Color waveguide structure

Abstract

The present application provides a color waveguide structure. The color waveguide structure comprises: a waveguide carrier; an input grating, the input grating being arranged on the waveguide carrier, and the input grating being used for coupling light into the waveguide carrier; an intermediate grating, the intermediate grating being used for receiving the light transmitted by the input grating, and performing pupil expansion and steering on the light; an out-coupling grating, the out-coupling grating being used for receiving the light from the intermediate grating, and coupling the light out of the waveguide carrier; and modulation filling portions, at least the gaps in the intermediate grating being filled with the modulation filling portions, and the distance between the surface of the side of the intermediate grating away from the waveguide carrier and the waveguide carrier being equal to or less than the distance between the surface of the side of each modulation filling portion away from the waveguide carrier and the waveguide carrier. The refractive index of the intermediate grating is greater than or equal to 1.8, and a refractive index difference is present between the intermediate grating and the modulation filling portions. The present application solves the problem in the prior art of poor color uniformity of color waveguide structures.

Description

Color waveguide structure

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the Patent Office of China on December 29, 2023, with application number 202311870257.8 and application name “Color Waveguide Structure”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the technical field of diffraction optical devices, and in particular to a color waveguide structure. Background Art

[0004] With the development of augmented reality (AR) technology, lightweight AR glasses are becoming more popular in the market. To achieve lightweight AR glasses, the first step is to use fewer waveguide carriers when designing the waveguide structure. At the same time, to achieve color display, red, green, and blue images need to be transmitted through a waveguide carrier. However, due to the dispersion effect of the grating itself, it is very easy to cause the total internal reflection angles of red, green, and blue light in the waveguide carrier to be different. Specifically, the total internal reflection angle of red light is large and the total internal reflection angle of blue light is small, resulting in the lowest efficiency for red light and the highest efficiency for blue light, which leads to poor diffraction uniformity of the final output image. To ensure color uniformity in the color waveguide structure, the grating needs to have high diffraction efficiency for light with large total internal reflection angles (red light) and low diffraction efficiency for light with small total internal reflection angles (blue light). However, there is currently no good method in the industry to achieve this.

[0005] That is to say, the color waveguide structure in the prior art has the problem of poor color uniformity.

[0006] Application Contents

[0007] The main purpose of the present application is to provide a color waveguide structure to solve the problem of poor color uniformity in the color waveguide structure in the prior art.

[0008] To achieve the above-mentioned objectives, the present application provides a color waveguide structure, comprising: a waveguide carrier; an input grating, the input grating being arranged on the waveguide carrier and being used to couple light into the waveguide carrier; an intermediate grating, the intermediate grating being used to receive light transmitted by the input grating and to dilate the light; an outcoupling grating, the outcoupling grating being used to receive light from the intermediate grating and to couple the light out of the waveguide carrier; a modulation filling portion, at least the gaps in the intermediate grating being filled with the modulation filling portion, and the distance from the surface of the intermediate grating on the side away from the waveguide carrier to the waveguide carrier being equal to or less than the distance from the surface of the modulation filling portion on the side away from the waveguide carrier to the waveguide carrier; wherein the refractive index of the intermediate grating is greater than or equal to 1.8, and there is a refractive index difference between the intermediate grating and the modulation filling portion.

[0009] Optionally, the refractive index of the modulation filling portion is greater than the refractive index of the waveguide carrier; and / or the refractive index of the modulation filling portion is greater than the refractive index of the intermediate grating.

[0010] Optionally, the refractive index difference between the intermediate grating and the modulation filling portion is greater than or equal to 0.1.

[0011] Optionally, when the distance between the side surface of the middle grating away from the waveguide carrier and the waveguide carrier is smaller than the distance between the side surface of the modulation filling part away from the waveguide carrier and the waveguide carrier, the side surface of the middle grating away from the waveguide carrier is covered by the modulation filling part.

