Multi-stage two-dimensional grating structure, its manufacturing method, optical waveguide device and AR device

Abstract

The present invention relates to a multi-level two-dimensional grating structure, a manufacturing method thereof, an optical waveguide device, and an AR device. The multi-level two-dimensional grating structure has an array group, which includes: a plurality of first cylinders, which are arranged on the surface of a substrate and arranged in a two-dimensional periodic array, wherein each first cylinder has a top surface and a bottom surface opposite to each other, and the bottom surface is located on the surface of the substrate; and a plurality of second cylinders, which are respectively arranged on the top surfaces of their corresponding first cylinders, wherein each second cylinder has a top surface and a bottom surface opposite to each other, the bottom surface of the second cylinder is included in the top surface of the corresponding first cylinder, and the bottom surface shape of the second cylinder is different from the bottom surface shape of the corresponding first cylinder. The multi-level two-dimensional grating structure can be applied to waveguide sheets, AR devices, etc., so as to effectively reduce the leakage light energy loss pointing to the world side existing in the existing waveguide sheets, improve the energy utilization rate of the waveguide sheets, and reduce the risk of information leakage, etc.

Description

Technical Field

[0001] The present invention relates to the field of optical imaging technology. More specifically, the present invention relates to a multi-order two-dimensional grating structure and a manufacturing method thereof, an optical waveguide device, and an AR device. Background Art

[0002] An optical waveguide sheet is a key core component in the new generation of Augmented Reality (AR) technology. It combines the total internal reflection waveguide principle and diffraction elements to replicate and expand the exit pupil in an imaging system. Due to its advantages such as a large pupil, small volume, and light weight, it has become an inevitable trend in the development of AR technology. In some existing solutions, a two-dimensional grating is used as an out-coupling optical element in an optical waveguide lens. At this time, while having the two-dimensional pupil expansion function, it also has high compactness. However, there is a high leakage light energy loss on the side pointing to the real world, which reduces its energy utilization rate, causes information leakage, and affects eye contact with people around.

[0003] By adopting a multi-order two-dimensional grating, several of the above-mentioned disadvantages can be improved. However, the manufacturing of a multi-order micro-nano structure usually needs to be realized through multi-step lithography with high alignment accuracy. Generally, n lithography steps can produce 2n steps, but it is limited by the alignment accuracy of lithography tools and etching processes. And when preparing multi-layer patterns with feature sizes below 100 nm, or when very high stack alignment accuracy is required, both are very challenging, and it will be difficult to meet the requirements in terms of the quality, production efficiency, and cost of the multi-order two-dimensional grating.

[0004] The content described in this section is for the convenience of understanding the present application. Therefore, it should not be assumed that it belongs to the prior art only because it is included in this section. Summary of the Invention

[0005] In view of this, the present invention provides a multi-order two-dimensional grating structure and a manufacturing method thereof, an optical waveguide device, and an AR device, thereby being able to solve or at least alleviate one or more of the above problems and other problems.

[0006] First, according to one aspect of the present invention, a multi-order two-dimensional grating structure is provided. The multi-order two-dimensional grating structure has an array group, and the array group includes:

[0007] a plurality of first cylinders, which are arranged on the surface of a substrate in a two-dimensional periodic array, wherein each first cylinder has a top surface and a bottom surface opposite to each other, and the bottom surface is located on the surface of the substrate; and

[0008] A plurality of second cylinders, which are respectively disposed on the top surfaces of their corresponding first cylinders, wherein each second cylinder has a top surface and a bottom surface opposite to each other, the bottom surface of the second cylinder is included in the top surface of the corresponding first cylinder, and the shape of the bottom surface of the second cylinder is different from the shape of the bottom surface of the corresponding first cylinder.

[0009] In the multi-level two-dimensional grating structure according to the present invention, optionally, the array group further includes one or more additional arrays, and the additional arrays include:

[0010] A plurality of third cylinders, which are respectively disposed on the adjacent base surfaces, wherein each third cylinder has a top surface and a bottom surface opposite to each other, the bottom surface of the third cylinder is included in the base surface, and the shape of the bottom surface of the third cylinder is different from the shape of the bottom surface of the cylinder corresponding to the base surface, and the base surface is the top surface of the second cylinder in the array group or the top surface of the third cylinder in another additional array.

[0011] In the multi-level two-dimensional grating structure according to the present invention, optionally, the cross-sectional shapes of the first cylinder and / or the second cylinder are configured to be circular, elliptical, polygonal and any combination thereof, and / or the bottom surface of the second cylinder is proportionally reduced according to the bottom surface of the first cylinder at a preset reduction rate.

