Diffraction waveguide structure and near-eye display device

Abstract

The present application provides a diffraction waveguide structure and a near-eye display device. The diffraction waveguide structure includes a first waveguide, an in-coupling grating and a first out-coupling grating arranged on the same side of the first waveguide; and a selectively transmissive film layer and a second out-coupling grating arranged on the other side of the first waveguide. The out-coupling directions of the first out-coupling grating and the second out-coupling grating are the same. The selectively transmissive film layer can reflect a first light ray and transmit a second light ray, and the propagation angle of the first light ray in the first waveguide is greater than the propagation angle of the second light ray in the first waveguide. The second out-coupling grating is used to out-couple the second light ray that passes through the selectively transmissive film layer. The first out-coupling grating is used to out-couple the first light ray propagating in the first waveguide and the second light ray, thereby increasing the amount of the second light ray out-coupled, thereby minimizing the difference in the amount of the first light ray and the second light ray out-coupled, and improving the display effect.

Description

Technical Field

[0001] The present application relates to the field of mold technology, and in particular to a diffraction waveguide structure and a near-eye display device. Background Art

[0002] Augmented Reality (AR) technology combines virtual scenes with the real world. AR devices based on diffractive waveguides offer advantages such as lightweight, high transmittance, and low mass production costs. Therefore, diffractive waveguides are a mainstream solution for AR devices.

[0003] In a conventional diffraction waveguide layout, light emitted by the optical engine enters the waveguide through diffraction at the incoupling grating, changing its propagation direction. Light that meets the total internal reflection condition propagates along the waveguide to the transition grating, which serves to increase the exit pupil range. Light redirected by the transition grating propagates to the outcoupling grating, where it diffracts and exits the waveguide, entering the human eye and forming an image on the retina.

[0004] However, diffraction waveguides are extremely sensitive to wavelength, resulting in different diffraction efficiencies for different colors of light. This ultimately leads to poor color uniformity in full-color AR devices based on diffraction waveguides. After the pattern is transmitted, the ratio of RGB colors changes, affecting the visual effect. Summary of the Invention

[0005] The present application provides a diffraction waveguide structure and a near-eye display device, which are used to improve the display effect of the near-eye display device.

[0006] In a first aspect, the present application provides a diffraction waveguide structure, comprising a first waveguide, an incoupling grating and a first outcoupling grating disposed on the same side of the first waveguide; a selective transmission film layer disposed on a side of the first waveguide facing away from the incoupling grating; and a second outcoupling grating disposed on a side of the selective transmission film layer facing away from the first waveguide;

[0007] The first outcoupling grating and the second outcoupling grating are arranged opposite to each other along the thickness direction of the first waveguide, and the outcoupling directions of the first outcoupling grating and the second outcoupling grating are the same;

[0008] The selective transmission film layer can reflect a first light and transmit a second light, and a propagation angle of the first light in the first waveguide is greater than a propagation angle of the second light in the first waveguide;

[0009] The second outcoupling grating is used for outcoupling the second light that passes through the selective transmission film layer; the first outcoupling grating is used for outcoupling the first light and the second light that propagate in the first waveguide.

[0010] In the above technical solution, the selective transmission film layer is set to reflect and transmit different light rays, so that the second light ray with a large propagation angle can be coupled out through the second coupling grating, thereby increasing the amount of second light ray coupled out, thereby minimizing the difference in the amount of first light ray coupled out and the second light ray coupled out, thereby improving the display effect.

[0011] In a specific embodiment, the invention further comprises a second waveguide stacked with the first waveguide; wherein the selective transmission film layer is sandwiched between the first waveguide and the second waveguide; and the thickness of the first waveguide is greater than the thickness of the second waveguide;

[0012] The second outcoupling grating is arranged on a side of the second waveguide facing away from the first waveguide.

[0013] In a specific embodiment, the thickness of the second waveguide is greater than 0.1 mm.

