed to be half the thickness of the lattice, and in the diffraction grating, the region of the microstructure unit is a high refractive index portion, and the remaining region surrounding the region of the microstructure unit is a low refractive index portion, or in the diffraction grating, the region of the microstructure unit is a low refractive index portion, and the remaining region surrounding the region of the microstructure unit is a high refractive index portion, and in the case of a volume holographic lattice in which the refractive index changes in steps, the region of the microstructure unit corresponds to half the thickness of the lattice, and the region of the microstructure unit is a portion enclosed by contour lines corresponding to the average refractive index of the optical material, as described in claim 13.

15. The base and, The base comprises at least one of a light intake grating, a light extraction grating, and an intermediate grating, An optical waveguide element wherein at least one of the light intake grating, the light extraction grating, and the intermediate grating employs a diffraction grating according to any one of claims 1 to 14 in a portion of its region.

16. The optical waveguide element according to claim 15, wherein the diffraction grating has one or more layers of coating on the side closer to the human eye or on the side farther from the human eye, and the base has one or more layers of coating on the side where the grating is not provided.

17. A display device comprising an optical waveguide element according to any one of claims 15 to 16.

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