Optical waveguide and method of manufacturing the same, display device

Abstract

The application relates to an optical waveguide and a manufacturing method thereof and a display device. The optical waveguide comprises a waveguide substrate, a metasurface area, an in-coupling area and an out-coupling area arranged on the waveguide substrate. The waveguide substrate is a single-layer structure. The waveguide substrate comprises a first surface and a second surface arranged oppositely. One of the metasurface area and the in-coupling area is located on the first surface, and the other is located on the second surface. The metasurface area is configured to receive image light emitted by a display module, and the in-coupling area is configured to receive and in-couple the image light transmitted by the metasurface area. The application can simultaneously improve the lightness and thinness and the optical effect.

Description

Technical Field

[0001] This application relates to the field of optical waveguide technology, and in particular to an optical waveguide and its manufacturing method, and a display device. Background Technology

[0002] With the development of augmented reality technology, AR headsets, AR glasses, and automotive HUDs (head-up displays) are gradually being recognized as next-generation computing and display platforms, and more and more manufacturers are investing heavily in research and development. The key optical components of these display devices are the optical engine that generates the image and the light transmission module that transmits the image to the eyes. The light transmission module is the most critical part, directly affecting the size, image quality, and viewing comfort of these display devices. Currently, the mainstream light transmission module in the industry is represented by optical waveguide devices.

[0003] However, existing optical waveguide technologies suffer from the problem of simultaneously achieving both thinness and good optical performance. Summary of the Invention

[0004] Therefore, it is necessary to address the problem that existing optical waveguides cannot simultaneously achieve both thinness and good optical performance, and to provide an optical waveguide, its manufacturing method, and a display device.

[0005] According to a first aspect of this application, an optical waveguide is provided, including a waveguide substrate and a metasurface region, a coupling-in region, and a coupling-out region disposed on the waveguide substrate;

[0006] The waveguide substrate is a single-layer structure; the waveguide substrate includes a first surface and a second surface arranged opposite to each other, and one of the metasurface region and the coupling region is located on the first surface and the other is located on the second surface;

[0007] The metasurface region is configured to receive image light emitted by the display module, and the coupling region is configured to receive and couple the image light transmitted by the metasurface region.

[0008] In some embodiments, the metasurface region includes a plurality of nanopillars, which are integral with the waveguide substrate.

[0009] In some embodiments, the coupling-in region includes a coupling-in grating, and the coupling-out region includes a coupling-out grating; and / or,

[0010] The coupling-in region and the coupling-out region are disposed on the same surface of the waveguide substrate.

[0011] In some embodiments, the orthographic projection of the metasurface region onto the plane of the first surface at least partially overlaps with the orthographic projection of the coupling region onto the plane of the first surface.

[0012] In some embodiments, the refractive index of the waveguide substrate is greater than 2.

[0013] In some embodiments, the waveguide substrate is made of at least one of silicon carbide and lithium niobate.

[0014] According to a second aspect of this application, a method for manufacturing an optical waveguide is provided, comprising:

[0015] A waveguide substrate is provided, the waveguide substrate is a single-layer structure, and the waveguide substrate includes a first surface and a second surface disposed opposite to each other;

[0016] A metasurface region is formed in one of the first surface and the second surface;

[0017] A protective layer is formed in the metasurface region, and the protective layer covers the metasurface region;

[0018] A coupling region is formed in the other of the first surface and the second surface.

[0019] In some embodiments, the step of forming a metasurface region in one of the first surface and the second surface includes: forming a first hard mask layer and patterning the first hard mask layer to obtain a first hard mask pattern;

[0020] Multiple nanopillars are formed by etching the surface of the waveguide substrate under the first hard mask pattern.

[0021] In some embodiments, the step of forming a coupling region in the other of the first surface and the second surface includes:

[0022] The coupling-in region and the coupling-out region are formed on the same surface, the coupling-in region including a coupling-in grating and the coupling-out region including a coupling-out grating.

[0023] According to a third aspect of this application, a display device is provided, comprising:

[0024] A display module, wherein the display module is used to emit image light; and

[0025] The optical waveguide described in any one of the above, wherein the optical waveguide is used to receive the image light.

