Optical waveguide structure and optical waveguide module

Abstract

The present invention provides an optical waveguide structure and an optical waveguide module. The optical waveguide structure includes: a multilayer waveguide sheet, the multilayer waveguide sheets are arranged in a superimposed manner; at least one coupling-in grating, at least one turning grating and at least one coupling-out grating, a coupling-in grating and / or a turning grating and / or a coupling-out grating are arranged between at least two adjacent layers of waveguide sheets in a group, and the coupling-in grating, the turning grating and the coupling-out grating are not located on the surfaces of the waveguide sheets on both sides that are away from each other, glue is filled between the two adjacent layers of waveguide sheets so that the coupling-in grating, the turning grating and the coupling-out grating are covered, and the multilayer waveguide sheets are formed into one piece at the same time; wherein the coupling-in grating is used to couple the light emitted by an external optical machine into the multilayer waveguide sheet, the turning grating is used to receive the light of the coupling-in grating and transmit the light in a pupil-expanding manner, and the coupling-out grating is used to receive the light of the turning grating and couple the light out of the multilayer waveguide sheet. The present invention solves the problem of poor display efficiency of the optical waveguide structure in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of diffraction optical equipment, and in particular to an optical waveguide structure and an optical waveguide module. Background Art

[0002] With the continuous updating of science and technology, virtual reality (VR), augmented reality (AR) and mixed reality (MR) have gradually entered people's lives. Among them, in terms of AR augmented reality, optical waveguide technology is an indispensable key technology and is also the current mainstream AR display solution.

[0003] At present, the diffraction-based optical waveguide structure (such as embossed grating optical waveguide or holographic optical waveguide, etc.) has the following problems: 1. The overall weight of the optical waveguide structure is too heavy. In order to protect the grating structure exposed on the surface of the optical waveguide structure, it is usually necessary to add an additional cover plate, which will further increase the weight. 2. In color display, there is crosstalk between different colors, resulting in poor display uniformity. 3. The overall thickness of the optical waveguide structure is affected by many factors such as the incident wavelength, grating period and diffraction efficiency. If the overall thickness is too thick, it will lead to pupil separation (the light in the pupil of the waveguide coupled into the grating is distributed discretely in the eye box after being transmitted through the waveguide, and cannot fill the entire eye box, resulting in reduced display effect). If the overall thickness is too small, the number of reflections of light in the waveguide will increase, and the energy loss will be serious, resulting in a significant reduction in the final display efficiency. In the past few years, many manufacturers have solved the above problems to varying degrees, but various problems still exist.

[0004] That is to say, the optical waveguide structure in the prior art has the problem of poor display efficiency. Summary of the invention

[0005] The main purpose of the present invention is to provide an optical waveguide structure and an optical waveguide module to solve the problem of poor display efficiency of the optical waveguide structure in the prior art.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, there is provided an optical waveguide structure, comprising: a multilayer waveguide sheet, the multilayer waveguide sheets are arranged in a stacked manner; at least one coupling-in grating, at least one turning grating and at least one coupling-out grating, a coupling-in grating and / or a turning grating and / or a coupling-out grating are arranged between at least two adjacent layers of the waveguide sheets of a group, and the coupling-in grating, the turning grating and the coupling-out grating are not located on the surfaces of the waveguide sheets on both sides that are away from each other, glue is filled between the two adjacent layers of the waveguide sheets so that the coupling-in grating, the turning grating and the coupling-out grating are covered, and the multilayer waveguide sheets are formed into one piece; wherein the coupling-in grating is used to couple the light emitted by an external optical machine into the multilayer waveguide sheet, the turning grating is used to receive the light of the coupling-in grating and transmit the light in a pupil-expanding manner, and the coupling-out grating is used to receive the light of the turning grating and couple the light out of the multilayer waveguide sheet.

[0007] Furthermore, the optical waveguide structure includes two layers of waveguide plates.

[0008] Further, at least two layers of the waveguide sheet in the multi-layer waveguide sheet have equal thickness.

