Method for manufacturing optical waveguide structure, optical waveguide structure, and display device

Abstract

A method for manufacturing an optical waveguide structure, an optical waveguide structure, and a display device, which belong to the technical field of display. The method for manufacturing an optical waveguide structure comprises: providing a first waveguide layer (1) and a second waveguide layer (2), wherein the refractive index of the first waveguide layer (1) is greater than that of the second waveguide layer (2); bonding the first waveguide layer (1) to the second waveguide layer (2); and forming a grating layer (4) on the side of the first waveguide layer (1) facing away from the second waveguide layer (2).

Description

Method for manufacturing optical waveguide structure, optical waveguide structure and display device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based on the Chinese application with application number 202410093799.7 and application date January 23, 2024, and claims its priority. The disclosed content of the Chinese application is hereby introduced as a whole into this application. Technical Field

[0003] The present application belongs to the field of display technology, and in particular relates to a method for manufacturing an optical waveguide structure, an optical waveguide structure, and a display device. Background Art

[0004] Augmented reality (AR) technology combines virtual information with the real world. Optical display technologies primarily include arrayed waveguides, volume holography, birdbaths, and freeform surfaces. Diffractive waveguides based on surface relief have become a mainstream optical display solution due to their advantages, including small size, light weight, high transmittance, and ease of fabrication into desired display devices (such as glasses). Optical waveguide structures are essential components in diffractive waveguide solutions.

[0005] Summary of the Invention

[0006] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes a method for manufacturing an optical waveguide structure, an optical waveguide structure, and a display device.

[0007] In a first aspect, the present application provides a method for manufacturing an optical waveguide structure, comprising:

[0008] providing a first waveguide layer and a second waveguide layer, the first waveguide layer having a refractive index greater than a refractive index of the second waveguide layer;

[0009] bonding the first waveguide layer to the second waveguide layer;

[0010] A grating layer is formed on a side of the first waveguide layer facing away from the second waveguide layer.

[0011] According to one embodiment of the present application, bonding the first waveguide layer to the second waveguide layer includes:

[0012] performing a hydrophilic treatment on the first waveguide layer and the second waveguide layer to pre-bond the first waveguide layer and the second waveguide layer;

[0013] The pre-bonded first waveguide layer and the second waveguide layer are subjected to a high-temperature annealing process to achieve stable bonding between the first waveguide layer and the second waveguide layer.

[0014] According to one embodiment of the present application, both the first waveguide layer and the second waveguide layer include at least one of glass and resin.

[0015] According to one embodiment of the present application, the refractive index of the first waveguide layer is between 1.7 and 2.1, and the refractive index of the second waveguide layer is between 1.4 and 1.8.

[0016] According to one embodiment of the present application, the thickness of the second waveguide layer is smaller than the thickness of the first waveguide layer.

[0017] According to one embodiment of the present application, bonding the first waveguide layer to the second waveguide layer includes:

[0018] forming a bonding layer on one side of the first waveguide layer and / or the second waveguide layer;

[0019] The first waveguide layer and the second waveguide layer are bonded together through the bonding layer.

[0020] According to one embodiment of the present application, the bonding layer includes at least one of silicon oxide and silicon nitride.

[0021] According to one embodiment of the present application, before forming the grating layer on the side of the first waveguide layer facing away from the second waveguide layer, the method further includes:

[0022] providing a third waveguide layer, the third waveguide layer having a refractive index less than that of the second waveguide layer;

[0023] The third waveguide layer is bonded to a side of the second waveguide layer facing away from the first waveguide layer.

[0024] According to one embodiment of the present application, forming a grating layer on a side of the first waveguide layer facing away from the second waveguide layer includes:

[0025] forming a grating material layer on a side of the first waveguide layer facing away from the second waveguide layer;

[0026] The grating material layer is processed by a nanoimprint process or an etching process to obtain a grating layer.

[0027] According to one embodiment of the present application, the method further includes:

[0028] An optical functional layer is formed on a side of the grating layer facing away from the first waveguide layer.

[0029] In a second aspect, the present application provides an optical waveguide structure, comprising:

[0030] a first waveguide layer;

[0031] a second waveguide layer bonded to the first waveguide layer, wherein the refractive index of the first waveguide layer is greater than the refractive index of the second waveguide layer;

[0032] The grating layer is located on a side of the first waveguide layer facing away from the second waveguide layer.

[0033] According to one embodiment of the present application, both the first waveguide layer and the second waveguide layer include at least one of glass and resin.

