Light guide device and near-eye display device

Abstract

Embodiments of the present application provide a light guide device and a near-eye display device. The light guide device comprises a substrate provided with a coupling-in region and a coupling-out region; a micro display component and a metasurface element are provided in the coupling-in region, and the micro display component and the metasurface element are attached along a light transmission direction; the micro display component is used for emitting image light, and the metasurface element is used for modulating the image light and coupling the modulated image light into the substrate; and a coupling-out element is provided in the coupling-out region, and the coupling-out element is used for coupling out light propagated thereto.

Description

A light guide device and a near-eye display device Technical Field

[0001] This application relates to the field of optical display technology, and more specifically, to a light guide device and a near-eye display device. Background Technology

[0002] Traditional light guide devices are used in technologies such as AR and VR, and usually need to be used in conjunction with traditional projection optical engines to achieve functions such as light transmission, control and modulation.

[0003] When traditional projection optical engines and traditional light guides are used together, the separation between the two is quite strong, increasing the overall size of the system. Furthermore, coupling the light emitted from a traditional projection optical engine into the light guide requires passing through numerous components, introducing additional light loss and errors, thus affecting the imaging effect.

[0004] In view of this, a new technical solution is needed to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this application is to provide a new technology solution for a light guide device and a near-eye display device.

[0006] In a first aspect, embodiments of this application provide a light guide device. The light guide device includes:

[0007] A substrate having an insertion region and an exit region;

[0008] The coupling region is provided with a micro-display component and a metasurface element, and the micro-display component and the metasurface element are attached together along the light transmission direction;

[0009] The microdisplay component is used to emit image light, and the metasurface element is used to modulate the image light and couple the modulated image light into the substrate.

[0010] The coupling region is provided with a coupling element, which is used to couple out the light propagating thereto.

[0011] Secondly, embodiments of this application also provide a near-eye display device. The near-eye display device includes the light guide device described in the first aspect.

[0012] According to embodiments of this application, both the microdisplay component and the metasurface element are integrated in the coupling region of the substrate, achieving light output, effective modulation, coupling, and transmission. Compared to the traditional scheme that combines a projection optical engine and a traditional light guide device to transmit image light, this significantly reduces the size of the combined traditional projection optical engine and light guide device. Furthermore, because both the microdisplay component and the metasurface element are integrated in the coupling region, the overall integration of the light guide device is higher, resulting in better transmission efficiency of the image light emitted from the microdisplay component.

[0013] Other features and advantages of this specification will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0014] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of this specification and, together with their description, serve to explain the principles of this specification.

[0015] Figure 1 shows a schematic diagram of the structure of the optical engine provided in an embodiment of this application.

[0016] Figure 2 shows a schematic diagram of the optical path corresponding to a certain pixel in the optical engine provided in the embodiment of this application.

[0017] Figures 3a and 3b show schematic diagrams of the metasurface element provided in the embodiments of this application.

[0018] Figure 4 shows a schematic diagram of the optical path corresponding to a certain pixel in the optical engine provided in the embodiment of this application.

[0019] Figure 5 shows a second schematic diagram of the structure of the metasurface element provided in the embodiment of this application.

[0020] Figure 6 shows a schematic diagram of the structure of the micro-display component provided in an embodiment of this application.

[0021] Figure 7 shows a structural diagram of the light guide device provided in an embodiment of this application.

[0022] Figure 8 shows a top view of the light guide device in Figure 7.

[0023] Figure 9 shows a second structural diagram of the light guide device provided in an embodiment of this application.

[0024] Figure 10 shows a top view of the light guide device in Figure 9.

[0025] Figure 11 shows a schematic diagram of the optical path of the light guide device in Figure 7.

[0026] Figure 12 shows a schematic diagram of the optical path of the light guide device in Figure 9.

[0027] Figure 13 shows the structure of the light guide device provided in the embodiment of this application.

[0028] Figure 14 shows a top view of the light guide device in Figure 13.

[0029] Figure 15 shows the structure of the light guide device provided in the embodiment of this application.

[0030] Figure 16 shows a top view of the light guide device in Figure 15.

[0031] Figure 17 shows the structure of the light guide device provided in the embodiment of this application.

[0032] Figure 18 shows a top view of the light guide device in Figure 17.

[0033] Figure 19 shows a schematic diagram of the structure of a near-eye display device.

[0034] Figure 20 shows a schematic diagram of the near-eye display device.

[0035] Explanation of reference numerals in the attached figures: 1. Substrate; 11. Side surface; 2. Optical engine; 21. Microdisplay component; 210. Pixel; 211. Light source; 212. Microdisplay chip; 22. Metasurface element; 221. Substrate; 222. Micro / nano structure; 22a. First part; 22b. Second part; 3. Coupling element; 31. First one-dimensional grating; 32. Second one-dimensional grating; 4. Transition element; 5. Frame module; 51. Temple; 61. Coupling area; 62. Coupling area. Detailed Implementation

[0036] Various exemplary embodiments of this application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of this application.

[0037] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0038] Technologies and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies and equipment should be considered part of the specification.

[0039] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0040] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0041] Before detailing the novel light guide device provided in the embodiments of this application, a novel optomechanical structure is provided. This optomechanical structure can be used as an integral structure in the light guide device, or a part of the optomechanical structure can be grown on the substrate of the light guide device, forming an integral structure with the substrate of the light guide device.

[0042] In traditional projection optical engines, the primary functions of the waveguide are image generation and light source provision. Specifically, a traditional projection optical engine generates image information through an internal display chip (such as LCOS, DLP, or LBS), and converts this information into light signals through a series of lens components. These light signals are then coupled into the waveguide by coupling elements formed on the waveguide, and guided by the waveguide, are finally coupled out by coupling elements formed on the waveguide and projected onto the user's eyes, forming a clear image.

[0043] In order to couple image light into the waveguide, traditional projection optical engines need to use a special coupling element (such as a coupling grating), which is set in the coupling area of ​​the traditional light guide device.

[0044] Therefore, this application provides a novel optical engine structure to solve the technical problem of complex overall architecture and large size of traditional projection optical engines.

[0045] Optical Mechanics

[0046] This application proposes a novel optical engine structure. This optical engine not only possesses the functions of generating and modulating image rays, as in traditional projection optical engines, but also innovatively incorporates light coupling capabilities, simplifying the optical engine structure, reducing its size, and enriching its performance.

[0047] In this embodiment of the application, referring to FIG1, the optical engine includes: a micro-display component 21 for emitting image light; and a metasurface element 22, wherein the micro-display component 21 and the metasurface element 22 are attached together along the light transmission direction, and the metasurface element 22 is used to modulate the image light and couple the modulated image light into a light guide device.

[0048] In this embodiment, the optical engine consists of only two parts: a micro-display component 21 and a metasurface element 22. These two components of the optical engine will be analyzed in detail below.

[0049] In this embodiment, the main function of the microdisplay component 21 in the optomechanical system is to emit image light rays. The image light rays emitted by the microdisplay component 21 can be collimated light rays (parallel light rays) or decollimated light rays.

[0050] When the image light emitted by the microdisplay component 21 is collimated, the complexity of light control and phase modulation of the metasurface element 22 is simplified, and the design difficulty of the metasurface element 22 is reduced.

[0051] When the image light of the microdisplay component 21 is non-collimated, it will increase the difficulty of designing the metasurface element 22, but it will not affect the overall architecture of the optomechanical system in the embodiments of this application.

[0052] In this embodiment, the microdisplay component 21 and the metasurface element 22 are attached together along the light transmission direction. This attachment ensures that image light emitted from the microdisplay component 21 can be directly and efficiently transmitted to the metasurface element 22, reducing light loss and scattering.

[0053] Furthermore, the metasurface element 22 can modulate the light incident upon it. For example, the metasurface element 22 can modulate the phase, polarization, amplitude, and other characteristics of the image light. The bonding arrangement between the microdisplay component 21 and the metasurface element 22 further ensures the accuracy of the modulation process and also guarantees that the light will not be subjected to additional interference during transmission.

[0054] Furthermore, the micro-display component 21 and the metasurface element 22 are attached along the light transmission direction, making the entire optical engine structure more compact, which helps to reduce the size and weight of the optical engine and improve its portability and ease of use.

[0055] In this embodiment, the metasurface element 22 is composed of a metasurface structure. A metasurface structure is a structure including micro / nano structures 222. These micro / nano structures 222 are artificial layered material structures with dimensions at the subwavelength scale. These micro / nano structures 222 can achieve modulation of the polarization, amplitude, phase, and propagation characteristics of image light.

[0056] The metasurface element 22 modulates light through its micro / nano structures 222. When light is incident on the metasurface element 22, it interacts with these micro / nano structures 222, thereby changing the polarization, amplitude, phase, and propagation (direction and angle) properties of the light.

[0057] Referring to Figures 3a and 3b, an example structure of a metasurface element 22 is shown. The metasurface element 22 may include a substrate 221 and micro / nanostructures 222 located on the substrate 221. The micro / nanostructures 222 located on the substrate 221 may have the same or different shapes.