[0026] In this embodiment, the optical waveguide includes a waveguide substrate and a metasurface region, a coupling region, and a coupling-out region disposed on the waveguide substrate. The waveguide substrate is a single-layer structure; it includes a first surface and a second surface disposed opposite to each other, with one of the metasurface region and the coupling region located on the first surface and the other on the second surface. The metasurface region is configured to receive image light emitted by the display module, and the coupling region is configured to receive and couple the image light transmitted through the metasurface region. In this first aspect, the waveguide substrate is a single-layer structure, with the metasurface region and the coupling region located on two different surfaces of the waveguide substrate. The image light first passes through the metasurface region and then is transmitted to the coupling region. This eliminates the need for multi-layer waveguide substrates, different material layers, refractive index matching adhesive layers, or bonding structures. The display module does not need to be equipped with / bonded aspherical glass or plastic lenses based on geometric optics principles to achieve beam collimation, simplifying the optical waveguide structure, reducing weight, and decreasing the volume of the display device and display module, thus achieving a thinner and lighter display device (e.g., an AR headset). Secondly, the optical waveguide and display module do not require lens bonding or other film bonding, thus avoiding optical performance degradation caused by bonding misalignment and the absence of reflection at multi-film interface. Optical correction is also unnecessary, resulting in improved optical performance of the optical waveguide and reduced alignment assembly time and manufacturing costs. In other words, the embodiments of this application can simultaneously achieve both a thinner and lighter optical waveguide and excellent optical performance. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments or exemplary embodiments of this application, the drawings used in the description of the embodiments or exemplary embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the overall cross-section of an optical waveguide provided in an embodiment of this application.

[0029] Figure 2 This is a schematic diagram of a detailed structure of an optical waveguide provided in an embodiment of this application.

[0030] Figure 3 This is a schematic diagram of a coupling grating for an optical waveguide provided in an embodiment of this application.

[0031] Figure 4 This is a schematic diagram of light transmission in an optical waveguide provided in an embodiment of this application.

[0032] Figure 5 This is a schematic diagram for verifying the metasurface microstructure of the related technology.

[0033] Figure 6This is a schematic diagram illustrating the verification of a metasurface region in an optical waveguide, as provided in an embodiment of this application.

[0034] Figure 7 This is a schematic diagram comparing a metasurface region in an optical waveguide provided in an embodiment of this application with a metasurface microstructure in the prior art.

[0035] Figure 8 This is a schematic diagram illustrating the process steps of a method for manufacturing an optical waveguide according to an embodiment of this application.

[0036] Reference numerals: Optical waveguide 100; Waveguide substrate 10; Display module 20; Metasurface region 11; Coupling region 12; Coupling out region 13; First surface 101a; Second surface 102b; Image light g1; Metasurface microstructure 11C; Nanopillar 11a; Coupling grating 12W; Coupling out grating 13W; First recess 12a; First protrusion 12b; Second recess 13a; Second protrusion 13b; Coupling protrusion 12c. Detailed Implementation

[0037] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0038] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0039] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0040] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0041] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0042] It should be noted that if a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or there may be an intermediate component. If a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be an intermediate component. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0043] Existing optical waveguide technologies face the challenge of simultaneously achieving both thinness and good optical performance. To enhance optical performance, current waveguide technologies typically require multi-layered waveguide substrates, layers of different materials, refractive index-matching adhesive layers, or bonding structures, resulting in complex structures, large size, and heavy weight. Furthermore, display modules require the placement / bonding of aspherical glass or plastic lenses based on geometric optics principles to achieve beam collimation, hindering the achievement of thinner and lighter display devices. Simultaneously, misalignment between the waveguide and display module during bonding leads to deterioration of optical performance, necessitating optical correction, which makes it difficult to reduce alignment assembly time and manufacturing costs.

[0044] In view of the above problems, this application provides an optical waveguide, a method for manufacturing the same, and a display device.

[0045] Please see Figures 1 to 7 . Figure 1This is a schematic diagram of the overall cross-section of an optical waveguide provided in an embodiment of this application. Figure 2 This is a schematic diagram of a detailed structure of an optical waveguide provided in an embodiment of this application. Figure 3 This is a schematic diagram of a coupling grating for an optical waveguide provided in an embodiment of this application. Figure 4 This is a schematic diagram of light transmission in an optical waveguide provided in an embodiment of this application.

[0046] Figure 5 This is a schematic diagram for verifying the metasurface microstructure of the related technology. Figure 6 This is a schematic diagram illustrating the verification of a metasurface region in an optical waveguide, as provided in an embodiment of this application. Figure 7 This is a schematic diagram comparing a metasurface region in an optical waveguide provided in an embodiment of this application with a metasurface microstructure in the prior art.