[0034] According to one embodiment of the present application, the refractive index of the first waveguide layer is between 1.7 and 2.1, and the refractive index of the second waveguide layer is between 1.4 and 1.8.

[0035] According to one embodiment of the present application, the thickness of the second waveguide layer is smaller than the thickness of the first waveguide layer.

[0036] According to one embodiment of the present application, the optical waveguide structure further includes a bonding layer;

[0037] The bonding layer is located between the first waveguide layer and the second waveguide layer, and the first waveguide structure and the second waveguide structure are bonded and connected via the bonding layer.

[0038] According to one embodiment of the present application, the bonding layer includes at least one of silicon oxide and silicon nitride.

[0039] According to one embodiment of the present application, the optical waveguide structure further includes a third waveguide layer;

[0040] The third waveguide layer is bonded to a side of the second waveguide layer facing away from the first waveguide layer, and a refractive index of the third waveguide layer is smaller than a refractive index of the second waveguide layer.

[0041] According to one embodiment of the present application, the optical waveguide structure further includes an optical functional layer;

[0042] The optical functional layer is located on a side of the grating layer facing away from the first waveguide layer.

[0043] In a third aspect, the present application provides a display device comprising the above-mentioned optical waveguide structure.

[0044] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0046] FIG1 is a schematic flow chart of a method for manufacturing an optical waveguide structure according to an embodiment of the present application;

[0047] FIG2 is a schematic diagram showing bonding between a first waveguide layer and a second waveguide layer in a method for manufacturing an optical waveguide structure according to an embodiment of the present application;

[0048] FIG3 is a second schematic diagram of bonding the first waveguide layer and the second waveguide layer in the method for manufacturing the optical waveguide structure provided by an embodiment of the present application;

[0049] FIG4 is a third schematic diagram of bonding the first waveguide layer and the second waveguide layer in the method for manufacturing the optical waveguide structure provided by an embodiment of the present application;

[0050] FIG5 is a schematic diagram of one of the structures of the method for manufacturing an optical waveguide structure provided in an embodiment of the present application;

[0051] FIG6 is a second structural diagram of the method for manufacturing an optical waveguide structure provided in an embodiment of the present application;

[0052] FIG7 is a third structural diagram of the method for manufacturing an optical waveguide structure provided in an embodiment of the present application;

[0053] FIG8 is a fourth structural diagram of the method for manufacturing an optical waveguide structure provided in an embodiment of the present application;

[0054] FIG9 is a schematic diagram of a structure of an optical waveguide structure provided in an embodiment of the present application;

[0055] FIG10 is a fifth structural diagram of a method for manufacturing an optical waveguide structure provided in an embodiment of the present application;

[0056] FIG11 is a sixth structural diagram of a method for manufacturing an optical waveguide structure provided in an embodiment of the present application;

[0057] FIG12 is a second structural schematic diagram of the optical waveguide structure provided in an embodiment of the present application;

[0058] FIG13 is a third structural diagram of an optical waveguide structure provided in an embodiment of the present application;

[0059] FIG14 is a schematic diagram of an optical waveguide structure in the related art;

[0060] FIG15 is a schematic diagram of the optical waveguide structure provided in an embodiment of the present application. DETAILED DESCRIPTION

[0061] The following describes in detail embodiments of the present application. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and are not to be construed as limiting the present application.

[0062] The following describes a method for manufacturing an optical waveguide structure, an optical waveguide structure, and a display device provided by embodiments of the present application with reference to the accompanying drawings.

[0063] Augmented reality (AR) technology combines virtual information with the real world. Optical display technologies primarily include arrayed waveguides, volume holography, birdbaths, and freeform surfaces. Diffractive waveguides based on surface relief have become a mainstream optical display solution due to their advantages, including small size, light weight, high transmittance, and ease of fabrication into desired display devices (such as glasses). Optical waveguide structures are essential components in diffractive waveguide solutions.

[0064] To reduce the thickness and weight of the diffraction waveguide, a single-layer diffraction waveguide is used. However, for a single-layer diffraction waveguide, the propagation paths and exit pupil densities of red, blue, and green (RGB) light of different wavelengths vary within the waveguide, resulting in uneven color at different locations within the eyebox.

[0065] In view of this, the present application proposes an improved method for manufacturing an optical waveguide structure, an optical waveguide structure, and a display device, which can reduce the thickness and weight of the optical waveguide structure while improving the color uniformity of the waveguide and improving the yield of the optical waveguide structure.

[0066] FIG1 is a schematic flow chart of a method for manufacturing an optical waveguide structure provided in an embodiment of the present application.

