An ar diffractive waveguide and a method of manufacturing the same, and an ar optical device

Abstract

The application provides an AR diffraction waveguide and a preparation method thereof and an AR optical device, the AR diffraction waveguide comprising a substrate and a composite transition layer and a titanium dioxide functional layer which are sequentially arranged on the surface of the substrate; the composite transition layer comprises a titanium nitride containing bonding layer, a nitrogen-titanium oxygen gradient buffer layer and a titanium dioxide seed adaptation layer which are sequentially arranged, and the titanium nitride containing bonding layer is arranged on the side close to the substrate. By arranging the multilayer composite transition layer between the substrate and the titanium dioxide functional layer, the adhesion of the titanium dioxide functional layer and the substrate can be obviously improved, the optical performance of the AR diffraction waveguide can be improved, the preparation cost of the AR diffraction waveguide is low, the yield of mass production is high, and the demand for low cost, high optical transmission efficiency and long service life is met.

Description

An AR diffractive waveguide, its fabrication method, and AR optical devices Technical Field

[0001] This invention belongs to the field of optical device manufacturing technology, and relates to an AR diffraction waveguide, its preparation method, and AR optical devices. Background Technology

[0002] Augmented reality (AR) diffraction waveguides, as the core optical components of AR glasses, rely on high-refractive-index TiO2 thin films to complete the coupling, transmission, and emission of optical signals. The current mainstream method for preparing TiO2 thin films is "direct deposition on a glass substrate," but this technical route has three major drawbacks: Insufficient interfacial adhesion: Residual organic matter and moisture on the glass surface form an isolation layer, causing TiO2 to be bonded to the substrate only by weak van der Waals forces, which easily leads to film peeling and delamination during subsequent etching and annealing processes; Poor high-temperature process compatibility: Existing solutions to improve adhesion mostly use "high-temperature deposition of a transition layer at 300-400℃," while the glass substrate of AR diffraction waveguides is not resistant to high temperatures (easily softens and deforms at >300℃), leading to process conflicts; Weak performance balance: Existing transition layers are mostly single-layer structures (such as Ti and SiO2), which can only solve one problem of "adhesion" or "thermal stress," and cannot simultaneously take into account interfacial stability, low optical loss, and long-term reliability, making it difficult to meet the requirements of AR diffraction waveguides for optical transmission efficiency (>80%) and service life (no failure after 1000h of damp heat aging).

[0003] The aforementioned problems result in low mass production yield and high cost of AR diffractive waveguides, becoming a key bottleneck restricting the popularization of consumer-grade AR products. There is an urgent need for a TiO2 thin film preparation method that is compatible with glass substrates and takes into account both high adhesion and optical performance. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide an AR diffraction waveguide, its fabrication method, and an AR optical device. By setting a multilayer composite transition layer between the substrate and the titanium dioxide functional layer, the present invention can not only significantly improve the adhesion between the titanium dioxide functional layer and the substrate, but also improve the optical performance of the AR diffraction waveguide. Furthermore, the AR diffraction waveguide has low fabrication cost and high mass production yield, while simultaneously meeting the requirements of low cost, high optical transmission efficiency, and long service life.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides an AR diffraction waveguide, the AR diffraction waveguide comprising a substrate and a composite transition layer and a titanium dioxide functional layer stacked on the surface of the substrate;

[0007] The composite transition layer includes a titanium nitride bonding layer, a nitrogen-containing titanium oxygen gradient buffer layer, and a titanium dioxide seed layer stacked together, with the titanium nitride bonding layer disposed on the side close to the substrate.

[0008] Preferably, the thickness of the composite transition layer is 10nm to 17nm, for example: 10nm, 12nm, 14nm, 15nm, or 17nm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0009] Preferably, the thickness of the titanium nitride bonding layer is 5nm to 8nm, for example: 5nm, 5.5nm, 6nm, 7nm or 8nm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0010] Preferably, the thickness of the nitrogen-containing titanium-oxygen gradient buffer layer is 3nm to 5nm, for example: 3nm, 3.5nm, 4nm, 4.5nm or 5nm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0011] Preferably, the thickness of the titanium dioxide seed layer is 2nm to 4nm, for example: 2nm, 2.5nm, 3nm, 3.5nm or 4nm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0012] Preferably, the material of the titanium nitride bonding layer includes TiN and / or TiAlN.

[0013] Preferably, the material of the nitrogen-containing titanium-oxygen gradient buffer layer includes a titanium-nitrogen-oxygen mixed phase and a pure titanium-oxygen phase.

[0014] Preferably, the nitrogen element in the nitrogen-containing titanium-oxygen gradient buffer layer decreases in a gradient from the titanium nitride bonding layer side to the titanium dioxide seed adapter layer side.

[0015] Preferably, the crystal phase of the titanium dioxide seed adapter layer includes the anatase phase.

[0016] Preferably, the substrate comprises a transparent glass substrate.

[0017] Preferably, the thickness of the titanium dioxide functional layer is 50nm~150nm, for example: 50nm, 80nm, 100nm, 120nm or 150nm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0018] Secondly, the present invention provides a method for fabricating an AR diffraction waveguide, the method comprising the following steps:

[0019] A first titanium source and a nitrogen source are introduced into the substrate surface to perform a first deposition process, forming a titanium nitride bonding layer on the substrate surface;

[0020] A second titanium source and a first oxygen source are introduced for a second deposition process. By adjusting the ratio of the second titanium source and the first oxygen source, a nitrogen-containing titanium-oxygen gradient buffer layer is formed on the surface of the titanium-containing nitride bonding layer.

[0021] A third titanium source and a second oxygen source are introduced to perform a third deposition process, forming a titanium dioxide seed layer on the surface of a nitrogen-containing titanium-oxygen gradient buffer layer.