[0009] Furthermore, the coupling-in grating includes a transmissive-reflective coupling-in grating, so that the coupling-in grating can couple the light of the external optical machine into the multilayer waveguide in the form of transmission and reflection respectively.

[0010] Furthermore, the refractive index of the coupled-in grating is different from the refractive index of the glue.

[0011] Furthermore, the glue is transparent glue; and / or the refractive index of the glue is greater than or equal to 1.3 and less than or equal to 2.6.

[0012] Furthermore, the thickness of the waveguide plate is greater than or equal to 0.1 mm and less than or equal to 1 mm; and / or the refractive index of the waveguide plate is greater than or equal to 1.3 and less than or equal to 2.6.

[0013] Furthermore, the coupling-in grating, the turning grating and the coupling-out grating are all one-dimensional gratings, or are all two-dimensional gratings.

[0014] According to another aspect of the present invention, there is provided an optical waveguide module, comprising: an optical machine, wherein the optical machine is one or more, and when there is one optical machine, the optical machine can emit light of at least three colors; at least two of the above-mentioned optical waveguide structures, wherein at least two optical waveguide structures are stacked and arranged on one side of the optical machine, and the coupling-in grating, turning grating and coupling-out grating on the at least two stacked optical waveguide structures are arranged correspondingly.

[0015] Furthermore, the optical waveguide module also includes a color filter, which is arranged on an optical waveguide structure located away from the optical machine in at least two stacked optical waveguide structures, and the color filter is located on a side surface of the optical waveguide structure where it is located close to the optical machine, and the color filter corresponds to the coupling grating.

[0016] According to the technical solution of the present invention, the optical waveguide structure includes a multilayer waveguide sheet, at least one coupling-in grating, at least one turning grating and at least one coupling-out grating. The multilayer waveguide sheets are arranged in a stacked manner; a coupling-in grating and / or a turning grating and / or a coupling-out grating are arranged between at least two adjacent layers of the waveguide sheets, and the coupling-in grating, the turning grating and the coupling-out grating are not located on the surfaces of the waveguide sheets on both sides that are away from each other, and glue is filled between the two adjacent layers of the waveguide sheets so that the coupling-in grating, the turning grating and the coupling-out grating are covered, and the multilayer waveguide sheet is formed into a whole; wherein the coupling-in grating is used to couple the light emitted by the external optical machine into the multilayer waveguide sheet, the turning grating is used to receive the light of the coupling-in grating and transmit the light in a pupil-expanding manner, and the coupling-out grating is used to receive the light of the turning grating and couple the light out of the multilayer waveguide sheet.

[0017] The coupling-in grating, the turning grating and the coupling-out grating are not located on the surfaces of the waveguide plates on both sides that are far away from each other. This arrangement ensures that the coupling-in grating, the turning grating and the coupling-out grating are not exposed on the outside of the waveguide plate, but are located between two adjacent layers of waveguide plates, that is, the grating in the optical waveguide structure is inside it. This arrangement enables the two adjacent layers of waveguide plates to protect the coupling-in grating, the turning grating and the coupling-out grating. While meeting the performance requirements of the normal optical waveguide structure, there is no need to add an additional cover plate to protect the grating, which saves components and costs. At the same time, the weight, volume and thickness of the entire optical waveguide structure are effectively reduced, which is conducive to achieving lightweight, miniaturization and thinness. Glue is filled between two adjacent layers of waveguide sheets so that the coupling-in grating, the turning grating and the coupling-out grating are covered, and the multi-layer waveguide sheets are integrated at the same time. In this way, the glue can not only connect the two adjacent layers of waveguide sheets, but also protect the coupling-in grating, the turning grating and the coupling-out grating therebetween, so as to ensure that the grating is not exposed to the air, and can effectively avoid the grating from being polluted by fine particles in the air, which is conducive to ensuring the reliability of the grating. By filling glue between two adjacent layers of waveguide sheets, it can be ensured that the glue layer formed by the glue is relatively thin, which further ensures that the optical waveguide structure is relatively thin as a whole, and reduces the degree of pupil separation during subsequent display without additionally increasing the loss of light when diffracted by the grating, so as to ensure that the light coupled out of the final optical waveguide structure can evenly and fully cover the entire eye box, thereby greatly improving the coupling-out efficiency, and enhancing the display efficiency and display uniformity. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0019] Figure 1 A schematic diagram of light transmission of an optical waveguide module in the prior art is shown;