[0014] In a specific embodiment, along the length direction of the first waveguide, the length of the selective transmission film layer is greater than or equal to the length of the first outcoupling grating and the second outcoupling grating.

[0015] In a specific embodiment, along the length direction of the first waveguide, the length of the selective transmission film layer is equal to the length of the first waveguide, and both ends of the selective transmission film layer are flush with both ends of the first waveguide.

[0016] In a specific implementation manner, along the length direction of the first waveguide, the lengths of the first outcoupling grating and the second outcoupling grating are equal, and two ends of the first outcoupling grating are flush with two ends of the second outcoupling grating.

[0017] In a specific embodiment, the first outcoupling grating is a transmissive grating; and the second outcoupling grating is a reflective grating.

[0018] In a specific embodiment, the first out-coupling grating and the in-coupling grating are integrated with the first waveguide;

[0019] The second outcoupling grating and the second waveguide are an integrated structure.

[0020] In a specific embodiment, the selective transmission film layer is a Bragg reflector.

[0021] In a second aspect, a near-eye display device is provided, comprising a display device and any of the above-mentioned diffraction waveguide structures; wherein,

[0022] The light emitted from the display device couples the coupling grating into the first waveguide.

[0023] In the above technical solution, the selective transmission film layer is set to reflect and transmit different light rays, so that the second light ray with a large propagation angle can be coupled out through the second coupling grating, thereby increasing the amount of second light ray coupled out, thereby minimizing the difference in the amount of first light ray coupled out and the second light ray coupled out, thereby improving the display effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of an application scenario of the diffraction waveguide structure provided in an embodiment of the present application;

[0025] Figure 2 Schematic diagram of light propagation in a diffraction waveguide structure in the prior art;

[0026] Figure 3 A schematic structural diagram of a diffraction waveguide structure provided in an embodiment of the present application;

[0027] Figure 4 A graph showing the relationship between the thickness ratio of the first waveguide and the second waveguide and the outcoupling amounts of the first light and the second light provided in an embodiment of the present application;

[0028] Figure 5 A schematic diagram of another diffraction waveguide structure provided in an embodiment of the present application;

[0029] Figure 6 Schematic diagram of simulation of a diffraction waveguide structure in the prior art;

[0030] Figure 7 A schematic diagram of a simulation of a diffraction waveguide structure provided in an embodiment of the present application;

[0031] Figure 8 A simulation schematic diagram of another diffraction waveguide structure provided in an embodiment of the present application. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of this application clearer, this application will be further described in detail below with reference to the accompanying drawings.

[0033] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in one or more embodiments of this specification should have the usual meanings understood by people with ordinary skills in the field to which this disclosure belongs. The "first", "second" and similar words used in one or more embodiments of this specification do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative position relationships. When the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0034] To facilitate understanding of the optical device provided in the embodiments of this application, its application scenarios are first described. The display device provided in the embodiments of this application is used in various near-eye display systems, such as AR (Augmented Reality) or VR (Virtual Reality), to achieve virtual displays. However, current near-eye display systems generally suffer from uneven light coupling out of the light guide, which affects the user's viewing experience.

[0035] like Figure 1 As shown in Figure 1 A schematic diagram of an application scenario of an optical device in the prior art is shown. The existing optical device includes a light guide 1, a light coupling device 2, a light coupling device 3, and a light generator 9. The light generator 9 is used to emit light for displaying an image. The light coupling device 2 is used to couple the light emitted by the light generator 9 into the light guide 1. The light guide 1 is used to propagate light and has two oppositely arranged total internal reflection surfaces. The light in the light guide 1 can propagate light by total internal reflection of the total internal reflection surfaces. The light coupling device 3 is used to couple the light in the light guide 1 out to the user's eyes so that the user can observe the image displayed by the light generator.

