Diffractive optical waveguide and manufacturing method therefor, near-eye display device, and ar glasses

Abstract

A diffractive optical waveguide (100) and a manufacturing method therefor, a near-eye display device, and AR glasses. The manufacturing method for the diffractive optical waveguide (100) comprises: providing a cladding (130), wherein the cladding (130) is provided with a grating area corresponding to a grating (120) and a non-grating area located outside the grating area; forming a liquid adhesive layer (160) on a first surface (S1) of the cladding (130), wherein the liquid adhesive layer (160) at least covers the non-grating area; attaching the grating (120) and a first waveguide layer (110) to the side where the first surface (S1) of the cladding (130) is located, wherein the grating (120) is located in the grating area, and the liquid adhesive layer (160) and the grating (120) are located between the first waveguide layer (110) and the cladding (130); and solidifying the liquid adhesive layer (160) to obtain a solid adhesive layer (140), wherein the solid adhesive layer (140) and the grating (120) jointly fill a gap between the first waveguide layer (110) and the cladding (130). According to the manufacturing method for the diffractive optical waveguide (100), the relative deformation between layer structures in the diffractive optical waveguide (100) can be reduced, thereby improving the stability of the display effect.

Description

Diffractive optical waveguide, manufacturing method thereof, near-eye display device and AR glasses

[0001] Cross-reference to Related Applications

[0002] The present application claims priority to the Chinese patent application No. 202410469730.X, filed on April 18, 2024, and entitled “Manufacturing method of diffractive optical waveguide, diffractive optical waveguide and near-eye display device”, the Chinese patent application No. 202420814594.9, filed on April 18, 2024, and entitled “Diffractive optical waveguide, display device and AR glasses”, and the Chinese patent application No. 202411345607.3, filed on September 25, 2024, and entitled “Manufacturing method of diffractive optical waveguide, diffractive optical waveguide and near-eye display device”, the contents of which are incorporated herein by reference in their entirety. TECHNICAL FIELD

[0003] The present application relates to the field of near-eye display, in particular to a diffractive optical waveguide, a manufacturing method thereof, a near-eye display device and AR glasses. BACKGROUND

[0004] An augmented reality (AR) near-eye display device generally includes an optical engine and a diffractive optical waveguide, the diffractive optical waveguide includes a plurality of waveguide layers and at least one protective layer, and one side surface of the waveguide layer is provided with an optical grating. Taking the diffractive optical waveguide including one waveguide layer and one protective layer as an example, in the prior art, after the waveguide layer and the protective layer are assembled, there is a gap layer between the waveguide layer and the protective layer in the state without external force. When the air pressure of the gap layer is less than the external air pressure or the diffractive optical waveguide is subjected to external force, the waveguide layer and the protective layer can produce relative deformation, which affects the stability of the display effect. SUMMARY

[0005] The present application provides a diffractive optical waveguide, a manufacturing method thereof, a near-eye display device and AR glasses, which can reduce the relative deformation between the layer structures in the diffractive optical waveguide, so as to improve the stability of the display effect.

[0006] In a first aspect, the embodiments of the present application provide a method for manufacturing a diffraction optical waveguide, which comprises: providing a cover layer, the cover layer having a grating region corresponding to a grating and a non-grating region outside the grating region; forming a liquid adhesive layer on a first surface of the cover layer, the liquid adhesive layer covering at least the non-grating region; attaching the grating and a first waveguide layer to the side of the first surface of the cover layer, wherein the grating is located in the grating region, the liquid adhesive layer and the grating are located between the first waveguide layer and the cover layer; and solidifying the liquid adhesive layer to obtain a solid adhesive layer, the solid adhesive layer and the grating jointly filling the gap between the first waveguide layer and the cover layer.

[0007] The method for manufacturing a diffraction optical waveguide according to the embodiments of the present application can provide a diffraction optical waveguide with a specific structure, in which the solid adhesive layer and the grating jointly fill the gap between the first waveguide layer and the cover layer. Therefore, the gap between the first waveguide layer and the cover layer is eliminated, and the Young's modulus of the solid adhesive layer itself under normal temperature and pressure is obviously greater than that of air. Thus, even if the diffraction optical waveguide is subjected to external force, the relative deformation between the first waveguide layer and the cover layer is smaller, thereby improving the stability and reliability of the display effect of the diffraction optical waveguide after transmitting signal light.

[0008] According to the foregoing embodiments of the first aspect of the present application, the step of forming a liquid adhesive layer on the first surface of the cover layer comprises: forming a liquid adhesive layer on the first surface of the cover layer, the liquid adhesive layer being located outside the grating region and covering the non-grating region; and the step of attaching the grating and the first waveguide layer to the side of the first surface of the cover layer comprises: placing the grating between the cover layer and the first waveguide layer, and attaching the first waveguide layer to the cover layer through the liquid adhesive layer, wherein the grating is in contact with the first waveguide layer and the cover layer on opposite sides in the thickness direction.

[0009] According to any one of the foregoing embodiments of the first aspect of the present application, the step of forming a liquid adhesive layer on the first surface of the cover layer comprises: forming a liquid adhesive layer on the first surface of the cover layer, the liquid adhesive layer covering the grating region and the non-grating region; and before the step of attaching the grating and the first waveguide layer to the side of the first surface of the cover layer, the method for manufacturing a diffraction optical waveguide further comprises: pre-solidifying the portion of the liquid adhesive layer corresponding to the grating region into a solid filling portion.

[0010] According to any one of the foregoing embodiments of the first aspect of the present application, the pre-solidifying the part of the liquid adhesive layer corresponding to the grating region into a solid filled part comprises: disposing a pre-solidification mask on a side of the liquid adhesive layer away from the cover layer, the pre-solidification mask having a mask opening corresponding to the shape of the grating region; and exposing the liquid adhesive layer to light using the pre-solidification mask, so that the part of the liquid adhesive layer corresponding to the grating region is converted into a solid filled part, and the part of the liquid adhesive layer corresponding to the non-grating region is kept in a liquid state by being shielded by the pre-solidification mask.

[0011] According to any one of the foregoing embodiments of the first aspect of the present application, the attaching the grating and the first waveguide layer to the side of the cover layer on which the first surface is located comprises: placing the grating between the filled part and the first waveguide layer, and attaching the first waveguide layer to the cover layer via the liquid adhesive layer.

[0012] According to any one of the foregoing embodiments of the first aspect of the present application, the attaching the grating and the first waveguide layer to the side of the cover layer on which the first surface is located comprises: attaching the grating and the first waveguide layer to the side of the cover layer on which the first surface is located in an oxygen-free environment.

[0013] According to any one of the foregoing embodiments of the first aspect of the present application, the cover layer is provided with a first alignment mark, and the first waveguide layer is provided with a second alignment mark; the attaching the grating and the first waveguide layer to the side of the cover layer on which the first surface is located comprises: placing the grating between the cover layer and the first waveguide layer, and attaching the first waveguide layer to the side of the cover layer on which the first surface is located; identifying the position of the first alignment mark and the position of the second alignment mark by an image acquisition module, and obtaining a positional deviation between the second alignment mark and the first alignment mark; and compensating the relative position of the first waveguide layer and the cover layer based on the positional deviation until the second alignment mark coincides with the first alignment mark.

[0014] According to any one of the foregoing embodiments of the first aspect of the present application, the forming the liquid adhesive layer on the first surface of the cover layer comprises: applying the liquid adhesive layer to a target area of the first surface by electrostatic adsorption, electromagnetic field adsorption or centrifugal force.

[0015] According to any one of the foregoing embodiments of the first aspect of the present application, the cover layer is a protective layer; or the cover layer is a second waveguide layer.

[0016] In a second aspect, the embodiments of the present application provide a diffractive optical waveguide obtained by the manufacturing method of the diffractive optical waveguide according to any one of the foregoing embodiments of the first aspect of the present application.

[0017] In a third aspect, the embodiments of the present application provide a near-eye display device, comprising: an optical machine configured to emit signal light; and the diffraction optical waveguide according to any one of the preceding embodiments of the second aspect of the present application, configured to transmit the signal light.

[0018] In a fourth aspect, the embodiments of the present application provide a diffraction optical waveguide, comprising: a first waveguide layer; a grating; a cover layer, the cover layer and the grating being located on the same side of the first waveguide layer, and the grating being located between the first waveguide layer and the cover layer; and a solid adhesive layer located between the first waveguide layer and the cover layer, the solid adhesive layer and the grating jointly filling a gap between the first waveguide layer and the cover layer.

[0019] According to the diffraction optical waveguide of the embodiments of the present application, the diffraction optical waveguide comprises a first waveguide layer, a grating, a cover layer, and a solid adhesive layer, wherein the solid adhesive layer is located between the first waveguide layer and the cover layer, and the solid adhesive layer and the grating jointly fill a gap between the first waveguide layer and the cover layer. The gap between the first waveguide layer and the cover layer is eliminated, and the Young's modulus of the solid adhesive layer itself under normal temperature and pressure is obviously greater than that of air. Therefore, even if the diffraction optical waveguide is subjected to external force, the relative deformation between the first waveguide layer and the cover layer is smaller, thereby improving the stability and reliability of the display effect after the diffraction optical waveguide transmits signal light.

[0020] According to the preceding embodiments of the fourth aspect of the present application, the cover layer has a grating area corresponding to the position of the grating and a non-grating area outside the grating area, and the solid adhesive layer comprises an adhesive portion, the adhesive portion being arranged in the non-grating area, and the adhesive portion bonding the first waveguide layer and the cover layer.

[0021] According to any one of the preceding embodiments of the fourth aspect of the present application, the thickness of the grating is the same as the thickness of the adhesive portion, and the grating is in contact with the first waveguide layer and the cover layer on opposite sides in the thickness direction.

[0022] According to any one of the preceding embodiments of the fourth aspect of the present application, the thickness of the grating is less than the thickness of the adhesive portion.

[0023] According to any one of the preceding embodiments of the fourth aspect of the present application, the solid adhesive layer further comprises a filling portion located between the grating and the cover layer, and the sum of the thickness of the filling portion and the thickness of the grating is equal to the thickness of the adhesive portion.

[0024] According to any one of the preceding embodiments of the fourth aspect of the present application, the cover layer is a protective layer.

[0025] According to any one of the preceding embodiments of the fourth aspect of the present application, the cover layer is a second waveguide layer.

[0026] According to any one of the foregoing embodiments of the fourth aspect of the application, the grating comprises an in-coupling grating and an out-coupling grating arranged at a distance from each other.

[0027] In a fifth aspect, the embodiments of the application provide a near-eye display device, comprising: an optical engine configured to emit a signal light; and a diffractive optical waveguide according to any one of the foregoing embodiments of the fourth aspect of the application, configured to transmit the signal light.