[0020] Figure 2 A schematic diagram of light transmission of another optical waveguide module in the prior art is shown;

[0021] Figure 3 A schematic diagram showing an optical waveguide structure of an optional embodiment of the present invention;

[0022] Figure 4 A schematic diagram showing an optical waveguide module according to an alternative embodiment of the present invention;

[0023] Figure 5 A schematic diagram showing the manufacture of an optical waveguide structure according to an alternative embodiment of the present invention.

[0024] The above drawings include the following reference numerals:

[0025] 101. blue light; 102. red light; 103. cover plate; 501. substrate; 502. material; 503. motherboard; 504. waveguide structure; 10. optical waveguide structure; 11. waveguide plate; 12. coupling-in grating; 13. turning grating; 14. coupling-out grating; 20. color filter; 30. glue layer; 40. optical machine. DETAILED DESCRIPTION

[0026] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0027] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs.

[0028] In the present invention, unless otherwise specified, the directional words used, such as "up, down, top, bottom", usually refer to the directions shown in the drawings, or to the components themselves in the vertical, perpendicular or gravity directions; similarly, for ease of understanding and description, "inside and outside" refer to the inside and outside relative to the outline of each component itself, but the above-mentioned directional words are not used to limit the present invention.

[0029] like Figure 1 As shown, it is a schematic diagram of the structure of a color optical waveguide module in the prior art. The optical waveguide module adopts the method of stacking two waveguide plates, each waveguide plate is provided with a coupling grating 12, a turning grating 13 and a coupling grating 14, and the side of the upper waveguide plate with the grating is arranged toward the side of the lower waveguide plate with the grating; the two waveguide plates in the figure are two independent waveguide plates, which are responsible for transmitting blue light 101 and red light 102 respectively. Specifically, the upper waveguide plate is used to transmit blue light 101, and the lower waveguide plate is used to transmit red light 102. The green light (not shown in the figure) is transmitted in the form of partially propagating in the upper waveguide plate and partially propagating in the lower waveguide plate. In order to reduce the crosstalk of the blue light 101 into the lower waveguide plate, a color filter 20 is added between the two waveguide plates to filter out the transmitted blue light 101. However, when adding the color filter 20, the distance between the two waveguide plates needs to be increased, which is also a severe challenge to the stacking process. Figure 1 In the embodiment, the upper waveguide plate adopts a reflective coupling grating 12, and the lower waveguide plate adopts a transmissive coupling grating 12. Another factor is that a large number of previous studies have shown that the performance of a reflective grating configuration is better than that of a transmissive grating configuration. Therefore, the prior art can be improved as follows: Figure 2 Optical waveguide module.

[0030] like Figure 2, which is a schematic diagram of the structure of another color optical waveguide module in the prior art. Both waveguide plates adopt a reflective grating configuration to couple the grating 12, and the gratings of the two waveguide plates are arranged on their lower surfaces; at the same time, the gap between the two waveguide plates can be reduced by directly coating the color filter 20 on the upper surface of the lower waveguide plate, thereby reducing the difficulty of the lamination process, but the coupling grating 12 on the lower surface of the lower waveguide plate will be exposed to the air, and an additional cover plate 103 needs to be added for sealing protection. Figure 2 Although this method is Figure 1 There are many advantages, but it will increase the overall size and weight of the optical waveguide module, which is not conducive to the use of portable AR consumer products.

[0031] In order to solve the problem of poor display efficiency of the optical waveguide structure 10 in the prior art, the present invention provides an optical waveguide structure 10 and an optical waveguide module.