[0067] As shown in FIG. 1 , the method for manufacturing an optical waveguide structure provided in an embodiment of the present application includes steps 110 to 130 .

[0068] Step 110: Provide a first waveguide layer and a second waveguide layer, wherein the refractive index of the first waveguide layer is greater than the refractive index of the second waveguide layer.

[0069] 2 to 5 , a first waveguide layer 1 and a second waveguide layer 2 are provided. The refractive index of the first waveguide layer 1 is greater than that of the second waveguide layer 2 .

[0070] In some embodiments, the refractive index of the first waveguide layer 1 is between 1.7 and 2.1, and the refractive index of the second waveguide layer 2 is between 1.4 and 1.8.

[0071] The material of the first waveguide layer 1 and the material of the second waveguide layer 2 may be the same or different.

[0072] In some embodiments, both the first waveguide layer 1 and the second waveguide layer 2 comprise at least one of glass and resin. When the first waveguide layer 1 and / or the second waveguide layer 2 are made of glass, the rigidity of the optical waveguide structure can be increased, thereby improving the reliability of the optical waveguide structure. When the first waveguide layer 1 and / or the second waveguide layer 2 are made of resin, the weight of the optical waveguide structure can be reduced, contributing to the development of a lighter and thinner optical waveguide structure.

[0073] The thickness of the second waveguide layer 2 may be smaller than that of the first waveguide layer 1 , so as to avoid excessive influence of the second waveguide layer 2 on the thickness and weight of the optical waveguide structure.

[0074] In some embodiments, the thickness of the first waveguide layer 1 is between 0.3 mm and 3 mm, and the thickness of the second waveguide layer 2 is between 0.2 mm and 1 mm.

[0075] The size of the second waveguide layer 2 is the same as that of the first waveguide layer 1. For example, the size of the first waveguide layer 1 and the second waveguide layer 2 may be any one of 4 inches, 6 inches, 8 inches, and 12 inches.

[0076] Step 120: Bond the first waveguide layer and the second waveguide layer.

[0077] 2 to 5 , a bonding process is used to bond the first waveguide layer 1 and the second waveguide layer 2. The bonding process may be a fusion bonding (FB) process or a hybrid bonding (HB) process, which is not specifically limited herein.

[0078] In some embodiments, bonding the first waveguide layer to the second waveguide layer in step 120 includes:

[0079] performing a hydrophilic treatment on the first waveguide layer and the second waveguide layer to pre-bond the first waveguide layer to the second waveguide layer;

[0080] The pre-bonded first waveguide layer and the pre-bonded second waveguide layer are subjected to a high-temperature annealing process to achieve stable bonding between the first waveguide layer and the second waveguide layer.

[0081] As shown in Figure 2, the first and second waveguide layers 1 and 2 are first hydrophilized, introducing a large number of hydrophilic -OH groups to form silanol bonds (Si-OH) on the surfaces of the first and second waveguide layers 1 and 2. At room temperature, as shown in Figure 3, pre-bonding is achieved via the -OH and H bonds on the surfaces of the first and second waveguide layers 1 and 2. Then, as shown in Figure 4, a high-temperature annealing process is performed, causing a polymerization reaction between the silanol bonds (Si-OH) on the surfaces of the first and second waveguide layers 1 and 2, producing water (H2O) and silicon-oxygen bonds (Si-O-Si), thereby achieving stable bonding between the first and second waveguide layers 1 and 2, as shown in Figure 5. The high-temperature annealing process can be performed at a temperature between 400°C and 1000°C.

[0082] Step 130: forming a grating layer on a side of the first waveguide layer facing away from the second waveguide layer.

[0083] In some embodiments, forming a grating layer on a side of the first waveguide layer facing away from the second waveguide layer in step 130 includes:

[0084] forming a grating material layer on a side of the first waveguide layer facing away from the second waveguide layer;

[0085] The grating material layer is processed by a nanoimprint process or an etching process to obtain a grating layer.

[0086] As shown in FIG6 , before forming the grating material layer, an adhesive layer 3 can be formed on the side of the first waveguide layer 1 facing away from the second waveguide layer 2. The adhesive layer 3 can be coated on the surface of the first waveguide layer 1 facing away from the second waveguide layer 2. The coating process can include spin coating, inkjet printing (IJP), or slit coating. The thickness of the adhesive layer 3 can be less than or equal to 1 nm.