[0058] For example, referring to FIG5, another structure of the metasurface element 22 is shown. As shown in FIG3b and FIG5, the arrangement of the micro-nano structures 222 on the substrate 221 is not unique. Those skilled in the art can design the arrangement of the micro-nano structures 222 on the substrate 221 and the shape of each micro-nano structure according to the type of image light emitted from the micro-display component 21 and the type of optomechanical application to the light guide device.

[0059] There are no specific requirements for the thickness of the micro / nano structure 222; the thickness is typically a few wavelengths, usually a few micrometers. In the embodiments of this application, the main limitation is that the lateral (perpendicular to the direction of light propagation) dimension of the micro / nano structure 222 must be smaller than or close to the wavelength. For example, in the case where the micro / nano structure 222 is a nanopillar, the width of the nanopillar must be close to or smaller than the wavelength.

[0060] In this embodiment, the microdisplay component 21 and the metasurface element 22 are bonded together to form an optomechanical system, utilizing the structural features of the metasurface element 22. The metasurface element 22 has the function of modulating image light and coupling the modulated image light into a light guide device.

[0061] Specifically, in the embodiments of this application, the metasurface element 22 primarily functions to modulate image light. When image light emitted from the microdisplay component 21 shines onto the metasurface element 22, this light is modulated by the micro / nano structure 222 of the metasurface element 22.

[0062] Based on the micro / nano structure characteristics of the metasurface element 22, light undergoes changes in phase, amplitude, or polarization as it passes through, thereby achieving light modulation.

[0063] This part of the metasurface element 22 functions similarly to optical elements such as lenses in conventional optical engines. However, compared to conventional lenses, the metasurface element 22 has advantages such as being lighter, thinner, and easier to integrate.

[0064] Furthermore, the metasurface element 22 can also achieve more complex optical functions, such as multifocal focusing, zooming, and polarization control, which are difficult to achieve with traditional lenses. In other words, in this embodiment, the light modulation effect of the metasurface element 22 is superior to the light modulation effect of optical elements such as lenses in traditional optomechanical systems.

[0065] Furthermore, the metasurface element 22 also has the function of coupling the modulated image light into the light guide device. The light modulated by the metasurface element 22 has its propagation direction and characteristics adjusted according to predetermined requirements, which makes it easier and more efficient for these lights to couple into the light guide device. Light guide devices are typically used to guide light along a specific path to achieve specific imaging or illumination effects.

[0066] This part of the function of the metasurface element 22 is similar to that of the coupling element (such as a coupling grating) in a conventional light guide device. A coupling grating is a device used to couple light into the waveguide, and it usually has specific structures and parameters to achieve directional coupling of light. In the embodiments of this application, the metasurface element 22 directly couples the modulated light into the waveguide of the light guide device.

[0067] Compared to coupling gratings, metasurface elements 22 offer greater flexibility and customizability. By adjusting the microstructure and parameters of metasurface elements 22, image light emitted from them can be directly coupled into a light guide device without the need for coupling gratings, thus meeting a wider range of optical requirements. Furthermore, metasurface elements 22 also offer advantages such as being lighter, thinner, and easier to integrate.

[0068] In summary, by bonding the microdisplay component 21 to the metasurface element 22 and utilizing the structural features of the metasurface element 22 to modulate and couple light, the optomechanical design in this embodiment achieves a highly integrated, efficient, and flexible optical system. This design not only improves the overall performance of the optomechanical system but also facilitates further miniaturization and integration of the system.

[0069] In this embodiment of the application, referring to FIG1, the microdisplay component 21 and the metasurface element 22 are bonded together.

[0070] In this embodiment, the microdisplay component 21 and the metasurface element 22 are connected together by an adhesive bonding method. Firstly, the adhesive bonding provides stable mechanical support. As core components of the optomechanical system, the microdisplay component 21 and the metasurface element 22 need to maintain precise relative positions to ensure accurate light transmission and modulation. The adhesive bonding ensures a strong bond between these two components, preventing displacement or loosening under external factors such as vibration or impact, thereby guaranteeing the stability and reliability of the optomechanical system.

[0071] Secondly, adhesive bonding can also achieve good optical contact. In optomechanics, the quality of the contact surface between the microdisplay component 21 and the metasurface element 22 has a significant impact on the light transmission effect. Through adhesive bonding, the contact surface between the microdisplay component 21 and the metasurface element 22 can be ensured to be flat and smooth, reducing light scattering and loss on the contact surface, thereby improving the transmission efficiency and imaging quality of the optical system.

[0072] Furthermore, adhesive bonding offers advantages such as simple processing and low cost. Compared to traditional mechanical bonding methods, adhesive bonding eliminates the need for complex machining and assembly processes, significantly reducing production costs and time. Simultaneously, adhesive bonding can accommodate optical components of different shapes and sizes, providing greater flexibility and choice for the design and manufacturing of optical systems.

[0073] In a further embodiment, the adhesive layer between the microdisplay component 21 and the metasurface element 22 is annular.

[0074] In this embodiment, the adhesive layer between the microdisplay component 21 and the metasurface element 22 is annular. The annular adhesive layer can be located in the non-display area of ​​the microdisplay component 21 and in the non-working area of ​​the metasurface element 22, ensuring the normal transmission of image light emitted from the microdisplay component 21 and ensuring the modulation and coupling effect of the image light by the metasurface element 22.

[0075] Specifically, the annular adhesive layer is located in the non-display area of ​​the microdisplay component 21, meaning it does not block image light emitted from the microdisplay component 21. Thus, image light can be modulated and coupled through the metasurface element 22 without being obstructed by the adhesive layer.

[0076] Similarly, the annular adhesive layer is also located in the non-working area of ​​the metasurface element 22 (e.g., the edge region of the substrate 221 where no micro / nano structures 222 are disposed). This ensures that the working area of ​​the metasurface element 22 (i.e., the portion used to modulate and couple image light) is not adversely affected by the adhesive layer, such as stress, contamination, or damage.

[0077] It should be noted that although the adhesive layer is annular, it still provides a stable mechanical connection between the microdisplay component 21 and the metasurface element 22. This connection ensures that the relative positions of the two components in the optomechanism remain fixed, thereby guaranteeing the stability and reliability of the optomechanism.

[0078] For example, the type of adhesive between the microdisplay component 21 and the metasurface element 22 can be UV adhesive, epoxy AB adhesive, or optical resin adhesive, etc.

[0079] In a further embodiment, the bonding air gap between the microdisplay component 21 and the metasurface element 22 is less than 1 μm.

[0080] In this embodiment, the microdisplay component 21 and the metasurface element 22 do not need to be in direct contact. When the microdisplay component 21 emits image light, there can be a smaller gap between them. The smaller the gap between them, the less light leakage will occur.

[0081] In this embodiment, when the bonding air gap between the microdisplay component 21 and the metasurface element 22 is less than 1 μm, the pixel size 210 of the microdisplay component 21 (plus the lateral size expansion during light transmission) can be smaller than the size of the corresponding pixel region on the metasurface element 22 (the micro / nano structure 222 corresponding to a certain pixel 210). The metasurface element 22 can then modulate and couple the light emitted from its corresponding pixel 210. This modulation and coupling enables precise control of the light, including direction, intensity, and phase, thereby meeting various application requirements.

[0082] In a preferred embodiment of this application, the light emitted by the microdisplay component 21 is collimated light. The method by which the microdisplay component 21 emits collimated light includes: defining the light source 211 of the microdisplay component 21 as a collimated light source 211.

[0083] When the light source 211 of the micro display component 21 is a collimated light source 211, for example, the light source 211 is a laser light source 211 or the light source 211 is another collimated light source 211, such as an LED light source 211.

[0084] When the light source 211 is another light source 211 that has been collimated, the micro-display component 21 includes a light source body and a collimation assembly. The collimation assembly is located in the light emission path of the light source body.

[0085] In this example, the light source 211 is typically a high-brightness LED or other type of light-emitting element. These light sources 211 are capable of emitting light of sufficient intensity for subsequent processing and projection by the microdisplay chip 212.

[0086] The collimation component is a key part of the micro-display component 21 for achieving light collimation. It is located on the light emission path of the light source body to expand and collimate the light transmitted to it, making the light rays parallel and aligned in the same direction.

[0087] Alternatively, this can be understood as follows: In this approach, the microdisplay component 21 needs to achieve light collimation through an additional optical system (collimation assembly). Light collimation is achieved at the pixel level and may include optical elements such as microlens arrays or microcavity mirrors, which can collect, focus, and guide the light emitted by the light source 211 to form collimated image light.

[0088] When the light source 211 of the microdisplay component 21 is a laser light source 211, referring to Figure 6, the microdisplay component 21 includes only the light source 211 and the microdisplay chip 212. The collimated light source 211 can directly emit collimated light rays. The microdisplay chip 212 is typically a display element with high resolution and high-speed response capabilities, such as an LCD screen (transmissive screen). These display elements can modulate and image the light emitted by the collimated light source 211 to form a clear projected image.