[0028] In a sixth aspect, the embodiments of the application provide an AR (Augmented Reality) glasses, comprising: a near-eye display device according to any one of the foregoing embodiments of the fifth aspect of the application; and a glasses frame, wherein the near-eye display device is mounted on the glasses frame.

[0029] In a seventh aspect, the embodiments of the application provide a method for manufacturing a diffractive optical waveguide, comprising: forming a liquid adhesive layer on a first surface of a cover layer; pre-solidifying the liquid adhesive layer so that the liquid adhesive layer is converted into a pre-solidified layer; patterning the pre-solidified layer to form a groove on a surface of the pre-solidified layer facing away from the cover layer; adhering a first waveguide layer having a grating to the cover layer through the pre-solidified layer, wherein the first waveguide layer is provided with a second surface of the grating facing the first surface, and the grating is in position correspondence with the groove; and solidifying the pre-solidified layer so that the pre-solidified layer is converted into a solid adhesive layer and the first waveguide layer is adhered to the cover layer.

[0030] The method for manufacturing a diffractive optical waveguide according to the embodiments of the application can provide a diffractive optical waveguide with a specific structure, wherein the solid adhesive layer fully adheres the first waveguide layer to the cover layer, and the relative deformation between the first waveguide layer and the cover layer is smaller when the diffractive optical waveguide is subjected to external force, thereby improving the stability and reliability of the display effect after the diffractive optical waveguide transmits the signal light.

[0031] According to any one of the foregoing embodiments of the seventh aspect of the application, the forming of the liquid adhesive layer on the first surface of the cover layer comprises: forming a liquid adhesive layer with uniform thickness on the first surface of the cover layer by electrostatic adsorption coating, electromagnetic adsorption coating or centrifugal force coating.

[0032] According to any one of the foregoing embodiments of the seventh aspect of the application, the pre-solidifying of the liquid adhesive layer so that the liquid adhesive layer is converted into a pre-solidified layer comprises: performing viscosity improvement treatment on the liquid adhesive layer to obtain a pre-solidified layer capable of maintaining the shape unchanged when subjected to external force within a preset range.

[0033] According to any one of the preceding embodiments of the seventh aspect of the present application, the patterning the pre-cured layer to form the grooves on the surface of the pre-cured layer away from the cover layer comprises: disposing a patterning mask on the side of the pre-cured layer away from the cover layer, the patterning mask having mask openings; etching the pre-cured layer using the patterning mask to form the grooves on the pre-cured layer corresponding to the mask openings; and peeling off the patterning mask.

[0034] According to any one of the preceding embodiments of the seventh aspect of the present application, the etching depth of the etching of the pre-cured layer is 200 nm or less, so that the depth of the grooves is 200 nm or less.

[0035] According to any one of the preceding embodiments of the seventh aspect of the present application, in the step of adhering the first waveguide layer having the grating to the cover layer through the pre-cured layer, the adhering pressure and the adhering time are controlled so that the thickness variation of the pre-cured layer is within 200 nm.

[0036] According to any one of the preceding embodiments of the seventh aspect of the present application, the cover layer is a protective layer; or the cover layer is a second waveguide layer.

[0037] In an eighth aspect, embodiments of the present application provide a diffractive optical waveguide obtained by the manufacturing method of the diffractive optical waveguide according to any one of the preceding embodiments of the seventh aspect of the present application.

[0038] In a ninth aspect, embodiments of the present application provide a diffractive optical waveguide, comprising: a cover layer having a first surface; a first waveguide layer having a second surface, the first waveguide layer having a grating on the second surface; and an adhesive layer, the first waveguide layer being adhered and bonded to the cover layer through the adhesive layer, the second surface and the first surface being oppositely arranged, the adhesive layer being arranged between the first waveguide layer and the cover layer or on the peripheral surface of the region where the first waveguide layer and the cover layer meet, the adhesive layer being used to bond the first waveguide layer and the cover layer in a vacuum environment and eliminate air in the adhering surface of the first waveguide layer and the cover layer.

[0039] In a tenth aspect, embodiments of the present application provide a diffractive optical waveguide, comprising: a cover layer having a first surface; a first waveguide layer having a second surface, the first waveguide layer having a grating on the second surface; and an adhesive layer, the first waveguide layer being adhered and bonded to the cover layer through the adhesive layer, the second surface and the first surface being oppositely arranged, the adhesive layer being arranged between the first waveguide layer and the cover layer, the surface of the adhesive layer away from the cover layer having grooves, the grating and the grooves being positionally corresponding, so that there is a gap between the grating and the surface of the adhesive layer.

[0040] According to the foregoing embodiment of the tenth aspect of the present application, the depth of the groove is 0-200 nm.

[0041] According to any one of the foregoing embodiments of the tenth aspect of the present application, the cover layer is a second waveguide layer.

[0042] According to any one of the foregoing embodiments of the tenth aspect of the present application, a first alignment mark is arranged on the cover layer, and a second alignment mark corresponding to the first alignment mark is arranged on the first waveguide layer.

[0043] In a eleventh aspect, the embodiments of the present application provide a diffractive optical waveguide, comprising: a cover layer having a first surface; a first waveguide layer having a second surface, the first waveguide layer having a grating on the second surface; and an adhesive layer, the first waveguide layer being attached to the cover layer through the adhesive layer, the second surface and the first surface being oppositely arranged, the adhesive layer being arranged on the outer peripheral edge of the region where the first waveguide layer and the cover layer meet, the adhesive layer being used to bond the first waveguide layer and the cover layer in a vacuum environment and eliminate air in the attached surface of the first waveguide layer and the cover layer.

[0044] According to the foregoing embodiment of the eleventh aspect of the present application, the adhesive layer is arranged on the outer peripheral edge and the outer peripheral side region of the region where the first waveguide layer and the cover layer meet.

[0045] In a twelfth aspect, the embodiments of the present application provide a near-eye display device, comprising: an optical machine for emitting signal light; and a diffractive optical waveguide according to any one of the foregoing embodiments of the present application, for transmitting the signal light. BRIEF DESCRIPTION OF DRAWINGS

[0046] FIG. 1 is a flowchart of a first embodiment of a manufacturing method of a diffractive optical waveguide according to the present application;

[0047] FIG. 2 is a schematic diagram of the cross-sectional structure of the diffractive optical waveguide after the step of forming a liquid adhesive layer on the first surface of the cover layer in the first embodiment of the manufacturing method of the diffractive optical waveguide according to the present application;

[0048] FIG. 3 is a schematic diagram of the cross-sectional structure of the diffractive optical waveguide after the step of attaching the grating and the first waveguide layer to the side where the first surface of the cover layer is located in the first embodiment of the manufacturing method of the diffractive optical waveguide according to the present application;

[0049] FIG. 4 is a schematic diagram of the cross-sectional structure of the first embodiment of the diffractive optical waveguide according to the present application;

[0050] FIG. 5 is a schematic diagram of the top view structure of the cover layer and the first waveguide layer in the first embodiment of the manufacturing method of the diffractive optical waveguide according to the present application;

[0051] FIG. 6 is a flowchart of a second embodiment of the manufacturing method of the diffractive optical waveguide according to the present application;

[0052] FIG. 7 is a schematic view of a cross-sectional structure after the step of forming a liquid adhesive layer on the first surface of the cover layer in the second embodiment of the method for manufacturing the diffractive optical waveguide of the present application;

[0053] FIG. 8 is a schematic view of a cross-sectional structure after the step of pre-solidifying the portion of the liquid adhesive layer corresponding to the grating region into a solid filling portion in the second embodiment of the method for manufacturing the diffractive optical waveguide of the present application;

[0054] FIG. 9 is a schematic view of a cross-sectional structure after the step of attaching the grating and the first waveguide layer to the side of the cover layer on which the first surface is located in the second embodiment of the method for manufacturing the diffractive optical waveguide of the present application;

[0055] FIG. 10 is a schematic view of a cross-sectional structure of the second embodiment of the diffractive optical waveguide of the present application;

[0056] FIG. 11 is a schematic view of a cross-sectional structure of an embodiment of the near-eye display device of the present application;

[0057] FIG. 12 is a schematic view of a cross-sectional structure of the third embodiment of the diffractive optical waveguide of the present application;

[0058] FIG. 13 is a schematic view of a cross-sectional structure of the fourth embodiment of the diffractive optical waveguide of the present application;

[0059] FIG. 14 is a schematic view of a cross-sectional structure of another embodiment of the near-eye display device of the present application;

[0060] FIG. 15 is a flowchart of an embodiment of the method for manufacturing the diffractive optical waveguide of the present application;

[0061] FIG. 16 is a schematic view of a structure of the step of forming a liquid adhesive layer on the first surface of the cover layer in an embodiment of the method for manufacturing the diffractive optical waveguide of the present application;

[0062] FIG. 17 is a schematic view of a structure of the step of pre-solidifying the liquid adhesive layer in an embodiment of the method for manufacturing the diffractive optical waveguide of the present application, so that the liquid adhesive layer is converted into a pre-solidified layer;

[0063] FIG. 18 is a schematic view of a structure of the step of patterning the pre-solidified layer in an embodiment of the method for manufacturing the diffractive optical waveguide of the present application, so that grooves are formed on the surface of the pre-solidified layer facing away from the cover layer;

[0064] FIG. 19 is a schematic view of a structure of the step of attaching the first waveguide layer having a grating to the cover layer through the pre-solidified layer in an embodiment of the method for manufacturing the diffractive optical waveguide of the present application;

[0065] FIG. 20 is a schematic view of a structure of the step of solidifying the pre-solidified layer in an embodiment of the method for manufacturing the diffractive optical waveguide of the present application, so that the pre-solidified layer is converted into a solid adhesive layer and the first waveguide layer is adhered to the cover layer;

[0066] FIG. 21 is a schematic view of a structure of an embodiment of the diffractive optical waveguide of the present application;

[0067] FIG. 22 is a structural schematic diagram of another embodiment of the diffraction optical waveguide of the present application;

[0068] FIG. 23 is a structural schematic diagram of still another embodiment of the diffraction optical waveguide of the present application;

[0069] FIG. 24 is a cross-sectional structural schematic diagram of still another embodiment of the near-eye display device of the present application. DETAILED DESCRIPTION

[0070] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0071] It should be noted that all the directionality indications such as up, down, left, right, front, back, and the like in the embodiments of the present application are only used to explain the relative positional relationship and movement condition between components in a certain specific posture, such as shown in the drawings, and if the specific posture changes, the directionality indications also change accordingly. When describing the structure of a component, when a layer or a region is referred to as being located “on” or “above” another layer or another region, it can mean being directly located above the other layer or the other region, or other layers or regions can be included between the layer or the region and the other layer or the other region. Moreover, if the component is flipped, the layer or the region will be located “below” or “under” the other layer or the other region.