[0022] A fourth titanium source and a third oxygen source are introduced to perform a fourth deposition process, forming a titanium dioxide functional layer on the surface of the titanium dioxide seed adapter layer. After annealing and oxygen plasma treatment, the AR diffraction waveguide as described in the first aspect is obtained.

[0023] Preferably, the substrate is pretreated before the first deposition process, including sequential organic solvent washing, alkaline solution immersion, supercritical treatment, and plasma-ozone synergistic activation.

[0024] Preferably, the detergent used in the organic solvent wash includes acetone and / or isopropanol.

[0025] Preferably, the alkaline solution used for soaking in the alkaline solution includes a sodium hydroxide solution.

[0026] Preferably, the plasma-ozone synergistic activation includes plasma treatment by introducing a mixture of Ar and O2 gases, followed by irradiation with 185nm ultraviolet ozone.

[0027] Preferably, the first titanium source, the second titanium source, the third titanium source, and the fourth titanium source each independently comprise TiCl4.

[0028] Preferably, the nitrogen source includes ammonia.

[0029] Preferably, the first oxygen source, the second oxygen source, and the third oxygen source each independently include ozone.

[0030] Preferably, the first deposition process, the second deposition process, the third deposition process, and the fourth deposition process each independently include an atomic layer deposition process.

[0031] Preferably, the temperature of the first deposition treatment is 200℃~220℃, for example: 200℃, 205℃, 210℃, 215℃ or 220℃, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0032] Preferably, the temperature of the second deposition treatment is 200℃~230℃, for example: 200℃, 205℃, 210℃, 220℃ or 230℃, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0033] Preferably, the temperature of the third deposition process is 220℃~250℃, for example: 220℃, 225℃, 230℃, 240℃ or 250℃, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0034] Preferably, the fourth deposition process includes a preliminary deposition process, a middle deposition process, and a final deposition process performed sequentially. The preliminary deposition process includes performing the preliminary deposition process at 220℃~230℃, for example: 200℃, 205℃, 210℃, 220℃, or 230℃, etc., not limited to the listed values. Other unlisted values ​​within this range are also applicable. The preliminary deposition process is carried out until the thickness of the titanium dioxide functional layer is 15%~25% of the target titanium dioxide functional layer thickness, for example: 15%, 18%, 20%, 22%, or 25%, etc., not limited to the listed values. Other unlisted values ​​within this range are also applicable. The middle deposition process includes performing the preliminary deposition process at 230℃~250℃, for example: 2 The intermediate deposition process is performed at temperatures ranging from 30℃, 235℃, 240℃, 245℃, or 250℃, not limited to the listed values. Other unlisted values ​​within this range are also applicable. The intermediate deposition process is performed at temperatures ranging from 220℃ to 230℃, for example, 200℃, 205℃, 210℃, 220℃, or 230℃, not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0035] Preferably, the annealing atmosphere includes nitrogen.

[0036] Preferably, the annealing includes a first annealing at 140℃~160℃, for example: 140℃, 145℃, 150℃, 155℃ or 160℃, etc., not limited to the listed values, and other unlisted values ​​within this range are also applicable; a second annealing at 240℃~260℃, for example: 240℃, 245℃, 250℃, 255℃ or 260℃, etc., not limited to the listed values, and other unlisted values ​​within this range are also applicable; and a third annealing at 280℃~320℃, for example: 280℃, 290℃, 300℃, 310℃ or 320℃, etc., not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0037] Preferably, the power of the oxygen plasma treatment is 50W to 150W, for example: 50W, 80W, 100W, 120W or 150W, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0038] Thirdly, the present invention provides an AR optical device comprising the AR diffraction waveguide as described in the first aspect.

[0039] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] (1) By setting a multilayer composite transition layer between the substrate and the titanium dioxide functional layer, the present invention can not only significantly improve the adhesion between the titanium dioxide functional layer and the substrate, but also improve the optical performance of the AR diffraction waveguide. Moreover, the AR diffraction waveguide has low manufacturing cost and high mass production yield, while meeting the requirements of low cost, high light transmission efficiency and long service life.

[0042] (2) The interface adhesion of the AR diffraction waveguide of the present invention can reach level three (i.e., the peeling area is 5%~15%) or above, the optical transmission efficiency can reach 77% or above, and the damp heat aging failure time can reach 750h or above. By controlling the thickness of each layer, the interface adhesion of the AR diffraction waveguide can reach level one (i.e., no peeling), the optical transmission efficiency can reach 86% or above, and it does not fail after 1000h of damp heat aging. Attached Figure Description

[0043] Figure 1 is a schematic diagram of the AR diffraction waveguide provided in an embodiment of the present invention. 1 is the substrate, 2 is the titanium nitride bonding layer, 3 is the nitrogen-containing titanium oxygen gradient buffer layer, 4 is the titanium dioxide seed adapter layer, and 5 is the titanium dioxide functional layer. Detailed Implementation

[0044] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0045] The "range" disclosed in this invention can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. This type of range definition can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be arbitrarily combined, meaning any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0046] In this invention, "a combination of at least two" refers to a quantity greater than or equal to two, unless otherwise specified. For example, "any combination of one or at least two" means one or more or more items. It can be understood that when referring to "a combination of at least two," it refers to any suitable combination of multiple items, that is, a combination of "at least two" items carried out in a manner that does not conflict with and enables the implementation of this invention.

[0047] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0048] The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0049] Those skilled in the art will understand that the order in which the steps are written in the methods of the various embodiments does not imply a strict execution order. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, but are preferably performed sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), meaning that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0050] In this invention, open-ended technical features or solutions described using terms such as "comprising" do not exclude additional members beyond those listed unless otherwise specified. They can be considered as providing both closed-ended features or solutions comprised of the listed members and open-ended features or solutions that include additional members beyond the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or exclude additional members. This can be considered as providing both technical features or solutions where "A is composed of a1, a2, and a3" or "A is selected from a1, a2, and a3," and technical features or solutions where "A includes not only a1, a2, and a3, but also other members."