[0032] like Figures 3 to 5 As shown, the optical waveguide structure 10 includes a multilayer waveguide sheet 11, at least one coupling-in grating 12, at least one turning grating 13 and at least one coupling-out grating 14. The multilayer waveguide sheets 11 are arranged in a stacked manner; the coupling-in grating 12, the turning grating 13 and the coupling-out grating 14 are arranged between at least one group of two adjacent waveguide sheets 11, and the coupling-in grating 12, the turning grating 13 and the coupling-out grating 14 are not located on the surfaces of the waveguide sheets 11 on both sides that are away from each other, and glue is filled between the two adjacent waveguide sheets 11 so that the coupling-in grating 12, the turning grating 13 and the coupling-out grating 14 are covered, and the multilayer waveguide sheet 11 is formed into one piece; wherein the coupling-in grating 12 is used to couple the light emitted by the external optical engine 40 into the multilayer waveguide sheet 11, the turning grating 13 is used to receive the light of the coupling-in grating 12 and transmit the light in pupil expansion, and the coupling-out grating 14 is used to receive the light of the turning grating 13 and couple the light out of the multilayer waveguide sheet 11.

[0033] The coupling-in grating 12, the turning grating 13 and the coupling-out grating 14 are not located on the surfaces of the waveguide plates 11 on both sides that are away from each other. This arrangement makes the coupling-in grating 12, the turning grating 13 and the coupling-out grating 14 not exposed on the outside of the waveguide plate 11, but located between two adjacent layers of waveguide plates 11, that is, the grating in the optical waveguide structure 10 is inside it. This arrangement makes the two adjacent layers of waveguide plates 11 able to protect the coupling-in grating 12, the turning grating 13 and the coupling-out grating 14. While meeting the performance requirements of the normal optical waveguide structure 10, there is no need to add an additional cover plate to protect the grating, which saves components and costs. At the same time, the weight, volume and thickness of the entire optical waveguide structure 10 are effectively reduced, which is conducive to achieving lightweight, miniaturization and thinness. Glue is filled between two adjacent layers of waveguide sheets 11 so that the coupling-in grating 12, the turning grating 13 and the coupling-out grating 14 are covered, and the multi-layer waveguide sheets 11 are integrated at the same time. In this way, the glue can not only connect the two adjacent layers of waveguide sheets 11, but also protect the coupling-in grating 12, the turning grating 13 and the coupling-out grating 14 therebetween, so as to ensure that the grating is not exposed to the air, and can effectively avoid the grating from being polluted by fine particles in the air, which is conducive to ensuring the reliability of the grating. By filling glue between two adjacent layers of waveguide sheets 11, it is possible to ensure that the glue layer 30 formed by the glue is relatively thin, which further ensures that the optical waveguide structure 10 is relatively thin as a whole, and reduces the degree of pupil separation during subsequent display without additionally increasing the loss of light when diffracted by the grating, so as to ensure that the light coupled out of the optical waveguide structure 10 can evenly and fully cover the entire eye box, thereby greatly improving the coupling-out efficiency, and enhancing the display efficiency and display uniformity.

[0034] It should be noted that the present application provides a monolithic optical waveguide structure 10, that is, when in use, the optical waveguide structure 10 is generally used as a whole piece, and the optical waveguide structure 10 will not be disassembled for use. The optical waveguide structure 10 of the present application wraps the grating therein, which can effectively suppress Fresnel scattering and improve the grating diffraction efficiency. The optical waveguide structure 10 itself also has good diffraction characteristics of wavelength bandwidth and angle bandwidth. These properties are perfectly matched to the diffraction requirements of the optical waveguide structure 10 for grating performance, so it is very suitable for application in optical waveguide modules. This optical waveguide structure 10 not only solves the problems of heavy weight, light crosstalk affecting display uniformity, pupil separation, poor diffraction efficiency, and poor display efficiency to a certain extent, but also increases the design freedom, providing the possibility of improving the display performance of the optical waveguide structure 10.