[0012] Optionally, when the distance from the side surface of the intermediate grating away from the waveguide carrier to the waveguide carrier is less than the distance from the side surface of the modulation filling part away from the waveguide carrier to the waveguide carrier, the distance between the side surface of the intermediate grating away from the waveguide carrier and the side surface of the modulation filling part away from the waveguide carrier is greater than 0 nm and less than or equal to 100 nm.

[0013] Optionally, the modulation filling portion includes a first portion and a second portion along its height direction, and the first portion and the second portion are made of different materials.

[0014] Optionally, there are one or more first parts and one second part. When there is one first part, the first part is located on the surface of the second part on the side away from the waveguide carrier or on the surface of the second part on the side facing the waveguide carrier; when there are multiple first parts, the first part is provided on at least one surface of the second part on the side facing the waveguide carrier and on the side away from the waveguide carrier; and / or the height of the first part is less than the height of the second part.

[0015] Optionally, the shape of the intermediate grating is one or more of a straight tooth grating and a trapezoidal grating.

[0016] Optionally, the modulation filling portion is one of a silicon nitride filling portion, a magnesium oxide filling portion, an aluminum oxide filling portion, a titanium dioxide filling portion, a hafnium oxide filling portion, a zinc oxide filling portion, a niobium oxide filling portion, and a tantalum pentoxide filling portion.

[0017] Optionally, the outcoupling grating and the intermediate grating are respectively arranged on both side surfaces of the waveguide carrier, and the projections of the outcoupling grating and the intermediate grating on the waveguide carrier at least partially overlap, and the gap in the outcoupling grating is also filled with a modulation filling portion.

[0018] Applying the technical solution of the present application, a color waveguide structure includes a waveguide carrier, an input grating, an intermediate grating, an outcoupling grating and a modulation filling portion, wherein the input grating is arranged on the waveguide carrier, and is used to couple light into the waveguide carrier; the intermediate grating is used to receive light transmitted by the input grating and dilate the light; the outcoupling grating is used to receive light from the intermediate grating and couple the light out of the waveguide carrier; at least the gap in the intermediate grating is filled with the modulation filling portion, and the distance from the side surface of the intermediate grating away from the waveguide carrier to the waveguide carrier is equal to or less than the distance from the side surface of the modulation filling portion away from the waveguide carrier to the waveguide carrier; wherein the refractive index of the intermediate grating is greater than or equal to 1.8, and there is a refractive index difference between the intermediate grating and the modulation filling portion.

[0019] By arranging a modulation filling portion in the gap of the intermediate grating and planning the refractive index of the intermediate grating to be greater than or equal to 1.8, a refractive index difference is created between the intermediate grating and the modulation filling portion. At the same time, the distance from the surface of the intermediate grating on the side away from the waveguide carrier to the waveguide carrier is reasonably constrained to be equal to or less than the distance from the surface of the modulation filling portion on the side away from the waveguide carrier to the waveguide carrier. This allows the modulation filling portion to adjust the angular response curve of the diffraction efficiency of the intermediate grating, reduce the diffraction efficiency of blue light in diffraction transmission, and increase the diffraction efficiency of red light, so that the diffraction efficiency of red light is higher than that of blue light, thereby balancing the overall color and improving the color uniformity of the overall color waveguide structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings that constitute part of this application are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation on this application. In the drawings:

[0021] FIG1 shows a schematic structural diagram of a color waveguide structure according to the first embodiment of the present application;

[0022] FIG2 shows a schematic structural diagram of another color waveguide structure according to the first embodiment of the present application;

[0023] FIG3 shows a diffraction light distribution diagram of the color waveguide structure of Example 1 of the present application;

[0024] FIG4 shows a comparison of diffraction efficiency curves before and after the modulation filling portion is provided in the color waveguide structure of Example 1 of the present application;

[0025] FIG5 shows the distribution of blue light B, green light G and red light R in the K domain;

[0026] FIG6 shows a schematic structural diagram of a color waveguide structure according to the first embodiment of the present application;

[0027] FIG7 shows a top view of the color waveguide structure in FIG6 ;

[0028] FIG8 shows a schematic structural diagram of a color waveguide structure according to the second embodiment of the present application;