[0012] In the multi-level two-dimensional grating structure according to the present invention, optionally, the range of the reduction rate is 0.45 - 0.65.

[0013] In the multi-level two-dimensional grating structure according to the present invention, optionally, the central axis of the second cylinder is offset with respect to the central axis of the first cylinder.

[0014] In the multi-level two-dimensional grating structure according to the present invention, optionally, the bottom surface of the second cylinder is tangent to the bottom surface of the first cylinder, and the tangent point is located in the offset direction of the central axis of the second cylinder with respect to the central axis of the first cylinder.

[0015] In the multi-level two-dimensional grating structure according to the present invention, optionally, the first cylinder and the second cylinder respectively have a first height and a second height in a direction perpendicular to the surface of the substrate, the range of the first height is 30nm - 65nm, and the second height has a height substantially equivalent to the first height.

[0016] In the multi-level two-dimensional grating structure according to the present invention, optionally, in the two-dimensional plane formed by the first dimension direction and the second dimension direction of the two-dimensional periodic array, the projection of the second cylinder in this two-dimensional plane is at least smaller than the projection of the corresponding first cylinder in this two-dimensional plane in three directions.

[0017] In the multi - order two - dimensional grating structure according to the present invention, optionally, the array group is arranged to protrude outward or recess inward from the surface of the substrate.

[0018] Secondly, according to another aspect of the present invention, there is also provided an optical waveguide device, which includes an optical waveguide substrate, an input coupling region, and an output coupling region. Incident light is coupled into the optical waveguide substrate through the input coupling region and then coupled out through the output coupling region. The output coupling region is configured to have the multi - order two - dimensional grating structure described in any one of the above.

[0019] In addition, according to yet another aspect of the present invention, there is further provided an AR device, which includes:

[0020] One or more optical waveguide devices as described above; and

[0021] An imaging device, which is arranged on the light - incident side of the optical waveguide device for emitting image light and making it incident on the input coupling region of the optical waveguide device.

[0022] Furthermore, according to another aspect of the present invention, there is also provided a manufacturing method of a multi - order two - dimensional grating structure, including the steps of:

[0023] Providing a substrate; and

[0024] Constructing a plurality of first cylinders and a plurality of second cylinders on the surface of the substrate to form an array group, wherein each first cylinder and each second cylinder are configured to have a top surface and a bottom surface opposite to each other. The bottom surface of the first cylinder is located on the surface of the substrate and the first cylinders are arranged in a two - dimensional periodic array. The second cylinders are respectively located on the top surfaces of their corresponding first cylinders. The bottom surface of the second cylinder is included in the top surface of the corresponding first cylinder, and the shape of the bottom surface of the second cylinder is different from the shape of the bottom surface of the corresponding first cylinder.

[0025] In the manufacturing method of the multi - order two - dimensional grating structure according to the present invention, optionally, it further includes the step of:

[0026] Constructing one or more additional arrays to form an array group. The additional arrays are configured to include a plurality of third cylinders, wherein each third cylinder has a top surface and a bottom surface opposite to each other. The third cylinders are respectively arranged on their adjacent base surfaces and the bottom surface of the third cylinder is included in the base surface, and the shape of the bottom surface of the third cylinder is different from the shape of the bottom surface of the cylinder corresponding to the base surface. The base surface is the top surface of the second cylinder in the array group or the top surface of the third cylinder in another additional array.

[0027] In the manufacturing method of the multi - order two - dimensional grating structure according to the present invention, optionally, the array group is constructed by performing the following steps at least twice and then etching.

[0028] Deposit a buffer layer on the surface or current exposed surface of the substrate;

[0029] Coat a photoresist layer on the buffer layer and perform photolithography, and then deposit a mask layer; and

[0030] Remove the remaining photoresist layer.

[0031] In the method for manufacturing a multi-order two-dimensional grating structure according to the present invention, optionally, sputtering, evaporation or atomic layer deposition is used to form the buffer layer, and / or the material of the buffer layer includes Si, SiO2 or SiN.

[0032] In the method for manufacturing a multi-order two-dimensional grating structure according to the present invention, optionally, photolithography is used to etch the mask layer, the photolithography includes ultraviolet photolithography, electron beam lithography and nanoimprinting, and / or the material of the mask layer includes a metal material or a metal oxide material, the metal material includes Au, Al, Ag, Ni or Cr, and the metal oxide material includes SiO2 or TiO2.