[0047] It should be noted that, Figure 1 The metasurface region, coupling-in region, and coupling-out region are represented by bold black lines; Figure 4 The diagram also illustrates the display module, and uses arrows of varying thicknesses to represent different colors of light.

[0048] It should be noted that, Figure 5 and Figure 7 The illustration shows the verification results of the same prior art samples. Figure 6 and Figure 7 The verification results of the metasurface region of the same optical waveguide provided in this application are illustrated.

[0049] Firstly, such as Figures 1 to 4 As shown, this application provides an optical waveguide 100, which includes a waveguide substrate 10 and a metasurface region 11, a coupling region 12, and a coupling-out region 13 disposed on the waveguide substrate 10. The waveguide substrate 10 is a single-layer structure; it includes a first surface 101a and a second surface 102b disposed opposite to each other. One of the metasurface region 11 and the coupling region 12 is located on the first surface 101a, and the other is located on the second surface 102b. The metasurface region 11 is configured to receive image light g1 emitted by a display module 20, and the coupling region 12 is configured to receive and couple the image light g1 transmitted by the metasurface region 11.

[0050] For example, the metasurface region 11 refers to the region where a metasurface structure is formed. The metasurface region 11 includes an artificial thin-layer material composed of subwavelength-scale unit structures arranged periodically or aperiodically on a two-dimensional plane. It enables flexible and efficient control of the amplitude, phase, polarization state, and propagation mode of incident electromagnetic waves (or sound waves, water waves) at the interface.

[0051] For example, in some embodiments, the waveguide substrate 10 is provided with three functional regions, namely the metasurface region 11, the coupling-in region 12, and the coupling-out region 13.

[0052] For example, in some other embodiments, the waveguide substrate 10 may also have other functional regions, such as four functional regions: metasurface region 11, coupling region 12, transition region (pupil expansion region) and coupling out region 13.

[0053] For example, combined Figure 4 As shown, when the optical waveguide 100 does not include the transition region (pupil expansion region), the image light g1 emitted by the display module 20 first enters the optical waveguide substrate 10 through the metasurface region 11, and then the image light g1 is transmitted to the coupling region 12. The coupling region 12 is used to couple the image light g1 into the waveguide substrate 10 for total internal reflection transmission. The coupling region 13 is used to receive the image light g1 from the coupling region 12 and couple the image light g1 out of the waveguide substrate 10. The image light g1 coupled out of the coupling region 13 can form an image that is seen by the human eye.

[0054] For example, combined Figure 4 As shown, when the optical waveguide 100 includes a transition region (pupil expansion region), the image light g1 emitted by the display module 20 first enters the optical waveguide substrate 10 through the metasurface region 11, and then the image light g1 is transmitted to the coupling region 12. The coupling region 12 is used to couple the image light g1 into the waveguide substrate 10 for total internal reflection transmission. The transition region is used to expand the pupil of the received image light g1 and propagate it to the corresponding coupling region 13. The coupling region 13 is used to receive the image light g1 from the coupling region 12 and the transition region, and couple the image light g1 out of the waveguide substrate 10. The image light g1 coupled out of the coupling region 13 can form an image that is viewed by the human eye.

[0055] For example, the waveguide substrate 10 is a single-layer structure. The waveguide substrate 10 is provided with a metasurface region 11, a coupling region 12 and a coupling region 13. This means that the waveguide substrate 10 is a one-piece structure, the waveguide substrate 10 is a single material structure, the waveguide substrate 10 does not need to include multiple waveguide substrates, the waveguide substrate 10 does not need to include different material layers, the waveguide substrate 10 does not need to include a refractive index matching adhesive layer or bonding structure, thus simplifying the structure of the waveguide substrate 10.

[0056] For example, the waveguide substrate 10 is a single-layer structure, and the waveguide substrate 10 is provided with a metasurface region 11, a coupling region 12 and a coupling region 13. This does not mean that the optical waveguide 100 is necessarily a single-layer structure. Other additional structural layers can be formed in some areas / local areas on the surface of the waveguide substrate 10. For example, protective adhesive layers and other structures can be provided in areas such as the metasurface region 11.