[0089] Alternatively, in this approach, the micro-display component 21 directly uses a laser light source 211 with collimation characteristics to directly achieve light collimation.

[0090] For example, the light source 211 is a VCSEL laser, namely a vertical-cavity surface-emitting laser. In this embodiment, a VCSEL array is used as a micro-display array, resulting in high overall brightness and efficiency for the micro-display component 21. For instance, the VCSEL array provides light emission over a large area, enabling regional backlight modulation, reducing power consumption and improving overall efficiency. The array provides the backlight effect, while the light modulation employs a transmissive LCD screen or a reflective LCOS screen (requiring a specially designed waveguide, see the optical system disclosed in 202411254381.6) to achieve greater pixel density and control the light flux to achieve modulation.

[0091] In the overall architecture of a traditional optical-mechanical system, the micro-display component 21 usually needs to work in conjunction with a series of other optical components (such as lenses, mirrors, etc.) and mechanical structures (such as supports, adjustment mechanisms, etc.) to achieve the desired imaging or projection effect.

[0092] However, in this embodiment, we employ an innovative design approach: the microdisplay component 21 directly emits collimated image rays, which do not need to pass through intermediate traditional optical elements but are directly transmitted to the metasurface element 22. The metasurface element 22 is responsible for modulating the image rays emitted by the microdisplay component 21, thereby efficiently coupling these modulated image rays into the interior of a light guide device (e.g., an optical waveguide).

[0093] In this embodiment of the application, referring to FIG6, the micro display component 21 further includes a micro display chip 212, which is disposed on the light emission path of the light source 211.

[0094] In this embodiment, the microdisplay chip 212 is located in the light-emitting path of the light source 211, and its main function is to output image light carrying image information. The microdisplay chip 212 can employ different technologies, such as LCD (Liquid Crystal Display), LCOS (Liquid Crystal on Silicon), or Micro LED. These technologies utilize different physical principles to control the passage or reflection of light, thereby forming an image on the microdisplay chip 212.

[0095] It is important to note that when using Micro LED, the light source 211 itself has image modulation capabilities, thus eliminating the need for an integrated microdisplay chip 212. When the light source 211 uses Micro LED, the light source itself is the microdisplay chip, requiring no external modulation; that is, the Micro LED itself is the microdisplay component 21. However, the light scattering angle of Micro LED is too large, necessitating the design shown in Figure 4, i.e., collimating the light emitted by the Micro LED.

[0096] For example, considering the size requirements of the micro-display component 21, the micro-display component 21 is preferably a Micro LED. According to the specifications of Micro LED, the effective display sizes of Micro LED are 0.12 inches, 0.61 inches and 0.69 inches, and Micro LEDs of different sizes all have high resolution, which meets the requirements of optomechanical imaging.

[0097] In this embodiment of the application, referring to Figures 2, 3a, and 3b, and Figures 4 and 5, the metasurface element 22 is composed of subwavelength micro / nano structures 222. Each micro / nano structure 222 in the metasurface element 22 corresponds one-to-one with a pixel 210 in the microdisplay component 21. The micro / nano structure 222 modulates and refracts the light emitted from its corresponding pixel 210 into the light guide device.

[0098] In this embodiment, the subwavelength micro / nano structures 222 can modulate light with high precision. These micro / nano structures 222 can manipulate the phase, amplitude, polarization, and propagation characteristics of light, thereby achieving customized control of light. This allows the metasurface elements 22 to modulate the image light emitted from the microdisplay component 21 on the one hand, and to couple the modulated light into the light guide device on the other.

[0099] Specifically, by designing and optimizing the subwavelength micro / nano structure 222, the metasurface element 22 can achieve focusing, deflection, and phase modulation of light, which have advantages in imaging, display, and light coupling.

[0100] Furthermore, the extremely small size of the subwavelength micro / nano structure 222 enables the metasurface element 22 to achieve a high degree of integration. Compared with traditional optical elements, the metasurface element 22 is smaller and lighter, and is easier to integrate with the microdisplay component 21, thereby creating a powerful and compact optomechanical system.

[0101] For example, the subwavelength-sized micro / nano structure 222 includes any one or a combination of several of nanoblocks, nanopillars, nanostrips, and irregular structures (e.g., L-shaped or V-shaped).

[0102] In this example, the subwavelength micro / nanostructures 222 encompass regular and irregular structures such as nanoblocks, nanopillars, and nanostrips, and can be flexibly selected and designed according to the functions required by the metasurface element 22. When constructing the same metasurface element 22, a single type of micro / nanostructure 222 can be used, or at least two different types of micro / nanostructures 222 can be integrated to achieve the required functions of the metasurface element 22. For example, if the micro / nanostructure 222 is a V-shaped design, modulation can be achieved by changing the angle of the V-shape to alter the limiting of the light passing through it.

[0103] In this embodiment, referring to Figures 2 and 4, the micro / nano structure 222 (the smallest unit of the metasurface element 22) of the metasurface element 22 is adapted to the size of the pixel 210 in the microdisplay component 21. Due to this size effect, the micro / nano structure 222 can interact strongly with light waves, thereby achieving modulation of the light wave characteristics. The micro / nano structure 222 of the metasurface element 22 encodes (i.e., modulates the characteristics of the light) the image light emitted from its corresponding pixel 210, realizing the modulation and coupling of the image light.

[0104] Specifically, metasurface element 22 is a device composed of micro- and nanostructures that can precisely control the properties of light waves, such as phase, amplitude, polarization, and propagation.

[0105] Micro- and nanostructures 222 are the basic building blocks of metasurface elements 22. Their shape, size, and arrangement determine the metasurface's ability to control light waves.

[0106] Pixel 210 is the basic building block of microdisplay component 21, and each pixel 210 can emit light of a specific color and brightness.

[0107] Here, "encoding" refers to the specific manipulation of image light using the micro / nano structures 222 of the metasurface element 22, enabling the light to carry specific information or characteristics. This encoding is achieved through the shape, size, and arrangement of the micro / nano structures 222, which can influence the phase, amplitude, polarization, and propagation characteristics of the light.

[0108] "Modulation" refers to the precise control of the characteristics of light in an image, such as changing the phase, amplitude, polarization state, or propagation direction and angle of the light to achieve specific optical effects.

[0109] "Coupling" refers to the efficient connection of modulated light with light guide devices to ensure that the light can propagate and form an image in the expected manner.

[0110] In this embodiment, the micro / nano structure 222 of the metasurface element 22 achieves precise modulation of the image light emitted from its corresponding pixel 210 by specifically encoding (i.e., controlling the characteristics of the light). This modulated light is then efficiently coupled into a light guide device to achieve specific display effects or optical functions.

[0111] For example, the metasurface element 22 also includes a substrate 221 on which micro / nano structures 222 are formed.

[0112] In one embodiment, referring to Figures 2, 3a and 3b, the metasurface element 22 includes a dielectric layer formed by arranging a plurality of subwavelength-sized micro / nano structures 222 along the light transmission direction. The dielectric layer is configured to modulate the image light and couple the modulated image light into a light guide device.

[0113] In this embodiment, referring to Figures 3a and 3b, the metasurface element 22, along the light transmission path, includes a dielectric layer composed of a plurality of subwavelength micro / nano structures 222 arranged in an orderly manner. This dielectric layer is specially designed to precisely modulate image light, thereby effectively coupling the modulated image light into the light guide device to achieve light transmission and control.

[0114] In other words, in this embodiment, the metasurface element 22 includes only one dielectric layer. This single dielectric layer has two functions: on the one hand, it can modulate the image light emitted from the microdisplay component 21; on the other hand, it enables the modulated light to couple into the light guide device.

[0115] Referring to Figure 2, a schematic diagram of the optical path corresponding to a certain pixel in the optomechanical system is shown. The light emitted from a certain pixel 210 in the micro-display component 21 is transmitted to the corresponding micro / nano structure 222, and the transmission characteristics of the light change.

[0116] In this embodiment, the metasurface element 22 includes a dielectric layer, which is a planar or curved structure composed of subwavelength micro / nanostructures 222 (such as nanoblocks, nanopillars, nanostrips, etc.) arranged in an orderly manner. These micro / nanostructures 222 are much smaller than the wavelength of light, so they can interact strongly with light waves, thereby changing the propagation characteristics of light.

[0117] When light rays pass through this dielectric layer, they interact with the micro / nano structures 222 within it. This interaction causes changes in the phase, amplitude, polarization state, and propagation characteristics of the light rays, i.e., the light rays are modulated.

[0118] The modulated image light is then effectively coupled into the light guide. The coupling process involves guiding the modulated light to the input of the light guide and ensuring that the light propagates in the desired manner within the light guide. Once coupled into the light guide, the light can then travel along the path of the light guide.

[0119] By precisely designing the structure of the dielectric layer and light guide device of the metasurface element 22, precise control over parameters such as light transmission path, direction, and intensity can be achieved.

[0120] It should be noted that Figures 3a and 3b only illustrate one structure of the metasurface element 22. Based on the light emission characteristics of the micro-display component 21, those skilled in the art can adjust the arrangement (e.g., density) and shape of the micro-nano structures 222 in the metasurface element 22.