[0033] In the method for manufacturing a multi-order two-dimensional grating structure according to the present invention, optionally, a solvent is used to remove the remaining photoresist layer, and the solvent is determined based on the type of photoresist used.

[0034] In the method for manufacturing a multi-order two-dimensional grating structure according to the present invention, optionally, the thickness of the buffer layer corresponds to a first height or a second height, and the first height and the second height are the heights of the first column and the second column in a direction perpendicular to the surface of the substrate, respectively.

[0035] The multi-order two-dimensional grating structure according to the present invention not only has a compact overall structure and an efficient manufacturing process, but also can especially precisely control the depth of each grating order, so as to reach a high quality level. Applying this multi-order two-dimensional grating structure to a waveguide sheet, an AR device, etc. can effectively reduce the leakage light energy loss to the world side existing in the existing waveguide sheet, thereby improving the energy utilization rate of the waveguide sheet, reducing the risk of information leakage, and improving the battery life of the AR device, etc. The solution of the present invention is very suitable for large-scale manufacturing and has outstanding application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The technical solutions of the present invention will be further described in detail below with reference to the drawings and embodiments, but it should be understood that these drawings are only for illustrative purposes and do not have to be drawn to scale.

[0037] Figure 1a and Figure 1bIt is a schematic top - down view of a local array group in an embodiment of a multi - order two - dimensional grating structure according to the present invention, and a schematic three - dimensional structure of one of the first cylinders and the corresponding second cylinder.

[0038] Figure 2a and Figure 2b It is another schematic top - down view of a local array group in an embodiment of a multi - order two - dimensional grating structure according to the present invention, and a schematic three - dimensional structure of one of the first cylinders and the corresponding second cylinder.

[0039] Figure 3 It shows a schematic diagram of an incident image light ray when it is coupled out through a coupling - out region applying an example of a multi - order two - dimensional grating structure according to the present invention in an embodiment of an optical waveguide device according to the present invention, simultaneously generating an outward transmitted diffraction order T1 and an inward reflected diffraction order R1.

[0040] Figure 4 It shows in Figure 3 The coupling - out diffraction efficiency curves of the respective transmitted diffraction orders T1 and reflected diffraction orders R1 of s - polarized light and p - polarized light transmitted in the coupling - out region of the optical waveguide device embodiment shown, varying with the incident angle.

[0041] Figure 5 It is a flowchart of an embodiment of a manufacturing method of a multi - order two - dimensional grating structure according to the present invention.

[0042] Figures 6a to 6j They respectively show schematic side - view structures in different process steps when manufacturing a multi - order two - dimensional grating structure using the method embodiment of the present invention. Detailed implementation manners

[0043] First of all, it should be noted that the following will illustrate the steps, structures, characteristics, advantages, etc. of the multi - order two - dimensional grating structure, its manufacturing method, optical waveguide device, and AR device according to the present invention by way of examples. However, all descriptions should not be used to impose any limitations on the present invention. In this article, the technical terms "first", "second", "third" are only for the purpose of differential expression and are not intended to indicate their order and relative importance, etc. The technical term "substantially" is intended to include non - substantial errors associated with a specific measurement, such as ranges of ±8%, ±5%, or ±2% of a given value, etc. The technical term "multi - order" means three - order or higher. The technical terms "upper", "lower", "top", "bottom", "horizontal", "vertical" and their derivatives should be related to the orientation in the respective drawings, and it should be understood that the present invention can adopt various alternative orientations.

[0044] In addition, for any single technical feature described or implied in the embodiments of this article, or any single technical feature shown or implied in the respective drawings, the present invention still allows any combination or deletion to continue between these technical features (or their equivalents) without any technical obstacles, thereby covering more embodiments according to the present invention. Additionally, for the sake of brevity, identical or similar components and features may be labeled only at one or several places in the same drawing, and general matters already well-known to those skilled in the art are not elaborated herein.

[0045] The present invention first provides a multi-order two-dimensional grating structure, which is demonstrated exemplarily by two specific examples shown in Figure 1a 、 Figure 1b 、 Figure 2a and Figure 2b . Specifically speaking, the multi-order two-dimensional grating structure is configured to have an array group protruding outward or recessing inward from the substrate surface. Such an array group can be formed by two or more series of different columnar structures, and their specific settings can be selected and designed according to actual application requirements, ease of processing, manufacturing cost, etc. It should be understood that the columnar shape has a broad meaning in this article, for example, covering many types of relatively simple or quite complex configurations such as frustum of a pyramid, oblique prism, cylinder, etc. By adopting these different structural shapes, the energy distribution of different diffraction orders of the two-dimensional grating can be changed without changing the light transmission path.