[0072] In addition, the description involving “first”, “second”, and the like in the present application is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined with “first”, “second” can explicitly or implicitly include at least one of the features. The terms “include”, “contain” or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the elements defined by the statement “include” do not exclude the presence of other identical elements in the process, method, article or device including the elements. In addition, the technical solutions of various embodiments can be combined with each other, but it must be based on the fact that a person of ordinary skill in the art can realize it, and when the combination of technical solutions contradicts each other or cannot be realized, it should be considered that the combination of technical solutions does not exist, and is not within the scope of protection claimed by the present application.

[0073] Diffractive optical waveguides can be used in augmented reality (AR) display devices, for example in AR glasses. Diffractive optical waveguides can be used to implement the transmission of signal light out of the optical machine.

[0074] In the related art, taking a diffractive optical waveguide including a waveguide layer and a protective layer as an example, after the waveguide layer and the protective layer are assembled, there is a gap layer between the waveguide layer and the protective layer in the state of not being subjected to external force. When the air pressure of the gap layer is less than the external air pressure or the diffractive optical waveguide is subjected to external force, the waveguide layer and the protective layer can generate relative deformation, after the deformation, the part of the diffractive optical waveguide is prone to interference, Newton's ring is generated, the observation effect is affected when a user observes, and the stability of the display effect of the diffractive optical waveguide needs to be improved.

[0075] Embodiments of the present application provide a manufacturing method of a diffractive optical waveguide and a diffractive optical waveguide manufactured according to the manufacturing method of the diffractive optical waveguide.

[0076] FIG. 1 is a flowchart of a first embodiment of the manufacturing method of the diffractive optical waveguide of the present application. The manufacturing method of the diffractive optical waveguide of the first embodiment includes steps S110 to S140.

[0077] In step S110, a cover layer is provided, the cover layer has a grating area corresponding to a grating and a non-grating area outside the grating area.

[0078] In some embodiments, the cover layer is a protective layer. The material of the protective layer can be resin, glass, or silicon wafer, etc.

[0079] In some embodiments, the cover layer is a second waveguide layer, that is, the diffractive optical waveguide can include two or more waveguide layers, and the cover layer is another waveguide layer different from the first waveguide layer.

[0080] In the present embodiment, taking the cover layer as the protective layer and taking a diffractive optical waveguide including a waveguide layer and a protective layer as an example for description, in other embodiments, the diffractive optical waveguide can include other number of waveguide layers, and can also include multiple protective layers.

[0081] In step S120, a liquid adhesive layer 160 is formed on the first surface S1 of the cover layer 130, and the liquid adhesive layer 160 covers at least the non-grating area.

[0082] FIG. 2 is a schematic diagram of the cross-sectional structure of the diffractive optical waveguide after the step of forming the liquid adhesive layer on the first surface of the cover layer in the first embodiment of the manufacturing method of the diffractive optical waveguide of the present application. In the present embodiment, the step S120 of forming the liquid adhesive layer 160 on the first surface S1 of the cover layer 130 includes: forming the liquid adhesive layer 160 outside the grating area and covering the non-grating area on the first surface S1 of the cover layer 130.

[0083] In some embodiments, the step S120 of forming the liquid adhesive layer 160 on the first surface S1 of the cover layer 130 comprises: coating the liquid adhesive layer 160 on the target region of the first surface S1 by electrostatic adsorption, electromagnetic field adsorption or centrifugal force.

[0084] In the step S130, the grating and the first waveguide layer are attached to the side where the first surface S1 of the cover layer 130 is located, wherein the grating is located in the grating region, and the liquid adhesive layer 160 and the grating are located between the first waveguide layer and the cover layer 130.

[0085] FIG. 3 is a schematic diagram of the cross-sectional structure of the diffractive optical waveguide after the step of attaching the grating and the first waveguide layer to the side where the first surface of the cover layer is located in the first embodiment of the manufacturing method of the diffractive optical waveguide. In this embodiment, the step S130 of attaching the grating and the first waveguide layer to the side where the first surface S1 of the cover layer 130 is located comprises: placing the grating 120 between the cover layer 130 and the first waveguide layer 110, and attaching the first waveguide layer 110 to the cover layer 130 through the liquid adhesive layer 160, wherein the grating 120 is in contact with the first waveguide layer 110 and the cover layer 130 on opposite sides along the thickness direction.

[0086] In some embodiments, the grating 120 comprises the in-coupling grating 120a and the out-coupling grating 120b arranged at intervals. The in-coupling grating 120a is used to couple the signal light emitted by the light engine (or light engine) into the first waveguide layer 110 and undergo total reflection. The signal light is transmitted to the out-coupling grating 120b through total reflection in the first waveguide layer 110. The out-coupling grating 120b diffracts the signal light in the first waveguide layer 110 into the free space. The signal light diffracted into the free space forms a virtual image to be displayed on the retina after entering the human eye.

[0087] In the step S140, the liquid adhesive layer 160 is solidified to obtain the solid adhesive layer 140. The solid adhesive layer 140 and the grating 120 jointly fill the gap between the first waveguide layer 110 and the cover layer 130. Thus, the diffractive optical waveguide 100 of the first embodiment is obtained. FIG. 4 is a schematic diagram of the cross-sectional structure of the diffractive optical waveguide of the first embodiment. In the diffractive optical waveguide 100 of this embodiment, the solid adhesive layer 140 and the grating 120 jointly fill the gap between the first waveguide layer 110 and the cover layer 130.

[0088] According to the manufacturing method of the diffraction optical waveguide in the above embodiment, a diffraction optical waveguide 100 with a specific structure can be provided, in which the solid-state adhesive layer 140 and the grating 120 jointly fill the gap between the first waveguide layer 110 and the cover layer 130. Therefore, the gap between the first waveguide layer 110 and the cover layer 130 is eliminated, and the Young's modulus of the solid-state adhesive layer 140 itself at normal temperature and pressure is obviously greater than that of air. Therefore, even if the diffraction optical waveguide is subjected to external force, the relative deformation between the first waveguide layer 110 and the cover layer 130 is smaller, thereby improving the stability and reliability of the display effect of the diffraction optical waveguide after transmitting the signal light.

[0089] According to the diffraction optical waveguide 100 provided in the above embodiment, the solid-state adhesive layer 140 and the grating 120 jointly fill the gap between the first waveguide layer 110 and the cover layer 130, which is equivalent to achieving the full-laminated structure of the first waveguide layer 110 and the cover layer 130. The relative deformation between the first waveguide layer 110 and the cover layer 130 when subjected to external force is reduced, thereby avoiding the generation of Newton's rings, improving the observation effect when a user observes, improving the imaging clarity, improving the light diffraction efficiency, and reducing the possibility of ghosting phenomenon.

[0090] In the above embodiment, in the grating area, the grating 120 is in contact with the first waveguide layer 110 and the cover layer 130 on the opposite sides in the thickness direction, and in the non-grating area, the liquid-state adhesive layer 160 is converted into the solid-state adhesive layer 140 after solidification, thereby bonding the first waveguide layer 110 and the cover layer 130 and filling the gap therebetween. The liquid-state adhesive layer 160 and the solid-state adhesive layer 140 do not invade or melt into the grating 120, thereby avoiding the solid-state adhesive layer 140 from entering the grating 120 to affect the micro-nano structure of the grating 120, and the duty cycle of the micro-nano structure of the grating 120 can remain consistent with the design value. Meanwhile, the full reflection of the signal light in the first waveguide layer 110 and the cover layer 130 is not affected, and the bonding firmness of the first waveguide layer 110 and the cover layer 130 is not affected.

[0091] In the above embodiment, since the liquid-state adhesive layer 160 does not enter the grating 120 to affect the function of the grating 120, the refractive index of the liquid-state adhesive layer 160 is no longer limited when selecting the material, thereby reducing the material requirements for the liquid-state adhesive layer 160.

[0092] In some embodiments, the step S130 of attaching the grating 120 and the first waveguide layer 110 to the side of the first surface S1 of the cover layer 130 can include: attaching the grating 120 and the first waveguide layer 110 to the side of the first surface S1 of the cover layer 130 in an oxygen-free environment.

[0093] In the above embodiment, the first waveguide layer 110 and the cover layer 130 are attached and bonded in an oxygen-free environment. This attachment and bonding method can neutralize the oxygen in the microstructure gap of the grating 120, improve the bonding force and optical performance between the first waveguide layer 110 and the cover layer 130, increase the rigidity and Young's modulus of the diffractive optical waveguide, and improve the stability of the optical performance of the diffractive optical waveguide.

[0094] FIG. 5 is a top view of the cover layer and the first waveguide layer in the first embodiment of the manufacturing method of the diffractive optical waveguide. In some embodiments, the cover layer 130 is provided with a first alignment mark M1, and the first waveguide layer 110 is provided with a second alignment mark M2.

[0095] In some embodiments, the step S130 of attaching the grating 120 and the first waveguide layer 110 to the side of the first surface S1 of the cover layer 130 can include: placing the grating 120 between the cover layer 130 and the first waveguide layer 110, and attaching the first waveguide layer 110 to the side of the first surface S1 of the cover layer 130; identifying the position of the first alignment mark M1 and the position of the second alignment mark M2 by the image acquisition module, and obtaining the positional deviation between the second alignment mark M2 and the first alignment mark M1; compensating the relative position of the first waveguide layer 110 and the cover layer 130 based on the positional deviation until the second alignment mark M2 coincides with the first alignment mark M1. By identifying the first alignment mark M1 and the second alignment mark M2 using the image acquisition module, the position of the first waveguide layer 110 and the cover layer 130 can be accurately calibrated to ensure the alignment accuracy of the attachment of the first waveguide layer 110 and the cover layer 130.

[0096] FIG. 6 is a flowchart of the second embodiment of the manufacturing method of the diffractive optical waveguide. The manufacturing method of the diffractive optical waveguide of the second embodiment includes steps S210 to S250.

[0097] In step S210, a cover layer 130 is provided, which has a grating area corresponding to the grating 120 and a non-grating area outside the grating area.

[0098] In step S220, a liquid adhesive layer 160 is formed on the first surface S1 of the cover layer 130, and the liquid adhesive layer 160 covers at least the non-grating area.

[0099] FIG. 7 is a cross-sectional view of the manufacturing method of the diffractive optical waveguide of the second embodiment after the step of forming a liquid adhesive layer on the first surface of the cover layer. In this embodiment, the step S220 of forming a liquid adhesive layer 160 on the first surface S1 of the cover layer 130 includes forming a liquid adhesive layer 160 covering the grating area and the non-grating area on the first surface S1 of the cover layer 130.