[0051] In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" represents a group consisting of A, B, and "a combination of A and B". "Containing A and / or B" can mean "containing A, containing B, and containing A and B", or "containing A, containing B, or containing A and B", and can be appropriately understood according to the context.

[0052] In this invention, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on the quantity.

[0053] In a first aspect, the present invention provides an AR diffraction waveguide, the AR diffraction waveguide comprising a substrate and a composite transition layer and a titanium dioxide functional layer stacked on the surface of the substrate;

[0054] The composite transition layer includes a titanium nitride bonding layer, a nitrogen-containing titanium oxygen gradient buffer layer, and a titanium dioxide seed layer stacked together, with the titanium nitride bonding layer disposed on the side close to the substrate.

[0055] In the AR diffraction waveguide described in this invention, a multi-layer composite transition layer is formed between the substrate and the titanium dioxide functional layer. The titanium nitride bonding layer forms stable Si-O-Ti-N covalent bonds with the hydroxyl groups on the glass surface, upgrading the traditional van der Waals bonding to chemical bonding, thus fundamentally improving the interfacial bonding strength. The nitrogen-containing titanium-oxygen gradient buffer layer alleviates the difference in thermal expansion coefficients between the bottom nitride and the top TiO2, preventing cracking caused by interfacial stress concentration and eliminating light reflection at the heterogeneous interface. The titanium dioxide seed layer is highly matched to the crystal phase and lattice parameters of the subsequent TiO2 functional layer, guiding the directional growth of the functional layer and reducing grain boundary defects. The synergistic effect of the multiple composite transition layers significantly enhances the bonding force between the titanium dioxide functional layer and the substrate.

[0056] Preferably, the thickness of the composite transition layer is 10nm to 17nm, for example: 10nm, 12nm, 14nm, 15nm, or 17nm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0057] Preferably, the thickness of the titanium nitride bonding layer is 5nm to 8nm, for example: 5nm, 5.5nm, 6nm, 7nm or 8nm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0058] Preferably, the thickness of the nitrogen-containing titanium-oxygen gradient buffer layer is 3nm to 5nm, for example: 3nm, 3.5nm, 4nm, 4.5nm or 5nm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0059] Preferably, the thickness of the titanium dioxide seed layer is 2nm to 4nm, for example: 2nm, 2.5nm, 3nm, 3.5nm or 4nm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0060] Preferably, the material of the titanium nitride bonding layer includes TiN and / or TiAlN.

[0061] Preferably, the material of the nitrogen-containing titanium-oxygen gradient buffer layer includes a titanium-nitrogen-oxygen mixed phase and a pure titanium-oxygen phase.

[0062] Preferably, the nitrogen element in the nitrogen-containing titanium-oxygen gradient buffer layer decreases in a gradient from the titanium nitride bonding layer side to the titanium dioxide seed adapter layer side.

[0063] In the nitrogen-containing titanium-oxygen gradient buffer layer of the present invention, the composition within the layer smoothly transitions from a "titanium-nitrogen-oxygen mixed phase" to a "pure titanium-oxygen phase," alleviating the difference in thermal expansion coefficients between the bottom nitride and the top TiO2, avoiding cracking caused by interface stress concentration, and simultaneously eliminating light reflection at the heterogeneous interface.

[0064] Preferably, the crystal phase of the titanium dioxide seed adapter layer includes the anatase phase.

[0065] Preferably, the substrate comprises a transparent glass substrate.

[0066] Preferably, the thickness of the titanium dioxide functional layer is 50nm~150nm, for example: 50nm, 80nm, 100nm, 120nm or 150nm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0067] Secondly, the present invention provides a method for fabricating an AR diffraction waveguide, the method comprising the following steps:

[0068] A first titanium source and a nitrogen source are introduced into the substrate surface to perform a first deposition process, forming a titanium nitride bonding layer on the substrate surface;

[0069] A second titanium source and a first oxygen source are introduced for a second deposition process. By adjusting the ratio of the second titanium source and the first oxygen source, a nitrogen-containing titanium-oxygen gradient buffer layer is formed on the surface of the titanium-containing nitride bonding layer.

[0070] A third titanium source and a second oxygen source are introduced to perform a third deposition process, forming a titanium dioxide seed layer on the surface of a nitrogen-containing titanium-oxygen gradient buffer layer.

[0071] A fourth titanium source and a third oxygen source are introduced to perform a fourth deposition process, forming a titanium dioxide functional layer on the surface of the titanium dioxide seed adapter layer. After annealing and oxygen plasma treatment, the AR diffraction waveguide as described in the first aspect is obtained.

[0072] Preferably, the substrate is pretreated before the first deposition process, including sequential organic solvent washing, alkaline solution immersion, supercritical treatment, and plasma-ozone synergistic activation.

[0073] This invention pre-cleans and activates the substrate. First, it removes surface oil by ultrasonic cleaning with an organic solvent (acetone / isopropanol), then removes inorganic impurities by soaking in a weakly alkaline solution, and finally removes residual moisture and organic matter in the micropores of the substrate through supercritical treatment. Plasma-ozone synergistic activation: an Ar / O2 mixed gas is introduced for plasma treatment, followed by 185nm ultraviolet ozone irradiation to form high-density hydroxyl (-OH) active sites on the glass surface, reducing the surface contact angle to below 5°, laying the foundation for subsequent chemical bonding.

[0074] Preferably, the detergent used in the organic solvent wash includes acetone and / or isopropanol.

[0075] Preferably, the alkaline solution used for soaking in the alkaline solution includes a sodium hydroxide solution.