[0046] As an illustrative example, please refer to Figure 1a and Figure 1b (or Figure 2a and Figure 2b ). Under normal circumstances, the array group can be configured to have a plurality of first columns 11 and a plurality of second columns 12. In this article, unless otherwise specified, the present invention does not specifically limit the specific number, arrangement, shape structure, etc. of these columns in the array group. For example, the cross-sectional shapes of the first column 11 and the second column 12 can be selected and set as needed, and they can be configured into shapes such as circular, elliptical, polygonal or any combination thereof. For example, Figure 1a and Figure 1b show that the first column 11 and the second column 12 are configured to have cross-sectional shapes of hexagon and quadrilateral respectively, Figure 2a and Figure 2b show that the first column 11 and the second column 12 are configured to have cross-sectional shapes of a relatively large hexagon and a relatively small hexagon respectively.

[0047] In the array group, each first cylinder 11 has a top surface 111 and a bottom surface 112 opposite to each other, and each second cylinder 12 similarly has a top surface 121 and a bottom surface 122 opposite to each other. These first cylinders 11 are disposed on the substrate 10 and arranged in a two-dimensional periodic array, and the bottom surface 112 of each first cylinder 11 is located on the surface 101 of the substrate 10. The substrate 10 is generally in a flat plate shape and can be made of suitable materials such as silicon, quartz or others.

[0048] For the second cylinders 12, they are respectively disposed on the top surfaces 111 of the corresponding first cylinders 11. The bottom surface 122 of each second cylinder 12 is included in the top surface 111 of the corresponding first cylinder 11, and the shape of the bottom surface 122 is set to be different from the shape of the bottom surface 112 of the corresponding first cylinder 11, so as to form a gradually changing stepped structure. For example, as an alternative embodiment, the bottom surface 122 of the second cylinder 12 can be set to be proportionally reduced according to the bottom surface 112 of the first cylinder 11 at a preset reduction rate, which is demonstratively shown in Figure 2a and Figure 2b In practical applications, the value range of the reduction rate can be optionally set to 0.45 - 0.65. Of course, it can also adopt any other suitable value to meet different application requirements.

[0049] As an alternative case, it can be considered that the central axis of the second cylinder 12 is offset with respect to the central axis of the first cylinder 11, and the offset direction can be, for example, the direction where the coupling grating is located. Optionally, the bottom surface of the second cylinder 12 can be tangent to the bottom surface of the first cylinder 11, and the tangent point is located in the offset direction of the central axis of the second cylinder 12 with respect to the central axis of the first cylinder 11. In addition, optionally, the first cylinder 11 and the second cylinder 12 can be set to have a first height H1 and a second height H2 respectively in the direction perpendicular to the surface of the substrate 10. For the first height H1, its selection range can be 30nm - 65nm, or any other suitable value. For the second height H2, it is generally considered to be set to have a height substantially equivalent to the first height H1. That is to say, as can be understood by those skilled in the art, as long as the second height H2 and the first height H1 are approximately equivalent in the height dimension order of magnitude and the height difference between the two is not too large.

[0050] In addition, as an alternative case, for example Figure 1b and Figure 2bAs shown, the multi-order two-dimensional grating structure can be configured such that in the two-dimensional plane formed by the first dimension direction and the second dimension direction of the two-dimensional periodic array formed by the first cylinders 11, the projection of the second cylinders 12 in this two-dimensional plane is at least smaller than the projection of the corresponding first cylinders 11 in this two-dimensional plane in three directions (such as the transmission direction of the grating-coupled incident light, the transmission direction of the light turning on the left side of the grating, the transmission direction of the light turning on the right side of the grating, etc.), so that a gradient of height reduction can be formed in these directions.

[0051] It should be noted that the higher the order of the columnar array in the multi-order two-dimensional grating structure, the closer its side view is to a triangle, and the more significant the blazing characteristic. Therefore, in the solution of the present invention, by creating a series of different cylinders (such as the above-mentioned first cylinders 11 and second cylinders 12), a gradually changing stepped structure can be simulated, so that a grating structure approaching the required triangular pattern can be obtained. The blazed grating has a high reflection diffraction efficiency and a low transmission diffraction efficiency because the optical path of the light reaching the diffraction maximum point in each period unit is exactly the same, resulting in constructive superposition.