[0035] In an optional embodiment of the present application, the optical waveguide structure 10 includes two layers of waveguide sheets 11, the two layers of waveguide sheets 11 are stacked, an in-coupling grating 12, a turning grating 13, and an out-coupling grating 14 are arranged between the two stacked layers of waveguide sheets 11, and glue is filled between the two layers of waveguide sheets 11 to form a glue layer 30 to achieve the connection and fixation of the two layers of waveguide sheets 11. The present application is formed by stacking two layers of waveguide sheets 11 with similar refractive indices. On the premise of ensuring that the light is normally transmitted inside the two layers of waveguide sheets 11, the in-coupling grating 12, the turning grating 13, and the out-coupling grating 14 are hidden inside, which is conducive to improving the performance stability of the optical waveguide structure 10, ensuring that the grating will not be polluted by the environment, and at the same time improving the design freedom of the optical waveguide structure 10, and further improving the diffraction efficiency, eye box uniformity, and angle uniformity of the optical waveguide structure 10.

[0036] In another optional embodiment of the present application, the optical waveguide structure 10 may also include three layers, four layers or even more layers, which can be configured according to specific circumstances.

[0037] Specifically, at least two layers of the waveguide plates 11 in the multi-layer waveguide plates 11 have equal thickness. In a specific embodiment of the present application, the two layers of the waveguide plates 11 of the optical waveguide structure 10 have equal thickness. This arrangement is conducive to uniform transmission of light in the two layers of the waveguide plates 11.

[0038] Specifically, the glue is transparent glue, so that the glue will not block the diffracted light, and will not affect the normal transmission of the diffracted light in the optical waveguide structure 10, which is conducive to ensuring the diffraction efficiency of the light in the two-layer waveguide sheet 11. The refractive index of the glue is greater than or equal to 1.3 and less than or equal to 2.6. In this way, the glue with a refractive index in the range of 1.3 to 2.6 is used to glue the two layers of waveguide sheets 11, so that the waveguide sheet 11 can transmit light normally, and the glue has a low absorption rate for the light transmitted in the waveguide sheet 11; the glue used in this application requires good optical transmittance, good filling property, stable physical and chemical properties, and good adhesion.

[0039] Specifically, the thickness of the single-layer waveguide sheet 11 is greater than or equal to 0.1 mm and less than or equal to 1 mm; the refractive index of the single-layer waveguide sheet 11 is greater than or equal to 1.3 and less than or equal to 2.6. The optical waveguide structure 10 is formed by stacking two or more thin waveguide sheets 11, and the stacked waveguide sheets 11 can have the same thickness and the same or different material refractive indexes. The thickness and refractive index of the waveguide sheet 11 can be used as a design parameter for optimization design, which greatly improves the design freedom of the grating on the waveguide sheet 11 and improves the overall performance of the optical waveguide structure 10.

[0040] In the present application, the coupling-in grating 12, the turning grating 13 and the coupling-out grating 14 are all in the shape of one-dimensional gratings, or two-dimensional gratings. The coupling-in grating 12 can diffract the incident light into different angles and orders for transmission, and its purpose is to guide the light emitted by the optical machine 40 into the two-layer waveguide plate 11 with maximum efficiency; the turning grating 13 can transmit the light transmitted by the coupling-in grating 12 in one-dimensional or two-dimensional directions, and its purpose is to expand the pupil and transmit the light along a specific direction; the coupling-out grating 14 can receive the light from the turning grating 13 and the coupling-in grating 12, further transmit it along a specific direction and couple it out of the waveguide plate 11, and its purpose is to evenly and efficiently couple the information of the optical machine 40 to the human eye for imaging. One-dimensional gratings can transmit the light in the waveguide 11 in one-dimensional direction. One-dimensional gratings include blazed gratings, tilted gratings, rectangular gratings, double-ridge gratings, one-dimensional multi-layer gratings, triangular gratings, trapezoidal gratings, etc. Two-dimensional gratings have periodic changes in two directions, including rectangular gratings, parallelogram gratings and diamond gratings.