[0029] FIG9 shows a top view of the color waveguide structure in FIG8 ;

[0030] FIG10 shows a comparison diagram of diffraction efficiency curves of the color waveguide structure of Example 2 of the present application;

[0031] FIG11 shows a schematic structural diagram of a color waveguide structure according to the third embodiment of the present application;

[0032] FIG12 shows a top view of the color waveguide structure in FIG11 ;

[0033] FIG13 shows a comparison diagram of diffraction efficiency curves of the color waveguide structure of Example 3 of the present application;

[0034] FIG14 shows a schematic structural diagram of a color waveguide structure according to a fourth embodiment of the present application;

[0035] FIG15 shows a top view of the color waveguide structure in FIG14 ;

[0036] FIG16 shows a comparison diagram of diffraction efficiency curves of the color waveguide structure of the fourth embodiment of the present application.

[0037] The above drawings include the following reference numerals: 10, input grating; 20, intermediate grating; 30, modulation filling portion; 301, first portion; 302, second portion; 40, outcoupling grating; 50, waveguide carrier. DETAILED DESCRIPTION

[0038] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0039] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by ordinary technicians in the technical field to which this application belongs.

[0040] In this application, unless otherwise specified, directional words such as "up, down, top, bottom" are usually used with reference to the directions shown in the drawings, or with reference to the components themselves in the vertical, perpendicular or gravity direction; 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 directional words are not used to limit this application.

[0041] In order to solve the problem of poor color uniformity in the color waveguide structure in the prior art, the present application provides a color waveguide structure.

[0042] As shown in Figures 1 to 16, the color waveguide structure includes a waveguide carrier 50, an input grating 10, an intermediate grating 20, an outcoupling grating 40, and a modulation filling portion 30. The input grating 10 is disposed on the waveguide carrier 50 and is used to couple light into the waveguide carrier 50. The intermediate grating 20 is used to receive light transmitted by the input grating 10 and redirect the light through pupil expansion. The outcoupling grating 40 is used to receive light from the intermediate grating 20 and couple the light out of the waveguide carrier 50. At least the gaps in the intermediate grating 20 are filled with the modulation filling portion 30, and the distance from the surface of the intermediate grating 20 away from the waveguide carrier 50 to the waveguide carrier 50 is equal to or less than the distance from the surface of the modulation filling portion 30 away from the waveguide carrier 50 to the waveguide carrier 50. The refractive index of the intermediate grating 20 is greater than or equal to 1.8, and there is a refractive index difference between the intermediate grating 20 and the modulation filling portion 30.

[0043] By providing a modulation filling portion 30 in the gap of the intermediate grating 20 and planning the refractive index of the intermediate grating 20 to be greater than or equal to 1.8, a refractive index difference is created between the intermediate grating 20 and the modulation filling portion 30. At the same time, the distance from the surface of the intermediate grating 20 away from the waveguide carrier 50 to the waveguide carrier 50 is reasonably constrained to be equal to or less than the distance from the surface of the modulation filling portion 30 away from the waveguide carrier 50 to the waveguide carrier 50. This allows the modulation filling portion 30 to adjust the angular response curve of the diffraction efficiency of the intermediate grating 20, thereby reducing the diffraction efficiency of blue light in diffraction transmission while increasing the diffraction efficiency of red light, thereby making the diffraction efficiency of red light higher than that of blue light, thereby balancing the overall color and improving the color uniformity of the overall color waveguide structure.

[0044] Specifically, the refractive index of the modulation filling portion 30 is greater than the refractive index of the waveguide carrier 50. This configuration can increase the equivalent refractive index of the intermediate grating 20 and the modulation filling portion 30, thereby increasing the angular bandwidth of the intermediate grating 20 and achieving better uniformity.