[0087] Then, a grating material layer 40 is formed on the side of the adhesive layer 3 facing away from the first waveguide layer 1. The grating material layer 40 may cover the surface of the adhesive layer 3 facing away from the first waveguide layer 1. The grating material layer 40 is processed to form a grating layer 4 on the side of the adhesive layer 3 facing away from the first waveguide layer 1, thereby forming an optical waveguide structure. The process for processing the grating material layer 40 may be a nanoimprint process, an etching process, or other processes, which are not specifically limited here.

[0088] For example, the grating material layer 40 can be an embossed material layer. The thickness of the embossed material layer can be between 50 nm and 5000 nm. As shown in FIG7 , a mold 41 is disposed on the side of the grating material layer 40 facing away from the first waveguide layer 1. The grating material layer 40 is embossed, exposed, and demolded using the mold 41 to obtain the grating layer 4, as shown in FIG8 . The embossing process can include a roll-to-plate or plate-to-plate embossing process. The UV exposure wavelength can be 365 nm.

[0089] For example, the grating material layer 40 is an inorganic film layer, and an etching process is used to etch the grating material layer 40 into the grating layer 4. The etching process may include an ICP (Inductively Coupled Plasma) or a RIBE (Reactive Ion Beam Etching) process.

[0090] Optionally, a semiconductor process flow is used to perform processes such as exposure, development, etching, and cleaning on the grating material layer 40 to obtain the grating layer 4.

[0091] In some embodiments, the refractive index of the grating layer 4 is consistent with the refractive index of the first waveguide layer 1. The material of the grating layer 4 may include titanium oxide, silicon nitride, zirconium oxide or hafnium oxide.

[0092] Optical waveguide structures are mainly divided into one-dimensional and two-dimensional structures. For a one-dimensional optical waveguide structure, the grating layer 4 can include an in-coupling grating and a turning and out-coupling grating. For a two-dimensional optical waveguide structure, the grating layer 4 includes an in-coupling grating and an out-coupling grating.

[0093] The basic principle of the optical waveguide structure is that the coupling grating 1 couples the light from the external optical machine into the waveguide layer, which is then totally reflected inside the waveguide layer and propagates forward. The light is then coupled out after pupil expansion through the turning and coupling grating (or coupling grating), so that the external ambient light is integrated with the virtual information and reaches the human eye to enhance the display.

[0094] In related technologies, to reduce the weight and thickness of optical waveguide structures and improve waveguide color uniformity, a lamination process is used to bond the first and second waveguide layers, such as using an adhesive. However, the lamination process is prone to numerous issues, such as poor TTV (thickness uniformity), the presence of bubbles, and poor alignment accuracy between the first and second waveguide layers, which can lead to a decrease in the MTF (Modulation Transfer Function) of the bonded waveguide, poor waveguide clarity, and a reduction in overall yield.

[0095] The present embodiment utilizes a bonding process to bond the first waveguide layer 1 to the second waveguide layer 2, eliminating issues such as bubbles, poor TTV, and decreased MTF associated with lamination, effectively improving the yield of the optical waveguide structure. Furthermore, the refractive index of the first waveguide layer 1 is greater than that of the second waveguide layer 2, improving the propagation distance and exit pupil density of red, green, and blue light within the waveguide and enhancing color uniformity. Furthermore, the first waveguide layer 1 and grating layer 4 are designed as a single-layer optical waveguide structure, reducing the thickness and weight of the optical waveguide structure. The relatively thin second waveguide layer 2 does not significantly impact the thickness and weight of the optical waveguide structure.

[0096] In some embodiments, the method for manufacturing the optical waveguide structure further includes:

[0097] An optical functional layer is formed on a side of the grating layer facing away from the first waveguide layer.

[0098] As shown in FIG9 , depending on the actual requirements of the optical waveguide structure, an optical functional layer 5 can be deposited on the side of the grating layer 4 facing away from the first waveguide layer 1. Deposition processes may include evaporation, ALD (Atomic Layer Deposition), PECVD (Plasma Enhanced Chemical Vapor Deposition), TFECVD, or PVD (Physical Vapor Deposition).

[0099] The optical functional layer 5 may include a reflective layer or other film layers, which are not specifically limited herein. The thickness of the optical functional layer 5 may be between 20 nm and 500 nm.

[0100] In some embodiments, the material of the optical functional layer 5 may include at least one of TiO 2 , Al, Si 3 N 4 , and HfO 2 .

[0101] It should be noted that the optical waveguide structure in this embodiment may be a waveguide sheet or a waveguide wafer.