[0052] For the multi-order two-dimensional grating of the present invention, because its side view in the two main image beam expansion directions has the constructive superposition effect brought by the above steps, it can reduce the leakage light energy loss towards the world side and increase the energy utilization rate towards the human eye side. For example Figure 3 As shown, when the incident image light is coupled and output towards the observer's eye E along the arrow direction in the figure, each time the image light is coupled out, an outward transmission diffraction order T1 (i.e., the world side) and an inward reflection diffraction order R1 (i.e., the user side) will be generated simultaneously. Generally speaking, more image light needs to be directed towards the user side rather than the world side because the image light directed towards the world side is not only essentially wasted but also allows other people around the observer to see the output content unnecessarily, increasing the risk of information leakage. By adopting the multi-order two-dimensional grating structure of the present invention, the above very beneficial and remarkable technical effects can be achieved.

[0053] Continue to refer to Figure 4 , in this figure, the output diffraction efficiency curves of the respective transmission diffraction orders T1 and reflection diffraction orders R1 of the s-polarized light and p-polarized light transmitted in the third-order hexagonal array-coupled grating exemplified by Figure 2a and Figure 2b changing with the incident angle are shown. As Figure 4 shown, in the same polarization state, the diffraction efficiency of the reflection order R1 facing the user side can reach 2-3 times that of the transmission order T1 on the world side. It can be seen that by adopting the above solution according to the present invention, the reflection order R1 can be greatly enhanced, thereby improving the diffraction efficiency on the user side, and the transmission order T1 can be effectively suppressed, achieving quite good results.

[0054] In the above-introduced content, the three-order two-dimensional grating structure implemented according to the present invention has been described in combination with some specific examples. It should be understood that in addition to the above embodiments, the present invention also allows for the further setting of one or more additional arrays, in which one or more series of third cylinders can be provided.

[0055] Specifically, the third cylinders (not shown) can be respectively provided on the adjacent base surfaces. For example, they can be provided on the top surface of the existing second cylinder 12 in the multi-order two-dimensional grating structure to form a structure with three different cylinder period arrays, or they can also be provided on the top surface of the third cylinders in another additional array, thereby forming a structure with four, five or more different cylinder period arrays. This is very advantageous for fully and flexibly meeting any possible different requirements.

[0056] For each third cylinder, it also has a top surface and a bottom surface opposite to each other, and each bottom surface is included in the corresponding base surface described above, and the shape of the bottom surface is configured to be different from the bottom surface shape of the corresponding cylinder corresponding to the base surface (i.e., the above-mentioned second cylinder 12 or the third cylinder in another additional array), thereby forming a gradually changing stepped structure.

[0057] It should be noted that unless otherwise specified, the descriptions of the structural configurations, arrangements, etc. of the first cylinder or the second cylinder in the foregoing also apply to the third cylinder, so they will not be repeated here.

[0058] The above has introduced the basic structure, setting, advantages, etc. of the multi-order two-dimensional grating structure according to the present invention. Regarding the specific construction formation, implementation methods, etc. of the substrate, the first cylinder, the second cylinder, and the third cylinder among them, they will be described in detail subsequently in combination with the manufacturing method of the multi-order two-dimensional grating structure according to the present invention.

[0059] Based on the multi-order two-dimensional grating structure as described above, the present invention further provides an optical waveguide device. The optical waveguide device includes an optical waveguide substrate, an input coupling region, and an output coupling region, and the output coupling region can be configured to have a multi-order two-dimensional grating structure according to the present invention. When incident light is coupled into the optical waveguide substrate through the input coupling region of the optical waveguide device, it will then be coupled out through the above-mentioned output coupling region. In practical applications, the optical waveguide device can be configured into any suitable shape such as a sheet shape, a block shape, etc.

[0060] Due to the application of the multi-order two-dimensional grating structure as described above in the optical waveguide device, this not only makes the overall structure more compact, but also, because the multi-order two-dimensional grating structure has a high quality level and can especially reduce the energy loss of the transmitted diffracted light that often exists in the existing waveguide sheet and points to the world side, thereby improving the energy utilization rate and reducing the risk of information leakage. Therefore, the optical waveguide device provided by the present invention has obvious technical advantages and application values compared with the prior art.

[0061] In addition, the present invention also provides an AR device. One or more optical waveguide devices according to the present invention discussed above can be configured on the AR device, and an imaging device is arranged on the light incident side of the optical waveguide device to send image light rays to it and enter the coupling region of the optical waveguide device. In this way, in addition to the advantages such as being easy to achieve two-dimensional pupil expansion and having a large field of view angle, the AR device can especially effectively reduce the transmitted diffracted light to improve energy efficiency, enhance the battery life of the AR device, and improve the product competitiveness.