[0057] For example, the waveguide substrate 10 is a single-layer structure, and the waveguide substrate 10 is provided with a metasurface region 11, a coupling region 12 and a coupling region 13. This does not mean that the optical waveguide 100 is necessarily a single-layer structure. It means that the main film layer forming the metasurface region 11, the coupling region 12 and the coupling region 13 is a single-layer structure, or in other words, the film layer in which light is transmitted within the optical waveguide 100 is a single-layer structure.

[0058] For example, the waveguide substrate 10 is a single-layer structure, and a metasurface region 11, a coupling region 12 and a coupling region 13 are provided on the waveguide substrate 10. This can mean that the nanopillar structure of the metasurface region 11, the coupling grating 12W and the subsequent coupling grating 13W are located in the same waveguide substrate layer.

[0059] It should be noted that the display module 20 is the image source (optical engine). The display module 20 can be a microdisplay, which is used to provide display content for the device. The display module 20 can be a self-emissive active device, such as a micro-OLED (µOLED) and micro-LED (µLED), or it can be a liquid crystal display (including transmissive Liquid Crystal Display (LCD) and reflective Liquid Crystal on Silicon (LCOS), as well as a digital micromirror array (DMD, the core of Digital Light Processing (DLP)) and a linear beam scanner (LBS) based on microelectromechanical systems (MEMS) technology. The type of display module 20 is not limited to these.

[0060] For example, the waveguide substrate 10 includes a first surface 101a and a second surface 102b arranged opposite to each other. One of the metasurface region 11 and the coupling region 12 is located on the first surface 101a, and the other is located on the second surface 102b. That is, the metasurface region 11 and the coupling region 12 are located on two different surfaces of the waveguide substrate 10. The image light g1 first passes through the metasurface region 11 and then is transmitted to the coupling region 12. The functions of the metasurface region 11 include, but are not limited to: beam shaping to collimate the image light g1; and / or, wavefront pre-correction to eliminate inherent aberrations of the projection source, introducing spatially related phase delays through different nanopillars, and compensating for phase distortion point-by-point across the entire field of view beam. In summary, the metasurface region 11 can correct and preprocess the image light g1 before it enters the coupling region 12, modifying the original image light g1 into an ideal incident light that is compatible with the coupling region 12 / coupling grating 12W and waveguide transmission, before sending it into the coupling region 12 / coupling grating 12W and coupling it into the waveguide. This can improve the optical performance of the optical waveguide 100.

[0061] For example, such as Figure 2As shown, the metasurface region 11 includes a metasurface microstructure 11C, which is a plurality of nanopillars 11a. The metasurface microstructure 11C (the plurality of nanopillars 11a) functions as a collimating lens and is directly integrated on the waveguide substrate 10.

[0062] For example, in this embodiment of the application, the high refractive index waveguide substrate 10 can increase the total internal reflection angle range, support the transmission of light at a larger angle, and improve the display field of view (FOV). The high refractive index of the silicon carbide waveguide substrate 10 enables a single-layer optical waveguide 100 to achieve an FOV greater than 70°. o The single-layer structure reduces assembly interfaces, which can reduce the risk of optical misalignment; it reduces the number of waveguides and optical bonding materials, thus reducing material costs; the alignment process is simplified, reducing the number of workstations and manufacturing manpower and time, thereby reducing production costs; it reduces the use of aspherical glass or plastic collimating lenses and optical bonding adhesives in the display module 20; and it can reduce the manpower required for optical alignment and inspection.

[0063] In the embodiments of this application, firstly, structurally, a single-layer structure is integrated: the grating of the coupling region 12, the grating of the coupling region 13, and the collimating metasurface (metasurface region 11) are integrated together on the same waveguide substrate 10, reducing assembly steps and lowering the risk of optical axis misalignment and bonding errors; ultra-thin and lightweight, with a superlens replacing the geometric lens, reduce the volume and weight of the optomechanical module. Secondly, functionally, the high-refractive-index waveguide substrate 10 increases the angular range of light that can be transmitted within the optical waveguide 100, providing a large field of view. Thirdly, in terms of process, the grating structure and collimating metasurface (metasurface region 11) of this proposal are both micron / nanoscale structures, which can be directly formed on the surface of the waveguide substrate 10 by NIL+ICP etching (Nanoimprint Lithography), improving yield and mass production capability.