[0076] Preferably, the plasma-ozone synergistic activation includes plasma treatment by introducing a mixture of Ar and O2 gases, followed by irradiation with 185nm ultraviolet ozone.

[0077] Preferably, the first titanium source, the second titanium source, the third titanium source, and the fourth titanium source each independently comprise TiCl4.

[0078] Preferably, the nitrogen source includes ammonia.

[0079] Preferably, the first oxygen source, the second oxygen source, and the third oxygen source each independently include ozone.

[0080] Preferably, the first deposition process, the second deposition process, the third deposition process, and the fourth deposition process each independently include an atomic layer deposition process.

[0081] Preferably, the temperature of the first deposition treatment is 200℃~220℃, for example: 200℃, 205℃, 210℃, 215℃ or 220℃, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0082] The present invention performs a first deposition process at 200℃~220℃. Through the atomic-level densification process of ALD (porosity <1%), the nitride reacts chemically with the hydroxyl groups on the glass surface to form stable Si-O-Ti-N covalent bonds, upgrading the traditional van der Waals force bonding to chemical bonding, thereby improving the interfacial bonding strength from the root.

[0083] Preferably, the temperature of the second deposition treatment is 200℃~230℃, for example: 200℃, 205℃, 210℃, 220℃ or 230℃, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0084] In the second deposition process, this invention adjusts the pulse ratio of the two precursors to smoothly transition the composition within the layer from a "titanium-nitrogen-oxygen mixed phase" to a "pure titanium-oxygen phase," thereby alleviating the difference in thermal expansion coefficients between the bottom nitride and the top TiO2, avoiding cracking caused by interface stress concentration, and eliminating light reflection at the heterogeneous interface.

[0085] Preferably, the temperature of the third deposition process is 220℃~250℃, for example: 220℃, 225℃, 230℃, 240℃ or 250℃, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0086] In the third deposition process, this invention uses a TiCl4+O3 precursor that is consistent with the subsequent functional layers, and deposits it at 220℃~250℃. The process parameters are controlled to ensure that the seed layer is anatase phase, which is highly matched with the crystal phase and lattice parameters of the subsequent TiO2 functional layer, guiding the directional growth of the functional layer and reducing grain boundary defects.

[0087] Preferably, the fourth deposition process includes a preliminary deposition process, a middle deposition process, and a final deposition process performed sequentially. The preliminary deposition process includes performing the preliminary deposition process at 220℃~230℃, for example: 200℃, 205℃, 210℃, 220℃, or 230℃, etc., not limited to the listed values. Other unlisted values ​​within this range are also applicable. The preliminary deposition process is carried out until the thickness of the titanium dioxide functional layer is 15%~25% of the target titanium dioxide functional layer thickness, for example: 15%, 18%, 20%, 22%, or 25%, etc., not limited to the listed values. Other unlisted values ​​within this range are also applicable. The middle deposition process includes performing the preliminary deposition process at 230℃~250℃, for example: 2 The intermediate deposition process is performed at temperatures ranging from 30℃, 235℃, 240℃, 245℃, or 250℃, not limited to the listed values. Other unlisted values ​​within this range are also applicable. The intermediate deposition process is performed at temperatures ranging from 220℃ to 230℃, for example, 200℃, 205℃, 210℃, 220℃, or 230℃, not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0088] The thickness of the titanium dioxide functional layer in each deposition process described in this invention is the total thickness of the titanium dioxide functional layer.

[0089] The fourth deposition process of this invention includes a preliminary deposition process, a middle deposition process, and a final deposition process performed sequentially. The preliminary deposition process is performed at 220℃~230℃ to ensure a tight bond between the titanium dioxide functional layer and the seed layer. The middle deposition process is performed at 230℃~250℃ to improve the film density and refractive index uniformity (stabilizing at 2.4-2.5). The final deposition process is performed at 220℃~230℃ to reduce residual stress in the film (down to <50MPa) and prevent internal stress from damaging the interfacial bonding.

[0090] Preferably, the annealing atmosphere includes nitrogen.

[0091] Preferably, the annealing includes a first annealing at 140℃~160℃, for example: 140℃, 145℃, 150℃, 155℃ or 160℃, etc., not limited to the listed values, and other unlisted values ​​within this range are also applicable; a second annealing at 240℃~260℃, for example: 240℃, 245℃, 250℃, 255℃ or 260℃, etc., not limited to the listed values, and other unlisted values ​​within this range are also applicable; and a third annealing at 280℃~320℃, for example: 280℃, 290℃, 300℃, 310℃ or 320℃, etc., not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0092] This invention stabilizes the TiO2 anatase crystal phase through stepwise annealing, releasing residual stress in each layer.

[0093] Preferably, the power of the oxygen plasma treatment is 50W to 150W, for example: 50W, 80W, 100W, 120W or 150W, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0094] Thirdly, the present invention provides an AR optical device comprising the AR diffraction waveguide as described in the first aspect.

[0095] In the AR diffraction waveguide of the present invention, the bonding strength between the TiO2 thin film and the substrate meets the requirements of subsequent AR diffraction waveguide processes and long-term use, and is suitable for AR optical device production scenarios that require efficient control of optical signals through TiO2 thin films.

[0096] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0097] Example 1

[0098] This embodiment provides an AR diffraction waveguide. The structural schematic diagram of the AR diffraction waveguide is shown in Figure 1. The AR diffraction waveguide includes a substrate 1 and a titanium nitride bonding layer 2, a nitrogen-containing titanium oxygen gradient buffer layer 3, a titanium dioxide seed adapter layer 4, and a titanium dioxide functional layer 5 stacked on the surface of the substrate.

[0099] The thickness of the composite transition layer is 13 nm, the thickness of the titanium nitride bonding layer is 6 nm, the thickness of the nitrogen-containing titanium oxygen gradient buffer layer is 4 nm, the thickness of the titanium dioxide seed adapter layer is 3 nm, and the thickness of the titanium dioxide functional layer is 80 nm.