[0036] For reference Figure 2 As shown in FIG, when light is coupled into the waveguide 100 through the coupling grating 200, light of different wavelengths has different propagation angles. The propagation angle refers to the angle formed by the light with the surface of the waveguide when it propagates in the waveguide. Figure 2The solid line shown in FIG represents the first light ray 2000, and the dashed line represents the second light ray 1000. When the first light ray 2000 and the second light ray 1000 propagate in the waveguide 100, the propagation angle of the first light ray 2000 is α, and the propagation angle of the second light ray 1000 is β. The propagation angle α of the first light ray 2000 is greater than the propagation angle β of the second light ray 1000. Therefore, the first light ray 2000 is reflected more frequently in the waveguide 100, and the interval between two adjacent reflection locations on the same surface of the waveguide 100 is shorter. In contrast, because the second light ray 1000 has a smaller propagation angle, the second light ray 1000 is reflected less frequently in the waveguide 100, and the interval between two adjacent reflection locations on the same surface of the waveguide 100 is larger. When the first light 2000 and the second light 1000 propagate to the outcoupling grating 300, it can be intuitively seen that the outcoupling amount of the first light 2000 is greater than the outcoupling amount of the second light 1000, resulting in a large difference in the outcoupling amount of light of different wavelengths, affecting the user's viewing experience. The first light 2000 and the second light 1000 described above can be lights of different colors. For example, the first light 2000 is blue light and the second light 1000 is red light.

[0037] To this end, the present invention provides a diffraction waveguide structure to improve the viewing experience of users. Detailed description is provided below with reference to specific figures and embodiments.

[0038] refer to Figure 3 As shown, Figure 3 A schematic diagram of a diffraction waveguide structure provided in an embodiment of the present application is shown. The diffraction waveguide structure provided in an embodiment of the present application mainly includes a first waveguide 10, an input grating 20, a first output grating 30, a second output grating 60, and a selective transmission film layer 50. Among them, the first waveguide 10 is used to propagate light, and is used to propagate the light coupled in by the input grating 20 to the output gratings (the first output grating 30 and the second output grating 60). The selective transmission film layer 50 is used to selectively transmit and reflect different light. In the embodiment of the present application, the selective transmission film layer is used to reflect the first light 2000 and transmit the second light 1000. So that the first light 2000 and the second light 1000 are emitted along different output paths.

[0039] In a specific configuration, the in-coupling grating 20 and the first out-coupling grating 30 are disposed on the same side of the first waveguide 10. In one specific arrangement, the in-coupling grating 20 and the out-coupling grating can be located at opposite ends of the first waveguide 10. Light (including the first light ray 2000 and the second light ray 1000) coupled into the first waveguide 10 by the in-coupling grating 20 can propagate through the first waveguide 10 to the first out-coupling grating 30 and be out-coupled. The functions and positions of the in-coupling grating 20 and the first out-coupling grating 30 are identical to those of the conventional in-coupling grating 20 and will not be further described herein.

[0040] In the embodiment of the present application, the propagation angle of the first light 2000 in the first waveguide 10 is greater than the propagation angle of the second light 1000 in the first waveguide 10, so that the number of total reflections of the first light 2000 in the first waveguide 10 is greater than the number of total reflections of the second light 1000 in the first waveguide 10. Therefore, when the light is coupled out only through the first outcoupling grating 30, the outcoupling amount of the first light 2000 is greater than the outcoupling amount of the second light 1000.

[0041] To improve the outcoupling effect of the diffraction waveguide structure on light, the diffraction waveguide structure provided in the embodiment of the present application increases the outcoupling amount of the second light 1000 by cooperating with the selective transmission film layer 50 and the second outcoupling grating 60 .

[0042] In a specific configuration, the selective transmission film layer 50 and the second outcoupling grating 60 are both located on the same side of the first waveguide 10 that is away from the incoupling grating 20. The selective transmission film layer 50 is disposed on the side of the first waveguide 10 that is away from the incoupling grating 20, while the second outcoupling grating 60 is disposed on the side of the selective transmission film layer 50 that is away from the first waveguide 10. In other words, the second outcoupling grating 60, the selective transmission film layer 50, and the first waveguide 10 are stacked, with the selective transmission film layer 50 located between the second outcoupling grating 60 and the first waveguide 10. The second outcoupling grating 60 is used to outcouple the second light 1000 that has passed through the selective transmission film layer 50.