[0064] In this embodiment, the optical waveguide 100 includes a waveguide substrate 10, and a metasurface region 11, a coupling region 12, and a coupling-out region 13 disposed on the waveguide substrate 10. The waveguide substrate 10 is a single-layer structure; it includes a first surface 101a and a second surface 102b disposed opposite to each other. One of the metasurface region 11 and the coupling region 12 is located on the first surface 101a, and the other is located on the second surface 102b. The metasurface region 11 is configured to receive image light g1 emitted by the display module 20, and the coupling region 12 is configured to receive and couple the image light g1 transmitted by the metasurface region 11. Firstly, the waveguide substrate 10 is a single-layer structure, with the metasurface region 11 and the coupling region 12 located on two different surfaces of the waveguide substrate 10. The image light g1 first passes through the metasurface region 11 and then is transmitted to the coupling region 12. This eliminates the need for multi-layer waveguide substrates, different material layers, refractive index matching adhesive layers, or bonding structures, simplifying the optical waveguide structure, reducing its weight, and decreasing the size of the display module 20 and display device, thus achieving a thinner and lighter display device (e.g., an AR headset). Secondly, the optical waveguide 100 and display module 20 do not require lens bonding or other film bonding, eliminating the optical performance degradation caused by bonding misalignment and the reflection at multi-film interface. Optical correction is not required, improving the optical performance of the optical waveguide 100 and reducing alignment assembly time and manufacturing costs. In other words, the embodiments of this application can simultaneously achieve a thinner and lighter optical waveguide and excellent optical performance.

[0065] In some embodiments, the metasurface region 11 includes a plurality of nanopillars 11a, which are integral with the waveguide substrate 10.

[0066] For example, the metasurface region 11 includes multiple nanopillars 11a, which are integrally formed with the waveguide substrate 10. That is, the nanopillars 11a are microstructures etched from the waveguide substrate 10, and the nanopillars 11a and the waveguide substrate 10 are integral structures made of the same material. No bonding process is required, allowing the optical waveguide 100 to be thinner and lighter while still achieving good optical performance.

[0067] In some embodiments, the coupling-in region 12 includes a coupling-in grating 12W, and the coupling-out region 13 includes a coupling-out grating 13W; and / or, the coupling-in region 12 and the coupling-out region 13 are disposed on the same surface of the waveguide substrate 10.

[0068] For example, the coupling grating 12W can be a diffractive coupling grating, and the coupling grating 13W can be a diffractive coupling grating, but is not limited to this.

[0069] For example, the coupling region 12 and the coupling region 13 are disposed on the same surface of the waveguide substrate 10, and the coupling grating 12W and the coupling grating 13W can be formed by the same process, thereby simplifying the manufacturing process.

[0070] In some implementations, such as Figure 1 and Figure 4 As shown, the orthographic projection of the metasurface region 11 onto the plane containing the first surface 101a at least partially overlaps with the orthographic projection of the coupling region 12 onto the plane containing the first surface 101a.

[0071] For example, in order to transmit the image light g1 incident through the metasurface region 11 to the coupling region 12, the orthographic projection of the metasurface region 11 on the plane where the first surface 101a is located can be set to at least partially overlap with the orthographic projection of the coupling region 12 on the plane where the first surface 101a is located.

[0072] For example, when image light g1 is incident perpendicularly or nearly perpendicularly on metasurface region 11, the orthographic projection of metasurface region 11 onto the plane containing first surface 101a can be positioned within the range of the orthographic projection of coupling region 12 onto the plane containing first surface 101a; or, the orthographic projection of coupling region 12 onto the plane containing first surface 101a can be positioned within the range of the orthographic projection of metasurface region 11 onto the plane containing first surface 101a. This allows more image light g1 incident through metasurface region 11 to be transmitted to coupling region 12.

[0073] In some implementations, the refractive index of the waveguide substrate 10 is greater than 2.

[0074] For example, the refractive index of the waveguide substrate 10 is greater than 2, such as 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, or 2.8.

[0075] For example, the refractive index of the waveguide substrate 10 is greater than 2. In this case, the refractive index of the nanopillars 11a of the metasurface region 11 is also greater than 2. Since the refractive index of the nanopillars 11a is the same as that of the waveguide substrate 10, the metasurface region 11 can possess a predetermined and better phase modulation capability, resulting in better beam collimation and modulation capabilities. Simultaneously, it allows for better total internal reflection conditions between the image light g1 and the surface of the waveguide substrate 10 during propagation, enabling more light rays to be coupled into the waveguide substrate 10 through the coupling region 12 for total internal reflection, thus improving the light coupling efficiency.

