Optical waveguide stacking device and display equipment

Abstract

The invention relates to the technical field of display, in particular to an optical waveguide stacking device and display equipment, and the optical waveguide stacking device comprises an optical stacking body, an input coupling plate and an output coupling plate. The optical stack vertically overlaps the first, second and third waveguide substrate layers, and is coated with a first dielectric layer and a second dielectric layer. The input coupling plate is arranged on the outer surface of the first waveguide substrate layer, receives input light beams and couples the input light beams into the waveguide substrate layers according to wavebands, so that the input coupling plate guides light beams with specific wavebands in a layered mode. The output coupling plate is arranged on the outer surface of the first waveguide substrate layer and guides the light beam to be coupled out in the first direction. Layered guidance and final synthesis of multi-band light can be realized by using the refractive index difference between the multi-layer waveguide and the dielectric layer, and it is ensured that an output image has a single and complete color effect.

Description

Technical Field

[0001] This application relates to the field of display technology, and in particular to an optical waveguide structure and its application, especially an optical waveguide stacking device and display device for improving dark patterns in waveguide images. Background Technology

[0002] Waveguide augmented reality head-up display (AR HUD) is a display technology that combines virtual images with the real field of vision. Images generated by a micro-projection module are evenly diffused into the driver's line of sight through a waveguide structure, achieving a "virtual-real fusion" effect. Compared to traditional head-up displays, waveguide AR HUDs are smaller, lighter, and have higher light transmittance, allowing navigation, warnings, and vehicle information to be displayed directly on the road scene, thereby improving driving safety and immersion.

[0003] In existing optical waveguide technology, light transmission through the waveguide can lead to a "stripe line phenomenon" in images, caused by variations in waveguide thickness, inhomogeneous in-coupler size, or changes in diffraction angle. This results in bright or dark stripes or uneven brightness of varying degrees. The stripe phenomenon causes areas of the image to be too bright or too dark, reducing visibility and degrading display quality, while also significantly increasing driving safety risks. A common approach is to reduce the waveguide thickness to mitigate the stripe phenomenon; however, this method results in excessive diffraction of light of different wavelengths, preventing some wavelengths from effectively reaching the viewing field at the back of the waveguide, thus affecting image uniformity, brightness, and display quality.

[0004] Therefore, in view of the problems of the prior art, this application further proposes an optical waveguide stacking device and display device to improve the dark fringes of waveguide images, so as to solve the problems currently existing. Summary of the Invention

[0005] In view of the above problems, the purpose of this application is to provide a method for optical waveguide stacking design that effectively solves the stripe phenomenon in optical waveguide images in the prior art by using a multilayer waveguide substrate, a dielectric layer and a specially designed grating structure, while maintaining or improving image quality.

[0006] To achieve the above objectives, this application provides an optical waveguide stacking device, including an optical stack, an input coupling plate, and an output coupling plate. The optical stack includes a third waveguide substrate layer, a second waveguide substrate layer, and a first waveguide substrate layer, all stacked perpendicularly along a first direction, as well as a first dielectric layer and a second dielectric layer, wherein the first direction refers to the direction in which an input light beam is incident on the optical stack. The first waveguide substrate layer is disposed on the second waveguide substrate layer, and the second waveguide substrate layer is disposed on the third waveguide substrate layer. The first dielectric layer is disposed between the first waveguide substrate layer and the second waveguide substrate layer, and the second dielectric layer is disposed between the second waveguide substrate layer and the third waveguide substrate layer. The input coupling plate is disposed on the outer surface of the first waveguide substrate layer and receives the input light beam input from the outer surface of the third waveguide substrate layer along the first direction. The input coupling plate is coupled into the first waveguide substrate layer, the second waveguide substrate layer, or the third waveguide substrate layer according to the wavelength of the light beam, so that the first waveguide substrate layer, the second waveguide substrate layer, or the third waveguide substrate layer guides and propagates their respective specific wavelength light beams in layers along a second direction. An output coupling plate is disposed on the outer surface of the first waveguide substrate layer and spaced apart from the input coupling plate by a certain distance. This allows specific wavelength beams propagating along the second direction to be guided and coupled together via the output coupling plate, and then coupled out along the first direction to form an output beam. Therefore, by using multiple stacked waveguide substrate layers and dielectric layers, the refractive index difference can be used to achieve layered guidance and propagation of beams of different wavelengths, completely solving the problem of traditional single-layer waveguides' inability to handle multicolor light. Furthermore, at least two reflections ensure effective light transmission within the waveguide, culminating in a final overlapping coupling output, ensuring that the user's eye receives a single and complete color image.