[0102] When the optical waveguide structure is a waveguide wafer, as shown in FIG10 , the waveguide wafer 100 includes a plurality of waveguide slices 10. A cutting process is used to cut the outer shapes of the waveguide slices 10 in the waveguide wafer 100 to obtain a plurality of waveguide slices 10, as shown in FIG11 . The cutting process may include picosecond laser cutting, CO2 laser cleaving, or CNC (Computer Numerical Control) processing. After the waveguide slices 10 are cut, subsequent processes such as waveguide bonding and black coating may be performed on the waveguide slices 10, which are not specifically limited here.

[0103] In some embodiments, bonding the first waveguide layer to the second waveguide layer in step 120 includes:

[0104] forming a bonding layer on one side of the first waveguide layer and / or the second waveguide layer;

[0105] The first waveguide layer and the second waveguide layer are bonded together through the bonding layer.

[0106] Before the first waveguide layer 1 is bonded to the second waveguide layer 2, a bonding layer may be formed on one side of the first waveguide layer 1 and / or the second waveguide layer 2 to bond the first waveguide layer 1 to the second waveguide layer 2 via the bonding layer, thereby improving the bonding effect between the first waveguide layer 1 and the second waveguide layer 2.

[0107] In some embodiments, the material of the bonding layer includes at least one of silicon oxide and silicon nitride, such as silicon monoxide, silicon dioxide, and silicon nitride.

[0108] As shown in FIG12 , a first waveguide layer 1 and a second waveguide layer 2 are first provided. A first bonding layer 61 is then formed on one side of the first waveguide layer 1, and a second bonding layer 62 is formed on one side of the second waveguide layer 2. The first waveguide layer 1 and the second waveguide layer 2 are bonded together by the first bonding layer 61 and the second bonding layer 62.

[0109] The step of bonding the first waveguide layer 1 to the second waveguide layer 2 via the first bonding layer 61 and the second bonding layer 62 may include: firstly performing a hydrophilic treatment on the first bonding layer 61 and the second bonding layer 62 to pre-bond the first waveguide layer 1 to the second waveguide layer 2 via the first bonding layer 61 and the second bonding layer 62. Then, performing a high-temperature annealing treatment on the pre-bonded first waveguide layer 1 and the second waveguide layer 2 to achieve stable bonding between the first waveguide layer 1 and the second waveguide layer 2 via the first bonding layer 61 and the second bonding layer 62.

[0110] After the first waveguide layer 1 and the second waveguide layer 2 are bonded, a grating layer 4 is formed on a side of the first waveguide layer 1 facing away from the second waveguide layer 2 .

[0111] In some embodiments, before forming the grating layer on the side of the first waveguide layer facing away from the second waveguide layer, the method further includes:

[0112] providing a third waveguide layer, the third waveguide layer having a refractive index less than that of the second waveguide layer;

[0113] The third waveguide layer is bonded to a side of the second waveguide layer facing away from the first waveguide layer.

[0114] As shown in Figure 13, a first waveguide layer 1 and a second waveguide layer 2 are first provided, and then the first waveguide layer 1 and the second waveguide layer 2 are bonded together. A third waveguide layer 7 is provided, and the refractive index of the third waveguide layer 7 is lower than that of the second waveguide layer 2. That is, the refractive indices of the first waveguide layer 1, the second waveguide layer 2, and the third waveguide layer 7 gradually decrease. The third waveguide layer 7 is then bonded to the side of the second waveguide layer 2 facing away from the first waveguide layer 1. The bonding process may include a fusion bonding process or a hybrid bonding process.

[0115] In some embodiments, before bonding the third waveguide layer 7 to the side of the second waveguide layer 2 facing away from the first waveguide layer 1, a bonding layer may be formed on one side of the third waveguide layer 7 and / or the side of the second waveguide layer 2 facing away from the first waveguide layer 1, so that the third waveguide layer 7 and the side of the second waveguide layer 2 facing away from the first waveguide layer 1 are bonded via the bonding layer, thereby improving the bonding effect between the third waveguide layer 7 and the second waveguide layer 2.

[0116] In some embodiments, the material of the third waveguide layer 7 may include at least one of glass and resin. The material of the third waveguide layer 7 may be the same as or different from the materials of the first waveguide layer 1 and the second waveguide layer 2.

[0117] After the third waveguide layer 7 is bonded to the second waveguide layer 2 , the grating layer 4 is formed on the side of the first waveguide layer 1 facing away from the second waveguide layer 2 .