[0076] In some embodiments, the waveguide substrate 10 is made of at least one of silicon carbide and lithium niobate.

[0077] For example, experimental verification shows that silicon carbide and lithium niobate have high refractive indices and are suitable as optical waveguide substrates in this application embodiment. The waveguide substrate 10 is made of silicon carbide or lithium niobate, which have high refractive indices. For example, when the waveguide substrate 10 is made of silicon carbide, its refractive index is 2.66, and the light preprocessing performance of the metasurface region 11 is good.

[0078] For example, such as Figure 5 and Figure 6 As shown, Figure 5 This is a schematic diagram for verifying the metasurface microstructure of the related technology. Figure 6 This is a schematic diagram illustrating the verification of a metasurface region in an optical waveguide, as provided in an embodiment of this application. Figure 5 and Figure 6 In the figure, the horizontal axis represents the diameter of the nanopillar (denoted by Pillar Diameter), the left vertical axis represents the phase adjustment capability of the metasurface microstructure (denoted by Phase, with database scanning performed at a wavelength of 530 nm, and the result figure is represented by covering the 2π phase), and the right vertical axis represents the light transmittance of the metasurface microstructure (denoted by Transmittance). Figure 5 and Figure 6 The verification results are for incident light with a wavelength of 530 nm. Figure 5 The middle one is a nanopillar made of titanium dioxide in the existing technology. Figure 6 Nanopillars made of silicon carbide. Figure 5 and Figure 6 In the figure, curve Phase illustrates the phase modulation capability of the metasurface microstructure as a function of the nanopillar diameter, and curve Tr illustrates the light transmittance of the metasurface microstructure as a function of the nanopillar diameter. (Comparison) Figure 5 This demonstrates that the metasurface microstructures made of silicon carbide in the embodiments of this application also have good phase modulation capabilities and light transmittance.

[0079] For example, taking incident light with a wavelength of 530 nm as an example, Figure 7 This is a schematic diagram comparing a metasurface region in an optical waveguide provided in an embodiment of this application with a metasurface microstructure in the prior art. Figure 7 The refractive index (n), pitch, height, and diameter of the nanopillars were compared. Since higher nanopillar heights increase process risk, [further details are needed]. Figure 7 As can be seen from the above, the height of the silicon carbide nanopillars in this application embodiment is 500 nm, and the height of the titanium dioxide nanopillars is 800 nm. The nanopillars in this application embodiment have advantages in the manufacturing process. Figure 7 This demonstrates that the nanopillars in the embodiments of this application exhibit superior performance in terms of refractive index and nanopillar height.

[0080] It should be noted that, as Figure 2As shown, both the coupling grating 12W and the coupling grating 13W are diffractive grating structures, and the grating structure can include multiple protrusions and multiple recesses. For example, the coupling grating 12W includes multiple first recesses 12a and multiple first protrusions 12b, which are alternately arranged. The extension direction of the first recesses 12a and the first protrusions 12b in the direction parallel to the first surface 101a can be set according to the requirements of the coupling grating 12W. Similarly, the coupling grating 13W includes multiple second recesses 13a and multiple second protrusions 13b, which are alternately arranged. The extension direction of the second recesses 13a and the second protrusions 13b in the direction parallel to the first surface 101a can be set according to the requirements of the coupling grating 13W.

[0081] It should be noted that, as Figure 3 As shown, with Figure 2 In different examples, the coupling grating 12W may include multiple coupling protrusions 12c, which are arranged in a continuous stepped shape.

[0082] It should be noted that both the input grating 12W and the output grating 13W are diffraction grating structures. Therefore, the specific structures of the input grating 12W and the output grating 13W are not limited to these specific structures. Figure 2 and Figure 3 As shown.

[0083] Please see Figure 8 , Figure 8 This is a schematic diagram illustrating the process steps of a method for manufacturing an optical waveguide according to an embodiment of this application.

[0084] Secondly, based on the same concept, this application provides a method for manufacturing an optical waveguide, and the optical waveguide 100 in any of the above embodiments can be manufactured using this method. The method for manufacturing an optical waveguide includes steps S100, S200, S300, and S400.

[0085] Step S100: A waveguide substrate is provided. The waveguide substrate has a single-layer structure and includes a first surface and a second surface arranged opposite to each other.