[0007] In some embodiments of this application, the optical stack is sequentially divided into an input region, a diffusion region, and an output region along the second direction from the input coupling plate to the output coupling plate, with the input region corresponding to the position of the input coupling plate, the output region corresponding to the position of the output coupling plate, and the diffusion region located between the input region and the output region.

[0008] In some embodiments of this application, specific wavelength beams are horizontally transmitted from the input region to the output region along a second direction. Due to the refractive index difference between the layers, each specific wavelength beam forms a different total internal reflection angle, allowing it to propagate between different numbers of layers in the first, second, or third waveguide substrate layer. Therefore, each specific wavelength beam can propagate along its optimal optical path, avoiding wavelength interference and improving light transmission efficiency, thereby improving image quality, achieving full-color display, and reducing stripe phenomena.

[0009] In some embodiments of this application, multiple grating structures with different grating parameters are provided on the inner surface of the first waveguide substrate layer. In the input region, the grating structure on the inner surface of the first waveguide substrate layer is a surface relief grating to couple the input beam to the interior of the optical stack.

[0010] In some embodiments of this application, a plurality of grating structures with different grating parameters are provided on the inner surface of the first waveguide substrate layer. In the diffusion region and the output region, at least two sub-regions are provided on the inner surface of the corresponding first waveguide substrate layer. Each grating structure in each sub-region has different grating parameters, and the difference in grating parameters between two adjacent sub-regions conforms to the default difference rule.

[0011] In some embodiments of this application, the default difference rules include: the difference in grating depth between two adjacent sub-regions is less than 200 nm; or / and the difference in grating linewidth between two adjacent sub-regions is less than 300 nm.

[0012] In some embodiments of this application, the grating parameters of the grating structure include: a period between 200 nm and 800 nm, a linewidth between 40 nm and 500 nm, a depth between 10 nm and 400 nm, and a tilt angle between 50 degrees and 90 degrees.

[0013] In some embodiments of this application, the refractive indices of the first waveguide substrate layer, the second waveguide substrate layer, and the third waveguide substrate layer are between 1.3 and 2.5.

[0014] In some embodiments of this application, the thickness of each of the first waveguide substrate layer, the second waveguide substrate layer, and the third waveguide substrate layer is between 0.5 mm and 5 mm.

[0015] In some embodiments of this application, the refractive indices of the first dielectric layer and the second dielectric layer are between 1.2 and 2.

[0016] In some embodiments of this application, the thickness of each of the first dielectric layer and the second dielectric layer is between 50 μm and 300 μm.

[0017] Therefore, based on the above parameters and ranges, such a wide range of refractive indices allows for a sufficient refractive index difference between the waveguide substrate layer and the dielectric layer, thereby forming a specific total internal reflection angle and enabling multi-band beams to be transmitted in layers without interference.

[0018] In accordance with the above objectives, this application further provides a display device, including a display and the optical waveguide stacking device as described above. The display generates a beam of light of an image and guides it into the optical waveguide stacking device to output the coupled image beam, providing image output with high uniformity and no ghosting.

[0019] As described above, the optical waveguide stacking device and display device of this application can simultaneously and effectively couple incident and outgoing light beams through a multi-layer waveguide substrate combined with a single-layer grating structure, thereby improving the overall efficiency of optical transmission. Since the light field within the multi-layer waveguide can converge and superimpose interference in the grating structure region, the optical diffraction effect is enhanced and the uniformity of light intensity distribution is improved, thus reducing problems such as uneven stripes or dispersion separation. Furthermore, by achieving optical coupling of multiple waveguide layers with only a single-layer grating, the manufacturing process is simplified, and alignment errors and scattering losses of multi-color light are reduced, making it particularly suitable for full-color augmented reality displays. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the first embodiment of the optical waveguide stacking device of this application. Figure 1 ;

[0021] Figure 2 for Figure 1 A magnified schematic diagram of a local region R;

[0022] Figure 3 This is a schematic diagram of the structure of the first embodiment of the optical waveguide stacking device of this application. Figure 2 ;

[0023] Figure 4 This is a first embodiment of the grating structure of this application;

[0024] Figure 5 for Figure 4 A magnified schematic diagram of the local region R1;

[0025] Figure 6 This is a second embodiment of the grating structure of this application;

[0026] Figure 7 This is the third embodiment of the grating structure in this application;

[0027] Figure 8 This is the fourth embodiment of the grating structure in this application;

[0028] Figure 9 This is a schematic diagram of the structure of a second embodiment of the optical waveguide stacking device of this application;

[0029] Figure 10 for Figure 9 A magnified schematic diagram of the local region R2;

[0030] Figure 11 This is a schematic diagram of the structure of the third embodiment of the optical waveguide stacking device of this application;

[0031] Figure 12 This is a schematic diagram of optical diffraction coupling in a third embodiment of the optical waveguide stacking device of this application;

[0032] Figure 13 This is a schematic diagram of an embodiment of the display device of this application.