[0062] In addition, the present invention also provides a method for manufacturing a multi-order two-dimensional grating structure. Referring to Figure 5 , the following basic steps of the manufacturing method according to the present invention are shown in this figure:

[0063] First, a substrate can be provided in step S11. The substrate can be made of any suitable material that meets the application requirements, such as silicon, quartz, etc.

[0064] Then, in step S12, a plurality of first columns and a plurality of second columns can be constructed on the surface of the substrate to form an array group. Each of these first columns and second columns has a top surface and a bottom surface. Referring to the foregoing content, the bottom surface of each first column is located on the surface of the substrate provided in step S11, and these first columns are arranged in a two-dimensional periodic array, while these second columns are respectively located on the top surfaces of their corresponding first columns. The bottom surface of each second column is not only included in the top surface of the corresponding first column, but also has a different shape from the bottom surface shape of the corresponding first column. Thus, a multi-order two-dimensional grating structure can be manufactured.

[0065] As an alternative case, additional processing steps can be considered to be added alone or in combination in the method of the present invention.

[0066] For example, in some embodiments, on the basis of having constructed the array group formed by the above-mentioned first columns and second columns, a step of constructing one or more additional arrays can be further added. For example, such an additional array can be formed by continuing to construct a series of third columns to form a grating structure of three orders or more.

[0067] Specifically, a third cylinder can be constructed on the top surface of the second cylinder such that the bottom surface of the third cylinder is included within the top surface of the corresponding second cylinder, and the shape of the bottom surface of the third cylinder is different from the shape of the bottom surface of the corresponding second cylinder. Of course, it is also allowed to then construct another or more additional arrays on top of the completed additional array, that is, to construct the third cylinder in the next additional array on the top surface of the third cylinder in the previous additional array, with the bottom surface of the subsequent third cylinder located on the top surface of the adjacent previous third cylinder, and the shape of the bottom surface of the subsequent third cylinder being different from the shape of the bottom surface of the previous third cylinder.

[0068] For another example, in some embodiments, any feasible process steps can be considered to have a mask layer between the surface of the substrate and the bottom surface of the first cylinder, which will be described in more detail with reference to Figure 6i and other attached drawings.

[0069] To facilitate a better understanding of the technical solution of the present invention, the following will further illustrate the content of the method of the present invention through Figures 6a to 6j specific examples. However, it should be understood that the following description is only exemplary and should not form any limitation to the present invention, that is, the present invention completely allows other process procedures, operation steps, etc. to be used to fabricate a multi-order two-dimensional grating structure.

[0070] First, Figure 6a shows the starting substrate 10, which can be made of suitable materials such as silicon, quartz, etc., and generally has a shape such as a flat plate. Subsequently, relying on the substrate 10, cyclic process procedures such as depositing a buffer layer, coating a photoresist layer, performing photolithography, depositing a mask layer, and removing the remaining photoresist layer can be carried out in sequence as needed. Each processing cycle can generate one grating order, that is, more cyclic process procedures can be executed as needed to obtain more grating orders.

[0071] Next, Figure 6b shows that a mask layer S can be first deposited on the surface 101 of the substrate 10, which is used to resist the subsequent ion beam etching. Regarding the material, thickness, deposition method, etc. of the mask layer S, it can be set according to the specific application requirements. For example, it can use metal materials such as Au, Al, Ag, Ni, or Cr, or any suitable materials such as metal oxide materials such as SiO2 or TiO; the deposition method can use, for example, sputtering, evaporation, atomic layer deposition, etc.

[0072] Figures 6c - 6e and Figures 6f - 6h respectively show two cyclic process procedures. As shown in these attached drawings, in Figure 6c and Figure 6fThe first step in each cyclic process is shown, which is to deposit the substrate layer T. Specifically, the substrate layer T can be deposited on the surface of the substrate 10 or the currently exposed surface (such as the deposited mask layer S or substrate layer T), and this can be implemented using deposition methods such as sputtering, evaporation, or atomic layer deposition. The substrate layer T can have good etching selectivity, and the materials available for use can include but are not limited to, for example, Si, SiO2, SiN, etc. For the thickness of the substrate layer T, it can correspond to the first height of the aforementioned first column or the second height of the second column.