[0045] Specifically, the refractive index difference between the intermediate grating 20 and the modulation filling portion 30 is greater than or equal to 0.1. By constraining the refractive index difference between the intermediate grating 20 and the modulation filling portion 30 to be greater than or equal to 0.1, while ensuring that the intermediate grating 20 has a high refractive index and high diffraction efficiency, the reliability of the modulation filling portion 30 is guaranteed, and the modulation filling portion 30 is ensured to increase the diffraction efficiency of the intermediate grating 20 for red light while reducing the diffraction efficiency of blue light, thereby improving the color uniformity of the final color display.

[0046] In a specific embodiment of the present application, the intermediate grating 20 and the modulation filling portion 30 have different refractive indices, and there is a refractive index difference between the two. In an optional embodiment, the refractive index of the intermediate grating 20 is greater than the refractive index of the modulation filling portion 30. In another optional embodiment, the refractive index of the modulation filling portion 30 is greater than the refractive index of the intermediate grating 20. The refractive index of the modulation filling portion 30 being greater than the refractive index of the intermediate grating 20 is the preferred embodiment.

[0047] In an optional embodiment of the present application, a residual layer still exists at the bottom of the input grating 10, the intermediate grating 20, and the out-coupling grating 40, that is, the input grating 10, the intermediate grating 20, and the out-coupling grating 40 are connected to the waveguide carrier 50 through the residual layer. The residual layer is a very thin layer. Due to the different manufacturing processes of the grating, the residual layer is inevitable when the grating is manufactured by nanoimprinting.

[0048] Optionally, when the distance between the side surface of the intermediate grating 20 away from the waveguide carrier 50 and the waveguide carrier 50 is less than the distance between the side surface of the modulation filling portion 30 away from the waveguide carrier 50 and the waveguide carrier 50, specifically, when the height of the modulation filling portion 30 is greater than the height of the intermediate grating 20, the side surface of the intermediate grating 20 away from the waveguide carrier 50 is covered by the modulation filling portion 30.

[0049] Optionally, when the distance between the surface of the intermediate grating 20 away from the waveguide carrier 50 and the waveguide carrier 50 is less than the distance between the surface of the modulation filling portion 30 away from the waveguide carrier 50 and the waveguide carrier 50, the distance between the surface of the intermediate grating 20 away from the waveguide carrier 50 and the surface of the modulation filling portion 30 away from the waveguide carrier 50 is greater than 0 nm and less than or equal to 100 nm. In other words, when the height of the modulation filling portion 30 is greater than the height of the intermediate grating 20, the height difference between the modulation filling portion 30 and the intermediate grating 20 is greater than 0 nm and less than 100 nm. This configuration helps increase manufacturing tolerances while improving the structural stability of the modulation filling portion 30.

[0050] In an optional embodiment shown in Figures 6 and 7, the input grating 10, the intermediate grating 20, and the outcoupling grating 40 are all periodic structures. Therefore, the input grating 10, the intermediate grating 20, and the outcoupling grating 40 all have periodic gaps, and all gaps in the intermediate grating 20 are filled with a modulated filling portion 30. The duty cycle of the intermediate grating 20 is greater than or equal to 20% and less than or equal to 80%. The period of the intermediate grating 20 is greater than or equal to 300nm and less than or equal to 400nm, and the height of the intermediate grating 20 is greater than or equal to 50nm and less than or equal to 140nm. By reasonably constraining the period, size, and duty cycle of the intermediate grating 20, it is beneficial to increase the stability of the diffracted light from the intermediate grating 20, ensure diffraction uniformity, reduce backlight leakage, improve diffraction efficiency, and improve the field of view (FOV).

[0051] Of course, the height and duty cycle of the intermediate grating 20 can be modulated. For example, the height of the intermediate grating 20 is equal and the duty cycle is the same; or the height of the intermediate grating 20 gradually increases along its arrangement direction, and the duty cycle remains unchanged or changes; or the duty cycle of the intermediate grating 20 gradually increases along its arrangement direction. The above configuration is not limited thereto and can be set according to actual conditions to achieve changes in the overall diffraction efficiency of the intermediate grating 20 at different positions, thereby improving the efficiency and uniformity of the color waveguide structure.