[0033] Explanation of reference numerals in the attached figures:

[0034] 1: Optical waveguide stacking device;

[0035] 10: Optical stack;

[0036] 110: First waveguide substrate layer;

[0037] 111: Inner surface;

[0038] 112: Outer surface;

[0039] 120: Second waveguide substrate layer;

[0040] 130: Third waveguide substrate layer;

[0041] 140: First dielectric layer;

[0042] 150: Second dielectric layer;

[0043] 20: Input coupling plate;

[0044] 30: Output coupling plate;

[0045] y: First direction;

[0046] x: Second direction;

[0047] Ra: Input range;

[0048] Rb: diffusion region;

[0049] Rc: Output region;

[0050] R: Local region;

[0051] Rb1, Rb2, Rc1, Rc2, Rc3: Subregions;

[0052] g, G1, G2, G3, G4: grating structure;

[0053] g'、 , : trench;

[0054] C, C': Shining angle;

[0055] λ: grating period;

[0056] w: raster linewidth;

[0057] d: grating depth;

[0058] θg: Grating tilt angle;

[0059] λin: Input beam;

[0060] λR: First specific band beam;

[0061] λG: Second specific band beam;

[0062] λB: Third specific band beam;

[0063] λM: Output beam;

[0064] 2: Monitor;

[0065] 21: Beam output area. Detailed Implementation

[0066] The embodiments of this application will be further explained below with reference to the accompanying drawings. Wherever possible, the same reference numerals represent the same or similar components in the drawings and specification. In the drawings, shapes and thicknesses may be exaggerated for simplicity and convenience. It is understood that elements not specifically shown in the drawings or described in the specification are forms known to those skilled in the art. Those skilled in the art can make various changes and modifications based on the content of this application.

[0067] For ease of explanation, the "first direction" and "second direction" mentioned in this application are defined according to a three-dimensional Cartesian coordinate system. The first direction corresponds to the y-axis and represents the direction in which the input beam is incident on the optical stack, i.e., the coupling direction after the beams of each specific wavelength band are coupled. The second direction corresponds to the x-axis and describes the propagation direction of the beam in each layer. Unless otherwise specified, all directions mentioned in this specification are defined accordingly.

[0068] The following describes an optical waveguide stacking device provided in this application. Please refer to [link / reference]. Figure 1 and Figure 2The optical waveguide stacking device 1 includes an optical stack 10, an input coupling plate 20, and an output coupling plate 30. The optical stack 10 includes a third waveguide substrate layer 130, a second waveguide substrate layer 120, and a first waveguide substrate layer 110, all stacked perpendicularly along a first direction y, and a first dielectric layer 140 and a second dielectric layer 150 disposed between the respective waveguide substrate layers. The first waveguide substrate layer 110 is disposed on the second waveguide substrate layer 120, and the second waveguide substrate layer 120 is disposed on the third waveguide substrate layer 130. The first dielectric layer 140 is disposed between the first waveguide substrate layer 110 and the second waveguide substrate layer 120, and the second dielectric layer 150 is disposed between the second waveguide substrate layer 120 and the third waveguide substrate layer 130. An input coupling plate 20 is disposed on the outer surface 112 of the first waveguide substrate layer 110 to receive an input beam input from the first direction y. The input coupling plate 20 couples the beam into the first waveguide substrate layer 110, the second waveguide substrate layer 120, or the third waveguide substrate layer 130 according to the beam's wavelength, thereby guiding the specific wavelength beams propagating in each layer of the first waveguide substrate layer 110, the second waveguide substrate layer 120, or the third waveguide substrate layer 130. An output coupling plate 30 is disposed on the outer surface 112 of the first waveguide substrate layer 110 and spaced a distance from the input coupling plate 20 to guide the specific wavelength beams to couple out along the first direction y. In the optical stack 10, each specific band beam is guided and propagated in layers along the second direction x within the first waveguide substrate layer 110, the second waveguide substrate layer 120, or the third waveguide substrate layer 130, and undergoes at least two reflections within the first waveguide substrate layer 110, the second waveguide substrate layer 120, or the third waveguide substrate layer 130, so that each specific band beam is overlapped, coupled, and output on the output coupling plate 30.