[0086] For example, a waveguide substrate 10 is provided. The waveguide substrate 10 is a single-layer structure and includes a first surface 101a and a second surface 102b disposed opposite to each other.

[0087] Step S200: A metasurface region is formed in one of the first surface and the second surface.

[0088] For example, a metasurface region 11 is formed in one of the first surface 101a and the second surface 102b; including a plurality of nanopillars 11a forming the metasurface region 11.

[0089] Step S300: A protective layer is formed in the metasurface region, the protective layer covering the metasurface region.

[0090] For example, a protective layer is formed in the metasurface region 11, covering the metasurface region 11; the protective layer can protect the metasurface region 11 when the coupling-in region 12 and the coupling-out region 13 are subsequently formed.

[0091] Step S400: A coupling region is formed in the other of the first surface and the second surface.

[0092] For example, a coupling region 12 is formed in the other of the first surface 101a and the second surface 102b.

[0093] It should be noted that in some embodiments, the protective layer is retained so that the protective layer can also protect the metasurface area 11 in the display device.

[0094] It should be noted that, in some other embodiments, the manufacturing method of the optical waveguide further includes step S500, removing the protective layer.

[0095] For example, the method of manufacturing an optical waveguide has the same or similar beneficial effects as those described in the optical waveguide 100 in the above embodiments, and will not be repeated here.

[0096] In some embodiments, the step of forming a metasurface region 11 in one of the first surface 101a and the second surface 102b (step S200) includes: forming a first hard mask layer and patterning the first hard mask layer to obtain a first hard mask pattern; etching the surface of the waveguide substrate 10 under the first hard mask pattern to form a plurality of nanopillars 11a.

[0097] For example, a patterned first hard mask layer is first formed on the surface of the waveguide substrate 10, the first hard mask layer including a first hard mask pattern, then the surface of the waveguide substrate 10 under the first hard mask pattern is etched to form a plurality of nanopillars 11a, and then the first hard mask layer is removed.

[0098] In some embodiments, the step of forming a coupling region 12 in the other of the first surface 101a and the second surface 102b (step S400) includes forming a coupling region 12 and a coupling region 13 on the same surface, wherein the coupling region 12 includes a coupling grating 12W and the coupling region 13 includes a coupling grating 13W.

[0099] For example, the coupling region 12 and the coupling region 13 are disposed on the same surface of the waveguide substrate 10, and the coupling grating 12W and the coupling grating 13W can be formed by the same process, thereby simplifying the manufacturing process.

[0100] It should be noted that, in some embodiments, the step of forming the metasurface region 11 in one of the first surface 101a and the second surface 102b (step S200) includes: step S11, cleaning the waveguide substrate 10 to remove surface impurities; step S12, depositing a first hard mask layer (first hard photomask layer), depositing a first hard mask layer as an etch-resistant layer on the surface of the waveguide substrate 10, typically using silicon dioxide, silicon nitride, or chromium metal, and employing chemical vapor deposition (CVD), physical vapor deposition (PVD), or spin coating (Spin). The process involves: step S13, spin coating of photoresist; step S14, photoresist exposure and development, where the array of nanopillars 11a is projected onto the photoresist through a pre-designed photomask, and a preset pattern is left on the photoresist after development; step S15, patterning of the first hard mask layer, where the photoresist pattern is etched downwards to the first hard mask layer using reactive ion etching (RIE) to form the first hard mask pattern; step S16, removal of the photoresist, leaving the first hard mask pattern (nano-patterned structure) on the surface of the optical waveguide substrate 10; step S17, etching of the optical waveguide substrate 10 to form multiple nanopillars 11a; and step S18, removal of the first hard mask layer, where the first hard mask layer is removed using a wet chemical solution.