[0052] Specifically, the modulation filler 30 is one of silicon nitride, magnesium oxide, aluminum oxide, titanium dioxide, hafnium oxide, zinc oxide, niobium oxide, and tantalum pentoxide. Proper selection of the material of the modulation filler 30 facilitates adjustment of the angular response curve of the diffraction efficiency of the intermediate grating 20.

[0053] In an optional embodiment of the present application, the intermediate grating 20 is in a shape of one or more of a straight-tooth grating and a trapezoidal grating, and the straight-tooth grating is arranged perpendicular to the waveguide carrier 50 .

[0054] As shown in FIG1 , in an optional embodiment of the present application, the outcoupling grating 40 and the intermediate grating 20 are spaced apart on one side surface of a waveguide carrier 50. In this case, the modulation filling portion 30 can be filled only in the gap between the intermediate grating 20. As shown in FIG2 , in another optional embodiment of the present application, the outcoupling grating 40 and the intermediate grating 20 are respectively disposed on both side surfaces of the waveguide carrier 50, and the projections of the outcoupling grating 40 and the intermediate grating 20 on the waveguide carrier 50 partially overlap or completely overlap. In this case, the gap between the intermediate grating 20 and the outcoupling grating 40 is filled with the modulation filling portion 30. This allows light with different field of view angles to be transmitted through two different paths, achieving FOV splicing and improving FOV.

[0055] The present application also provides a method for manufacturing a color waveguide structure, comprising:

[0056] 1. First, the tooth shape of the intermediate grating 20 is produced on the waveguide carrier 50 by embossing or etching;

[0057] 2. Filling the gaps of the intermediate grating 20 with a high refractive index material using an ALD or evaporation process until the gaps are completely filled, thereby forming a modulation filling portion 30;

[0058] 3. Grind the top of the modulation filling portion 30 flat by grinding or etching, so that the top of the modulation filling portion 30 is a plane.

[0059] The color waveguide structure of the present application is described below with reference to specific embodiments and accompanying drawings.

[0060] Example 1

[0061] As shown in FIG. 1 to FIG. 7 , the color waveguide structure of the first embodiment is described.

[0062] As shown in Figures 1 and 2, the color waveguide structure includes a waveguide carrier 50, an input grating 10, an intermediate grating 20, an outcoupling grating 40, and a modulation filling portion 30. In Figure 1, the intermediate grating 20 and the outcoupling grating 40 are spaced apart on one surface of the waveguide carrier 50. In this case, only the gap between the intermediate grating 20 is filled with the modulation filling portion 30, and the distance from the surface of the intermediate grating 20 away from the waveguide carrier 50 to the waveguide carrier 50 is equal to the distance from the surface of the modulation filling portion 30 away from the waveguide carrier 50 to the waveguide carrier 50. In Figure 2, the outcoupling grating 40 and the intermediate grating 20 are respectively disposed on both sides of the waveguide carrier 50, and the projections of the outcoupling grating 40 and the intermediate grating 20 on the waveguide carrier 50 partially or completely overlap. In this case, the gaps between the intermediate grating 20 and the outcoupling grating 40 are both filled with the modulation filling portion 30. The modulation filling portion 30 may be selectively filled according to the specific arrangement of the intermediate grating 20 and the outcoupling grating 40 , and the height of the outcoupling grating 40 is equal to the height of the modulation filling portion 30 .

[0063] In this embodiment, the intermediate grating 20 is in the shape of a straight tooth grating to achieve pupil expansion transmission of light inside the waveguide carrier 50 .

[0064] As shown in Figure 3, after external light is diffracted by the input light receiver, the diffraction angle of the short-wavelength (blue light B) light is small, while the diffraction angle of the long-wavelength (red light R) light is large. Therefore, when light propagates within the waveguide carrier 50, the total internal reflection angle of the short-wavelength light is small, while the total internal reflection angle of the long-wavelength light is large. Because the lateral propagation distance of each color light is the same, and the thickness of the waveguide carrier 50 is constant, the light with a small total internal reflection angle (red light R) is reflected many times and has a large pupil density, while the light with a large total internal reflection angle (blue light B) is reflected few times and has a small pupil density. To ensure color uniformity of the color waveguide structure, it is necessary to add a modulation filling portion 30 to the gaps in the intermediate grating 20 so that the intermediate grating 20 has high diffraction efficiency for light with a small total internal reflection angle (red light R) and low diffraction efficiency for light with a large total internal reflection angle (blue light B). In other words, the diffraction efficiency is low for blue light, while the diffraction efficiency is high for red light.