[0100] The substrate is a transparent glass substrate for AR diffraction waveguides. The material of the titanium nitride bonding layer is TiN. The material of the nitrogen-containing titanium oxide gradient buffer layer includes a titanium nitrogen-oxygen mixed phase and a pure titanium oxide phase. The nitrogen element in the nitrogen-containing titanium oxide gradient buffer layer decreases in a gradient from the titanium nitride bonding layer side to the titanium dioxide seed adapter layer side. The crystal phase of the titanium oxide seed adapter layer is anatase.

[0101] The AR diffraction waveguide is fabricated by the following method:

[0102] First, the transparent glass substrate is ultrasonically cleaned with acetone and isopropanol to remove surface oil. Then, it is soaked in sodium hydroxide solution to remove inorganic impurities. After that, residual moisture and organic matter in the micropores of the substrate are removed by supercritical treatment. Then, Ar / O2 mixed gas (volume ratio of 4:1) is introduced for plasma treatment. Then, 185nm ultraviolet ozone irradiation is used to form high-density hydroxyl active sites on the glass surface, so that the surface contact angle is reduced to below 5°, thus completing the pretreatment.

[0103] TiCl4 and ammonia were introduced and the first atomic layer deposition was performed at 210°C to form a titanium nitride bonding layer.

[0104] TiCl4 and ozone were introduced at 220°C, and the second atomic layer deposition process was carried out by adjusting the pulse ratio of the two precursors. This process allowed the composition within the layer to smoothly transition from a "mixed phase of titanium nitrogen and oxygen" to a "pure phase of titanium oxygen," forming a nitrogen-containing titanium oxygen gradient buffer layer.

[0105] TiCl4 and ozone were introduced at 240°C to perform a third atomic layer deposition process, forming an anatase phase titanium dioxide seed layer;

[0106] TiCl4 and ozone were introduced to perform initial atomic layer deposition at 225°C to form a titanium dioxide functional layer with a target thickness of 20%. Then, intermediate atomic layer deposition was performed at 240°C to form a titanium dioxide functional layer with a target thickness of 80%. Finally, the final atomic layer deposition was completed at 225°C.

[0107] After stepwise annealing at 150℃ / 30min-250℃ / 20min-300℃ / 10min in an N2 atmosphere, oxygen plasma treatment was performed at 80W to obtain the AR diffraction waveguide.

[0108] Example 2

[0109] This embodiment provides an AR diffraction waveguide. The structural schematic diagram of the AR diffraction waveguide is shown in Figure 1. The AR diffraction waveguide includes a substrate 1 and a titanium nitride bonding layer 2, a nitrogen-containing titanium oxygen gradient buffer layer 3, a titanium dioxide seed adapter layer 4, and a titanium dioxide functional layer 5 stacked on the surface of the substrate.

[0110] The composite transition layer has a thickness of 10 nm, the titanium nitride bonding layer has a thickness of 5 nm, the nitrogen-containing titanium oxygen gradient buffer layer has a thickness of 3 nm, the titanium dioxide seed adapter layer has a thickness of 2 nm, and the titanium dioxide functional layer has a thickness of 50 nm.

[0111] The substrate is a transparent glass substrate for AR diffraction waveguides. The material of the titanium nitride bonding layer is TiN. The material of the nitrogen-containing titanium oxide gradient buffer layer includes a titanium nitrogen-oxygen mixed phase and a pure titanium oxide phase. The nitrogen element in the nitrogen-containing titanium oxide gradient buffer layer decreases in a gradient from the titanium nitride bonding layer side to the titanium dioxide seed adapter layer side. The crystal phase of the titanium oxide seed adapter layer is anatase.

[0112] The AR diffraction waveguide is fabricated by the following method:

[0113] First, the transparent glass substrate is ultrasonically cleaned with acetone and isopropanol to remove surface oil. Then, it is soaked in sodium hydroxide solution to remove inorganic impurities. After that, residual moisture and organic matter in the micropores of the substrate are removed by supercritical treatment. Then, Ar / O2 mixed gas (volume ratio of 4:1) is introduced for plasma treatment. Then, 185nm ultraviolet ozone irradiation is used to form high-density hydroxyl active sites on the glass surface, so that the surface contact angle is reduced to below 5°, thus completing the pretreatment.

[0114] TiCl4 and ammonia were introduced and the first atomic layer deposition process was carried out at 200°C to form a titanium nitride bonding layer.

[0115] TiCl4 and ozone were introduced at 200°C, and the second atomic layer deposition process was carried out by adjusting the pulse ratio of the two precursors. This process allowed the composition within the layer to smoothly transition from a "mixed phase of titanium nitrogen and oxygen" to a "pure phase of titanium oxygen," forming a nitrogen-containing titanium oxygen gradient buffer layer.

[0116] TiCl4 and ozone were introduced at 220°C to perform a third atomic layer deposition process, forming an anatase phase titanium dioxide seed layer;

[0117] TiCl4 and ozone were introduced to perform initial atomic layer deposition at 220°C to form a titanium dioxide functional layer with a target thickness of 15%. Then, intermediate atomic layer deposition was performed at 230°C to form a titanium dioxide functional layer with a target thickness of 75%. Finally, the final atomic layer deposition was completed at 220°C.

[0118] After stepwise annealing at 140℃ / 40min-240℃ / 25min-280℃ / 15min in an N2 atmosphere, oxygen plasma treatment at 50W is performed to obtain the AR diffraction waveguide.

[0119] Example 3

[0120] This embodiment provides an AR diffraction waveguide. The structural schematic diagram of the AR diffraction waveguide is shown in Figure 1. The AR diffraction waveguide includes a substrate 1 and a titanium nitride bonding layer 2, a nitrogen-containing titanium oxygen gradient buffer layer 3, a titanium dioxide seed adapter layer 4, and a titanium dioxide functional layer 5 stacked on the surface of the substrate.