[0118] It should be noted that more waveguide layers can be formed in the optical waveguide structure. For example, before forming the grating layer 4 on the side of the first waveguide layer 1 facing away from the second waveguide layer 2, a fourth waveguide layer can be bonded to the side of the third waveguide layer 7 facing away from the second waveguide layer 2. The refractive index of the fourth waveguide layer is lower than that of the third waveguide layer 7. The number of waveguide layers in the optical waveguide structure can be set according to actual needs and is not specifically limited here.

[0119] In related art, an optical waveguide structure includes a first waveguide layer 1 and a grating layer 4 located on one side of the first waveguide layer 1, as shown in Figure 14. Red, blue, and green (RGB) light of different wavelengths has different propagation paths and exit pupil densities within the waveguide, resulting in uneven color at different locations within the eyebox.

[0120] In contrast, the present application provides a first waveguide layer 1 and a second waveguide layer 2, wherein the refractive index of the first waveguide layer 1 is greater than that of the second waveguide layer 2. The first waveguide layer 1 and the second waveguide layer 2 are bonded together, and a grating layer 4 is formed on the side of the first waveguide layer 1 facing away from the second waveguide layer 2 to form a single-layer optical waveguide structure. This reduces the thickness and weight of the optical waveguide structure. The provision of waveguide layers with different refractive indices improves the propagation distance and exit pupil density of red, green, and blue light within the waveguide (as shown in FIG. 15 , red light R propagates in the first waveguide layer 1, and blue light B propagates in the first waveguide layer 1 and the second waveguide layer 2). This improves the color uniformity of the waveguide, and the waveguide layers are bonded using a bonding process to improve the yield of the optical waveguide structure.

[0121] Correspondingly, an embodiment of the present application further provides an optical waveguide structure, which can be manufactured by the method for manufacturing the optical waveguide structure in the above embodiment.

[0122] As shown in FIG9 , the optical waveguide structure provided in an embodiment of the present application includes a first waveguide layer 1, a second waveguide layer 2, and a grating layer 4. The first waveguide layer 1 is bonded to the second waveguide layer 2, and the refractive index of the first waveguide layer 1 is greater than the refractive index of the second waveguide layer 2. The grating layer 4 is located on the side of the first waveguide layer facing away from the second waveguide layer 2.

[0123] In some embodiments, the refractive index of the first waveguide layer 1 is between 1.7 and 2.1, and the refractive index of the second waveguide layer 2 is between 1.4 and 1.8.

[0124] The material of the first waveguide layer 1 and the material of the second waveguide layer 2 may be the same or different.

[0125] In some embodiments, both the first waveguide layer 1 and the second waveguide layer 2 comprise at least one of glass and resin. When the first waveguide layer 1 and / or the second waveguide layer 2 are made of glass, the rigidity of the optical waveguide structure can be increased, thereby improving the reliability of the optical waveguide structure. When the first waveguide layer 1 and / or the second waveguide layer 2 are made of resin, the weight of the optical waveguide structure can be reduced, contributing to the development of a lighter and thinner optical waveguide structure.

[0126] The thickness of the second waveguide layer 2 may be smaller than that of the first waveguide layer 1 , so as to avoid excessive influence of the second waveguide layer 2 on the thickness and weight of the optical waveguide structure.

[0127] In some embodiments, the thickness of the first waveguide layer 1 is between 0.3 mm and 3 mm, and the thickness of the second waveguide layer 2 is between 0.2 mm and 1 mm.

[0128] The size of the second waveguide layer 2 is the same as that of the first waveguide layer 1. For example, the size of the first waveguide layer 1 and the second waveguide layer 2 may be any one of 4 inches, 6 inches, 8 inches, and 12 inches.

[0129] In some embodiments, the refractive index of the grating layer 4 is consistent with the refractive index of the first waveguide layer 1. The material of the grating layer 4 may include titanium oxide, silicon nitride, zirconium oxide or hafnium oxide.

[0130] Optical waveguide structures are mainly divided into one-dimensional and two-dimensional structures. For a one-dimensional optical waveguide structure, the grating layer 4 can include an in-coupling grating and a turning and out-coupling grating. For a two-dimensional optical waveguide structure, the grating layer 4 includes an in-coupling grating and an out-coupling grating.

[0131] The basic principle of the optical waveguide structure is that the coupling grating 1 couples the light from the external optical machine into the waveguide layer, which is then totally reflected inside the waveguide layer and propagates forward. The light is then coupled out after pupil expansion through the turning and coupling grating (or coupling grating), so that the external ambient light is integrated with the virtual information and reaches the human eye to enhance the display.