[0043] In addition, when the second outcoupling grating 60 is specifically arranged, it is arranged opposite to the first outcoupling grating 30 along the thickness direction of the first waveguide 10. Moreover, the outcoupling directions of the first outcoupling grating 30 and the second outcoupling grating 60 are the same.

[0044] Continue to refer Figure 3As shown in the figure, for ease of understanding, two opposing surfaces of the first waveguide 10 are defined as a first surface 11 and a second surface 12. The first outcoupling grating 30 and the incoupling grating 20 are both disposed on the first surface 11, while the selective transmission film layer 50 is disposed on the second surface 12, and the second outcoupling grating 60 is arranged on the selective transmission film layer 50. When the first light 2000 and the second light 1000 are incident on the first waveguide 10 from the incoupling grating 20, the first light 2000 and the second light 1000 are propagated by total internal reflection between the first surface 11 and the second surface 12. When the first light 2000 and the second light 1000 are irradiated by the selective transmission film 50, the first light 2000 is reflected by the selective transmission film 50 and continues to propagate in the first waveguide 10. However, when the second light 1000 passes through the selective transmission film 50, it transmits through the selective transmission film 50 and propagates to the second outcoupling grating 60, which outcouples the second light 1000. Since the first outcoupling grating 30 and the second outcoupling grating 60 are positioned relative to each other, the second light 1000 coupled out by the second outcoupling grating 60 passes through the selective transmission film 50, the first waveguide 10, and the first outcoupling grating 30 before being emitted. Furthermore, when both the first light 2000 and the second light 1000 are irradiated by the first outcoupling grating 30, the first outcoupling grating 30 outcouples the first light 2000 and the second light 1000.

[0045] like Figure 3 As shown in FIG, the number of first light rays 2000 coupled out through the first coupling grating 30 is 4, the number of second light rays 1000 coupled out through the first coupling grating 30 is 2, and the number of second light rays 1000 coupled out through the second coupling grating 60 is 1. Figure 3 It can be seen that in the embodiment of the present application, the second light 1000 is added with a coupling grating (second coupling grating 60), thereby increasing the coupling amount of the second light 1000 and reducing the difference in the light coupled out of the first light 2000 and the second light 1000.

[0046] It can be seen from the above description that in the diffraction waveguide structure provided in the embodiment of the present application, the selective transmission film layer 50 is provided to reflect and transmit different light rays, so that the second light 1000 with a large propagation angle can be coupled out through the second coupling grating 60, thereby increasing the number of second light rays 1000 coupled out, thereby minimizing the difference in the number of coupled out first light rays 2000 and second light rays 1000, and improving the display effect.

[0047] Specifically, different arrangements can be used when arranging the selective transmission film layer 50 and the second outcoupling grating 60. For easier understanding, they are described in detail below with reference to specific drawings.

[0048] The diffraction waveguide structure provided in the embodiment of the present application may further include a second waveguide 40 . The first waveguide 10 and the second waveguide 40 have the same material and function, and are used to propagate the first light 2000 and the second light 1000 by total internal reflection.

[0049] In a specific arrangement, the second waveguide 40 is stacked with the first waveguide 10, and the second waveguide 40 is located on the side of the first waveguide 10 facing away from the incoupling grating 20. A selectively transmissive film 50 is sandwiched between the first waveguide 10 and the second waveguide 40, and a second outcoupling grating 60 is disposed on the side of the second waveguide 40 facing away from the first waveguide 10. During light propagation, the first light 2000 is reflected by the selectively transmissive film 50 and is totally reflected only within the first waveguide 10. As for the second light 1000, since the selectively transmissive film 50 transmits the second light 1000, the first waveguide 10 and the second waveguide 40 can be considered as a single waveguide, and the second light 1000 is totally reflected within both the first waveguide 10 and the second waveguide 40. Although the above arrangement includes the second waveguide 40, it facilitates the placement of the second outcoupling grating 60.