[0065] As shown in Figure 4 , without the modulating filler 30, the efficiency curves for blue, green, and red light are represented by dashed lines. As can be seen from the figure, the diffraction efficiency of blue light B is high, while the diffraction efficiency of red light R is low. With the modulating filler 30 installed, the efficiency curves for blue, green, and red light are represented by solid lines. The diffraction efficiency of blue light B' is low, while the diffraction efficiency of red light R' is high. This is consistent with the desired trend. Therefore, the provision of the modulating filler 30 helps improve color uniformity.

[0066] As shown in FIG5 , the distribution of blue light B, green light G, and red light R in the K domain corresponds to the efficiency distribution positions of blue light, green light, and red light in FIG4 .

[0067] As shown in FIG6 and FIG7, the black arrow is the direction of total reflection of the light in the cross-sectional view, the white arrow is the direction of total reflection of the light in the top view, and the black arrow and the white arrow are the same beam of light.

[0068] In this embodiment, the waveguide carrier 50 is made of glass with a refractive index of 2.0. The intermediate grating 20 is made of SiN with a refractive index of 2.0. The modulation filler 30 is made of TiO2 with a refractive index of 2.4. The height of the intermediate grating 20 is the same as that of the modulation filler 30, and their top surfaces are flush. The intermediate grating 20 has the following three different parameter settings:

[0069] In an optional embodiment, the duty cycle of the intermediate grating 20 is 50%, the height is 100 nm, and the period is 345 nm.

[0070] In another optional embodiment, the duty cycle of the intermediate grating 20 is 20%, the height is 50 nm, and the period is 345 nm.

[0071] In another optional embodiment, the duty cycle of the intermediate grating 20 is 80%, the height is 140 nm, and the period is 345 nm.

[0072] Example 2

[0073] As shown in Figures 8 to 10, the color waveguide structure of the second embodiment is described.

[0074] As shown in Figures 8 and 9 , this embodiment differs from the first embodiment in that the height of the intermediate grating 20 is different from the height of the modulation filling portion 30 that fills the gap therebetween. Specifically, the distance between the surface of the intermediate grating 20 facing away from the waveguide carrier 50 and the waveguide carrier 50 is smaller than the distance between the surface of the modulation filling portion 30 facing away from the waveguide carrier 50 and the waveguide carrier 50. The surface of the intermediate grating 20 facing away from the waveguide carrier 50 is covered by the modulation filling portion 30, and the modulation filling portion 30 on the surface of the intermediate grating 20 facing away from the waveguide carrier 50 has a certain thickness.

[0075] This embodiment has a similar structure to that of the first embodiment. In this embodiment, the waveguide carrier 50 is made of glass with a refractive index of 1.9. The intermediate grating 20 is made of resin with a refractive index of 1.9. The modulation filler 30 is made of SiN with a refractive index of 2.0. In this embodiment, the distance from the surface of the modulation filler 30 facing away from the waveguide carrier 50 to the surface of the intermediate grating 20 facing away from the waveguide carrier 50 is 50 nm. In other words, the height of the modulation filler 30 is 50 nm higher than the top of the intermediate grating 20.

[0076] In this embodiment, the duty cycle of the intermediate grating 20 is 50%, the height is 100 nm, and the period is 345 nm.

[0077] As shown in Figure 10 , the efficiency curves for blue, green, and red light without the modulating filler 30 are represented by dashed lines. As can be seen from the figure, the diffraction efficiency of blue light B is high, while the diffraction efficiency of red light R is low. In the present application, after the modulating filler 30 is installed, the efficiency curves for blue, green, and red light are represented by solid lines. As can be seen from the figure, the diffraction efficiency of blue light B' is low, while the diffraction efficiency of red light R' is high. Although the B'G'R' curves in the figure show a low trend, those skilled in the art will understand that during color diffraction transmission, a red light efficiency of only approximately 5% is required to achieve optimal diffraction performance.