[0132] 9 , the optical waveguide structure may further include an adhesive layer 3 . The adhesive layer 3 is located between the first waveguide layer 1 and the grating layer 4 , so that the first waveguide layer 1 and the grating layer 4 are bonded together via the adhesive layer 3 .

[0133] In some embodiments, as shown in FIG9 , the optical waveguide structure may further include an optical functional layer 5 . The optical functional layer 5 is located on a side of the grating layer 4 facing away from the first waveguide layer 1 .

[0134] The optical functional layer 5 may include a reflective layer or other film layers, which are not specifically limited herein. The thickness of the optical functional layer 5 may be between 20 nm and 500 nm.

[0135] In some embodiments, the material of the optical functional layer 5 may include at least one of TiO 2 , Al, Si 3 N 4 , and HfO 2 .

[0136] In some embodiments, the optical waveguide structure may further include a bonding layer, wherein the bonding layer is located between the first waveguide layer 1 and the second waveguide layer 2, and the first waveguide layer 1 and the second waveguide layer 2 are bonded together via the bonding layer.

[0137] As shown in FIG12 , the optical waveguide structure may further include a first bonding layer 61 and a second bonding layer 62. The first bonding layer 61 is located on a side of the first waveguide layer 1 close to the second waveguide layer 2, and the second bonding layer 62 is located between the first bonding layer 61 and the second waveguide layer 2. The first waveguide layer 1 and the second waveguide layer 2 are bonded together via the first bonding layer 61 and the second bonding layer 62.

[0138] In some embodiments, the material of the bonding layer includes at least one of silicon oxide and silicon nitride, such as silicon monoxide, silicon dioxide, and silicon nitride, etc. The materials of the first bonding layer 61 and the second bonding layer 62 can be the same or different.

[0139] In some embodiments, as shown in FIG13 , the optical waveguide structure may further include a third waveguide layer 7. The refractive index of the third waveguide layer 7 is lower than that of the second waveguide layer 2. That is, the refractive indices of the first waveguide layer 1, the second waveguide layer 2, and the third waveguide layer 7 gradually decrease. The third waveguide layer 7 is located on the side of the second waveguide layer 2 facing away from the first waveguide layer 1.

[0140] In some embodiments, the material of the third waveguide layer 7 may include at least one of glass and resin. The material of the third waveguide layer 7 may be the same as or different from the materials of the first waveguide layer 1 and the second waveguide layer 2.

[0141] It should be noted that the number of waveguide layers in the optical waveguide structure can be set according to actual needs. For example, the optical waveguide structure may further include a fourth waveguide layer, the refractive index of the fourth waveguide layer is less than the refractive index of the third waveguide layer 7, and the fourth waveguide layer is located on the side of the third waveguide layer 7 away from the second waveguide layer 2.

[0142] According to the optical waveguide structure of the present application, a first waveguide layer, a second waveguide layer, and a grating layer are provided. The refractive index of the first waveguide layer is greater than that of the second waveguide layer. The first waveguide layer and the second waveguide layer are bonded together. The grating layer is located on the side of the first waveguide layer facing away from the second waveguide layer, thereby forming a single-layer optical waveguide structure. This reduces the thickness and weight of the optical waveguide structure. The provision of waveguide layers with different refractive indices improves the propagation distance and exit pupil density of red, green, and blue light within the waveguide, thereby enhancing the color uniformity of the waveguide. The first waveguide layer and the second waveguide layer are bonded together, thereby improving the yield of the optical waveguide structure.

[0143] Correspondingly, an embodiment of the present application further provides a display device, including the optical waveguide structure in the above embodiment, which will not be described in detail here.

[0144] According to a display device provided in an embodiment of the present application, a first waveguide layer, a second waveguide layer, and a grating layer are provided. The refractive index of the first waveguide layer is greater than that of the second waveguide layer. The first waveguide layer and the second waveguide layer are bonded together. The grating layer is located on the side of the first waveguide layer facing away from the second waveguide layer, thereby forming a single-layer optical waveguide structure. This reduces the thickness and weight of the optical waveguide structure. The provision of waveguide layers with different refractive indices improves the propagation distance and exit pupil density of red, green, and blue light within the waveguide, improves the color uniformity of the waveguide, and thereby improves the display effect of the display device. The first waveguide layer and the second waveguide layer are bonded together, thereby improving the yield rate of the optical waveguide structure.

[0145] The display device provided in the embodiment of the present application can be an AR display device, such as AR glasses or AR helmets, and other products or components with AR display functions.