[0100] In the present embodiment, before step S240, the method for manufacturing the diffractive optical waveguide further comprises step S230.

[0101] In step S230, the portion of the liquid adhesive layer 160 corresponding to the grating region is pre-solidified into a solid filling portion.

[0102] FIG. 8 is a schematic diagram of the cross-sectional structure of the step of pre-solidifying the portion of the liquid adhesive layer corresponding to the grating region into a solid filling portion in the second embodiment of the method for manufacturing the diffractive optical waveguide. In the present embodiment, the step S230 of pre-solidifying the portion of the liquid adhesive layer 160 corresponding to the grating region into a solid filling portion 142 comprises: disposing a pre-solidification mask 300 on the side of the liquid adhesive layer 160 away from the cover layer 130, the pre-solidification mask 300 having a mask opening 310 corresponding to the shape of the grating region; and exposing the liquid adhesive layer 160 to light using the pre-solidification mask 300, so that the portion of the liquid adhesive layer 160 corresponding to the grating region is converted into the solid filling portion 142, and the portion of the liquid adhesive layer 160 corresponding to the non-grating region is shielded by the pre-solidification mask 300 and remains in a liquid state.

[0103] In step S240, the grating 120 and the first waveguide layer 110 are attached to the side of the cover layer 130 on which the first surface S1 is located, wherein the grating 120 is located in the grating region, and the liquid adhesive layer 160 and the grating 120 are located between the first waveguide layer 110 and the cover layer 130.

[0104] FIG. 9 is a schematic diagram of the cross-sectional structure after the step of attaching the grating and the first waveguide layer to the side of the cover layer on which the first surface is located in the second embodiment of the method for manufacturing the diffractive optical waveguide. In the present embodiment, the step S240 of attaching the grating 120 and the first waveguide layer 110 to the side of the cover layer 130 on which the first surface S1 is located comprises: placing the grating 120 between the filling portion 142 and the first waveguide layer 110, and attaching the first waveguide layer 110 to the cover layer 130 via the liquid adhesive layer 160.

[0105] In some embodiments, the grating 120 comprises an in-coupling grating 120a and an out-coupling grating 120b arranged at a distance from each other.

[0106] In step S250, the liquid adhesive layer 160 is cured to obtain a solid adhesive layer 140, and the solid adhesive layer 140 and the grating 120 jointly fill the gap between the first waveguide layer 110 and the cover layer 130. Thus, the diffractive optical waveguide of the second embodiment is obtained. FIG. 10 is a schematic diagram of the cross-sectional structure of the diffractive optical waveguide of the second embodiment. In the present embodiment, the solid adhesive layer 140 and the grating 120 jointly fill the gap between the first waveguide layer 110 and the cover layer 130.

[0107] According to the manufacturing method of the diffraction optical waveguide in the above embodiment, a diffraction optical waveguide with a specific structure can be provided, in which the solid adhesive layer 140 and the grating 120 jointly fill the gap between the first waveguide layer 110 and the cover layer 130. Therefore, the gap between the first waveguide layer 110 and the cover layer 130 is eliminated, and the Young's modulus of the solid adhesive layer 140 itself at normal temperature and pressure is obviously greater than that of air. Therefore, even if the diffraction optical waveguide is subjected to external force, the relative deformation between the first waveguide layer 110 and the cover layer 130 is smaller, thereby improving the stability and reliability of the display effect of the diffraction optical waveguide after transmitting the signal light.

[0108] In the above embodiment, before the first waveguide layer 110 and the cover layer 130 are attached, the part corresponding to the grating region is pre-solidified by the area-selective pre-solidification method to obtain a solid filling part 142. In the final attachment process, the solid filling part 142 can maintain the shape and thus will not overflow into the grating 120, thereby avoiding the solid adhesive layer 140 formed finally from entering the grating 120, so that the micro-nano structure duty cycle of the grating 120 remains consistent with the design value, and meanwhile, the signal light is not affected to form total reflection in the first waveguide layer 110 and the cover layer 130, and the adhesion of the first waveguide layer 110 and the cover layer 130 is also not affected.

[0109] The embodiment of the present application also provides a near-eye display device. FIG. 11 is a schematic diagram of a cross-sectional structure of an embodiment of the near-eye display device of the present application. The near-eye display device includes an optical machine 200 and the diffraction optical waveguide 100 of any of the foregoing embodiments. The optical machine 200 is configured to emit signal light. The diffraction optical waveguide 100 is configured to transmit the signal light. In this embodiment, the diffraction optical waveguide 100 is, for example, the diffraction optical waveguide 100 of the second embodiment.

[0110] The diffraction optical waveguide 100 includes a first waveguide layer 110, a grating 120, a cover layer 130, and a solid adhesive layer 140. The grating 120 is located between the first waveguide layer 110 and the cover layer 130. The solid adhesive layer 140 is located between the first waveguide layer 110 and the cover layer 130. The solid adhesive layer 140 and the grating 120 jointly fill the gap between the first waveguide layer 110 and the cover layer 130.

[0111] The near-eye display device is, for example, an augmented reality (AR) glasses or a part of the AR glasses.

[0112] According to the near-eye display device provided in the embodiments of the present application, the diffractive optical waveguide 100 has a specific structure, and the solid adhesive layer 140 and the grating 120 jointly fill the gap between the first waveguide layer 110 and the cover layer 130. Therefore, the gap between the first waveguide layer 110 and the cover layer 130 is eliminated, and the Young's modulus of the solid adhesive layer 140 itself under normal temperature and pressure is obviously greater than that of air. Therefore, even if the diffractive optical waveguide is subjected to external force, the relative deformation between the first waveguide layer 110 and the cover layer 130 is smaller, thereby improving the stability and reliability of the display effect of the near-eye display device.

[0113] The embodiments of the present application provide a diffractive optical waveguide. FIG. 12 is a schematic diagram of a cross-sectional structure of a third embodiment of the diffractive optical waveguide of the present application. The diffractive optical waveguide 100 includes a first waveguide layer 110, a grating 120, a cover layer 130, and a solid adhesive layer 140. The cover layer 130 and the grating 120 are located on the same side of the first waveguide layer 110, and the grating 120 is located between the first waveguide layer 110 and the cover layer 130. The solid adhesive layer 140 is located between the first waveguide layer 110 and the cover layer 130, and the solid adhesive layer 140 and the grating 120 jointly fill the gap between the first waveguide layer 110 and the cover layer 130.

[0114] According to the diffractive optical waveguide 100 provided in the embodiments of the present application, the diffractive optical waveguide 100 includes a first waveguide layer 110, a grating 120, a cover layer 130, and a solid adhesive layer 140. The solid adhesive layer 140 is located between the first waveguide layer 110 and the cover layer 130, and the solid adhesive layer 140 and the grating 120 jointly fill the gap between the first waveguide layer 110 and the cover layer 130. The gap between the first waveguide layer 110 and the cover layer 130 is eliminated, and the Young's modulus of the solid adhesive layer 140 itself under normal temperature and pressure is obviously greater than that of air. Therefore, even if the diffractive optical waveguide 100 is subjected to external force, the relative deformation between the first waveguide layer 110 and the cover layer 130 is smaller, thereby improving the stability and reliability of the display effect after the diffractive optical waveguide 100 transmits the signal light.

[0115] According to the diffractive optical waveguide 100 provided in the embodiments of the present application, the solid adhesive layer 140 and the grating 120 jointly fill the gap between the first waveguide layer 110 and the cover layer 130, which is equivalent to achieving the full-laminated structure of the first waveguide layer 110 and the cover layer 130. The relative deformation between the first waveguide layer 110 and the cover layer 130 when subjected to external force is reduced, thereby avoiding the generation of Newton's ring, improving the observation effect when a user observes, improving the imaging clarity, improving the light diffraction efficiency, and reducing the possibility of ghost phenomenon.

[0116] In some embodiments, the cover layer 130 is a protective layer. The material of the protective layer can be resin, glass, or silicon wafer, etc.

[0117] In some embodiments, the cover layer 130 is a second waveguide layer, i.e., the diffractive optical waveguide 100 can include two or more waveguide layers, and the cover layer 130 is another waveguide layer different from the first waveguide layer 110.

[0118] In the present embodiment, the cover layer 130 is a protective layer, and the diffractive optical waveguide 100 includes one waveguide layer and one protective layer. In other embodiments, the diffractive optical waveguide 100 can include other numbers of waveguide layers and / or other numbers of protective layers.

[0119] In some embodiments, the grating 120 includes a coupling-in grating 120a and a coupling-out grating 120b arranged at a distance from each other. The coupling-in grating 120a is configured to couple signal light emitted by an optical engine (or light engine) into the first waveguide layer 110 and cause total reflection of the signal light. The signal light is transmitted to the coupling-out grating 120b through total reflection in the first waveguide layer 110. The coupling-out grating 120b diffracts the signal light in the first waveguide layer 110 into free space. The signal light diffracted into the free space forms a virtual image to be displayed on the retina of the human eye after entering the human eye.

[0120] The solid-state adhesive layer 140 can be an adhesive layer, which can be obtained by curing a liquid adhesive.

[0121] In some embodiments, the cover layer 130 has a grating region corresponding to the position of the grating 120 and a non-grating region outside the grating region. The solid-state adhesive layer 140 includes an adhesive portion 141 arranged in the non-grating region. The adhesive portion 141 bonds the first waveguide layer 110 and the cover layer 130. In the present embodiment, the grating region corresponds to the coupling-in grating 120a and the coupling-out grating 120b.

[0122] As shown in FIG. 12, in the present embodiment, the thickness of the grating 120 is the same as the thickness of the adhesive portion 141. The opposite sides of the grating 120 along the thickness direction are in contact with the first waveguide layer 110 and the cover layer 130, respectively.

[0123] In the above embodiments, in the grating region, the opposite sides of the grating 120 along the thickness direction are in contact with the first waveguide layer 110 and the cover layer 130, respectively. In the non-grating region, the adhesive portion 141 bonds the first waveguide layer 110 and the cover layer 130 and fills the gap therebetween. The adhesive portion 141 of the solid-state adhesive layer 140 does not intrude or merge into the grating 120, thereby avoiding the solid-state adhesive layer 140 from entering the grating 120 and affecting the duty cycle of the micro-nano structure of the grating 120. At the same time, the solid-state adhesive layer 140 does not affect the total reflection of the signal light in the first waveguide layer 110 and the cover layer 130, and does not affect the bonding strength of the first waveguide layer 110 and the cover layer 130.