[0041] It should be noted that the above-mentioned blazed grating is a grating with blazing characteristics in which the groove surface is not parallel to the grating normal, that is, there is a small angle between the two. The above-mentioned tilted grating is a grating in which the plane of the grating is inclined at a certain angle to the grating tangent. The above-mentioned rectangular grating is a grating that diffracts with a rectangular structure in cross section. The above-mentioned triangular grating is a grating that diffracts with a triangular structure in cross section. The above-mentioned trapezoidal grating is a grating that diffracts with a trapezoidal structure in cross section.

[0042] It should also be noted that the above-mentioned turning grating 13 and coupling-out grating 14 can be designed as an integral whole or separately, and the choice can be made according to the specific situation. This can be flexibly configured according to the optical waveguide structure. If a two-dimensional grating pupil expansion solution is adopted, the turning grating and the coupling-out grating can be designed as an integral structure, but if a traditional one-dimensional grating pupil expansion and coupling-out is adopted, the turning grating and the coupling-out grating need to be separately arranged in space, but the structural form remains unchanged, and both are sandwich structures.

[0043] like Figure 3As shown, it is a schematic diagram of an optical waveguide structure 10 of a specific embodiment of the present application. Two thin waveguide sheets 11 are stacked together to form an optical waveguide structure 10 for use, and the coupling grating 12, the turning grating 13 and the coupling grating 14 are hidden inside the entire optical waveguide structure 10, and the two waveguide sheets 11 are stacked together with a refractive index matching glue in the middle to form a whole for use. Since there is a refractive index difference between the refractive index of the coupling grating 12 material and the refractive index matching glue, the diffraction performance of the coupling grating 12, the turning grating 13 and the coupling grating 14 will not be affected, and the refractive index of the glue and the refractive index of the coupling grating 12 can be used as optimization parameters for optimization design, and the degree of freedom of design can be further improved. Since the thickness of the two waveguide sheets 11 is relatively small, for example, 0.2mm, 0.3mm, 0.4mm, etc., the overall thickness of the stacked optical waveguide structure 10 is no different from the thickness of a conventional single-piece waveguide.

[0044] like Figure 3 As shown, the coupling grating 12 includes a transmission-reflection coupling grating. The light emitted by the optical machine 40 is coupled into the two layers of waveguide plates 11 by the coupling grating 12 in the form of transmission and reflection. The upper waveguide plate 11 mainly receives the light reflected by the coupling grating 12, and the lower waveguide plate 11 mainly receives the light transmitted by the coupling grating 12. Then, the light coupled into the waveguide plate 11 by the coupling grating 12 passes through the subsequent turning grating 13 and the coupling-out grating 14 respectively. Although it passes through the grating for diffraction many times, the number of diffraction and the diffraction efficiency of each light ray passing through the turning grating 13 and the coupling-out grating 14 are the same as those of the ordinary relief grating waveguide, and no additional efficiency loss is caused. What's more, the transmission and reflection levels of the coupling grating 12 can be utilized, thereby increasing the utilization efficiency of the light to a certain extent, which is beneficial to improving the coupling efficiency, and then improving the final display efficiency, which helps to improve the overall performance of the optical waveguide structure 10.

[0045] It should be noted that the coupling grating on the optical waveguide structure in the prior art is generally of a transmission type or a reflection type. When light is coupled into the waveguide through the coupling grating, a portion of the light is either wasted in the form of reflection or wasted in the form of transmission, and both the transmitted light and the reflected light cannot be utilized. The coupling grating 12 of the present application can utilize both the transmitted light and the reflected light at the same time, avoiding the waste of light energy, thereby improving the transmission efficiency of the optical waveguide structure 10.