[0050] In this structure, when the incident angle of the light entering the first waveguide 10 is θ1, the propagation angle after passing through the coupling grating 20 becomes , the interval between the two outcouplings of the first light 2000 is , the interval between the two outcouplings of the second light 1000 is ; wherein λ1 is the wavelength of the incident light, T is the grating period, n1 and n2 are the refractive indices of air and the first waveguide 10 respectively, d1 is the rear end of the first waveguide 10, and d2 is the thickness of the second waveguide 40.

[0051] When the second waveguide 40 and the first waveguide 10 have the same thickness, the outcoupling frequency of the second light ray 1000 is the same as that of the conventional diffraction waveguide structure. When the second waveguide is thicker than the first waveguide, the outcoupling frequency of the second light ray 1000 begins to decrease. Therefore, to increase the outcoupling frequency, the upper limit of the thickness of the second waveguide 40 is less than the thickness of the first waveguide 10. The thinner the second waveguide 40, the greater the outcoupling frequency of the second light ray 1000.

[0052] As can be seen from the above description, the second waveguide 40 increases the path length of the second light 1000 during total internal reflection. Therefore, when the first waveguide 10 and the second waveguide 40 are specifically arranged, the thickness of the first waveguide 10 is greater than the thickness of the second waveguide 40, so that the added second waveguide 40 can minimize the impact on the second light 1000, ensuring that the number of second light rays 1000 increased by coupling out through the second coupling grating 60 is greater than the number of second light rays 1000 reduced due to the increase in the total internal reflection path of the second light 1000.

[0053] When the first waveguide 10 and the second waveguide 40 are specifically set, the thickness of the first waveguide 10 and the second waveguide 40 directly affects the outcoupling amount of the first light 2000 and the second light 1000. Figure 4 As shown, Figure 4 The figure shows the relationship between the ratio of the thickness of the first waveguide 10 and the second waveguide 40 and the ratio of the outcoupling amount of the first light 2000 and the second light 1000. Figure 4 It can be seen that the smaller the thickness of the second waveguide 40, the greater the outcoupling amount of the second light 1000. Therefore, in the specific configuration, the second waveguide 40 is made as small as possible while ensuring processing. However, it should be understood that in the embodiment of the present application, the thickness of the second waveguide 40 is greater than 0.1 mm to ensure that the second waveguide 40 meets the minimum processing size and facilitates the processing and preparation of the second waveguide 40.

[0054] As an example, the selective transmission film layer 50 provided in the embodiment of the present application is a Bragg reflector, which can select the first light 2000 and the second light 1000, reflect the first light 2000, and transmit the second light 1000.

[0055] In addition, the length of the selective transmission film 50 is greater than or equal to the length of the first outcoupling grating 30 and the second outcoupling grating 60 along the length direction of the first waveguide 10. This ensures that when the first light 2000 and the second light 1000 illuminate the first outcoupling grating 30 and the second outcoupling grating 60, they can be filtered by the selective transmission film 50.

[0056] In one embodiment, along the length of the first waveguide 10, the length of the selectively transparent film layer 50 is equal to the length of the first waveguide 10, and both ends of the selectively transparent film layer 50 are flush with both ends of the first waveguide 10. In this state, the first light 2000 propagates only in the first waveguide 10, while the second light 1000 propagates in both the first waveguide 10 and the second waveguide 40.

[0057] Of course, in addition to the above examples, the length of the selectively transmissive film layer 50 can also be smaller than the length of the first waveguide 10. When this approach is adopted, the propagation path of the first light 2000 is increased, the number of total reflections within the first waveguide 10 is reduced, the amount of outcoupling of the first light 2000 is reduced, and to a certain extent, the difference in the amount of outcoupling of the first light 2000 and the second light 1000 can be reduced.