[0124] In the above embodiment, since the solid adhesive layer 140 does not enter the grating 120 to affect the function of the grating 120, the refractive index of the solid adhesive layer 140 is no longer limited when selecting the material, thereby reducing the material requirement of the solid adhesive layer 140.

[0125] FIG. 13 is a schematic diagram of a cross-sectional structure of a fourth embodiment of the diffraction optical waveguide 100. The fourth embodiment has the same structure as the above-mentioned one embodiment, and the differences between the two will be described below, and the same parts will not be described in detail.

[0126] The cover layer 130 has a grating area corresponding to the position of the grating 120 and a non-grating area outside the grating area, and the solid adhesive layer 140 includes an adhesive portion 141 disposed in the non-grating area, which bonds the first waveguide layer 110 and the cover layer 130. The thickness of the grating 120 is less than the thickness of the adhesive portion 141. In this embodiment, the solid adhesive layer 140 further includes a filling portion 142 between the grating 120 and the cover layer, and the sum of the thickness of the filling portion 142 and the grating 120 is equal to the thickness of the adhesive portion 141.

[0127] In this embodiment, the solid adhesive layer 140 includes the adhesive portion 141 and the filling portion 142, the adhesive portion 141 is disposed in the non-grating area, and the filling portion 142 is disposed in the grating area and fills between the grating 120 and the cover layer 130. In this embodiment, the coupling-in grating 120a and the cover layer 130 are filled with the filling portion 142, and the coupling-out grating 120b and the cover layer 130 are filled with the filling portion 142.

[0128] According to the diffraction optical waveguide 100 of the above-mentioned embodiments, the sum of the thickness of the filling portion 142 and the grating 120 is equal to the thickness of the adhesive portion 141, so that the distance between the first waveguide layer 110 and the cover layer 130 is uniform in the grating area and the non-grating area, and the solid adhesive layer 140 and the grating 120 jointly fill the gap between the first waveguide layer 110 and the cover layer 130. Therefore, the above structure can reduce the relative deformation between the first waveguide layer 110 and the cover layer 130 when subjected to external force, and improve the observation effect when a user observes.

[0129] In this embodiment, the filling portion 142 is configured not to enter the grating 120 under the action of external force.

[0130] The filling portion 142 is configured not to enter the grating 120 under the action of external force, so as to avoid the solid adhesive layer 140 entering the grating 120 to keep the micro-nano structure duty cycle of the grating 120 consistent with the design value, while not affecting the total reflection of the signal light between the first waveguide layer 110 and the cover layer 130, and not affecting the bonding firmness of the first waveguide layer 110 and the cover layer 130.

[0131] The embodiment of the present application also provides a near-eye display device, and FIG. 14 is a schematic diagram of a cross-sectional structure of another embodiment of the near-eye display device of the present application. The near-eye display device comprises an optical machine 200 and the diffractive optical waveguide 100 of any of the foregoing embodiments. The optical machine 200 is configured to emit signal light. The diffractive optical waveguide 100 is configured to transmit the signal light. The diffractive optical waveguide 100 comprises a first waveguide layer 110, a grating 120, a cover layer 130, and a solid adhesive layer 140. The cover layer 130 and the grating 120 are located on the same side of the first waveguide layer 110, and the grating 120 is located between the first waveguide layer 110 and the cover layer 130. The solid adhesive layer 140 is located between the first waveguide layer 110 and the cover layer 130, and the solid adhesive layer 140 and the grating 120 jointly fill the gap between the first waveguide layer 110 and the cover layer 130.

[0132] According to the near-eye display device of the embodiment of the present application, the diffractive optical waveguide 100 comprises the first waveguide layer 110, the grating 120, the cover layer 130, and the solid adhesive layer 140, the solid adhesive layer 140 is located between the first waveguide layer 110 and the cover layer 130, and the solid adhesive layer 140 and the grating 120 jointly fill the gap between the first waveguide layer 110 and the cover layer 130. The gap between the first waveguide layer 110 and the cover layer 130 is eliminated, and the Young's modulus of the solid adhesive layer 140 itself is obviously greater than that of air under normal temperature and pressure. Therefore, even if the diffractive optical waveguide 100 is subjected to external force, the relative deformation between the first waveguide layer 110 and the cover layer 130 is smaller, thereby improving the stability and reliability of the display effect of the near-eye display device.

[0133] The embodiment of the present application also provides an AR glasses, which comprises the near-eye display device of any of the foregoing embodiments and a glasses frame, and the near-eye display device is mounted on the glasses frame. The near-eye display device comprises the optical machine 200 and the diffractive optical waveguide 100. The diffractive optical waveguide 100 is configured to transmit the signal light emitted by the optical machine 200. The diffractive optical waveguide 100 comprises the first waveguide layer 110, the grating 120, the cover layer 130, and the solid adhesive layer 140. The cover layer 130 and the grating 120 are located on the same side of the first waveguide layer 110, and the grating 120 is located between the first waveguide layer 110 and the cover layer 130. The solid adhesive layer 140 is located between the first waveguide layer 110 and the cover layer 130, and the solid adhesive layer 140 and the grating 120 jointly fill the gap between the first waveguide layer 110 and the cover layer 130.

[0134] According to the AR glasses provided in the embodiments of the present application, the gap between the first waveguide layer 110 and the cover layer 130 in the diffractive optical waveguide 100 is eliminated, so that the relative deformation between the first waveguide layer 110 and the cover layer 130 is smaller even when the diffractive optical waveguide 100 is subjected to external force, thereby improving the stability and reliability of the display effect of the AR glasses.

[0135] In the related art, for example, the diffractive optical waveguide includes one waveguide layer and one protective layer, and after the waveguide layer and the protective layer are assembled, there is a gap layer between the waveguide layer and the protective layer in the state without external force. When the air pressure of the gap layer is less than the external air pressure or the diffractive optical waveguide is subjected to external force, the waveguide layer and the protective layer can be deformed relatively, and after the deformation, the interference is prone to occur in part of the area of the diffractive optical waveguide, Newton's ring is generated, the observation effect is affected when a user observes, and the stability of the display effect of the diffractive optical waveguide needs to be improved.

[0136] The embodiments of the present application provide a manufacturing method of a diffractive optical waveguide and a diffractive optical waveguide manufactured according to the manufacturing method of the diffractive optical waveguide.

[0137] FIG. 15 is a flowchart of an embodiment of the manufacturing method of the diffractive optical waveguide of the present application. The manufacturing method of the diffractive optical waveguide includes steps S310 to S360.

[0138] In step S310, a cover layer is provided.

[0139] In some embodiments, the cover layer is a protective layer. The material of the protective layer can be resin, glass, or silicon wafer, etc.

[0140] In some embodiments, the cover layer is a second waveguide layer, that is, the diffractive optical waveguide can include two or more waveguide layers, and the cover layer is another waveguide layer different from the first waveguide layer.

[0141] In the embodiments, the cover layer is a protective layer, and the diffractive optical waveguide includes one waveguide layer and one protective layer, which is described as an example. In other embodiments, the diffractive optical waveguide can include other numbers of waveguide layers, and can also include multiple protective layers.

[0142] In step S320, a liquid adhesive layer is formed on the first surface of the cover layer. FIG. 16 is a structural schematic diagram of the formation of the liquid adhesive layer on the first surface of the cover layer in an embodiment of the manufacturing method of the diffractive optical waveguide of the present application. In the embodiment, the liquid adhesive is coated on the first surface of the cover layer to form the liquid adhesive layer.

[0143] In some embodiments, the step S320 of forming the liquid adhesive layer 160 on the first surface S1 of the cover layer 130 includes: forming the liquid adhesive layer 160 with uniform thickness on the first surface S1 of the cover layer 130 by electrostatic adsorption coating, electromagnetic adsorption coating or centrifugal force coating.

[0144] In step S330, the liquid adhesive layer 160 is pre-solidified so that the liquid adhesive layer 160 is converted into a pre-solidified layer 160b. FIG. 17 is a schematic structural diagram of the pre-solidification of the liquid adhesive layer 160 so that the liquid adhesive layer 160 is converted into a pre-solidified layer 160b in an embodiment of the method for manufacturing the diffractive optical waveguide.

[0145] In some embodiments, the step S330 of pre-solidifying the liquid adhesive layer 160 so that the liquid adhesive layer 160 is converted into a pre-solidified layer 160b includes: performing viscosity-enhancing treatment on the liquid adhesive layer 160 to obtain a pre-solidified layer 160b capable of maintaining the shape unchanged under a preset range of external force. The specific viscosity-enhancing treatment on the liquid adhesive layer 160 can be determined according to the physical properties of the liquid adhesive layer. For different types of glue (liquid adhesive layer 160) such as temperature-sensitive glue, humidity-curing glue and light-sensitive glue, the corresponding type of glue can be pre-solidified by adjusting temperature, humidity, light and the like. For example, for the liquid adhesive layer 160 sensitive to ultraviolet light, the liquid adhesive layer 160 is pre-solidified by ultraviolet light irradiation for a preset time, so that the pre-solidified glue can also be shaped when subjected to external force.

[0146] In step S340, the pre-solidified layer 160b is patterned to form grooves on the surface of the pre-solidified layer 160b away from the cover layer 130. FIG. 18 is a schematic structural diagram of the patterning of the pre-solidified layer 160b to form grooves 161 on the surface of the pre-solidified layer 160b away from the cover layer 130 in an embodiment of the method for manufacturing the diffractive optical waveguide.

[0147] In some embodiments, the step S340 of patterning the pre-solidified layer 160b to form grooves 161 on the surface of the pre-solidified layer 160b away from the cover layer 130 includes: disposing a patterned mask on the side of the pre-solidified layer 160b away from the cover layer 130, the patterned mask having mask openings; etching the pre-solidified layer 160b using the patterned mask to form grooves 161 on the pre-solidified layer 160b corresponding to the mask openings; and peeling off the patterned mask.

[0148] In one example, the patterned mask is a patterned photoresist layer, and thus the forming process of the patterned mask is, for example, as follows: a positive photoresist layer or a negative photoresist layer is spin-coated on the side of the pre-cured layer 160b facing away from the cover layer 130, and then the positive photoresist layer or the negative photoresist layer is exposed, developed, and the like under the mask plate, so that the photoresist layer in a specific area is removed, forming a mask opening, i.e., a patterned mask with a mask opening is obtained.

[0149] In step S350, the first waveguide layer 110 with the grating 120 is attached to the cover layer 130 through the pre-cured layer 160b, wherein the second surface S2 of the grating 120 is arranged opposite to the first surface S1 of the cover layer 130, and the grating 120 is positioned corresponding to the groove 161. FIG. 19 is a schematic structural diagram of attaching the first waveguide layer 110 with the grating 120 to the cover layer 130 through the pre-cured layer 160b in the embodiment of the manufacturing method of the diffractive optical waveguide.