[0046] like Figure 5As shown, the manufacturing method of the optical waveguide structure 10 of the present application is not complicated and is relatively easy to implement in the process. The manufacturing method of the optical waveguide structure 10 of the present application includes: cleaning the substrate 501 (optical material such as glass, plastic, etc.), uniformly forming a layer of material 502 on the substrate 501, which is used as the material 502 for the later coupling grating 12, the turning grating 13 and the coupling grating 14. The coupling grating 12, the turning grating 13 and the coupling grating 14 on the master plate 503 are transferred to the substrate 501 by nanoimprinting to form a waveguide structure 504 with the coupling grating 12, the turning grating 13 and the coupling grating 14, and then the substrate with the refractive index matching glue uniformly applied is superimposed with the waveguide structure 504 with the coupling grating 12, the turning grating 13 and the coupling grating 14, so as to form the optical waveguide structure 10 of the present application. Since the imprinting process is relatively mature, the use of the imprinting process to realize the production of the optical waveguide structure 10 is conducive to reducing the processing cost and ensuring low cost. At the same time, it is suitable for mass production and ensures processing efficiency. In addition, the implementation of the above-mentioned coupling grating 12, the turning grating 13 and the coupling grating 14 can be made by nanoimprinting technology, and can also be realized by a variety of process methods such as photolithography, particle beam etching, chemical corrosion, etc., which can be selected according to specific needs. On the basis of traditional grating molding technology, by adding fewer process steps, more superior optical waveguide diffraction performance can be achieved.

[0047] It should be noted that although the optical waveguide structure 10 of the present application is composed of two stacked waveguide sheets 11, since the thickness of the two stacked waveguide sheets 11 is relatively small, the thickness of the optical waveguide structure 10 is the same as that of a normal single-piece waveguide, or even smaller.

[0048] like Figure 4 As shown, an optical waveguide module provided by the present application includes an optical engine 40 and at least two of the above-mentioned optical waveguide structures 10. The optical engine 40 is one or more. When there is one optical engine 40, the optical engine 40 can emit at least three colors of light. The two optical waveguide structures 10 are stacked and located on one side of the optical engine 40. The coupling-in grating 12, the turning grating 13 and the coupling-out grating 14 on the stacked at least two optical waveguide structures 10 are respectively arranged correspondingly. That is, the coupling-in grating 12 in the upper optical waveguide structure 10 is arranged correspondingly to the coupling-in grating 12 in the lower optical waveguide structure 10, the turning grating 13 in the upper optical waveguide structure 10 is arranged correspondingly to the turning grating 13 in the lower optical waveguide structure 10, and the coupling-out grating 14 in the upper optical waveguide structure 10 is arranged correspondingly to the coupling-out grating 14 in the lower optical waveguide structure 10, so as to facilitate the stable transmission of the diffracted light.

[0049] like Figure 4As shown, two optical waveguide structures 10 can be stacked and used to realize color waveguide display. Since the coupling-in grating 12, the turning grating 13 and the coupling-out grating 14 are inside the optical waveguide structure 10, there is no need to worry about the conflict between the position of the color filter 20 and the grating position, and there is no need to add an additional cover plate to protect the grating, making the entire optical waveguide structure 10 more compact. At the same time, the design freedom is more flexible, and other functional film layers can be added on the front and back sides of the two optical waveguide structures 10, greatly improving the design freedom.

[0050] Specifically, the optical waveguide module also includes a color filter 20, which is arranged on the optical waveguide structure 10 far away from the optical engine 40 in the two stacked optical waveguide structures 10, and the color filter 20 is located on the side surface of the optical waveguide structure 10 where it is located close to the optical engine 40. The color filter 20 corresponds to the coupling gratings 12 in the two optical waveguide structures 10. This arrangement enables the color filter 20 to filter out light that does not belong to the optical waveguide structure 10 below, thereby avoiding the problem of light crosstalk, which is beneficial to ensuring display efficiency and display uniformity.

[0051] It should be noted that the above-mentioned optical waveguide structure 10 and optical waveguide module can be used in vehicle-mounted head-up display devices, and can also be used in AR head-mounted devices.