[0121] In another embodiment, referring to Figures 4 and 5, the metasurface element 22 includes a first portion 22a and a second portion 22b along the light transmission direction. Both the first portion 22a and the second portion 22b include a dielectric layer formed by arranging a plurality of subwavelength-sized micro / nano structures 222.

[0122] The first portion 22a is configured to modulate the image light, and the second portion 22b is configured to couple the modulated image light into the light guide device.

[0123] In this embodiment, the metasurface element 22 is divided into two main parts in the light transmission direction: a first part 22a and a second part 22b. Referring to FIG4, a schematic diagram of the optical path of a pixel in the optomechanism is shown. The light emitted from a pixel 210 in the microdisplay component 21 passes sequentially through a micro / nano structure 222 in the first part 22a of the metasurface element 22 and a micro / nano structure 222 in the second part 22a of the metasurface element 22.

[0124] Both the first part 22a and the second part 22b contain a dielectric layer formed by the orderly arrangement of multiple subwavelength micro / nano structures 222. This structural design enables the metasurface element 22 to modulate image light (collimate image light) and couple the modulated image light into the light guide device through the structures of the first part 22a and the second part 22b.

[0125] Specifically, referring to FIG4, the main function of the micro / nano structure 222 of the first portion 22a is to modulate (collimate) the image light. Since the first portion 22a contains subwavelength micro / nano structures 222, these structures can interact strongly with light, thereby achieving precise optical modulation. In this embodiment, the micro-display component 21 is a Micro LED.

[0126] Referring to Figure 4, the micro / nano structure 222 of the second part 22b further modulates (the phase, propagation, and other characteristics of the light) the image light modulated by the first part 22a and effectively couples it into the light guide device. The coupling process involves refracting the light emitted from each pixel 210 of the microdisplay component 21 to the light guide device (refractive effect) to ensure that the light can enter the light guide device efficiently and be transmitted therein.

[0127] This design, which divides the metasurface element 22 into two independent but cooperative parts, allows the entire element to adapt more flexibly to different optical requirements and provides higher optical performance and control precision.

[0128] It should be noted that Figure 5 only schematically illustrates the structure of a portion of the metasurface element 22. Those skilled in the art can adjust the structure of the first part 22a and the structure of the second part 22b according to the light emission characteristics of the microdisplay component 21.

[0129] <Light guide devices>

[0130] Traditional light guide devices are used in technologies such as AR and VR, and usually need to be used in conjunction with traditional optical engines to achieve functions such as light transmission, control and modulation.

[0131] Traditional projection optical engines generate image information through an internal display chip (such as LCOS, DLP, or LBS), and convert this image information into light signals through a series of lens components. These light signals are then coupled into the optical waveguide (a type of light guide device) by coupling elements (such as coupling gratings). Guided by the optical waveguide, the light signals are finally projected into the user's eyes through coupling elements (such as coupling gratings) formed on the optical waveguide, forming a clear image.

[0132] Therefore, when traditional projection optical engines and traditional light guides are used together, there is a strong sense of separation between the two, increasing the overall size of the system. Furthermore, coupling the light emitted from a traditional projection optical engine into the light guide requires passing through numerous components, introducing additional light loss and errors, thus affecting the imaging effect.

[0133] Therefore, this application provides a novel light guide device. This light guide device has a substrate 1 and an output element 3 formed on the substrate 1, retaining the performance of traditional light guide devices in terms of light transmission and output. Furthermore, the light guide device integrates a micro-display component 21 and a metasurface element 22 in the coupling region. This design not only endows the light guide device with the ability to generate and modulate image light like a traditional projection optical engine, but also achieves light coupling functionality through the introduction of the metasurface element 22, thus incorporating the coupling element function of traditional light guide devices and demonstrating unprecedented integration and functionality.

[0134] In this embodiment of the application, referring to Figures 7-18, the light guide device includes: a substrate 1, wherein the substrate 1 is provided with a coupling-in region and a coupling-out region;

[0135] The coupling region is provided with a micro-display component 21 and a metasurface element 22, which are attached together along the light transmission direction;

[0136] The microdisplay component 21 is used to emit image light, and the metasurface element 22 is used to modulate the image light and couple the modulated image light into the substrate 1.

[0137] The coupling region is provided with a coupling element 3, which is used to couple out the light propagating thereto.

[0138] In this embodiment, the light guide device includes a substrate 1, a microdisplay component 21 and a metasurface element 22 located in the coupling region of the substrate 1, and a coupling element 3 located in the coupling region of the substrate 1. This design integrates the performance characteristics of traditional projection optical engines and traditional optical waveguides, enabling the light guide device to not only generate and modulate image light, but also couple light into the waveguide and transmit and couple it out efficiently within the waveguide.

[0139] The components of a light guide device are analyzed in detail below.

[0140] In this embodiment, the light guide device includes a substrate 1, which has an insertion region and an exit region. In this embodiment, the substrate 1 serves as a carrier component of the light guide device.

[0141] For example, the material of the substrate 1 can be plastic, glass, lithium niobate, silicon carbide, or other high-transparency, low-light-absorption materials.

[0142] For example, the cross-sectional shape of the substrate 1 can be square, rectangle, ellipse, circle, or triangle. For practical purposes, the corners are usually rounded without affecting the overall optical path. The longitudinal section of the substrate 1 can be rectangular or arched. Among them, the cuboid structure is the most commonly used shape for the substrate 1.

[0143] In the design of traditional light guide devices, the function of the coupling region is simply to guide external light into the interior of the light guide device.

[0144] However, in the embodiments of this application, we have made an innovative design to the coupling region: integrating both the microdisplay component 21 and the metasurface element 22 into the coupling region. This region, through the design of the metasurface element 22, not only continues the original light coupling function of traditional light guide devices, but also, compared to traditional light guide devices, exhibits a higher degree of integration between the microdisplay component 21, the metasurface element 22, and the substrate 1, resulting in higher light coupling efficiency for the metasurface element 22.

[0145] Furthermore, the light guide device provided in this application embodiment also has other functions. First, the addition of the micro-display component 21 enables the coupling region to autonomously generate image light rays. Second, the integration of the metasurface element 22 also endows the coupling region with the ability to modulate image light rays, thereby further improving the performance of the light guide device in terms of image quality and optical performance.

[0146] Therefore, in this embodiment, the coupling region of the light guide device integrates multiple functions of light generation, coupling, and modulation. Furthermore, since both the microdisplay component 21 and the metasurface element 22 are integrated in the coupling region, the overall integration of the light guide device is higher, and the image light emitted from the microdisplay component 21 has better transmission efficiency.

[0147] In the design of traditional light guide devices, the function of the coupling region relies on the coupling-in grating and coupling-out grating structures. The function of the coupling region is to guide light, ensuring that the light rays propagating to the coupling region can be coupled out of the substrate as expected, thereby achieving efficient transmission and utilization of light.

[0148] However, in this embodiment, we have implemented a groundbreaking structural design for the coupling region of the light guide device. Based on this structural design, the function of the light guide device in the coupling region depends on the structural design of the metasurface element 22 and the coupling element 3 to achieve efficient light coupling. For example, the coupling region of the light guide device is provided with a coupling element 3, which can be a grating or a metasurface material.

[0149] In this embodiment, a microdisplay component 21 and a metasurface element 22 are disposed in the coupling region of the light guide device. The main function of the microdisplay component 21 in the light guide device is to emit image light. The image light emitted by the microdisplay component 21 can be collimated light (parallel light) or decollimated light.

[0150] When the image light emitted by the microdisplay component 21 is collimated, the complexity of light control and phase modulation of the metasurface element 22 is simplified, and the design difficulty of the metasurface element 22 is reduced.

[0151] When the image light of the microdisplay component 21 is non-collimated, it will increase the difficulty of designing the metasurface element 22, but it will not affect the overall architecture of the light guide device in this embodiment.

[0152] Preferably, the microdisplay component 21 outputs highly collimated image light. For highly collimated image light, the light emitted from each pixel 210 in the microdisplay component 21 is emitted perpendicularly. The function of the metasurface element 22 is to refract the incident light from each pixel 210 to the corresponding angle of the light guide device, achieving a one-to-one correspondence. In other words, for traditional light guide devices, in order to couple external light into the substrate, the diffraction formula is satisfied, and the phase information is automatically coupled through angle information. In this embodiment, the microdisplay component 21 and the metasurface element 22 are arranged in the coupling area of ​​the light guide device. The metasurface element 22 needs to modulate and refract the image light emitted from each pixel 210 in the microdisplay component 21 into the light guide device. It can also be understood that the metasurface element 22 performs point-to-point coupling of the image light emitted from the microdisplay component 21, realizing the light direction modulation at the pixel level, so that the coupling area of ​​the light guide device achieves the function of a traditional optomechanical system and a traditional coupling grating.

[0153] In this embodiment, the microdisplay component 21 and the metasurface element 22 are attached together along the light transmission direction. This attachment ensures that the image light emitted from the microdisplay component 21 can be directly and efficiently transmitted to the metasurface element 22, reducing light loss and scattering and improving light transmission efficiency.