[0078] Example 3

[0079] As shown in Figures 11 to 13, the color waveguide structure of the third embodiment is described.

[0080] As shown in FIG11 , the difference between this embodiment and the first embodiment lies in that the modulation and filling portion 30 is different.

[0081] Specifically, the modulation filling portion 30 includes a first portion 301 and a second portion 302 along its height. The first portion 301 and the second portion 302 are made of different materials. There are one or more first portions 301, and one second portion 302. When there is one first portion 301, the first portion 301 is located on the surface of the second portion 302 facing away from the waveguide carrier 50 or on the surface of the second portion 302 facing the waveguide carrier 50. When there are multiple first portions 301, the first portion 301 is provided on at least one surface of the second portion 302 facing the waveguide carrier 50 and on the surface of the second portion 302 facing away from the waveguide carrier 50. In other words, the modulation filling portion 30 includes, along the surface of the side facing away from the waveguide carrier 50, a first portion 301, a second portion 302, and another first portion 301.

[0082] In this embodiment, the height of the first portion 301 is smaller than that of the second portion 302 . The first portion 301 is SiO 2 with a height greater than 5 nm, and the material of the second portion 302 is TiO 2 or SiN.

[0083] When there is one first portion 301 and one second portion 302, and the first portion 301 is located on the surface of the second portion 302 away from the waveguide carrier 50, during the manufacturing process, the second portion 302 is first formed by vapor deposition, and then the first portion 301 is formed by vapor deposition or spin coating. By mixing the two materials, the equivalent refractive index of the modulation filling portion 30 is reduced, thereby reducing the overall diffraction efficiency of the intermediate grating 20 to a suitable value.

[0084] As shown in FIG13 , the efficiency curves for blue, green, and red light without the modulating filling portion 30 are represented by dashed lines. As can be seen from the figure, the diffraction efficiency of blue light B is high, while the diffraction efficiency of red light R is low. In the present application, after the modulating filling portion 30 is provided, the efficiency curves for blue, green, and red light are represented by solid lines. As can be seen from the figure, the diffraction efficiency of blue light B' is low, while the diffraction efficiency of red light R' is high.

[0085] Example 4

[0086] As shown in FIG. 14 to FIG. 16 , a color waveguide structure of a fourth embodiment is described.

[0087] As shown in Figure 14, the difference between this embodiment and the first embodiment is that the shape of the intermediate grating 20 is different. In this embodiment, the shape of the intermediate grating 20 is a trapezoidal grating.

[0088] Specifically, a trapezoidal grating has a trapezoidal cross-section perpendicular to the waveguide carrier 50, with the base of the trapezoid facing the waveguide carrier 50 being longer than the base of the trapezoid facing away from the waveguide carrier 50. This ensures that the intermediate grating 20 is trapezoidal in shape, with the angle between the hypotenuse and the normal less than 15°. The modulation filling portion 30 is a trapezoidal shape that is wider at the top and narrower at the bottom, with the same inclination angle as the intermediate grating 20. By properly adjusting the shape of the intermediate grating 20, the diffraction curve is improved. This configuration also enhances the stability of the grating structure and process.

[0089] As shown in FIG16 , the efficiency curves for blue, green, and red light without the modulation filling unit 30 are represented by dotted lines. As can be seen from the figure, the diffraction efficiency of blue light B is high, while the diffraction efficiency of red light R is low. In the present application, after the modulation filling unit 30 is provided, the efficiency curves for blue, green, and red light are represented by solid lines. As can be seen from the figure, the diffraction efficiency of blue light B' is low, while the diffraction efficiency of red light R' is high.

[0090] Obviously, the embodiments described above are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of this application.

[0091] 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, they indicate the presence of features, steps, tasks, devices, components and / or combinations thereof.