[0058] In an optional solution, along the length of the first waveguide 10, the first outcoupling grating 30 and the second outcoupling grating 60 are of equal length, and the two ends of the first outcoupling grating 30 are flush with the two ends of the second outcoupling grating 60. In other words, the first outcoupling grating 30 and the second outcoupling grating 60 are completely aligned across the thickness of the first waveguide 10. This approach facilitates the fixing of the first outcoupling grating 30 and the second outcoupling grating 60 to the first waveguide 10 and the second waveguide 40. Furthermore, by using the first outcoupling grating 30 and the second outcoupling grating 60 of the same length, it is also ensured that the second light 1000 coupled out by the second grating can be emitted through the first outcoupling grating 30, thereby improving the outcoupling effect of the second light 1000.

[0059] In the embodiments of the present application, the first outcoupling grating 30 and the second outcoupling grating 60 can employ different types of outcoupling gratings. For example, the first outcoupling grating 30 is a transmissive grating, while the second outcoupling grating 60 is a reflective grating. This ensures that the outcoupling directions of the first outcoupling grating 30 and the second outcoupling grating 60 are consistent, ensuring that the second light 1000 coupled by the second outcoupling grating 60 can pass through the first outcoupling grating 30 and then be emitted.

[0060] When fabricating the first outcoupling grating 30 and the second outcoupling grating 60, the first outcoupling grating 30 and the incoupling grating 20 are integrally formed with the first waveguide 10, while the second outcoupling grating 60 is integrally formed with the second waveguide 40. Specifically, the first outcoupling grating 30 is fabricated directly on the first waveguide 10, while the second outcoupling grating 60 is fabricated directly on the second outcoupling grating 60. This structure not only improves the structural strength between the various components of the diffraction waveguide structure, but also reduces the interface between the propagation of the first light ray 2000 and the second light ray 1000, thereby improving the light propagation effect.

[0061] In a variant embodiment, Figure 5 As shown, the diffraction waveguide structure provided in the embodiment of the present application may also not include the second waveguide 40, that is, the second outcoupling grating 60 is directly connected to the selective transmission film layer 50. When this structure is adopted, the selective transmission film layer 50 is directly provided on the second surface 12 of the first waveguide 10. In addition, the length of the selective transmission film layer 50 is the same as the length of the second outcoupling grating 60, and the ends of the two are aligned. When the second light 1000 propagates in the diffraction waveguide structure, the propagation path of the second light 1000 is basically the same as that of the diffraction waveguide structure in the prior art, but the outcoupling amount of the second light 1000 is equivalent to doubled, which can effectively improve the outcoupling amount of the second light 1000, reduce the difference in the outcoupling amount of the first light 2000 and the second light 1000, and improve the display effect of the near-eye display device.

[0062] To facilitate understanding of the effect of the diffraction waveguide structure provided in the embodiment of the present application, the following takes the structure of the diffraction waveguide structure including the first waveguide 10 and the second waveguide 40 as an example, and simulates and compares it with the diffraction waveguide structure in the prior art. Among them, the parameters of the diffraction waveguide structure provided in the embodiment of the present application are as follows: the thickness of the first waveguide 10 is 0.8 mm, and the refractive index is 2.0; the thickness of the second waveguide 40 is 0.3 mm, and the refractive index is 2.0. The thickness of the waveguide in the prior art is 0.8 mm, and the refractive index is 2.0. For light with a field of view angle of 30° in the horizontal direction, the relationship between the outcoupling times of the first light and the second light and the incident angle is as follows: Figure 6 and Figure 7 Reference Figure 6 It can be seen that by Figure 6 It can be seen that the average outcoupling times of the first light 2000 in the diffraction waveguide structure in the prior art is 2.05 times the average outcoupling times of the second light 1000. Figure 7 As shown, the average outcoupling times of the first light 2000 in the diffraction waveguide structure provided by the embodiment of the present application is 1.41 times the average outcoupling times of the second light 1000.