[0154] Furthermore, the metasurface element 22 can modulate the light incident upon it. For example, the metasurface element 22 can modulate the phase, polarization, amplitude, and other characteristics of the image light. The bonding arrangement between the microdisplay component 21 and the metasurface element 22 further ensures the accuracy of the modulation process and also guarantees that the light will not be subjected to additional interference during transmission.

[0155] Furthermore, the micro-display component 21 and the metasurface element 22 are attached along the light transmission direction, making the entire light guide device structure more compact. This helps to reduce the size and weight of the whole device and improve the portability and ease of use of the light guide device.

[0156] In this embodiment, the metasurface element 22 is composed of a metasurface structure. A metasurface structure is a structure including micro / nano structures 222. These micro / nano structures 222 are artificial layered material structures with dimensions at the subwavelength scale. These micro / nano structures 222 enable flexible control over the polarization, amplitude, phase, and propagation characteristics of light.

[0157] In this embodiment, the metasurface element 22 is composed of a metasurface structure. A metasurface structure is a structure including micro / nano structures 222. These micro / nano structures 222 are artificial layered material structures with dimensions at the subwavelength scale. These micro / nano structures 222 can achieve modulation of the polarization, amplitude, phase, and propagation characteristics of image light.

[0158] The metasurface element 22 modulates light through its micro / nano structures 222. When light is incident on the metasurface element 22, it interacts with these micro / nano structures 222, thereby changing the polarization, amplitude, phase, and propagation (direction and angle) properties of the light.

[0159] Referring to Figures 3a and 3b, an example structure of a metasurface element 22 is shown. The metasurface element 22 may include a substrate 221 and micro / nanostructures 222 located on the substrate 221. The micro / nanostructures 222 located on the substrate 221 may have the same or different shapes.

[0160] For example, referring to FIG5, another structure of the metasurface element 22 is shown. As shown in FIG3b and FIG5, the arrangement of the micro-nano structures 222 on the substrate 221 is not unique. Those skilled in the art can design the arrangement of the micro-nano structures 222 on the substrate 221 and the shape of each micro-nano structure according to the type of image light emitted from the micro-display component 21 and the type of optomechanical application to the light guide device.

[0161] In this embodiment, utilizing the structural features of the metasurface element 22, the microdisplay component 21 and the metasurface element 22 are bonded and disposed in the coupling region of the light guide device. The metasurface element 22 has the function of modulating image light and coupling the modulated image light into the substrate.

[0162] Specifically, in the embodiments of this application, the metasurface element 22 primarily functions to modulate image light. When image light emitted from the microdisplay component 21 shines onto the metasurface element 22, this light is modulated by the micro / nano structure 222 of the metasurface element 22.

[0163] Based on the micro / nano structure characteristics of the metasurface element 22, light undergoes changes in phase, amplitude, or polarization as it passes through, thereby achieving light modulation.

[0164] This part of the metasurface element 22 functions similarly to optical elements such as lenses in conventional optical engines. However, compared to conventional lenses, the metasurface element 22 has advantages such as being lighter, thinner, and easier to integrate.

[0165] For example, the material of metasurface element 22 is a metasurface material. Metasurface materials can encode the wavefront of light in a specific way to achieve the function of focusing or changing the direction of light. If you want to achieve the function of a lens, such as a focusing lens, you only need to map the phase information of the geometric lens to the phase information of the in-plane nanomaterial (the height and width of nanopillars, etc.). The encoded metasurface material can replicate the function of a traditional geometric lens, and the thickness is only a thin layer of nanomaterial.

[0166] Furthermore, the metasurface element 22 can also achieve more complex optical functions, such as multifocal focusing, zoom, and polarization control, which are difficult to achieve with traditional lenses. In other words, in this embodiment, the light modulation effect of the metasurface element 22 is superior to the light modulation effect of optical elements such as lenses in traditional projection optical engines.

[0167] Furthermore, the metasurface element 22 also has the function of coupling the modulated image light into the light guide device. The light modulated by the metasurface element 22 has its propagation direction and characteristics adjusted according to predetermined requirements, which makes it easier and more efficient for these lights to couple into the light guide device. Light guide devices are typically used to guide light along a specific path to achieve specific imaging or illumination effects.

[0168] This part of the metasurface functions similarly to the coupling element (e.g., a coupling grating) in a traditional light guide device. A coupling grating is a component used to couple light into a light guide device; it typically has specific structures and parameters to achieve directional coupling of light. In this embodiment, the metasurface element 22 directly couples the modulated light into the light guide device.

[0169] Compared to traditional coupling gratings, metasurface elements 22 offer greater flexibility and customizability. By adjusting the microstructure and parameters of metasurface elements 22, image light emitted from them can be directly coupled into a light guide device without the need for a coupling grating, thus meeting a wider range of optical requirements. Furthermore, metasurface elements 22 also offer advantages such as being lighter, thinner, and easier to integrate.

[0170] In this embodiment, the light guide device includes a substrate 1, a microdisplay component 21 and a metasurface element 22 located in the coupling region of the substrate 1, and a coupling element 3 located in the coupling region of the substrate 1, realizing light output, effective modulation, coupling, and transmission. This design not only improves the efficiency of light utilization, but also significantly reduces the size of the combined traditional projection optical engine and traditional light guide device compared to the traditional scheme of combining a traditional projection optical engine and a traditional light guide device to achieve image light transmission. In addition, since the microdisplay component 21 and the metasurface element 22 are both integrated in the coupling region, the overall integration of the light guide device is higher, and the image light transmission efficiency emitted by the microdisplay component 21 is better.

[0171] In this embodiment, the microdisplay component 21 and the metasurface element 22 are bonded together.

[0172] In this embodiment, the microdisplay component 21 and the metasurface element 22 are connected together by an adhesive bonding method. Firstly, the adhesive bonding provides stable mechanical support. As core components of the coupling region of the light guide device, the microdisplay component 21 and the metasurface element 22 need to maintain precise relative positions to ensure accurate light transmission and modulation. The adhesive bonding ensures a strong bond between these two components, preventing displacement or loosening under external factors such as vibration or impact, thereby guaranteeing the stability and reliability of the light guide device.

[0173] Secondly, adhesive bonding can also achieve good optical contact. In the structure of light guide devices, the quality of the contact surface between the micro-display component 21 and the metasurface element 22 has a significant impact on the light transmission effect. Through adhesive bonding, it can be ensured that the contact surface between the micro-display component 21 and the metasurface element 22 is flat and smooth, reducing light scattering and loss on the contact surface, thereby improving the transmission efficiency and imaging quality of the optical system.

[0174] Furthermore, adhesive bonding offers advantages such as simple processing and low cost. Compared to traditional mechanical bonding methods, adhesive bonding eliminates the need for complex machining and assembly processes, significantly reducing production costs and time. Simultaneously, adhesive bonding can accommodate optical components of different shapes and sizes, providing greater flexibility and choice for the design and manufacturing of optical systems.

[0175] In a further embodiment, the adhesive layer between the microdisplay component 21 and the metasurface element 22 is annular.

[0176] In this embodiment, the adhesive layer between the microdisplay component 21 and the metasurface element 22 is annular. The annular adhesive layer can be located in the non-display area of ​​the microdisplay component 21 and in the non-working area of ​​the metasurface element 22, ensuring the normal transmission of image light emitted from the microdisplay component 21 and ensuring the modulation and coupling effect of the image light by the metasurface element 22.

[0177] Specifically, the annular adhesive layer is located in the non-display area of ​​the microdisplay component 21, meaning it does not block image light emitted from the microdisplay component 21. Thus, image light can be freely modulated and coupled through the metasurface element 22 without being obstructed by the adhesive layer.

[0178] Similarly, the annular adhesive layer is also located in the non-working area of ​​the metasurface element 22 (e.g., the edge region of the substrate 221 where no micro / nano structures 222 are disposed). This ensures that the working area of ​​the metasurface element 22 (i.e., the portion used to modulate and couple image light) is not adversely affected by the adhesive layer, such as stress, contamination, or damage.

[0179] It should be noted that although the adhesive layer is annular, it still provides a stable mechanical connection between the microdisplay component 21 and the metasurface element 22. This connection ensures that the relative positions of the two components in the light guide device remain fixed, thereby guaranteeing the stability and reliability of the light guide device.

[0180] For example, the type of adhesive between the microdisplay component 21 and the metasurface element 22 can be UV adhesive, epoxy AB adhesive, or optical resin adhesive, etc.

[0181] In a further embodiment, the bonding air gap between the microdisplay component 21 and the metasurface element 22 is less than 1 μm.

[0182] In this embodiment, the microdisplay component 21 and the metasurface element 22 do not need to be in direct contact. When the microdisplay component 21 emits image light, there can be a smaller gap between them. The smaller the gap between them, the less light leakage will occur.