[0150] In some embodiments, the grating 120 includes a coupling-in grating 120a and a coupling-out grating 120b arranged at a distance from each other. The coupling-in grating 120a is used to couple the signal light emitted by the light engine (or light engine) into the first waveguide layer 110 and undergo total reflection. The signal light is transmitted to the coupling-out grating 120b through total reflection in the first waveguide layer 110, and the coupling-out grating 120b diffracts the signal light in the first waveguide layer 110 into the free space. The signal light diffracted into the free space forms a virtual image to be displayed on the retina after entering the human eye.

[0151] In some embodiments, the etching depth of etching the pre-cured layer 160b is 200 nm or less, so that the depth of the groove 161 is 200 nm or less.

[0152] In the above embodiment, the groove 161 is formed on the surface of the pre-cured layer 160b which is away from the cover layer 130, and the groove 161 corresponds to the position of the grating 120 on the first waveguide layer 110 after the first waveguide layer 110 is attached to the cover layer 130. The groove 161 allows a gap between the grating 120 and the pre-cured layer 160b or between the grating 120 and the surface of the solid adhesive layer. After the fabrication of the diffractive optical waveguide is completed, a thin gap space is formed between the grating 120 and the surface of the solid adhesive layer. According to the Newton's ring formation condition, when the thickness d of the gap space is less than λ / 2≈200nm (where λ is the minimum wavelength of visible light, λ≈400nm), the Newton's ring cannot be observed in appearance. In the fabrication method of the diffractive optical waveguide in the embodiment, the etching depth of the etching of the pre-cured layer 160b is less than 200nm, so that the depth of the groove 161 is less than 200nm. This can ensure that the adhesive layer (the pre-cured layer 160b or the solid adhesive layer) does not penetrate into the grating 120, and at the same time, the Newton's ring is avoided. Therefore, under the condition of using any adhesive layer, the display light efficiency can be ensured, and the Newton's ring can be avoided.

[0153] In some embodiments, the step of attaching the first waveguide layer 110 with the grating 120 to the cover layer 130 through the pre-cured layer 160b in the above embodiment can include: attaching the first waveguide layer 110 with the grating 120 to the cover layer 130 through the pre-cured layer 160b in a vacuum environment.

[0154] In the above embodiment, the first waveguide layer 110 and the cover layer 130 are attached in a vacuum environment (vacuum degree <30pa), and the first waveguide layer 110 and the cover layer 130 are attached by mechanical pressure. After the attachment is completed, the first waveguide layer 110 and the cover layer 130 are tightly bonded under the action of atmospheric pressure, and the diffractive optical waveguide assembly is obtained. This attachment method can reduce or even eliminate the air in the grating 120 gap, improve the bonding force and optical performance between the first waveguide layer 110 and the cover layer 130, and reduce the warping of the first waveguide layer 110 and the cover layer 130 after they are attached, thereby improving the display yield of the diffractive optical waveguide.

[0155] In some embodiments, the cover layer 130 is provided with a first alignment mark, and the first waveguide layer 110 is provided with a second alignment mark. The step of adhering the first waveguide layer 110 with the grating 120 to the cover layer 130 via the pre-cured layer 160b can include: identifying the position of the first alignment mark and the position of the second alignment mark by the image acquisition module, and obtaining the positional deviation between the second alignment mark and the first alignment mark; compensating the relative position of the first waveguide layer 110 and the cover layer 130 based on the positional deviation until the second alignment mark coincides with the first alignment mark. By identifying the first alignment mark and the second alignment mark by the image acquisition module, the position of the first waveguide layer 110 and the cover layer 130 can be accurately calibrated, and the alignment accuracy of adhering the first waveguide layer 110 to the cover layer 130 can be ensured.

[0156] In step S360, the pre-cured layer 160b is cured so that the pre-cured layer 160b is converted into the solid adhesive layer 140 and the first waveguide layer 110 is adhered to the cover layer 130. FIG. 20 is a structural schematic diagram of curing the pre-cured layer 160b so that the pre-cured layer 160b is converted into the solid adhesive layer 140 and the first waveguide layer 110 is adhered to the cover layer 130 in an embodiment of the method for manufacturing the diffractive optical waveguide.

[0157] In an example scheme, a liquid adhesive layer 160 sensitive to ultraviolet light is used. Accordingly, the step of curing the pre-cured layer 160b is, for example, specifically: after the adhered diffractive optical waveguide (i.e., the assembly obtained by adhering the first waveguide layer 110 to the cover layer 130 via the pre-cured layer 160b) is subjected to a degassing treatment under high temperature and high pressure conditions, the assembly is subjected to exposure under ultraviolet light to convert the pre-cured layer 160b into the solid adhesive layer 140, thereby achieving the curing of the liquid adhesive between the first waveguide layer 110 and the cover layer 130. The above treatment can increase the adhesion strength of the first waveguide layer 110 and the cover layer 130, and increase the stability of the diffractive optical waveguide and the lens assembly.

[0158] In some embodiments, in the step S360 of adhering the first waveguide layer 110 with the grating 120 to the cover layer 130 via the pre-cured layer 160b, the adhering pressure and the adhering time are controlled so that the thickness variation of the pre-cured layer 160b is within 200 nm.

[0159] According to the manufacturing method of the diffraction optical waveguide and the diffraction optical waveguide obtained by the manufacturing method, the solid adhesive layer 140 fully adheres the first waveguide layer 110 and the cover layer 130, and most of the area between the first waveguide layer 110 and the cover layer 130 is filled by the solid adhesive layer 140, thereby eliminating most of the gap between the first waveguide layer 110 and the cover layer 130. Therefore, even if the diffraction optical waveguide is subjected to external force, the relative deformation between the first waveguide layer 110 and the cover layer 130 is smaller under the filling effect of the solid adhesive layer 140, thereby improving the stability and reliability of the display effect of the diffraction optical waveguide after transmitting signal light. In the manufacturing process of the diffraction optical waveguide, the pre-solidification layer 160b obtained by pre-solidification of the liquid adhesive layer 160 can be patterned. By patterning the pre-solidification layer 160b, a groove 161 can be formed on the surface of the pre-solidification layer 160b away from the cover layer 130. The groove 161 corresponds to the position of the grating 120 on the first waveguide layer 110 after the first waveguide layer 110 is adhered to the cover layer 130. The groove 161 allows a gap to be formed between the grating 120 and the pre-solidification layer 160b or between the grating 120 and the surface of the solid adhesive layer 140. In this way, the adhesive layer (the pre-solidification layer 160b or the solid adhesive layer 140) does not penetrate into the grating 120 during the manufacturing process of the diffraction optical waveguide, thereby avoiding the influence of the adhesive layer penetrating into the grating 120 on the grating 120. The duty cycle of the grating 120 can remain consistent with the design value. Since the pre-solidification layer 160b does not penetrate into the grating 120, the refractive index of the liquid adhesive layer 160 is no longer limited when selecting the material, thereby reducing the material requirements for the liquid adhesive layer 160.

[0160] The embodiment of the present application also provides a diffraction optical waveguide, as shown in FIG. 21 or FIG. 22 or FIG. 23, the diffraction optical waveguide 100 includes a cover layer 130, a first waveguide layer 110, and an adhesive layer 140x. The cover layer 130 has a first surface S1. The first waveguide layer 110 has a second surface S2, and the first waveguide layer 110 has a grating 120 on the second surface S2. The first waveguide layer 110 is adhered to the cover layer 130 by the adhesive layer 140x, and the second surface S2 is arranged opposite to the first surface S1. The adhesive layer 140x is arranged between the first waveguide layer 110 and the cover layer 130 or arranged on the outer surface of the region where the first waveguide layer 110 and the cover layer 130 meet. The adhesive layer 140x is used to adhere the first waveguide layer 110 and the cover layer 130 in a vacuum environment and eliminate air in the adhered surface of the first waveguide layer 110 and the cover layer 130.

[0161] As shown in FIG. 21, in some embodiments, the adhesive layer 140x is arranged between the first waveguide layer 110 and the cover layer 130. The surface of the adhesive layer 140x facing away from the cover layer 130 has a groove 161, and the grating 120 is positionally corresponding to the groove 161, so that there is a gap between the grating 120 and the surface of the adhesive layer 140x. In some embodiments, the depth of the groove 161 is 200 nm or less. Meanwhile, the diffractive optical waveguide assembly is designed to achieve tight bonding by bonding the first waveguide layer 110 and the cover layer 130 under a vacuum environment (vacuum degree < 30 pa) through mechanical pressure, so that the air in the gap of the grating 120 can be eliminated, the bonding force and optical performance between the first waveguide layer 110 and the cover layer 130 can be improved, the warping of the two after bonding can be reduced, and the display yield of the diffractive optical waveguide can be improved.

[0162] The embodiments of the present application also provide a diffractive optical waveguide. FIG. 21 is a structural schematic diagram of an embodiment of the diffractive optical waveguide of the present application. The diffractive optical waveguide 100 includes a cover layer 130, a first waveguide layer 110, and an adhesive layer 140x. The cover layer 130 has a first surface S1. The first waveguide layer 110 has a second surface S2. The first waveguide layer 110 has a grating 120 on the second surface S2. The first waveguide layer 110 is bonded to the cover layer 130 through the adhesive layer 140x. The second surface S2 is arranged opposite to the first surface S1. The surface of the adhesive layer 140x facing away from the cover layer 130 has a groove 161, and the grating 120 is positionally corresponding to the groove 161, so that there is a gap between the grating 120 and the surface of the adhesive layer 140x. In the embodiment, the adhesive layer 140x is a solid adhesive layer, which is obtained by solidifying a liquid adhesive layer.

[0163] According to the diffractive optical waveguide 100 of the embodiments of the present application, the adhesive layer 140x fully bonds the first waveguide layer 110 and the cover layer 130, and most of the area between the first waveguide layer 110 and the cover layer 130 is filled by the adhesive layer 140x, so that most of the gap between the first waveguide layer 110 and the cover layer 130 is eliminated. Therefore, even if the diffractive optical waveguide 100 is subjected to external force, the relative deformation between the first waveguide layer 110 and the cover layer 130 is smaller under the filling effect of the adhesive layer 140x, so that the stability and reliability of the display effect after the diffractive optical waveguide 100 transmits signal light are improved. There is a gap between the grating 120 and the surface of the adhesive layer 140x, so that the glue layer used to form the adhesive layer 140x will not penetrate into the grating 120 on the first waveguide layer 110 during the manufacturing process of the diffractive optical waveguide 100, thereby avoiding the influence of the penetration of the glue layer into the grating 120 on the grating 120, and the duty cycle of the grating 120 can remain consistent with the design value. Since the glue layer will not penetrate into the grating 120, the refractive index of the glue layer is no longer limited when selecting the material, thereby reducing the material requirements for the glue layer.