[0063] For reference Figure 8 As shown, Figure 8 Schematic diagram showing the outcoupling times of the first light 2000 and the second light 1000 when a thinner second waveguide 40 is used. When the thickness of the second waveguide 40 is 0.1 mm, the average outcoupling times of the first light 2000 is 1.15 times that of the second light 1000.

[0064] It can be seen from the above description that in the diffraction waveguide structure provided in the embodiment of the present application, by adopting a thinner second waveguide or not adopting a second waveguide, the outcoupling amount of the second light can be increased, the difference between the outcoupling amounts of the first light and the second light can be improved, and the display effect of the near-eye display device can be improved.

[0065] The present application also provides a near-eye display device, comprising a display device and any of the aforementioned diffractive waveguide structures; wherein light emitted from the display device couples the coupling grating 20 into the first waveguide 10. The diffractive waveguide structure may refer to any of the aforementioned diffractive waveguide structures.

[0066] In the above technical solution, the selective transmission film layer 50 is set to reflect and transmit different light rays, so that the second light 1000 with a large propagation angle can be coupled out through the second coupling grating 60, thereby increasing the number of second light rays 1000 coupled out, thereby minimizing the difference in the number of coupled out first light rays 2000 and second light rays 1000, and improving the display effect.

[0067] The one or more embodiments of this specification are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of this specification shall be included within the scope of protection of this disclosure.

[0068] The above are only specific embodiments of the present application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A diffraction waveguide structure, characterized in that: The invention comprises a first waveguide, an in-coupling grating and a first out-coupling grating arranged on the same side of the first waveguide; a selective transmission film layer arranged on a side of the first waveguide away from the in-coupling grating; and a second out-coupling grating arranged on a side of the selective transmission film layer away from the first waveguide; The first outcoupling grating and the second outcoupling grating are arranged opposite to each other along the thickness direction of the first waveguide, and the outcoupling directions of the first outcoupling grating and the second outcoupling grating are the same; The selective transmission film layer can reflect a first light and transmit a second light, and a propagation angle of the first light in the first waveguide is greater than a propagation angle of the second light in the first waveguide; The second outcoupling grating is used to couple out the second light that passes through the selective transmission film layer; the first outcoupling grating is used to couple out the first light and the second light that propagate in the first waveguide; The first outcoupling grating is a transmissive grating; the second outcoupling grating is a reflective grating.

2. The diffraction waveguide structure according to claim 1, wherein: Also included is a second waveguide stacked with the first waveguide; wherein the selective transmission film layer is sandwiched between the first waveguide and the second waveguide; and the thickness of the first waveguide is greater than the thickness of the second waveguide; The second outcoupling grating is arranged on a side of the second waveguide facing away from the first waveguide.

3. The diffraction waveguide structure according to claim 2, wherein: The thickness of the second waveguide is greater than 0.1 mm.

4. The diffraction waveguide structure according to claim 2, wherein: Along the length direction of the first waveguide, the length of the selective transmission film layer is greater than or equal to the length of the first outcoupling grating and the second outcoupling grating.

5. The diffraction waveguide structure according to claim 4, characterized in that: Along the length direction of the first waveguide, the length of the selective transmission film layer is equal to the length of the first waveguide, and two ends of the selective transmission film layer are flush with two ends of the first waveguide.

6. The diffraction waveguide structure according to claim 2, wherein: Along the length direction of the first waveguide, the lengths of the first outcoupling grating and the second outcoupling grating are equal, and two ends of the first outcoupling grating are flush with two ends of the second outcoupling grating.

7. The diffraction waveguide structure according to any one of claims 2 to 6, wherein: The first out-coupling grating and the in-coupling grating are an integrated structure with the first waveguide; The second outcoupling grating and the second waveguide are an integrated structure.

8. The diffraction waveguide structure according to claim 7, characterized in that: The selective transmission film layer is a Bragg reflector.

9. A near-eye display device, characterized in that: Comprising a display device, and a diffraction waveguide structure according to any one of claims 1 to 8; wherein, The light emitted from the display device couples the coupling grating into the first waveguide.

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