[0183] In this embodiment, when the bonding air gap between the microdisplay component 21 and the metasurface element 22 is less than 1 μm, the pixel size 210 of the microdisplay component 21 (plus the lateral size expansion during light transmission) can be smaller than the size of the corresponding pixel region on the metasurface element 22 (the micro / nano structure 222 corresponding to a certain pixel 210). The metasurface element 22 can then modulate and couple the light emitted from its corresponding pixel 210. This modulation and coupling enables precise control of the light, including direction, intensity, and phase, thereby meeting various application requirements.

[0184] In one embodiment of this application, the metasurface element 22 is bonded to the substrate 1 on the side opposite to the microdisplay component 21.

[0185] In this embodiment, the microdisplay component 21 and the metasurface element 22 are bonded together to form an integral structure. The microdisplay component 21 and the metasurface element 22 constitute a novel optomechanical structure 2. The novel optomechanical structure 2 can be used alone or it can be used in combination with the substrate 1, as shown in FIG1, which shows the structure of the novel optomechanical structure 2 formed by the microdisplay component 21 and the metasurface element 22.

[0186] When the microdisplay component 21 and the metasurface element 22 are used together with the substrate 1 as a novel optomechanical structure, the side of the metasurface element 22 facing away from the microdisplay component 21 needs to be bonded to the substrate 1.

[0187] Specifically, the metasurface element 22 is configured such that its side facing away from the microdisplay component 21 is tightly bonded to the substrate 1 of the light guide device by an adhesive method. This design ensures a stable bond between the metasurface element 22 and the substrate 1, while also providing a basis for precise control and efficient transmission of light. With this structure, the metasurface element 22 can fully utilize its function of modulating light and coupling it into the interior of the substrate 1.

[0188] For example, the metasurface element 22 is directly bonded to the coupling region of the substrate 1 on the side opposite to the microdisplay component 21.

[0189] For example, the coupling region of the substrate 1 is formed with a recessed region, the shape of which matches the structure of the metasurface element 22. At least a portion of the metasurface element 22 is embedded in the recessed region, and the side of the metasurface element 22 facing away from the microdisplay component 21 is bonded to the bottom of the recessed region.

[0190] In a further embodiment, the refractive index of the adhesive layer between the metasurface element 22 and the substrate 1 matches the refractive index of the substrate 1 material.

[0191] In this embodiment, in order to ensure that the transmission efficiency and effect of light between the metasurface element 22 and the substrate 1 are optimal, an adhesive layer material that matches the refractive index of the substrate 1 material is selected.

[0192] This refractive index matching design aims to reduce light reflection and scattering at the interface between the metasurface element 22 and the substrate 1, thereby maximizing the preservation of light energy and directionality. When light travels from the metasurface element 22 to the substrate 1, if the refractive index of the adhesive layer matches the material of the substrate 1, the light will be able to transition more smoothly, avoiding unnecessary loss and interference.

[0193] For example, the substrate 1 of the light guide device typically includes optically transparent materials such as plastic and glass. These materials have different refractive indices, generally between 1.3 and 1.7. In this case, the adhesive material can be NOA150 UV adhesive, which has a refractive index of 1.505.

[0194] For example, the substrate 1 of the light guide device can also be a silicon carbide substrate 1. The refractive index of the silicon carbide substrate 1 is typically between 2.55 and 2.68. In this case, the adhesive material can be a high-refractive-index resin. For example, certain epoxy resins, polyurethane resins, or polyimide resins, etc., whose refractive index can be adjusted to approach or meet the requirement of 2.55 to 2.68 through specific formulations and curing methods.

[0195] In another embodiment of this application, the metasurface element 22 is formed in the coupling region of the substrate 1.

[0196] In this embodiment, a metasurface element 22 is formed in the coupling region of the substrate 1, meaning that the substrate 1 and the metasurface element 22 are an integral structure. When the substrate 1 and the metasurface element 22 are an integral structure, a microdisplay component 21 is disposed on the side of the metasurface element 22 facing away from the substrate 1. The microdisplay component 21 and the metasurface element 22 are bonded together.

[0197] The metasurface element 22 can be formed in the coupling region of the substrate 1 by deposition or etching.

[0198] Specifically, the material of metasurface element 22 is a metasurface material, TiO2, which has high light transmittance and high refractive index. TiO2 can be used to fabricate micro / nano structures 222 (nanopillars, nanostrips, or nanoblocks, etc.). However, TiO2 is not the only material for metasurface element 22. TiO2 can be fabricated through deposition. For example, a pattern can be formed using photolithography or EBL technology, followed by TiO2 deposition, and finally, a lift-off process can be used to transfer the pattern and achieve nanofabrication.

[0199] Of course, if a high refractive index waveguide is used, it can also be directly etched. For example, a metasurface design can be formed first using photolithography, and then etched to form the final three-dimensional structure.

[0200] In a preferred embodiment of this application, the light emitted by the microdisplay component 21 is collimated light. The method by which the microdisplay component 21 emits collimated light includes: defining the light source 211 of the microdisplay component 21 as a collimated light source 211.

[0201] When the light source 211 of the micro display component 21 is a collimated light source 211, for example, the light source 211 is a laser light source 211 or the light source 211 is another collimated light source 211, such as an LED light source 211.

[0202] When the light source 211 is another light source 211 that has been collimated, the light source 211 of the micro-display component 21 includes a light source body and a collimation assembly. The collimation assembly is located on the light emission path of the light source body.

[0203] In this example, the light source 211 is typically a high-brightness LED or other type of light-emitting element. These light sources 211 are capable of emitting light of sufficient intensity for subsequent processing and projection by the microdisplay chip 212.

[0204] The collimation component is a key part of the micro-display component 21 for achieving light collimation. It is located on the light emission path of the light source body to expand and collimate the light transmitted to it, making the light rays parallel and aligned in the same direction.

[0205] Alternatively, this can be understood as follows: In this approach, the microdisplay component 21 needs to achieve light collimation through an additional optical system (collimation assembly). Light collimation is achieved at the pixel level and may include optical elements such as microlens arrays or microcavity mirrors, which can collect, focus, and guide the light emitted by the light source 211 to form collimated image light.

[0206] When the light source 211 of the microdisplay component 21 is a laser light source, referring to Figure 6, the microdisplay component 21 includes only the light source 211 and the microdisplay chip 212. The collimated light source 211 can directly emit collimated light rays. The microdisplay chip 212 is typically a display element with high resolution and high-speed response capabilities, such as an LCD screen (transmissive screen). These display elements can modulate and image the light emitted by the collimated light source 211 to form a clear projected image.

[0207] Alternatively, this can be understood as follows: in this method, the micro-display component 21 directly uses a laser light source with collimation characteristics to directly achieve light collimation.

[0208] For example, the light source 211 is a VCSEL laser, namely a vertical-cavity surface-emitting laser. In this embodiment, a VCSEL array is used as a micro-display array, resulting in high overall brightness and efficiency for the micro-display component 21. For instance, the VCSEL array provides light emission over a large area, enabling regional backlight modulation, reducing power consumption and improving overall efficiency. The array provides the backlight effect, while the light modulation employs a transmissive LCD screen or a reflective LCOS screen (requiring a specially designed waveguide, see the optical system disclosed in 202411254381.6) to achieve greater pixel density and control the light flux to achieve modulation.

[0209] In the overall architecture of a traditional optical-mechanical system, the micro-display component 21 usually needs to work in conjunction with a series of other optical components (such as lenses, mirrors, etc.) and mechanical structures (such as supports, adjustment mechanisms, etc.) to achieve the desired imaging or projection effect.

[0210] However, in this embodiment, we employ an innovative design approach: the microdisplay component 21 directly emits collimated image rays, which do not need to pass through intermediate traditional optical elements but are directly transmitted to the metasurface element 22. The metasurface element 22 is responsible for modulating the image rays emitted by the microdisplay component 21, thereby efficiently coupling these modulated image rays into the interior of a light guide device (e.g., an optical waveguide).

[0211] In this embodiment of the application, referring to FIG6, the micro display component 21 further includes a micro display chip 212, which is disposed on the light emission path of the light source 211.

[0212] In this embodiment, the microdisplay chip 212 is located in the light-emitting path of the light source 211, and its main function is to output image light carrying image information. The microdisplay chip 212 can employ different technologies, such as LCD (Liquid Crystal Display), LCOS (Liquid Crystal on Silicon), or Micro LED. These technologies utilize different physical principles to control the passage or reflection of light, thereby forming an image on the microdisplay chip 212.

[0213] It is important to note that when using Micro LED, the light source 211 itself has image modulation capabilities, thus eliminating the need for an integrated microdisplay chip 212. When the light source 211 uses Micro LED, the light source itself is the microdisplay chip, requiring no external modulation; that is, the Micro LED itself is the microdisplay component 21. However, the light scattering angle of Micro LED is too large, necessitating the design shown in Figure 4, i.e., collimating the light emitted by the Micro LED.

[0214] For example, considering the size requirements of the microdisplay component, the type of microdisplay component 21 is preferably Micro LED. According to the specifications of Micro LED, the effective display sizes of Micro LED are 0.12 inches, 0.61 inches and 0.69 inches, and Micro LEDs of different sizes all have high resolution, which meets the requirements of optomechanical imaging.