[0073] In Figure 6d and Figure 6g The second step in each cyclic process is shown, which is to further deposit the etching mask layer S on the substrate layer T. Specifically, a photoresist layer P can be first coated on the substrate layer T, and then a photolithography process (such as ultraviolet lithography, electron beam lithography, or nanoimprinting) can be used to process the photoresist layer so that the mask layer S can be deposited on this basis after photolithography. The mask layer S can generally adopt the metal materials, metal oxide materials, etc. as described above, and the thickness is generally not greater than 100 nm, for example, it can be between several nanometers and dozens of nanometers.

[0074] In Figure 6e and Figure 6h The third step in each cyclic process is shown, which is to remove the remaining photoresist layer P after the above operation process. This can be achieved by using a solvent to remove the remaining photoresist layer P, and the solvent used can depend on the type of photoresist used in the previous process. For example, when using the ZEP520 type of photoresist in electron beam lithography, solvents such as NMP (N-Methylpyrrolidone) can be considered for the photoresist removal treatment.

[0075] In Figure 6h Afterwards, it further shows Figure 6i , that is, for the structure shown in Figure 6h , a single etching method can be carried out to remove the part not covered by the mask layer, so as to obtain the array group structure formed by the first column and the second column as shown in Figure 6i . In the figure, the mask layer S retained between the surface 101 of the substrate 10 and the bottom surface 111 of the first column 11 is also shown. In the above process, due to the simplified adoption of a one-time etching treatment, the depth of each step in the grating can be precisely controlled, a higher vertical sidewall of the column can be achieved, and the corner quality can be improved, thus facilitating the acquisition of a high-quality multi-order two-dimensional grating.

[0076] From Figures 6i to 6jThe mask layer S adjacent to the surface 101 of the substrate 10 is further etched away, but this process is not necessary but optional. For example, when the mask layer S is made of metal material, it may be more easily oxidized in some cases, so etching it away will be more conducive to preservation. Figure 6j The step of removing the mask layer as shown may be advantageous in some cases, since this will simplify a processing step, help improve production efficiency and save costs.

[0077] As described above, by combining the series of process steps described in the above figures, a multi-order two-dimensional grating structure according to the present invention can be obtained. Figures 6i to 6j The finished product shown is used as a template to emboss a sub-template, which is then used to emboss a waveguide, so that the surface of the waveguide is finally obtained. Figure 6i or Figure 6j The same grating structure is shown.

[0078] The above is only an example to explain in detail the multi-order two-dimensional grating structure and its manufacturing method, optical waveguide device and AR device according to the present invention. These examples are only used to illustrate the principles and implementation methods of the present invention, but not to limit the present invention. Without departing from the spirit and scope of the present invention, those skilled in the art can also make various modifications and improvements. Therefore, all equivalent technical solutions should belong to the scope of the present invention and be defined by the claims of the present invention.

Claims

1. A multi - order two - dimensional grating structure, characterized in that, The multi - order two - dimensional grating structure has an array group, and the array group includes: a plurality of first cylinders, which are arranged on the surface of the substrate and arranged in a two - dimensional periodic array, wherein each first cylinder has a top surface and a bottom surface opposite to each other, and the bottom surface is located on the surface of the substrate; and a plurality of second cylinders, which are respectively arranged on the top surfaces of their corresponding first cylinders, wherein each second cylinder has a top surface and a bottom surface opposite to each other, the bottom surface of the second cylinder is included in the top surface of the corresponding first cylinder, and the shape of the bottom surface of the second cylinder is different from the shape of the bottom surface of the corresponding first cylinder; The central axis of the second cylinder is offset with respect to the central axis of the first cylinder, and in the two - dimensional plane composed of the first dimension direction and the second dimension direction of the two - dimensional periodic array, the projection of the second cylinder in this two - dimensional plane is at least smaller than the projection of the corresponding first cylinder in this two - dimensional plane in three directions.

2. The multi-level two-dimensional grating structure according to claim 1, wherein, The array group further includes one or more additional arrays, and the additional array includes: a plurality of third cylinders, which are respectively arranged on the base surface adjacent to the third cylinder, wherein each third cylinder has a top surface and a bottom surface opposite to each other, the bottom surface of the third cylinder is included in the base surface, and the shape of the bottom surface of the third cylinder is different from the shape of the bottom surface of the cylinder corresponding to the base surface, and the base surface is the top surface of the second cylinder in the array group.

3. The multi-level two-dimensional grating structure according to claim 1, wherein, The cross - sectional shape of the first cylinder and / or the second cylinder is configured to be circular, elliptical, polygonal, and any combination thereof, and / or the bottom surface of the second cylinder is proportionally reduced according to the bottom surface of the first cylinder at a preset reduction rate.