[0146] The terms "first," "second," and the like in the specification and claims of this application are used to distinguish similar objects, and are not used to describe a particular order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of this application can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "first," "second," and the like generally distinguish objects of a class and do not limit the number of objects. For example, the first object may be one or more.

[0147] In the description of this application, “plurality” means two or more.

[0148] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0149] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and intent of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A method for fabricating an optical waveguide structure, comprising: Providing a first waveguide layer and a second waveguide layer, wherein the refractive index of the first waveguide layer is greater than that of the second waveguide layer; Bonding the first waveguide layer and the second waveguide layer; Forming a grating layer on a side of the first waveguide layer facing away from the second waveguide layer.

2. The manufacturing method of the optical waveguide structure according to claim 1, wherein, The step of bonding the first waveguide layer and the second waveguide layer includes: Performing a hydrophilic treatment on the first waveguide layer and the second waveguide layer to pre-bond the first waveguide layer and the second waveguide layer; Performing a high-temperature annealing treatment on the pre-bonded first waveguide layer and second waveguide layer to achieve stable bonding of the first waveguide layer and the second waveguide layer.

3. The manufacturing method of the optical waveguide structure according to claim 1, wherein, Both the first waveguide layer and the second waveguide layer include at least one of glass and resin.

4. The manufacturing method of the optical waveguide structure according to claim 1, wherein, The refractive index of the first waveguide layer is between 1.7 and 2.1, and the refractive index of the second waveguide layer is between 1.4 and 1.

8.

5. The manufacturing method of the optical waveguide structure according to claim 1, wherein, The thickness of the second waveguide layer is less than that of the first waveguide layer.

6. The manufacturing method of the optical waveguide structure according to claim 1, wherein, The step of bonding the first waveguide layer and the second waveguide layer includes: Forming a bonding layer on one side of the first waveguide layer and / or the second waveguide layer; Bonding the first waveguide layer and the second waveguide layer through the bonding layer.

7. The manufacturing method of the optical waveguide structure according to claim 6, wherein, The bonding layer includes at least one of silicon oxide and silicon nitride.

8. The manufacturing method of the optical waveguide structure according to claim 1, wherein, Before forming the grating layer on the side of the first waveguide layer facing away from the second waveguide layer, further comprising: Providing a third waveguide layer, wherein the refractive index of the third waveguide layer is less than that of the second waveguide layer; Bonding the third waveguide layer to a side of the second waveguide layer facing away from the first waveguide layer.

9. The manufacturing method of the optical waveguide structure according to claim 1, wherein, The step of forming the grating layer on the side of the first waveguide layer facing away from the second waveguide layer includes: Forming a grating material layer on the side of the first waveguide layer facing away from the second waveguide layer; Processing the grating material layer using a nanoimprint process or an etching process to obtain the grating layer.

10. The manufacturing method of the optical waveguide structure according to any one of claims 1-9, wherein, The method further includes: Forming an optical functional layer on a side of the grating layer facing away from the first waveguide layer.

11. An optical waveguide structure, comprising: A first waveguide layer; A second waveguide layer, bonded to the first waveguide layer, wherein the refractive index of the first waveguide layer is greater than that of the second waveguide layer; A grating layer, located on a side of the first waveguide layer facing away from the second waveguide layer.

12. The optical waveguide structure according to claim 11, wherein, Both the first waveguide layer and the second waveguide layer include at least one of glass and resin.

13. The optical waveguide structure according to claim 11, wherein, The refractive index of the first waveguide layer is between 1.7 and 2.1, and the refractive index of the second waveguide layer is between 1.4 and 1.

8.

14. The optical waveguide structure according to claim 11, wherein, The thickness of the second waveguide layer is less than that of the first waveguide layer.

15. The optical waveguide structure according to claim 11, wherein, The optical waveguide structure further includes a bonding layer; The bonding layer is located between the first waveguide layer and the second waveguide layer, and the first waveguide structure and the second waveguide structure are bonded through the bonding layer.

16. The optical waveguide structure according to claim 15, wherein, The bonding layer includes at least one of silicon oxide and silicon nitride.

17. The optical waveguide structure according to claim 11, wherein, The optical waveguide structure further includes a third waveguide layer; The third waveguide layer is bonded to a side of the second waveguide layer facing away from the first waveguide layer, and the refractive index of the third waveguide layer is less than that of the second waveguide layer.

18. The optical waveguide structure according to any one of claims 11-17, wherein, The optical waveguide structure further includes an optical functional layer; The optical functional layer is located on a side of the grating layer facing away from the first waveguide layer.

19. A display device, comprising the optical waveguide structure according to any one of claims 11-18.

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