[0215] In the embodiments of this application, the metasurface element 22 has similar structural features to the metasurface element 22 in the above-described optomechanical structure.

[0216] Referring to Figures 2, 3a, and 3b, and to Figures 4 and 5, the metasurface element 22 is composed of subwavelength micro / nano structures 222. The micro / nano structures 222 in the metasurface element 22 correspond one-to-one with the pixels 210 in the microdisplay component 21. The micro / nano structures 222 modulate and refract the light emitted from their corresponding pixels 210 into the light guide device.

[0217] In this embodiment, the subwavelength micro / nano structures 222 can modulate light with high precision. These micro / nano structures 222 can manipulate the phase, amplitude, polarization, and propagation characteristics of light, thereby achieving customized control of light. This allows the metasurface element 22 to modulate the image light emitted from the microdisplay component 21 on the one hand, and to couple the modulated light into the substrate 1 on the other hand.

[0218] Specifically, by designing and optimizing micro- and nano-structures, metasurface elements 22 can achieve focusing, deflection, and phase modulation of light, which have advantages in imaging, display, and light coupling.

[0219] Furthermore, the extremely small size of the micro / nano structure 222 enables the metasurface element 22 to achieve a high degree of integration. Compared with traditional optical elements, the metasurface element 22 is smaller and lighter, making it easier to integrate with the microdisplay component 21, thereby creating a compact new light guide device.

[0220] For example, subwavelength-sized micro / nano structures include any one of nanoblocks, nanopillars, and nanostrips.

[0221] For example, the subwavelength-sized micro / nano structure 222 includes any one or a combination of several of nanoblocks, nanopillars, nanostrips, and irregular structures (e.g., L-shaped or V-shaped).

[0222] In this example, the subwavelength micro / nanostructures 222 encompass regular and irregular structures such as nanoblocks, nanopillars, and nanostrips, and can be flexibly selected and designed according to the functions required by the metasurface element 22. When constructing the same metasurface element 22, a single type of micro / nanostructure 222 can be used, or at least two different types of micro / nanostructures 222 can be integrated to achieve the required functions of the metasurface element 22. For example, if the micro / nanostructure 222 is a V-shaped design, modulation can be achieved by changing the angle of the V-shape to alter the limiting of the light passing through it.

[0223] In this embodiment, referring to Figures 2 and 4, the micro / nano structure of the metasurface element 22 (the smallest unit of the metasurface element 22) is adapted to the size of the pixels 210 in the microdisplay component 21. Due to this size effect, the micro / nano structure 222 can interact strongly with light waves, thereby achieving the modulation of light wave characteristics. The micro / nano structure of the metasurface element 22 encodes (i.e., modulates the characteristics of the light) the image light emitted from its corresponding pixel 210, realizing the modulation and coupling of the image light. This method can avoid transmission errors caused by light during transmission and improve the light transmission efficiency.

[0224] Specifically, the metasurface element 22 is an element composed of micro- and nanostructures 222, which can precisely control the characteristics of light waves, such as phase, amplitude, polarization, and propagation.

[0225] Micro- and nanostructures 222 are the basic building blocks of metasurface elements 22. Their shape, size, and arrangement determine the metasurface's ability to control light waves.

[0226] Pixel 210 is the basic building block of microdisplay component 21, and each pixel 210 can emit light of a specific color and brightness.

[0227] Here, "encoding" refers to the specific manipulation of image light using the micro / nano structures 222 of the metasurface element 22, enabling the light to carry specific information or characteristics. This encoding is achieved through the shape, size, and arrangement of the micro / nano structures 222, which can influence the phase, amplitude, and polarization characteristics of the light.

[0228] "Modulation" refers to the precise control of the characteristics of light in an image, such as changing the phase, amplitude, polarization state, or propagation direction and angle of the light to achieve specific optical effects.

[0229] "Coupling" refers to the efficient connection of modulated light with light guide devices to ensure that the light can propagate and form an image in the expected manner.

[0230] In this embodiment, the micro / nano structure 222 of the metasurface element 22 achieves precise modulation of the image light emitted from its corresponding pixel 210 by specifically encoding (i.e., controlling the characteristics of the light). This modulated light is then efficiently coupled into a light guide device to achieve specific display effects or optical functions.

[0231] For example, the metasurface element 22 also includes a substrate 221 on which micro / nano structures 222 are formed.

[0232] In one embodiment, referring to Figures 2, 3a and 3b, the metasurface element 22 includes a dielectric layer formed by a plurality of micro-nano structures of the subwavelength dimensions along the light transmission direction. The dielectric layer is configured to modulate the image light and couple the modulated image light into the substrate 1.

[0233] In this embodiment, referring to Figures 3a and 3b, the metasurface element 22 includes a dielectric layer composed of a plurality of subwavelength micro / nano structures arranged in an orderly manner along the light transmission path. This dielectric layer is specially designed to precisely modulate the image light, thereby effectively coupling the modulated image light into the substrate 1 to achieve light transmission and control.

[0234] In other words, in this embodiment, the metasurface element 22 includes only one dielectric layer. This same dielectric layer has two functions: on the one hand, it can modulate the image light emitted from the microdisplay component 21, and on the other hand, it can couple the modulated light into the substrate 1.

[0235] Referring to Figure 2, a schematic diagram of the optical path corresponding to a certain pixel in the optomechanical system is shown. The light emitted from a certain pixel 210 in the micro-display component 21 is transmitted to the corresponding micro / nano structure 222, and the transmission characteristics of the light change.

[0236] In this embodiment, the metasurface element 22 includes a dielectric layer, which is a planar or curved structure composed of subwavelength micro / nanostructures 222 (such as nanoblocks, nanopillars, nanostrips, etc.) arranged in an orderly manner. These micro / nanostructures 222 are much smaller than the wavelength of light, so they can interact strongly with light waves, thereby changing the propagation characteristics of light.

[0237] When light rays pass through this dielectric layer, they interact with the micro / nano structures 222 within it. This interaction causes changes in the phase, amplitude, polarization state, and propagation characteristics of the light rays, i.e., the light rays are modulated.

[0238] The modulated image light is then effectively coupled into the light guide device. The coupling process refers to guiding the modulated light into the substrate 1 of the light guide device and ensuring that the light propagates in the desired manner within the substrate 1. Once the light is coupled into the substrate 1, it can propagate along the expected path.

[0239] By precisely designing the dielectric layer of the metasurface element 22, precise control can be achieved over parameters such as the light transmission path, direction, and intensity. This allows the dielectric layer to modulate the image light emitted from the microdisplay component 21 on the one hand, and to couple the modulated light into the substrate 1 on the other.

[0240] It should be noted that Figures 3a and 3b only illustrate one structure of the metasurface element 22. Based on the light emission characteristics of the micro-display component 21 and the total internal reflection condition of the image light in the substrate 1, those skilled in the art can adjust the arrangement (e.g., density) and shape of the micro-nano structures 222 in the metasurface element 22.

[0241] In another embodiment, referring to Figures 4 and 5, the metasurface element 22 includes a first part and a second part along the light transmission direction, and both the first part and the second part include a dielectric layer formed by arranging a plurality of subwavelength-sized micro / nano structures 222.

[0242] The first part is configured to modulate the image light, and the second part is configured to couple the modulated image light into the substrate 1.

[0243] In this embodiment, the metasurface element 22 is divided into two main parts in the light transmission direction: a first part 22a and a second part 22b. Referring to FIG4, a schematic diagram of the optical path of a pixel in the optomechanism is shown. The light emitted from a pixel 210 in the microdisplay component 21 passes sequentially through a micro / nano structure 222 in the first part 22a of the metasurface element 22 and a micro / nano structure 222 in the second part 22a of the metasurface element 22.

[0244] Both the first part 22a and the second part 22b contain a dielectric layer formed by the orderly arrangement of multiple subwavelength micro / nano structures 222. This structural design enables the metasurface element 22 to modulate image light (collimating image relationship) and couple the modulated image light into the light guide device through the first and second part structures.

[0245] Specifically, referring to Figure 4, the main function of the micro / nano structure 222 in the first part 22a is to modulate (collimate) the image light. Since the first part 22a contains subwavelength micro / nano structures 222, these structures can interact strongly with the light, thereby achieving precise optical modulation.

[0246] Referring to Figure 4, the micro / nano structure 222 of the second part 22b further modulates (the phase, propagation, and other characteristics of the light) the image light modulated by the first part 22a and effectively couples it into the light guide device. The coupling process involves refracting the light emitted from each pixel 210 of the microdisplay component 21 to the light guide device (refractive effect) to ensure that the light can enter the light guide device efficiently and be transmitted therein.

[0247] This design, which divides the metasurface element 22 into two independent but cooperative parts, allows the entire element to adapt more flexibly to different optical requirements and provides higher optical performance and control precision.