[0101] It should be noted that, in some other embodiments, the step of forming the metasurface region 11 in one of the first surface 101a and the second surface 102b (step S200) includes: step S21, cleaning the waveguide substrate 10 to remove surface impurities; step S22, depositing a lift-off layer (release layer) and a second hard mask layer (second hard mask layer), spin-coating an organic polymer underlayer (release layer) on the surface of the waveguide substrate 10 to facilitate subsequent metal layer lift-off, the second hard mask layer serving as an etch-resistant layer, which can be made of silicon dioxide; step S23, coating an imprinting adhesive layer (NIL Resist); step S24, performing an imprinting process on the imprinting adhesive layer, using a nanostructured PDMS (polydimethylsiloxane) soft mold to press the top imprinting adhesive layer; step S25, ultraviolet curing (UV curing). Curing and Demolding: Ultraviolet light irradiation rapidly crosslinks and cures the imprinting adhesive layer. After curing, the PDMS soft mold is peeled off, and the nanostructure is transferred onto the imprinting adhesive layer, leaving a residual layer at the bottom. Step S26: Residual Layer Etching: Remove the residual layer of the imprinting adhesive layer. Step S27: Etching: Etching the second hard mask layer down to the organic polymer bottom layer (Lift-off layer, release layer). Step S28: Reactive Ion Beam (RIBE) etching: Remove excess imprinting adhesive layer and material from the second hard mask layer. Step S29: Metal Deposition: Deposit a thin metal layer, such as nickel (Ni) or chromium (Cr) with high etch selectivity, onto the entire structure surface. Step S30: Lift-off: Immerse the substrate in a solvent; the lift-off layer (release layer) and the metal layer deposited on it will peel off, leaving a metal mask on the surface of the optical waveguide. (mask), at this time the metal mask is the first hard mask layer / first hard mask pattern; step S31, inductively coupled plasma etching (ICP etching) and removal of metal mask, the design pattern is transferred to the waveguide substrate 10 by etching, and finally the metal mask is removed.

[0102] Thirdly, this application provides a display device, which includes a display module 20 and an optical waveguide 100. The display module 20 is used to emit image light g1; the optical waveguide 100 is used to receive image light g1. The optical waveguide 100 in the display device can be any of the optical waveguides 100 in the above embodiments, and the optical waveguide 100 in the display device can have any one or any combination of the features in the above embodiments.

[0103] For example, the display device can be augmented reality (AR) glasses, in-vehicle HUD displays, aerial holographic displays, etc., but is not limited to these.

[0104] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0105] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. An optical waveguide, characterized by, It includes a waveguide substrate, and a metasurface region, a coupling-in region, and a coupling-out region disposed on the waveguide substrate; The waveguide substrate is a single-layer structure; the waveguide substrate includes a first surface and a second surface arranged opposite to each other, and one of the metasurface region and the coupling region is located on the first surface and the other is located on the second surface; The metasurface region is configured to receive image light emitted by the display module, and the coupling region is configured to receive and couple the image light transmitted by the metasurface region.

2. The optical waveguide according to claim 1, characterized in that, The metasurface region includes multiple nanopillars, which are integral with the waveguide substrate.

3. The optical waveguide according to claim 1, characterized in that, The coupling-in region includes a coupling-in grating, and the coupling-out region includes a coupling-out grating; and / or, The coupling-in region and the coupling-out region are disposed on the same surface of the waveguide substrate.

4. The optical waveguide according to claim 1, characterized in that, The orthographic projection of the metasurface region onto the plane of the first surface at least partially overlaps with the orthographic projection of the coupling region onto the plane of the first surface.

5. The optical waveguide according to claim 1, characterized in that, The refractive index of the waveguide substrate is greater than 2.

6. The optical waveguide according to claim 1, characterized in that, The waveguide substrate is made of at least one of silicon carbide and lithium niobate.

7. A method of manufacturing an optical waveguide, characterized by include: A waveguide substrate is provided, the waveguide substrate is a single-layer structure, and the waveguide substrate includes a first surface and a second surface disposed opposite to each other; A metasurface region is formed in one of the first surface and the second surface; A protective layer is formed in the metasurface region, and the protective layer covers the metasurface region; A coupling region is formed in the other of the first surface and the second surface.

8. The method for manufacturing an optical waveguide according to claim 7, characterized in that, The step of forming a metasurface region in one of the first surface and the second surface includes: forming a first hard mask layer and patterning the first hard mask layer to obtain a first hard mask pattern; Multiple nanopillars are formed by etching the surface of the waveguide substrate under the first hard mask pattern.

9. The method for manufacturing an optical waveguide according to claim 7, characterized in that, The step of forming a coupling region in the other of the first surface and the second surface includes: The coupling-in region and the coupling-out region are formed on the same surface, the coupling-in region including a coupling-in grating and the coupling-out region including a coupling-out grating.

10. A display device, characterized in that, include: The display module is used to emit image light; as well as The optical waveguide according to any one of claims 1-6, wherein the optical waveguide is used to receive the image light.

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