[0164] In some embodiments, the depth of the groove 161 is 0-200 nm, i.e. the depth of the groove 161 is less than 200 nm. In the above embodiments, the groove 161 makes the grating 120 and the pre-cured layer 160b or the grating 120 and the surface of the adhesive layer 140x have a gap, which is equivalent to a thin gap space reserved between the grating 120 and the surface of the adhesive layer 140x. According to the Newton ring formation condition, when the gap space thickness d < λ / 2≈200 nm (where λ is the minimum wavelength of visible light, λ≈400 nm), the bright and dark Newton rings cannot be seen in appearance. Since the depth of the groove 161 is less than 200 nm, it can be ensured that the glue layer does not penetrate into the grating 120, while avoiding the generation of Newton rings.

[0165] As shown in FIG. 22, in some other embodiments, the adhesive layer 140x is arranged at the outer peripheral edge of the region where the first waveguide layer 110 and the cover layer 130 meet, and the adhesive layer 140x is used to bond the first waveguide layer 110 and the cover layer 130 in a vacuum environment and eliminate air in the bonding surface of the first waveguide layer 110 and the cover layer 130.

[0166] Specifically, the diffractive optical waveguide 100 includes a cover layer 130, a first waveguide layer 110, and an adhesive layer 140x. The cover layer 130 has a first surface S1. The first waveguide layer 110 has a second surface S2, and the first waveguide layer 110 has a grating 120 at the second surface S2. The first waveguide layer 110 is bonded and adhered to the cover layer 130 through the adhesive layer 140x, the second surface S2 and the first surface S1 are arranged opposite to each other, and the adhesive layer 140x is arranged at the outer peripheral edge of the region where the first waveguide layer 110 and the cover layer 130 meet. The adhesive layer 140x is used to bond the first waveguide layer 110 and the cover layer 130 in a vacuum environment and eliminate air in the bonding surface of the first waveguide layer 110 and the cover layer 130.

[0167] In the above another embodiment, the adhesive layer 140x is not arranged or filled between the first waveguide layer 110 and the cover layer 130, and the first waveguide layer 110 and the cover layer 130 can be directly bonded in a vacuum environment.

[0168] Specifically, the first waveguide layer 110 and the cover layer 130 are directly bonded in a high vacuum condition (vacuum degree < 30 pa), and no adhesive is used in the bonding surface, so as to ensure the close contact of the first waveguide layer 110 and the cover layer 130, and the position of the grating 120 is also not filled with a glue layer, so as to not affect the optical properties. After the bonding is completed, the adhesive layer 140x is used to bond the four peripheral edges of the assembly obtained after the bonding in a vacuum state, so as to ensure that no gas can penetrate between the first waveguide layer 110 and the cover layer 130.

[0169] The manufacturing process of the diffraction optical waveguide of the above embodiment can further include a bonding step, a glue coating step, and a curing step.

[0170] In the bonding step, the first waveguide layer 110 is bonded to the cover layer 130 by mechanical pressure under high vacuum condition (vacuum degree < 30 Pa), and after the bonding, the first waveguide layer 110 and the cover layer 130 are tightly bonded under atmospheric pressure to obtain a diffraction optical waveguide assembly. The bonding environment is a high vacuum environment, for example, a high vacuum environment less than -10 Pa, and the bonding surface of the first waveguide layer 110 and the cover layer 130 has a low surface roughness.

[0171] In the glue coating step, the outer peripheral edge of the bonding surface of the first waveguide layer 110 and the cover layer 130 of the lens assembly obtained after the bonding is sealed by a liquid adhesive layer 140x under vacuum environment, so that air cannot penetrate between the first waveguide layer 110 and the cover layer 130, thereby avoiding cracking of the lens assembly.

[0172] In the curing step, the lens assembly coated with the liquid adhesive is cured by UV and / or heating, so as to obtain the adhesive layer 140x arranged on the outer peripheral edge of the bonding surface of the first waveguide layer 110 and the cover layer 130, thereby increasing the reliability of the diffraction optical waveguide and the lens assembly.

[0173] As shown in FIG. 23, in some other embodiments, the adhesive layer 140x is arranged on the outer peripheral edge and the outer peripheral side area of the bonding surface of the first waveguide layer 110 and the cover layer 130, and the adhesive layer 140x is used to bond the first waveguide layer 110 and the cover layer 130 under vacuum environment and eliminate air in the bonding surface of the first waveguide layer 110 and the cover layer 130.

[0174] According to the diffraction optical waveguide 100 of the embodiment of the present application, the adhesive layer 140x bonds the first waveguide layer 110 and the cover layer 130. Therefore, when the diffraction optical waveguide 100 is subjected to external force, the relative deformation between the first waveguide layer 110 and the cover layer 130 is smaller, thereby improving the stability and reliability of the display effect of the diffraction optical waveguide 100 after transmitting signal light.

[0175] In the above embodiment, the cover layer 130 is a protective layer. The material of the protective layer can be resin, glass, or silicon wafer, etc.

[0176] In the above embodiment, the cover layer 130 is a second waveguide layer, that is, the diffraction optical waveguide can include two or more waveguide layers, and the cover layer 130 is another waveguide layer different from the first waveguide layer 110.

[0177] In the above embodiment, the first alignment mark is arranged on the cover layer 130, and the second alignment mark corresponding to the first alignment mark is arranged on the first waveguide layer 110. When the first waveguide layer 110 is attached to the cover layer 130, the positions of the first alignment mark and the second alignment mark are recognized by the image acquisition module, and the positional deviation between the second alignment mark and the first alignment mark is obtained. The relative positions of the first waveguide layer 110 and the cover layer 130 are compensated based on the positional deviation until the second alignment mark coincides with the first alignment mark. By recognizing the first alignment mark and the second alignment mark by the image acquisition module, the positions of the first waveguide layer 110 and the cover layer 130 can be accurately calibrated, and the alignment accuracy of the attachment of the first waveguide layer 110 and the cover layer 130 is ensured.

[0178] The embodiment of the present application also provides a diffractive optical waveguide. FIG. 23 is a structural schematic diagram of another embodiment of the diffractive optical waveguide of the present application. The diffractive optical waveguide 100 includes a cover layer 130, a first waveguide layer 110, and an adhesive layer 140x. The cover layer 130 has a first surface S1. The first waveguide layer 110 has a second surface S2, and the first waveguide layer 110 has a grating 120 on the second surface S2. The first waveguide layer 110 is attached and bonded to the cover layer 130 through the adhesive layer 140x, the second surface S2 is arranged opposite to the first surface S1, the adhesive layer 140x is arranged on the outer peripheral edge of the area where the first waveguide layer 110 and the cover layer 130 meet, and the adhesive layer 140x is used to bond the first waveguide layer 110 and the cover layer 130 in a vacuum environment and eliminate air in the attached surface of the first waveguide layer 110 and the cover layer 130.

[0179] As shown in FIG. 23, in the embodiment, the adhesive layer 140x is arranged on the outer peripheral edge and the outer peripheral side area of the area where the first waveguide layer 110 and the cover layer 130 meet. In some embodiments, the outer contour shape and size of the first waveguide layer 110 and the cover layer 130 are the same, the adhesive layer 140x is arranged on the outer peripheral edge and the outer peripheral side area of the area where the first waveguide layer 110 and the cover layer 130 meet, which can further improve the sealing between the first waveguide layer 110 and the cover layer 130 and improve the bonding strength of the obtained lens assembly.

[0180] The embodiment of the present application also provides a near-eye display device. FIG. 24 is a schematic diagram of the cross-sectional structure of another embodiment of the near-eye display device of the present application. The near-eye display device includes an optical machine 200 and the diffractive optical waveguide 100 of any of the foregoing embodiments. The optical machine 200 is used to emit signal light. The diffractive optical waveguide 100 is used to transmit the signal light.

[0181] In one example, the diffractive optical waveguide 100 comprises a cover layer 130, a first waveguide layer 110, and an adhesive layer 140x. The cover layer 130 has a first surface S1. The first waveguide layer 110 has a second surface S2. The first optical waveguide is formed with a grating 120 at the second surface S2. The first waveguide layer 110 is attached and bonded to the cover layer 130 through the adhesive layer 140x. The second surface S2 is arranged opposite to the first surface S1. The surface of the adhesive layer 140x facing away from the cover layer 130 has a groove 161, and the grating 120 is positionally corresponding to the groove 161, so that there is a gap between the grating 120 and the surface of the adhesive layer 140x.

[0182] The near-eye display device is, for example, an augmented reality (AR) glasses or a part of the AR glasses.

[0183] The near-eye display device according to the embodiments of the present application comprises the diffractive optical waveguide 100, wherein the adhesive layer 140x fully attaches and bonds the first waveguide layer 110 and the cover layer 130. Therefore, when the diffractive optical waveguide 100 is subjected to an external force, the relative deformation between the first waveguide layer 110 and the cover layer 130 is smaller, thereby improving the stability and reliability of the display effect after the diffractive optical waveguide 100 transmits the signal light.

[0184] According to the near-eye display device of the above example, the adhesive layer 140x of the diffractive optical waveguide 100 fully attaches and bonds the first waveguide layer 110 and the cover layer 130, and the vast majority of the area between the first waveguide layer 110 and the cover layer 130 is filled by the adhesive layer 140x, eliminating the vast majority of the gap between the first waveguide layer 110 and the cover layer 130. Therefore, even when the diffractive optical waveguide 100 is subjected to an external force, the relative deformation between the first waveguide layer 110 and the cover layer 130 is smaller under the filling effect of the adhesive layer 140x, thereby improving the stability and reliability of the display effect after the diffractive optical waveguide 100 transmits the signal light. The gap between the grating 120 and the surface of the adhesive layer 140x is such that the glue layer used to form the adhesive layer 140x during the manufacturing process of the diffractive optical waveguide 100 does not penetrate into the grating 120 on the first waveguide layer 110, avoiding the influence of the penetration of the glue layer into the grating 120 on the grating 120. Since the glue layer does not penetrate into the grating 120, the refractive index of the glue layer is no longer limited when selecting the material, thereby reducing the material requirements of the glue layer.

[0185] The above only describes the preferred embodiments of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation made by using the content of the present application specification and drawings, or direct / indirect application in other related technical fields is included in the patent protection scope of the present application.