[0069] like Figure 2 As shown, the figures are not drawn to scale for clarity. The first waveguide substrate layer 110, the second waveguide substrate layer 120, and the third waveguide substrate layer 130 are transparent substrates, and the refractive indices of these transparent substrates may be the same or different. The first dielectric layer 140 and the second dielectric layer 150 are optical adhesives. In this application, the refractive indices of the first waveguide substrate layer 110, the second waveguide substrate layer 120, and the third waveguide substrate layer 130 are between 1.3 and 2.5, and the thickness of each layer of the first waveguide substrate layer 110, the second waveguide substrate layer 120, or the third waveguide substrate layer 130 is between 0.5 mm and 5 mm. The refractive indices of the first dielectric layer 140 and the second dielectric layer 150 are between 1.2 and 2, and the thickness of each layer of the first dielectric layer 140 and the second dielectric layer 150 is between 50 μm and 300 μm.

[0070] To achieve total internal reflection of the beam, the refractive indices of the first waveguide substrate layer 110, the second waveguide substrate layer 120, and the third waveguide substrate layer 130 are greater than the refractive indices of the first dielectric layer 140 and the second dielectric layer 150. For example, the refractive indices of the first waveguide substrate layer 110, the second waveguide substrate layer 120, and the third waveguide substrate layer 130 are all n1, the refractive index of the first dielectric layer 140 is n2, and the refractive index of the second dielectric layer 150 is n3, where n1 > n2 > n3. Since the materials and refractive indices selected for each waveguide substrate layer and each dielectric layer are related to the grating parameters of the multiple grating structures g and the wavelength of the incident beam, this application can improve the fringe interference phenomenon of the image. By vertically stacking the first, second, and third waveguide substrate layers and the first and second dielectric layers therein, the refractive index difference can be used to achieve layered guidance and propagation of beams of different wavelengths, thereby forming a specific total internal reflection angle. This enables multi-band beams to be transmitted in layers without interference, completely solving the problem that traditional single-layer waveguides (such as single holographic or PVG elements) cannot handle multi-color light due to their narrow wavelength range. At the same time, in order to enable the beam to be effectively transmitted within the optical stack 10, each specific wavelength beam undergoes at least two total internal reflections within the corresponding waveguide substrate. Finally, the beams are overlapped, coupled, and output through the output coupling plate 30, thereby ensuring that the human eye can receive a complete and clear color image.

[0071] Please see Figure 3 The optical stack 10 is sequentially divided into an input region Ra, a diffusion region Rb, and an output region Rc along the second direction x. The input region Ra corresponds to the position of the input coupling plate 20, the output region Rc corresponds to the position of the output coupling plate 30, and the diffusion region Rb is located between the input region Ra and the output region Rc. The first waveguide substrate layer 110 has opposing inner surfaces 111 and outer surfaces 112. The inner surface 111 is provided with multiple grating structures g with different grating parameters, especially at least two grating structures with different grating parameters in the diffusion region Rb and the output region Rc. In some embodiments of this application, the grating structure of the inner surface 111 of the first waveguide substrate layer 110 corresponding to the input region Ra is preferably a surface relief grating (SRG) to couple the input beam to the interior of the optical stack 10. For the sake of brevity, Figures 1 to 3 The grating structure is depicted using straight lines as a schematic representation, rather than representing actual dimensions or grating shapes. Furthermore, to enable those skilled in the art to understand the core concepts of this application, please refer to the following: Figures 4 to 8 The present application describes embodiments with different grating structures. The diffusion region Rb and the output region Rc each include at least two of the following grating structures.