[0121] The thickness of the composite transition layer is 17 nm, the thickness of the titanium nitride bonding layer is 8 nm, the thickness of the nitrogen-containing titanium oxygen gradient buffer layer is 5 nm, the thickness of the titanium dioxide seed adapter layer is 4 nm, and the thickness of the titanium dioxide functional layer is 150 nm.

[0122] The substrate is a transparent glass substrate for AR diffraction waveguides. The material of the titanium nitride bonding layer is TiN. The material of the nitrogen-containing titanium oxide gradient buffer layer includes a titanium nitrogen-oxygen mixed phase and a pure titanium oxide phase. The nitrogen element in the nitrogen-containing titanium oxide gradient buffer layer decreases in a gradient from the titanium nitride bonding layer side to the titanium dioxide seed adapter layer side. The crystal phase of the titanium oxide seed adapter layer is anatase.

[0123] The AR diffraction waveguide is fabricated by the following method:

[0124] First, the transparent glass substrate is ultrasonically cleaned with acetone and isopropanol to remove surface oil. Then, it is soaked in sodium hydroxide solution to remove inorganic impurities. After that, residual moisture and organic matter in the micropores of the substrate are removed by supercritical treatment. Then, Ar / O2 mixed gas (volume ratio of 4:1) is introduced for plasma treatment. Then, 185nm ultraviolet ozone irradiation is used to form high-density hydroxyl active sites on the glass surface, so that the surface contact angle is reduced to below 5°, thus completing the pretreatment.

[0125] TiCl4 and ammonia were introduced and the first atomic layer deposition process was carried out at 220°C to form a titanium nitride bonding layer.

[0126] TiCl4 and ozone were introduced at 230°C, and the second atomic layer deposition process was carried out by adjusting the pulse ratio of the two precursors. This process allowed the composition within the layer to smoothly transition from a "mixed phase of titanium nitrogen and oxygen" to a "pure phase of titanium oxygen," forming a nitrogen-containing titanium oxygen gradient buffer layer.

[0127] TiCl4 and ozone were introduced at 250°C to perform a third atomic layer deposition process, forming an anatase phase titanium dioxide seed layer;

[0128] TiCl4 and ozone were introduced to perform initial atomic layer deposition at 230°C to form a titanium dioxide functional layer with a target thickness of 25%. Then, intermediate atomic layer deposition was performed at 250°C to form a titanium dioxide functional layer with a target thickness of 85%. Finally, the final atomic layer deposition was completed at 230°C.

[0129] After stepwise annealing at 160℃ / 35min-260℃ / 20min-320℃ / 25min in an N2 atmosphere, oxygen plasma treatment at 150W is performed to obtain the AR diffraction waveguide.

[0130] Example 4

[0131] The only difference between this embodiment and Embodiment 1 is that the thickness of the titanium nitride bonding layer is 4 nm, while the other conditions and parameters are exactly the same as in Embodiment 1.

[0132] Example 5

[0133] The only difference between this embodiment and Embodiment 1 is that the thickness of the titanium nitride bonding layer is 9 nm, while the other conditions and parameters are exactly the same as in Embodiment 1.

[0134] Example 6

[0135] The only difference between this embodiment and Embodiment 1 is that the thickness of the nitrogen-containing titanium-oxygen gradient buffer layer is 2 nm. All other conditions and parameters are exactly the same as in Embodiment 1.

[0136] Example 7

[0137] The only difference between this embodiment and Embodiment 1 is that the thickness of the nitrogen-containing titanium-oxygen gradient buffer layer is 6 nm. All other conditions and parameters are exactly the same as in Embodiment 1.

[0138] Example 8

[0139] The only difference between this embodiment and Embodiment 1 is that the thickness of the titanium dioxide seed layer is 1 nm. All other conditions and parameters are exactly the same as in Embodiment 1.

[0140] Example 9

[0141] The only difference between this embodiment and Embodiment 1 is that the thickness of the titanium dioxide seed layer is 5 nm. All other conditions and parameters are exactly the same as in Embodiment 1.

[0142] Comparative Example 1

[0143] The only difference between this comparative example and Example 1 is that no titanium nitride bonding layer is provided; all other conditions and parameters are exactly the same as in Example 1.

[0144] Comparative Example 2

[0145] The only difference between this comparative example and Example 1 is that the nitrogen-containing titanium-oxygen gradient buffer layer is not set; all other conditions and parameters are exactly the same as in Example 1.

[0146] Comparative Example 3

[0147] The only difference between this comparative example and Example 1 is that the titanium dioxide seed adapter layer is not provided; all other conditions and parameters are exactly the same as in Example 1.

[0148] Performance testing:

[0149] The AR diffraction waveguides obtained in the embodiments and comparative examples were tested as follows:

[0150] 1. Interface adhesion test

[0151] Test steps:

[0152] Select an effective area of ​​the wafer (avoiding the edge by 5mm), and use a cross-cutting tool to make 100 squares of 1mm × 1mm on the surface of the titanium dioxide functional layer, cutting through to the glass substrate (ensuring that the cuts leave no residual film).

[0153] Wipe the surface dust with anhydrous ethanol, apply 3M 610 high-tack tape, and roll it three times at a uniform speed with a 2kg weight to ensure that the tape and film are completely adhered (without air bubbles).

[0154] Tearing the tape quickly at a 180° angle (tearing time ≤ 0.5s), then observing the film residue within the squares using a stereomicroscope (20x magnification);

[0155] Rating criteria: Level 1 (no shedding), Level 2 (shedding area <5%), Level 3 (shedding area 5%-15%), Level 4 (shedding area 15%-35%), Level 5 (shedding area >35%). Record the rating results.