[0092] It should be noted that the terms "first," "second," and the like in the specification and claims of this application and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0093] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A color waveguide structure, characterized in that, Comprising: A waveguide carrier (50); An input grating (10), the input grating (10) being disposed on the waveguide carrier (50), and the input grating (10) being configured to couple light into the waveguide carrier (50); An intermediate grating (20), the intermediate grating (20) being configured to receive light transmitted by the input grating (10) and perform pupil expansion and beam steering on the light; An output grating (40), the output grating (40) being configured to receive light from the intermediate grating (20) and couple the light out of the waveguide carrier (50); A modulation filling portion (30), at least the gap of the intermediate grating (20) being filled with the modulation filling portion (30), and the distance from the surface of the intermediate grating (20) away from the waveguide carrier (50) to the waveguide carrier (50) being equal to or less than the distance from the surface of the modulation filling portion (30) away from the waveguide carrier (50) to the waveguide carrier (50); Wherein, the refractive index of the intermediate grating (20) is greater than or equal to 1.8, and there is a refractive index difference between the intermediate grating (20) and the modulation filling portion (30).

2. The color waveguide structure according to claim 1, wherein The refractive index of the modulation filling portion (30) is greater than the refractive index of the waveguide carrier (50); and / or the refractive index of the modulation filling portion (30) is greater than the refractive index of the intermediate grating (20).

3. The color waveguide structure according to claim 1, wherein The refractive index difference between the intermediate grating (20) and the modulation filling portion (30) is greater than or equal to 0.

1.

4. The color waveguide structure according to claim 1, wherein When the distance from the surface of the intermediate grating (20) away from the waveguide carrier (50) to the waveguide carrier (50) is less than the distance from the surface of the modulation filling portion (30) away from the waveguide carrier (50) to the waveguide carrier (50), the surface of the intermediate grating (20) away from the waveguide carrier (50) is covered by the modulation filling portion (30).

5. The color waveguide structure according to claim 1, characterized in that, When the distance from the surface of the intermediate grating (20) away from the waveguide carrier (50) to the waveguide carrier (50) is less than the distance from the surface of the modulation filling portion (30) away from the waveguide carrier (50) to the waveguide carrier (50), the distance between the surface of the intermediate grating (20) away from the waveguide carrier (50) and the surface of the modulation filling portion (30) away from the waveguide carrier (50) is greater than 0 nm and less than or equal to 100 nm.

6. The color waveguide structure according to any one of claims 1 to 5, characterized in that The modulation filling portion (30) includes a first portion (301) and a second portion (302) along its height direction, and the materials of the first portion (301) and the second portion (302) are different.

7. The color waveguide structure according to claim 6, characterized in that, The first portion (301) is one or more, and the second portion (302) is one; When the first part (301) is single, the first part (301) is located on the surface of the second part (302) away from the waveguide carrier (50) or on the surface of the second part (302) facing the waveguide carrier (50); when the first part (301) is plural, the first part (301) is provided on at least the surface of the second part (302) facing the waveguide carrier (50) and the surface of the second part (302) away from the waveguide carrier (50); and / or The height of the first part (301) is less than the height of the second part (302).

8. The color waveguide structure according to any one of claims 1 to 5, characterized in that, The shape of the intermediate grating (20) is one or more of a straight-tooth grating and a trapezoidal grating.

9. The color waveguide structure according to any one of claims 1 to 5, characterized in that, The modulation filling part (30) is one of a silicon nitride filling part, a magnesium oxide filling part, an aluminum oxide filling part, a titanium dioxide filling part, a hafnium oxide filling part, a zinc oxide filling part, a niobium oxide filling part, and a tantalum pentoxide filling part.

10. The color waveguide structure according to any one of claims 1 to 5, characterized in that The output grating (40) and the intermediate grating (20) are respectively arranged on two side surfaces of the waveguide carrier (50), and the projections of the output grating (40) and the intermediate grating (20) on the waveguide carrier (50) at least partially overlap, and the modulation filling part (30) is also filled in the gap of the output grating (40).

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