4. The multi-stage two-dimensional grating structure according to claim 3, wherein, The range of the reduction rate is 0.45 - 0.

65.

5. The multi-level two-dimensional grating structure according to claim 1, wherein, The bottom surface of the second cylinder is tangent to the bottom surface of the first cylinder, and the tangent point is located in the offset direction of the central axis of the second cylinder with respect to the central axis of the first cylinder.

6. The multi-level two-dimensional grating structure according to claim 1, wherein The first cylinder and the second cylinder respectively have a first height and a second height in the direction perpendicular to the surface of the substrate, the range of the first height is 30nm - 65nm, and the second height is substantially equivalent to the first height.

7. The multi-level two-dimensional grating structure according to any one of claims 1-6, wherein, The array group is arranged to protrude outward or recess inward from the surface of the substrate.

8. An optical waveguide device, comprising an optical waveguide substrate, an input region and an output region, wherein incident light is coupled into the optical waveguide substrate via the input region and then coupled out via the output region, characterized in that, The light - coupling - out region is configured to have a multi - order two - dimensional grating structure as described in any one of claims 1 - 7.

9. An AR device, characterized in that, The AR device includes: one or more optical waveguide devices as described in claim 8; and a projection device, which is arranged on the light - incident side of the optical waveguide device for emitting image light rays so that they are incident on the light - coupling - in region of the optical waveguide device.

10. A manufacturing method of a multi - order two - dimensional grating structure, characterized in that, Including steps: providing a substrate; and A plurality of first pillars and a plurality of second pillars are constructed on the surface of the substrate to form an array group, wherein each first pillar and each second pillar are configured to have a top surface and a bottom surface opposite to each other, the bottom surface of the first pillar is located on the surface of the substrate and the first pillars are arranged in a two-dimensional periodic array, the second pillars are respectively located on the top surfaces of the corresponding first pillars, the bottom surface of the second pillar is included in the top surface of the corresponding first pillar, and the shape of the bottom surface of the second pillar is different from the shape of the bottom surface of the corresponding first pillar; wherein the central axis of the second pillar is offset with respect to the central axis of the first pillar, and in the two-dimensional plane formed by the first dimension direction and the second dimension direction of the two-dimensional periodic array, the projection of the second pillar in this two-dimensional plane is at least smaller than the projection of the corresponding first pillar in this two-dimensional plane in three directions.

11. The manufacturing method of the multi-level two-dimensional grating structure according to claim 10, wherein, It further includes the steps of: Constructing one or more additional arrays to form an array group, the additional arrays being configured to include a plurality of third pillars, wherein each third pillar has a top surface and a bottom surface opposite to each other, the third pillars are respectively disposed on the base surfaces adjacent to the third pillars such that the bottom surface of the third pillar is included in the base surface, and the shape of the bottom surface of the third pillar is different from the shape of the bottom surface of the pillar corresponding to the base surface, and the base surface is the top surface of the second pillar in the array group.

12. The manufacturing method of the multi-level two-dimensional grating structure according to claim 10 or 11, wherein, The array group is constructed by performing the following steps at least twice and then etching: Depositing a buffer layer on the surface or the currently exposed surface of the substrate; Coating a photoresist layer on the buffer layer and performing photolithography, and then depositing a mask layer; and Removing the residual photoresist layer.

13. The manufacturing method of the multi-level two-dimensional grating structure according to claim 12, wherein, The buffer layer is formed by sputtering, evaporation or atomic layer deposition, and / or the material of the buffer layer includes Si, SiO2 or SiN.

14. The manufacturing method of the multi-level two-dimensional grating structure according to claim 12, wherein, The photolithography includes ultraviolet lithography, electron beam lithography and nanoimprinting, and / or the material of the mask layer includes a metal material or a metal oxide material, the metal material includes Au, Al, Ag, Ni or Cr, and the metal oxide material includes SiO2 or TiO2.

15. The manufacturing method of the multi-stage two-dimensional grating structure according to claim 12, wherein, A solvent is used to remove the residual photoresist layer, and the solvent is determined based on the type of the photoresist used.

16. The manufacturing method of the multi-level two-dimensional grating structure according to claim 12, wherein, The thickness of the buffer layer corresponds to a first height or a second height, and the first height and the second height are the heights of the first pillar and the second pillar in the direction perpendicular to the surface of the substrate respectively.

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