Claims

1. A method for manufacturing a diffractive optical waveguide, comprising: providing a cover layer having a grating region corresponding to a grating and a non-grating region outside the grating region; forming a liquid adhesive layer on a first surface of the cover layer, the liquid adhesive layer covering at least the non-grating region; attaching a grating and a first waveguide layer to a side of the first surface of the cover layer, wherein the grating is located in the grating region, the liquid adhesive layer and the grating are located between the first waveguide layer and the cover layer; solidifying the liquid adhesive layer to obtain a solid adhesive layer, the solid adhesive layer and the grating together filling a gap between the first waveguide layer and the cover layer.

2. The method of fabricating a diffractive optical waveguide of claim 1, wherein, The forming of the liquid adhesive layer on the first surface of the cover layer comprises: forming a liquid adhesive layer on the first surface of the cover layer, the liquid adhesive layer being outside the grating region and covering the non-grating region. The attaching of the grating and the first waveguide layer to the side of the first surface of the cover layer comprises: placing the grating between the cover layer and the first waveguide layer, and attaching the first waveguide layer to the cover layer through the liquid adhesive layer, wherein opposite sides of the grating in the thickness direction are in contact with the first waveguide layer and the cover layer, respectively.

3. The method of fabricating a diffractive optical waveguide of claim 1, wherein, The forming of the liquid adhesive layer on the first surface of the cover layer comprises: forming a liquid adhesive layer on the first surface of the cover layer, the liquid adhesive layer covering the grating region and the non-grating region. Before the step of attaching the grating and the first waveguide layer to the side of the first surface of the cover layer, the method for manufacturing a diffractive optical waveguide further comprises: pre-solidifying a portion of the liquid adhesive layer corresponding to the grating region into a solid filling portion.

4. The method of fabricating a diffractive optical waveguide of claim 3, wherein, The pre-solidifying of the portion of the liquid adhesive layer corresponding to the grating region into the solid filling portion comprises: providing a pre-solidification mask on a side of the liquid adhesive layer away from the cover layer, the pre-solidification mask having a mask opening corresponding to a shape of the grating region; exposing the liquid adhesive layer to light using the pre-solidification mask, a portion of the liquid adhesive layer corresponding to the grating region being converted into the solid filling portion by the light, and a portion of the liquid adhesive layer corresponding to the non-grating region being kept in a liquid state by being blocked by the pre-solidification mask.

5. The method of fabricating a diffractive optical waveguide of claim 3, wherein, The attaching of the grating and the first waveguide layer to the side of the first surface of the cover layer comprises: placing the grating between the filling portion and the first waveguide layer, and attaching the first waveguide layer to the cover layer through the liquid adhesive layer.

6. The method of fabricating a diffractive optical waveguide of claim 1, wherein, The attaching of the grating and the first waveguide layer to the side of the first surface of the cover layer comprises: attaching the grating and the first waveguide layer to the side of the first surface of the cover layer in an oxygen-free environment.

7. The method of fabricating a diffractive optical waveguide of claim 1, wherein, The cover layer is provided with a first alignment mark, and the first waveguide layer is provided with a second alignment mark; the attaching of the grating and the first waveguide layer to the side of the first surface of the cover layer comprises: placing the grating between the cover layer and the first waveguide layer, and attaching the first waveguide layer to the side of the first surface of the cover layer. recognize the positions of the first pair of alignment marks and the second pair of alignment marks, and obtain a position deviation between the second pair of alignment marks and the first pair of alignment marks; compensate for the relative positions of the first waveguide layer and the cover layer based on the position deviation until the second pair of alignment marks coincide with the first pair of alignment marks.

8. The method of fabricating a diffractive optical waveguide as claimed in claim 1, wherein, forming the liquid adhesive layer on the first surface of the cover layer includes: applying the liquid adhesive layer to a target region on the first surface by electrostatic adsorption, electromagnetic field adsorption, or centrifugal force.

9. The method of fabricating a diffractive optical waveguide of claim 1, wherein, the cover layer is a protective layer; or the cover layer is a second waveguide layer.

10. A diffractive optical waveguide obtained by the manufacturing method of the diffractive optical waveguide according to any one of claims 1 to 9.

11. A near-eye display device, comprising: an optical engine configured to emit signal light; and the diffractive optical waveguide according to claim 10 configured to transmit the signal light.

12. A diffractive optical waveguide, comprising: a first waveguide layer; a grating; a cover layer, the cover layer and the grating being located on the same side of the first waveguide layer, the grating being located between the first waveguide layer and the cover layer; a solid-state adhesive layer located between the first waveguide layer and the cover layer, the solid-state adhesive layer and the grating together filling a gap between the first waveguide layer and the cover layer. the cover layer has a grating region corresponding to the position of the grating and a non-grating region outside the grating region, the solid-state adhesive layer includes an adhesive portion, the adhesive portion being arranged in the non-grating region, and the adhesive portion bonding the first waveguide layer and the cover layer.

13. The diffractive optical waveguide of claim 12, wherein, the thickness of the grating is the same as the thickness of the adhesive portion, and the grating is in contact with the first waveguide layer and the cover layer on opposite sides in the thickness direction.

14. The diffractive optical waveguide of claim 13, wherein, the thickness of the grating is less than the thickness of the adhesive portion.

15. The diffractive optical waveguide of claim 13, wherein, the solid-state adhesive layer further includes a filling portion between the grating and the cover layer, and the sum of the thickness of the filling portion and the thickness of the grating is equal to the thickness of the adhesive portion.

16. The diffractive optical waveguide of claim 15, wherein, the cover layer is a protective layer.

17. The diffractive optical waveguide of claim 12, wherein, the cover layer is a second waveguide layer.

18. The diffractive optical waveguide of claim 12, wherein, the grating includes an in-coupling grating and an out-coupling grating arranged at a distance from each other.

19. The diffractive optical waveguide of claim 12, wherein, 20. A near-eye display device, comprising: an optical engine configured to emit signal light; and the diffractive optical waveguide according to any one of claims 12 to 19 configured to transmit the signal light.

21. An AR glasses, comprising: the near-eye display device according to claim 20; and a glasses frame, the near-eye display device being mounted on the glasses frame.

22. A manufacturing method of a diffractive optical waveguide, comprising: forming a liquid adhesive layer on a first surface of a cover layer; pre-solidifying the liquid adhesive layer so that the liquid adhesive layer is converted into a pre-solidified layer; patterning the pre-solidified layer to form a groove on the surface of the pre-solidified layer facing away from the cover layer; attaching a first waveguide layer having a grating to the cover layer through the pre-solidified layer, wherein the first waveguide layer is arranged such that a second surface of the grating faces the first surface, and the grating corresponds in position to the groove; and ​ ​ ​ curing the pre-cured layer so that the pre-cured layer is transformed into a solid adhesive layer and bonds the first waveguide layer and the cover layer.

23. The method of fabricating a diffractive optical waveguide of claim 22, wherein, The forming a liquid adhesive layer on the first surface of the cover layer comprises: forming a liquid adhesive layer with uniform thickness on the first surface of the cover layer by electrostatic adsorption coating, electromagnetic adsorption coating or centrifugal force coating.

24. The method of fabricating a diffractive optical waveguide of claim 22, wherein, The pre-curing the liquid adhesive layer so that the liquid adhesive layer is transformed into a pre-cured layer comprises: The liquid adhesive layer is subjected to a viscosity-enhancing treatment to obtain a pre-cured layer that can maintain its shape under a preset range of external forces.

25. The method of fabricating a diffractive optical waveguide of claim 22, wherein, The patterning the pre-cured layer to form a groove on the surface of the pre-cured layer away from the cover layer comprises: a patterned mask is provided on the side of the pre-cured layer away from the cover layer, the patterned mask having mask openings; etching the pre-cured layer using the patterned mask to form a groove in the region of the pre-cured layer corresponding to the mask openings; stripping the patterned mask.

26. The method of fabricating a diffractive optical waveguide of claim 25, wherein, The etching depth of the etching of the pre-cured layer is 200 nm or less, so that the depth of the groove is 200 nm or less.

27. The method of fabricating a diffractive optical waveguide of claim 22, wherein, In the step of adhering the first waveguide layer having a grating to the cover layer through the pre-cured layer, the adhesion pressure and the adhesion time are controlled so that the thickness variation of the pre-cured layer is within 200 nm.

28. The method of fabricating a diffractive optical waveguide of claim 22, wherein, The cover layer is a protective layer; or The cover layer is a second waveguide layer.

29. A diffractive optical waveguide obtained by the method of any one of claims 22 to 28.

30. A diffractive optical waveguide comprising: a cover layer having a first surface; a first waveguide layer having a second surface, the first waveguide layer having a grating on the second surface; an adhesive layer, the first waveguide layer being adhered and bonded to the cover layer through the adhesive layer, the second surface and the first surface being arranged opposite to each other, the adhesive layer being arranged between the first waveguide layer and the cover layer or on the outer circumferential surface of the region where the first waveguide layer and the cover layer meet, the adhesive layer being used to bond the first waveguide layer and the cover layer in a vacuum environment and eliminate air in the adhering surface of the first waveguide layer and the cover layer.

31. A diffractive optical waveguide comprising: a cover layer having a first surface; a first waveguide layer having a second surface, the first waveguide layer having a grating on the second surface; an adhesive layer, the first waveguide layer being adhered and bonded to the cover layer through the adhesive layer, the second surface and the first surface being arranged opposite to each other, the adhesive layer being arranged between the first waveguide layer and the cover layer, the surface of the adhesive layer away from the cover layer having a groove, the grating and the groove being positionally corresponding, so that there is a gap between the grating and the surface of the adhesive layer.

32. The diffractive optical waveguide of claim 31, wherein, The depth of the groove is 0 to 200 nm.

33. The diffractive optical waveguide of claim 31, wherein, The cover layer is a second waveguide layer.

34. The diffractive optical waveguide of claim 31, wherein, A first alignment mark is provided on the cover layer, and a second alignment mark corresponding to the first alignment mark is provided on the first waveguide layer.

35. A diffractive optical waveguide comprising: a cover layer having a first surface; a first waveguide layer having a second surface, the first waveguide layer having a grating at the second surface; a bonding layer, the first waveguide layer being bonded to the cover layer through the bonding layer, the second surface being disposed opposite to the first surface, the bonding layer being disposed at a peripheral edge of an area where the first waveguide layer and the cover layer meet, the bonding layer being used to bond the first waveguide layer and the cover layer in a vacuum environment and eliminate air in a bonding surface of the first waveguide layer and the cover layer.

36. The diffractive optical waveguide of claim 35, wherein, The bonding layer is disposed at a peripheral edge of an area where the first waveguide layer and the cover layer meet and a peripheral side area.

37. A near-eye display device comprising: an optical engine configured to emit a signal light; and a diffractive optical waveguide according to any one of claims 29 to 36 configured to transmit the signal light.

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