[0052] Obviously, the above-described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0053] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0054] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An optical waveguide structure, characterized in that: include: A multi-layer waveguide sheet, wherein the multi-layer waveguide sheet is stacked; at least one coupling-in grating (12), at least one turning grating (13) and at least one coupling-out grating (14); the coupling-in grating (12), the turning grating (13) and / or the coupling-out grating (14) are arranged between at least two adjacent layers of the waveguide plates (11); the coupling-in grating (12), the turning grating (13) and / or the coupling-out grating (14) are not located on surfaces of the waveguide plates (11) at both sides that are away from each other; glue is filled between two adjacent layers of the waveguide plates (11) so that the coupling-in grating (12), the turning grating (13) and the coupling-out grating (14) are covered, and the multi-layer waveguide plates (11) are integrated; The coupling-in grating (12) is used to couple light emitted by an external optical machine into the multilayer waveguide plate (11), the turning grating (13) is used to receive the light of the coupling-in grating (12) and perform pupil expansion transmission on the light, and the coupling-out grating (14) is used to receive the light of the turning grating (13) and couple the light out of the multilayer waveguide plate (11); The coupling grating (12) comprises a transmissive-reflective coupling grating, and the light emitted by the optical machine (40) is coupled into the two layers of the waveguide plates (11) by the coupling grating (12) in the form of transmission and reflection, respectively; the waveguide plate (11) of the upper layer receives the light reflected by the coupling grating (12), and the waveguide plate (11) of the lower layer receives the light transmitted by the coupling grating (12); The refractive index of the coupling-in grating (12) is different from the refractive index of the glue.

2. The optical waveguide structure according to claim 1, characterized in that: The optical waveguide structure (10) comprises two layers of waveguide sheets (11).

3. The optical waveguide structure according to claim 1, characterized in that: At least two layers of the waveguide sheets (11) in the multi-layer waveguide sheet (11) have the same thickness.

4. The optical waveguide structure according to claim 1, characterized in that: The glue is transparent glue; and / or The refractive index of the glue is greater than or equal to 1.3 and less than or equal to 2.

6.

5. The optical waveguide structure according to claim 1, characterized in that: The thickness of the waveguide plate (11) is greater than or equal to 0.1 mm and less than or equal to 1 mm; and / or The refractive index of the waveguide plate (11) is greater than or equal to 1.3 and less than or equal to 2.

6.

6. The optical waveguide structure according to claim 1, characterized in that: The coupling-in grating (12), the turning grating (13) and the coupling-out grating (14) are all one-dimensional gratings, or are all two-dimensional gratings.

7. An optical waveguide module, characterized in that: include: an optical engine (40), wherein the optical engine (40) is one or more, and when the optical engine (40) is one, the optical engine (40) can emit light of at least three colors; At least two optical waveguide structures (10) according to any one of claims 1 to 6, wherein the at least two optical waveguide structures (10) are stacked and located on one side of the optical machine (40), and the coupling-in grating (12), the turning grating (13) and the coupling-out grating (14) on the at least two stacked optical waveguide structures (10) are respectively arranged correspondingly; The coupling grating (12) comprises a transmission-reflection coupling grating, and the light emitted by the optical machine (40) is coupled into two layers of waveguide plates (11) by the coupling grating (12) in the form of transmission and reflection, respectively; the waveguide plate (11) of the upper layer receives the light reflected by the coupling grating (12), and the waveguide plate (11) of the lower layer receives the light transmitted by the coupling grating (12); the refractive index of the coupling grating (12) is different from the refractive index of the glue.

8. The optical waveguide module according to claim 7, characterized in that: The optical waveguide module further comprises a color filter (20), wherein the color filter (20) is arranged on the optical waveguide structure (10) located away from the optical engine (40) among the at least two stacked optical waveguide structures (10), and the color filter (20) is located on a side surface of the optical waveguide structure (10) where the color filter (20) is located and close to the optical engine (40), and the color filter (20) corresponds to the coupling grating (12).

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