[0072] For example, such as Figure 4 and Figure 5As shown, the grating structure G1 can be a binary grating with rectangular or square grooves g' on its surface. In the grating parameters, the center distance between two adjacent grating lines is the grating period, denoted as λ; the lateral width of each line (stripe / groove) in the grating structure G1 is the grating linewidth, denoted as w; the vertical height etched on the surface of the grating structure G1 is the grating depth, denoted as d; and the tilt angle of the grating slope relative to the horizontal plane is the grating tilt angle, denoted as θg. In implementation, the grating parameters can conform to the following rules:

[0073] 200nm≤λ≤800nm;

[0074] 40nm≤w≤500nm;

[0075] 10nm≤d≤400nm;

[0076] 50°≤θg≤90°;

[0077] like Figure 6 As shown, the grating structure G2 can be a slanted grating. The periodic structure of the grating has a specific tilt angle with the inner surface of the first waveguide substrate layer 110 to control the diffraction direction of light, so that a specific wavelength beam diffracts at a specific angle, thereby optimizing its diffraction efficiency. Figure 7 As shown, the grating structure G3 can be a blazed grating with multiple grooves. and trench It has an asymmetrical serrated or triangular cross-section, where the serrated or triangular slope can be called the blaze angle C. For example... Figure 8 As shown, the grating structure G4 can be an echelle grating with multiple large blaze angles C' and grooves. It has a relatively wide slot pitch, falling between that of a binary grating and a blazed grating, and the slots... It is quite deep, so its shape resembles a steep staircase.

[0078] Please see Figure 9 and Figure 10At least two sub-regions, such as sub-region Rb1 and sub-region Rb2, are respectively provided on the inner surface 111 of the first waveguide substrate layer 110 corresponding to the diffusion region Rb, and at least two sub-regions, such as sub-region Rc1 and sub-region Rc2, are respectively provided on the inner surface 111 of the first waveguide substrate layer 110 corresponding to the output region Rc. In each sub-region, such as sub-region Rb1, sub-region Rb2, sub-region Rc1, and sub-region Rc2, the grating structure of the inner surface 111 corresponding to each region has different grating parameters, and the difference in grating parameters between two adjacent sub-regions conforms to the default difference rule, thereby effectively improving the coupling quality of each color beam and enhancing the color uniformity of the final output image beam, and improving the rainbow effect problem.

[0079] In some embodiments of this application, a surface relief grating can be set in the input region Ra, and grating structures with different grating parameters (such as one of a binary structure grating, tilted grating, blazed grating, or stepped grating) can be set in at least two sub-regions of the diffusion region Rb and at least two sub-regions of the output region Rc, so that the loss during beam transmission can be effectively reduced, thereby achieving the best optical coupling efficiency in the output region Rc.

[0080] like Figure 10 As shown, taking the diffusion region Rb as an example, the sub-regions Rb1 and Rb2 of the diffusion region Rb each have two different grating structures. For example, sub-region Rb1 has the following... Figure 6 The tilted grating and sub-region Rb2 are provided with, for example, Figure 7 The blazed grating, because each sub-region has different grating characteristics, such as differences in linewidth or etching depth, allows a specific wavelength beam to diffract at a specific angle, thereby controlling the direction of the beam. The same applies to the output region Rc, whose sub-regions Rc1 and Rc2 also have grating structures with different grating parameters. The differences in grating parameters between these two adjacent sub-regions preferably conform to one or a combination of the following default difference rules: Default difference rule (1): The difference in grating depth Δd between two adjacent sub-regions is less than 200nm; Default difference rule (2): The difference in grating linewidth Δw between two adjacent sub-regions is less than 300nm.

[0081] In the diffusion region Rb, the difference between the grating depth d1 of sub-region Rb1 and the grating depth d2 of sub-region Rb2 is Δd, and the difference between the grating linewidth w1 of sub-region Rb1 and the grating linewidth w2 of sub-region Rb2 is Δw. In this embodiment, the difference Δd between the grating depths of sub-regions Rb1 and Rb2 in the diffusion region Rb is less than 200nm, and the difference Δw between the grating linewidths is less than 300nm. This ensures that the diffraction efficiency of different gratings tends to be consistent, thereby improving the uniformity of beam coupling at a specific wavelength and reducing stripe phenomena.

[0082] Please see Figure 11 and Figure 12 For the sake of brevity, Figure 12 The grating structure, first dielectric layer 140, and second dielectric layer 150 are not shown in the diagram. Please refer to the attached diagram for detailed structures. Figure 11 . Figure 12 The different lines used to distinguish the transmission paths of beams in different wavelength bands are for illustrative purposes only and do not represent actual optical effects. The gray areas are used to represent the multiple superimposed light and shadows produced when the beam undergoes total internal reflection within the optical waveguide stacking device, which is used to illustrate the optical path superposition situation of this application.

[0083] like Figure 11 As shown, in this embodiment, the input region Ra is provided with a first grating structure, the two sub-regions Rb1 and Rb2 of the diffusion region Rb are respectively provided with a second grating structure and a third grating structure, and the sub-regions Rc1, Rc2, and Rc3 of the output region Rc are respectively provided with a fourth grating structure, a fifth grating structure, and a sixth grating structure. The second and third grating structures are grating structures with different grating parameters, and the fourth, fifth, and sixth grating structures are grating structures with different grating parameters.