[0156] 2. Optical transmission efficiency test

[0157] Test steps:

[0158] A UV-Vis-NIR spectrophotometer (accuracy ±0.1%) was used, with the test wavelength range set to 400nm-700nm (the core working band of AR glasses), and the scanning interval to 5nm.

[0159] Using blank transparent glass substrates from the same batch as a reference sample, the instrument baseline was calibrated.

[0160] The optical waveguide wafer sample is fixed on the sample stage, ensuring that the test area is free of scratches and stains, and transmittance scanning is performed to obtain the full-band transmittance curve.

[0161] Calculate the average optical transmission efficiency in the 400nm-700nm band (formula: average transmittance = ∑ transmittance of each wavelength / number of test wavelengths), and record the value (retain 1 decimal place).

[0162] 3. Damp heat aging life test

[0163] Test steps:

[0164] Three wafer samples were selected, cut into 2cm × 2cm test pieces, and the initial optical transmission efficiency (E) was marked. o );

[0165] Place in a damp heat aging chamber and set the conditions as follows: temperature 85℃, relative humidity 85%RH, and test continuously for 1000 hours (without interruption).

[0166] Samples were taken out every 200 hours, cooled to room temperature (25°C), and observed for failure phenomena such as peeling, cracking, and discoloration on the film surface. At the same time, the light transmission efficiency (En) was retested.

[0167] Calculate the efficiency decay rate (decay rate = (E) o -E n ) / E o (×100%), record whether it fails after 1000h and the final decay rate. The test results are shown in Table 1:

[0168] Table 1

[0169]

[0170] As can be seen from Table 1, and from Examples 1 to 9, the interface adhesion of the AR diffractive waveguide of the present invention can reach level three (i.e., detachment area of ​​5% to 15%) or higher, the optical transmission efficiency can reach 77% or higher, and the damp heat aging failure time can reach 750 hours or higher. By controlling the thickness of each layer, the interface adhesion of the AR diffractive waveguide can reach level one (i.e., no detachment), the optical transmission efficiency can reach 86% or higher, and it can remain unfailed after 1000 hours of damp heat aging.

[0171] A comparison of Examples 1 and 4-5 shows that the thickness of the titanium nitride bonding layer in the AR diffraction waveguide of the present invention affects its performance. Controlling the thickness of the titanium nitride bonding layer to 5nm-8nm results in better performance of the AR diffraction waveguide. If the thickness of the titanium nitride bonding layer is too small, it cannot fully react with the hydroxyl groups on the glass surface to form sufficient Si-O-Ti-N covalent bonds, leading to insufficient interfacial bonding strength. This can easily cause film peeling and delamination during subsequent etching and annealing processes, and weakens the support and adaptation effect on subsequent layers, resulting in a decrease in overall optical performance stability. If the thickness of the titanium nitride bonding layer is too large, it will lead to stress accumulation within the layer and poor transition between the composition of the titanium-nitrogen gradient buffer layer and the layer, causing interfacial stress concentration and cracking. Furthermore, excessive nitride content will disrupt the continuity of the optical refractive index, increase light reflection loss, reduce light transmission efficiency, and increase fabrication costs and process control difficulty.

[0172] A comparison of Examples 1 and 6-7 shows that the thickness of the nitrogen-containing titanium oxide gradient buffer layer in the AR diffraction waveguide of the present invention affects its performance. Controlling the thickness of the nitrogen-containing titanium oxide gradient buffer layer to 3nm-5nm results in better performance of the AR diffraction waveguide. If the thickness of the nitrogen-containing titanium oxide gradient buffer layer is too small, it cannot adequately alleviate the difference in thermal expansion coefficients between the titanium nitride bonding layer and the titanium dioxide seed layer, leading to significant interface stress concentration and a tendency to crack. Simultaneously, it is difficult to completely eliminate light reflection at the heterogeneous interface, resulting in increased light transmission loss and decreased optical performance stability. If the thickness of the nitrogen-containing titanium oxide gradient buffer layer is too large, the compositional gradient transition within the layer will become uneven, accumulating internal stress and increasing the risk of film cracking. Furthermore, an excessively thick buffer layer will disrupt the continuity of the overall optical refractive index, exacerbating light reflection and scattering, reducing light transmission efficiency, and also prolonging the deposition process time, increasing fabrication costs and the difficulty of parameter control.

[0173] A comparison of Examples 1 and 8-9 shows that the thickness of the titanium dioxide seed layer in the AR diffraction waveguide of the present invention affects its performance. Controlling the thickness of the titanium dioxide seed layer to 2nm-4nm results in better performance of the AR diffraction waveguide. If the thickness of the titanium dioxide seed layer is too small, it cannot provide sufficient anatase phase seed sites, leading to insufficient matching of the crystal phase and lattice parameters with the subsequent titanium dioxide functional layer. This makes it difficult to guide the directional growth of the functional layer, resulting in increased grain boundary defects and increased light transmission loss. Furthermore, the loose interlayer bonding indirectly reduces the interface stability of the overall structure. If the thickness of the titanium dioxide seed layer is too large, it will cause stress accumulation within the layer, easily leading to stress conflicts with the nitrogen-containing titanium-oxygen gradient buffer layer and the titanium dioxide functional layer, causing microcracks in the thin film. Simultaneously, an excessively thick seed layer will disrupt the continuous transition of optical refractive index, increase light reflection at the heterojunction, reduce light transmission efficiency, prolong the deposition process cycle, and increase the fabrication cost.

[0174] As can be seen from the comparison between Example 1 and Comparative Example 1, in the AR diffraction waveguide of the present invention, a stable Si-O-Ti-N covalent bond is formed between the titanium nitride bonding layer and the hydroxyl group on the glass surface, which upgrades the traditional van der Waals force bonding to chemical bonding, thereby improving the interfacial bonding strength from the source.