[0084] like Figure 12 As shown, the input beam λin can be an image beam generated by an external display, and is classified into a first specific band beam λR, a second specific band beam λG, and a third specific band beam λB according to its wavelength. In this embodiment, the wavelength of the first specific band beam λR is between 620nm and 750nm, the wavelength of the second specific band beam λG is between 495nm and 570nm, and the wavelength of the third specific band beam λB is between 450nm and 495nm. When the input beam λin is input from the first direction y into the optical stack 10 via the input coupling plate 20, the input coupling plate 20 receives the input beam λin and couples it into the first waveguide substrate layer 110, the second waveguide substrate layer 120, or the third waveguide substrate layer 130 according to each band of the input beam λin. A first specific wavelength beam λR propagates within the first waveguide substrate layer 110, a second specific wavelength beam λG propagates within the first waveguide substrate layer 110 and the second waveguide substrate layer 120, and a third specific wavelength beam λB propagates within the first waveguide substrate layer 110, the second waveguide substrate layer 120, and the third waveguide substrate layer 130. Because the refractive indices of each waveguide substrate layer and dielectric layer differ in the optical stack 10 of this application, the first specific wavelength beam λR, the second specific wavelength beam λG, and the third specific wavelength beam λB can generate total internal reflection angles and propagate between different layers according to the differences in their wavelengths.

[0085] Next, the first specific band beam λR, the second specific band beam λG, and the third specific band beam λB are transmitted horizontally from the input region Ra, through the diffusion region Rb, and to the output region Rc along the second direction x, respectively. Each specific band beam forms a different total internal reflection angle due to the refractive index difference of each layer, so that each specific band beam can be transmitted between different layers of the first waveguide substrate layer 110, the second waveguide substrate layer 120, or the third waveguide substrate layer 130.

[0086] It is worth noting that the optical waveguide stacking device of this application only requires a single grating structure to be set on the inner surface of the first waveguide substrate layer 110, and then combined with multiple waveguide substrate layers (first waveguide substrate layer 110, second waveguide substrate layer 120, and third waveguide substrate layer 130) and the dielectric layer between them. By utilizing the refractive index difference between the layers, the layered guided propagation of beams of different wavelength bands (e.g., red, green, and blue light) can be achieved. The grating structure set on the inner surface of the first waveguide substrate layer 110 allows reflected beams from different waveguide substrate layers to be coupled through this grating structure. In terms of manufacturing, only a single grating process needs to be performed inside the first waveguide substrate layer 110, which can reduce design complexity, simplify the overall structure, and provide optimized coupling efficiency for multiple layers. Therefore, this application not only simplifies the manufacturing difficulty of the grating structure, but also effectively solves the challenge of traditional single waveguide substrate layers being unable to achieve multicolor light transmission due to their narrow wavelength range, thereby effectively controlling the diffraction behavior of the beam, avoiding dispersion, effectively improving fringe interference, and improving the light uniformity of the final output beam.

[0087] Furthermore, the first specific band beam λR, the second specific band beam λG, and the third specific band beam λB are guided by the output coupling plate 30 to superimpose and couple the beams, and are coupled out along the first direction y perpendicular to the waveguide plane to form the output beam λM, so that the human eye can receive a single, complete color image, thereby improving color consistency and reducing distortion.

[0088] To facilitate understanding of the technical features and effects of this application, a set of experimental data is provided below for illustration. However, it should be understood that these data are only the results of one embodiment and are not intended to limit the scope of the patent application. In this embodiment, the first waveguide substrate layer 110, the second waveguide substrate layer 120, and the third waveguide substrate layer 130 are made of a transparent substrate with a refractive index n1 of 1.7. A first dielectric layer 140 with a refractive index n2 of 1.4 is coated between the first waveguide substrate layer 110 and the second waveguide substrate layer 120, and a second dielectric layer 150 with a refractive index n3 of 1.2 is coated between the second waveguide substrate layer 120 and the third waveguide substrate layer 130. The thickness of each layer of the first waveguide substrate layer 110, the second waveguide substrate layer 120, or the third waveguide substrate layer 130 is between 0.5 mm and 5 mm, and the thickness of each layer of the first dielectric layer 140 and the second dielectric layer 150 is between 50 μm and 300 μm. Finally, after the input beam λin passes through the optical waveguide stacking device 1 of this application, beams of different wavelengths are transmitted in layers and coupled out to form overlapping and uniform image beams on the observation surface, with the overlap error controlled within approximately 1.5 mm. Since the diameter of the human eye pupil is generally about 4 mm, the observer can perceive a single overlapping image without recognizing color separation. Therefore, the output beam of this application has uniform color, effectively reducing fringe interference. Furthermore, after image brightness profile analysis, contrast calculation, or frequency domain (FFT) analysis, the fringe effect is relatively weakened, indicating that this application can improve overall display uniformity.

[0089] Please see Figure 13 This application further provides a display device, including a display 2 and an optical waveguide stacking device 1 as described above. The structure and function of the optical waveguide stacking device 1 have been fully described above and will not be repeated here. The display 2 generates an image beam. The optical waveguide stacking device 1 is disposed in the beam output area 21 of the display 2. The optical waveguide stacking device 1 receives the image beam as an input beam λin and guides it into the optical waveguide stacking device 1 to form a coupled output beam λM. Due to the difference in refractive index within the optical stack 10, each specific wavelength of the input beam λin forms a different total internal reflection angle, and each specific wavelength beam is confined to propagate between different layers of the optical stack 10.

[0090] In summary, the optical waveguide stacking device and display device of this application can effectively improve the dark pattern phenomenon in waveguide images. Through the structural design of multiple vertically stacked waveguide substrate layers and dielectric layers, the refractive index difference between each layer can be used to guide light beams of different wavelengths, enabling different wavelength light beams (such as red, green, and blue light) to be transmitted in layers. At the same time, combined with multiple grating structures in a single layer, incident coupling or outgoing coupling of light beams in the multi-layer waveguide substrate layer can be performed, effectively improving the stripe phenomenon in image quality and realizing full-color image display. This effectively solves the problems of traditional multi-color light transmission and color consistency, not only reducing the complexity of grating process, but also effectively improving the optical coupling of multi-band light sources.

[0091] The above description is merely illustrative of preferred embodiments of this application and is not intended to limit the scope of implementation. Any simple substitutions and equivalent changes made in accordance with the scope of the patent application and the contents of the patent specification shall fall within the scope of this patent application.

Claims

1. An optical waveguide stack apparatus, characterized by, Comprising: An optical stack, comprising: a third waveguide substrate layer, a second waveguide substrate layer, and a first waveguide substrate layer vertically stacked along a first direction, and the first waveguide substrate layer is disposed on the second waveguide substrate layer, and the second waveguide substrate layer is disposed on the third waveguide substrate layer; and a first dielectric layer disposed between the first waveguide substrate layer and the second waveguide substrate layer, and a second dielectric layer disposed between the second waveguide substrate layer and the third waveguide substrate layer; an input coupling plate disposed on an outer surface of the first waveguide substrate layer to receive an input light beam input from an outer surface of the third waveguide substrate layer along the first direction, and the input coupling plate couples the input light beam into the first waveguide substrate layer, the second waveguide substrate layer, or the third waveguide substrate layer according to a wavelength band of the input light beam, so that the first waveguide substrate layer, the second waveguide substrate layer, or the third waveguide substrate layer guides and propagates a specific wavelength band light beam of each layer along a second direction; and an output coupling plate disposed on the outer surface of the first waveguide substrate layer and spaced apart from the input coupling plate by a distance, so that the specific wavelength band light beam propagating along the second direction is guided by the output coupling plate to superimpose and couple out each specific wavelength band light beam along the first direction to form an output light beam.

2. The optical waveguide stack apparatus of claim 1, wherein, The optical stack is sequentially divided into an input region, a diffusion region, and an output region along the second direction from the input coupling plate to the output coupling plate, and the input region corresponds to the position of the input coupling plate, the output region corresponds to the position of the output coupling plate, and the diffusion region is between the input region and the output region.

3. The optical waveguide stack apparatus of claim 2, wherein, Each specific wavelength band light beam horizontally transfers from the input region to the output region along the second direction, and each specific wavelength band light beam forms different total reflection angles due to the refractive index difference of each layer, so that each specific wavelength band light beam transfers between different layers of the first waveguide substrate layer, the second waveguide substrate layer, or the third waveguide substrate layer.

4. The optical waveguide stack apparatus of claim 2, wherein, In the first waveguide substrate layer, an inner surface opposite to the outer surface is provided with a plurality of grating structures with different grating parameters, and in the input region, the grating structure of the inner surface of the first waveguide substrate layer corresponding thereto is a surface relief grating to couple the input light beam into the optical stack.