[0175] As can be seen from the comparison between Example 1 and Comparative Example 2, in the AR diffraction waveguide of the present invention, the nitrogen-containing titanium-oxygen gradient buffer layer can alleviate the difference in thermal expansion coefficients between the bottom nitride and the top TiO2, avoid cracking caused by interface stress concentration, and eliminate light reflection at the heterogeneous interface.

[0176] As can be seen from the comparison between Example 1 and Comparative Example 3, in the AR diffraction waveguide of the present invention, the phase and lattice parameters of the titanium dioxide seed adapter layer are highly matched with those of the subsequent TiO2 functional layer, which guides the directional growth of the functional layer and reduces grain boundary defects.

[0177] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. An AR diffraction waveguide, characterized in that, The AR diffraction waveguide includes a substrate and a composite transition layer and a titanium dioxide functional layer stacked on the surface of the substrate; the composite transition layer includes a titanium nitride bonding layer, a nitrogen-containing titanium oxygen gradient buffer layer and a titanium dioxide seed adapter layer stacked sequentially, the titanium nitride bonding layer being disposed on the side close to the substrate; the substrate includes a transparent glass substrate.

2. The AR diffraction waveguide as described in claim 1, characterized in that, The thickness of the composite transition layer is 10 nm to 17 nm.

3. The AR diffraction waveguide as described in claim 1, characterized in that, The thickness of the titanium nitride bonding layer is 5 nm to 8 nm.

4. The AR diffraction waveguide as described in claim 1, characterized in that, The thickness of the nitrogen-containing titanium oxide gradient buffer layer is 3nm~5nm.

5. The AR diffraction waveguide as described in claim 1, characterized in that, The thickness of the titanium dioxide seed layer is 2nm~4nm.

6. The AR diffraction waveguide as described in claim 1, characterized in that, The material of the titanium nitride bonding layer includes TiN and / or TiAlN.

7. The AR diffraction waveguide as described in claim 1, characterized in that, The nitrogen-containing titanium-oxygen gradient buffer layer is made of a titanium-nitrogen-oxygen mixed phase and a pure titanium-oxygen phase.

8. The AR diffraction waveguide as described in claim 1, characterized in that, In the nitrogen-containing titanium-oxygen gradient buffer layer, the nitrogen element decreases in a gradient from the titanium nitride bonding layer side to the titanium dioxide seed adapter layer side.

9. The AR diffraction waveguide as described in claim 1, characterized in that, The phase of the titanium dioxide seed adapter layer includes the anatase phase.

10. The AR diffractive waveguide as described in claim 1, characterized in that, The thickness of the titanium dioxide functional layer is 50nm~150nm.

11. A method for fabricating an AR diffractive waveguide, characterized in that, The preparation method includes the following steps: a first deposition treatment is performed by introducing a first titanium source and a nitrogen source onto the substrate surface to form a titanium nitride bonding layer on the substrate surface; a second deposition treatment is performed by introducing a second titanium source and a first oxygen source to form a nitrogen-containing titanium-oxygen gradient buffer layer on the surface of the titanium nitride bonding layer by adjusting the ratio of the second titanium source and the first oxygen source; a third deposition treatment is performed by introducing a third titanium source and a second oxygen source to form a titanium dioxide seed adapter layer on the surface of the nitrogen-containing titanium-oxygen gradient buffer layer; a fourth deposition treatment is performed by introducing a fourth titanium source and a third oxygen source to form a titanium dioxide functional layer on the surface of the titanium dioxide seed adapter layer; and after annealing and oxygen plasma treatment, the AR diffraction waveguide as described in any one of claims 1-10 is obtained.

12. The preparation method according to claim 11, characterized in that, Prior to the first deposition process, the substrate is pretreated, including sequential organic solvent washing, alkaline solution immersion, supercritical treatment, and plasma-ozone synergistic activation.

13. The preparation method according to claim 11, characterized in that, The first titanium source, the second titanium source, the third titanium source, and the fourth titanium source each independently include TiCl4.

14. The preparation method according to claim 11, characterized in that, The nitrogen source includes ammonia.

15. The preparation method according to claim 11, characterized in that, The first oxygen source, the second oxygen source, and the third oxygen source each independently include ozone.

16. The preparation method according to claim 11, characterized in that, The first deposition process, the second deposition process, the third deposition process, and the fourth deposition process each independently include atomic layer deposition processes.

17. The preparation method according to claim 16, characterized in that, The temperature of the first deposition treatment is 200℃~220℃.

18. The preparation method according to claim 16, characterized in that, The temperature for the second deposition treatment is 200℃~230℃.

19. The preparation method according to claim 16, characterized in that, The temperature for the third deposition process is 220℃~250℃.

20. The preparation method according to claim 16, characterized in that, The fourth deposition process includes a preliminary deposition process, a middle deposition process, and a final deposition process performed sequentially. The preliminary deposition process includes performing a preliminary deposition process at 220℃~230℃ until the thickness of the titanium dioxide functional layer is 15%~25% of the target titanium dioxide functional layer thickness. The middle deposition process includes performing a middle deposition process at 230℃~250℃ until the thickness of the titanium dioxide functional layer is 75%~85% of the target titanium dioxide functional layer thickness. The final deposition process includes performing a final deposition process at 220℃~230℃.

21. The preparation method according to claim 11, characterized in that, The annealing atmosphere includes nitrogen.

22. The preparation method according to claim 11, characterized in that, The annealing process includes a first annealing at 140°C to 160°C, a second annealing at 240°C to 260°C, and a third annealing at 280°C to 320°C.

23. The preparation method according to claim 11, characterized in that, The power of the oxygen plasma treatment is 50W~150W.

24. An AR optical device, characterized in that, The AR optical device includes an AR diffraction waveguide as described in any one of claims 1-10.

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