5. The optical waveguide stack apparatus of claim 2, wherein, In the first waveguide substrate layer, an inner surface opposite to the outer surface is provided with a plurality of grating structures with different grating parameters, and in the input region, the grating structure of the inner surface of the first waveguide substrate layer corresponding thereto is a surface relief grating to couple the input light beam into the optical stack.

6. The optical waveguide stack apparatus of claim 5, wherein, The default difference rule includes: The difference between the grating depths of the adjacent two sub-regions is less than 200 nm; or / and The difference between the grating line widths of the adjacent two sub-regions is less than 300 nm.

7. The optical waveguide stack apparatus of claim 4 or 5, wherein, The grating parameters of the grating structure include: The grating period is between 200 nm and 800 nm, the grating line width is between 40 nm and 500 nm, the grating depth is between 10 nm and 400 nm, and the grating inclination angle is between 50 degrees and 90 degrees.

8. The optical waveguide stack apparatus of claim 1, wherein, The refractive index of the first waveguide substrate layer, the second waveguide substrate layer, and the third waveguide substrate layer is between 1.3 and 2.

5.

9. The optical waveguide stack apparatus of claim 1, wherein, The thickness of each layer of the first waveguide substrate layer, the second waveguide substrate layer, and the third waveguide substrate layer is between 0.5 mm and 5 mm.

10. The optical waveguide stack apparatus of claim 1, wherein, The refractive index of the first dielectric layer and the second dielectric layer is between 1.2 and 2.

11. The optical waveguide stack apparatus of claim 1, wherein, The thickness of each layer of the first dielectric layer and the second dielectric layer is between 50 μm and 300 μm.

12. A display device, characterized by comprising: Comprising: a display generating an image light beam; and The optical waveguide stack device of claim 1 is disposed in a light beam output area of the display, the optical waveguide stack device receives the image light beam as an input light beam and guides the input light beam into the optical waveguide stack device to form a coupled output light beam.

13. The display device of claim 12, wherein, The optical stack is sequentially divided into an input region, a diffusion region, and an output region between the input coupling plate and the output coupling plate in the second direction, and the input region corresponds to the position of the input coupling plate, the output region corresponds to the position of the output coupling plate, and the diffusion region is between the input region and the output region.

14. The display device of claim 13, wherein, Each of the specific waveband light beams horizontally passes from the input region to the output region in the second direction, and each of the specific waveband light beams forms different total reflection angles due to the refractive index difference of each layer, so that each of the specific waveband light beams passes between different layers of the first waveguide substrate layer, the second waveguide substrate layer, or the third waveguide substrate layer.

15. The display device of claim 13, wherein, In the first waveguide substrate layer, the inner surface opposite to the outer surface is provided with a plurality of grating structures with different grating parameters, and in the input region, the grating structures on the inner surface of the first waveguide substrate layer correspond to the surface relief grating to couple the input light beam into the first waveguide substrate layer.

16. The display device of claim 13, wherein, In the first waveguide substrate layer, the inner surface opposite to the outer surface is provided with a plurality of grating structures with different grating parameters, and in the input region, the grating structures on the inner surface of the first waveguide substrate layer correspond to the surface relief grating to couple the input light beam into the first waveguide substrate layer.

17. The display device of claim 16, wherein, In the default difference rule, the difference between the grating depths of the two adjacent sub-regions is less than 200 nm; or / and The difference between the grating line widths of the two adjacent sub-regions is less than 300 nm. The grating parameters include:

18. The display device of claim 15 or 16, wherein, The grating period is between 200 nm and 800 nm, the grating line width is between 40 nm and 500 nm, the grating depth is between 10 nm and 400 nm, and the grating inclination angle is between 50 degrees and 90 degrees. ​ 19. The display device of claim 12, wherein, The refractive index of the first waveguide substrate layer, the second waveguide substrate layer, the third waveguide substrate layer is between 1.3 to 2.5 respectively.

20. The display device of claim 12, wherein, The thickness of each layer of the first waveguide substrate layer, the second waveguide substrate layer, the third waveguide substrate layer is between 0.5 mm to 5 mm respectively.

21. The display device of claim 12, wherein, The refractive index of the first dielectric layer, the second dielectric layer is between 1.2 to 2 respectively.

22. The display device of claim 12, wherein, The thickness of each layer of the first dielectric layer, the second dielectric layer is between 50 μm to 300 μm respectively.

Images