[0248] It should be noted that Figure 5 only schematically illustrates the structure of a portion of the metasurface element 22. Those skilled in the art can adjust the structure of the first part 22a based on the light emission characteristics of the microdisplay component 21, for example, adjusting the arrangement and structure of the micro-nano structures within the first part 22a. Similarly, those skilled in the art can adjust the structure of the second part 22b based on the total internal reflection condition of the image light propagating within the substrate 1, for example, adjusting the arrangement and structure of the micro-nano structures within the second part 22b.

[0249] In this embodiment of the application, referring to Figures 15-18, the coupling region is located on the surface 11 of the side end of the substrate 1, the coupling region is located on the surface adjacent to the surface 11 of the side end, and the microdisplay component 21 and the metasurface element 22 are attached to each other in a direction perpendicular to the direction of the surface 11 of the side end.

[0250] In this embodiment, the coupling region is designed on the surface 11 of the side end of the substrate 1. This means that light does not enter the substrate 1 from the top or bottom, but from the surface 11 of the side end.

[0251] The coupling region is located adjacent to the coupling region and lies on another surface that is in contact with the side surface 11. This surface can be the top, bottom, or other side of the substrate 1, depending on the overall design and application requirements. The coupling region is responsible for effectively guiding the light transmitted and modulated inside the substrate 1 out of the substrate 1 for subsequent use or observation.

[0252] For example, the light guide device may include a coupling region, which may be located on the top, bottom or other side of the substrate 1.

[0253] For example, the light guide device may include two coupling regions, which may be located on two surfaces adjacent to and opposite to the substrate 1.

[0254] Referring to Figures 15 and 16, the coupling region is located on the surface 11 at the side end of the substrate 1, the micro-display component 21 and the metasurface element 22 are attached along the length direction of the substrate 1 (X direction in the figure), and the coupling region is located on the surface at the top of the substrate 1.

[0255] Referring to Figures 17 and 18, the coupling region is located on the side surface 11 of the substrate 1. In this embodiment, the side surface 11 is a slope, and the microdisplay component 21 and the metasurface element 22 are disposed on the slope. In this embodiment, the light guide device includes two coupling regions disposed opposite to each other, one coupling region being located on the top surface of the substrate 1 and the other coupling region being located on the bottom surface of the substrate 1.

[0256] In this embodiment, the two key components, the microdisplay component 21 and the metasurface element 22, are bonded together in a direction perpendicular to the direction of the side surface 11. This means that the bonding direction of the two components forms a right angle with the side surface 11, and they work together to influence light. The microdisplay component 21 is responsible for generating image light, while the metasurface element 22 modulates and couples this light to meet specific optical requirements. This perpendicular bonding arrangement helps ensure efficient light transmission and modulation while reducing unnecessary losses and interference.

[0257] Furthermore, in this embodiment, for the substrate 1, the image light entering the substrate 1 from the side must satisfy the condition of no light leakage. The condition of TIR (Total Internal Reflection) is the requirement for the light guide device to not leak light, which mainly depends on the refractive index of the substrate 1. By designing and optimizing the metasurface element 22, when the angle of the light within the substrate 1 is greater than the total internal reflection angle of the substrate 1, no light leakage will occur.

[0258] Furthermore, in this embodiment, the coupling element 3 and the metasurface element 22 are designed as a pair, and need to be able to couple normally at the required FOV angle in the coupling region, which depends on the specific design requirements. The metasurface element 22 is located in the coupling region, which typically receives light incident at 0 degrees or light incident from a lattice pattern with a small dispersion angle, that is, the coupling region typically receives light incident at a small angle.

[0259] To further optimize light output, the coupling element 3 can be designed as a butterfly grating. This design not only expands the image light rays in a two-dimensional angle, but also ensures that the light rays can be accurately coupled to the predetermined angle, thereby greatly improving the overall optical performance and user experience.

[0260] In one embodiment, referring to Figures 15 and 16, the surface 11 of the side end is arranged in a vertical direction, as shown in the Z direction, and the micro-display component 21 and the metasurface element 22 are attached in a horizontal direction, as shown in the X direction.

[0261] In this embodiment, the surface 11 of the side end of the light guide device is arranged along the vertical direction (i.e., the Z direction in the figure). This vertical arrangement provides a more direct and efficient path for the introduction and transmission of light, while also helping to reduce light loss and interference during transmission.

[0262] The microdisplay component 21 and the metasurface element 22 are bonded together in a horizontal direction (i.e., the X direction in the figure). This horizontal bonding not only ensures a tight connection between the two but also facilitates efficient light transmission and precise modulation. The microdisplay component 21 is responsible for generating image light, while the metasurface element 22 uses its arranged micro / nano structures 222 to modulate this light to meet specific optical requirements.

[0263] Furthermore, in this embodiment, at least a portion of the projection of the microdisplay component 21 in the Z direction overlaps with the projection of the metasurface element 22 in the Z direction, to ensure that the image light emitted from the microdisplay component 21 can be modulated and coupled by the metasurface element 22.

[0264] In another embodiment, referring to Figures 17 and 18, the surface 11 of the side end is a slope, and the microdisplay component 21 and the metasurface element 22 are attached to each other in the normal direction of the slope.

[0265] In this embodiment, the side surface 11 of the light guide device is designed as a bevel. This design makes the light guide device more flexible and adaptable, helping to optimize the light introduction angle and transmission path, thereby further improving the light utilization efficiency.

[0266] In this embodiment, the microdisplay component 21 and the metasurface element 22 are fitted together in the normal direction of the inclined plane. This means that the connection direction of the two is consistent with the normal of the inclined plane. This arrangement helps to ensure that the light maintains the optimal direction and angle during transmission, thereby achieving more efficient and precise light modulation and transmission.

[0267] Furthermore, in this embodiment, at least a portion of the projection of the microdisplay component 21 onto the surface 11 at the side end of the substrate 1 in the normal direction overlaps with the projection of the metasurface element 22 onto the surface 11 at the side end of the substrate 1 in the normal direction, so as to ensure that the image light emitted from the microdisplay component 21 can be modulated and coupled by the metasurface element 22.

[0268] In this embodiment of the application, referring to Figures 7 and 8, Figures 9 and 10, and Figures 13 and 14, the coupling-in region and the coupling-out region are both located on the surface adjacent to the side surface 11 of the substrate 1, and the micro-display component 21 and the metasurface element 22 are attached along the thickness direction of the substrate 1.

[0269] In this embodiment, both the coupling-in region and the coupling-out region are disposed on a surface adjacent to the surface 11 of the side end of the substrate 1. For example, the coupling-in region and the coupling-out region may be disposed on the top, bottom, or other side of the substrate 1. The coupling-in region and the coupling-out region may be located on the same surface of the substrate 1, or they may be located on different surfaces of the substrate 1.

[0270] For example, referring to Figures 7 and 8, and Figures 9 and 10, the substrate 1 is provided with an insertion region and an exit region. Both the insertion region and the exit region are located on the top of the substrate 1. That is, the microdisplay component 21 and metasurface element 22 disposed in the insertion region, and the exit element 3 disposed in the exit region are all located on the top surface of the substrate 1.

[0271] For example, referring to Figures 13 and 14, the substrate 1 is provided with one coupling-in region and two coupling-out regions. The coupling-in region is located on the top surface of the substrate 1, and the two coupling-out regions are arranged opposite to each other, with one coupling-out region located on the top surface of the substrate 1 and the other coupling-out region located on the bottom surface of the substrate 1.

[0272] In this embodiment, the microdisplay component 21 and the metasurface element 22 are bonded together along the thickness direction of the substrate 1. This means that the connection between them is perpendicular to the surface of the substrate 1. This arrangement helps to ensure that light maintains the optimal path and angle during transmission, thereby achieving more efficient and precise light modulation and transmission.

[0273] By arranging the coupling-in and coupling-out regions adjacent to each other on the surface 11 at the side end of the substrate 1, and by bonding the microdisplay component 21 and the metasurface element 22 along the thickness direction, these embodiments achieve a compact and flexible structure for the light guide device. This design not only helps to reduce the overall size of the device but also has the potential to improve optical performance, meeting the needs of a variety of complex optical applications.

[0274] In this embodiment of the application, regardless of whether the coupling region is disposed on the surface 11 at the side end of the substrate 1 or on the surface adjacent to the surface 11 at the side end of the substrate 1, the coupling element 3 of the coupling region is either a reflective coupling element 3 or a transmissive coupling element 3.

[0275] In this embodiment, the coupling element 3 is specified as either a "reflective coupling element 3" or a "transmissive coupling element 3".

[0276] The reflective coupling element 3 guides the image light from inside the light guide device through diffraction and reflection. The structure and materials of the reflective coupling element 3 are designed to reflect light of the desired wavelength.

[0277] The transmissive coupling element 3 allows image light of a specific wavelength to pass directly through the wall or a specific area of ​​the light guide device and be extracted. The transmissive coupling element 3 typically involves the use of transparent or translucent materials, and its structure is designed to diffract and transmit light of the desired wavelength.

[0278] In this embodiment, the coupling element 3 is a grating structure or a metasurface structure.

[0279] In this embodiment, the coupling element 3 can be a grating structure, such as a coupling grating. A grating is a periodic structure, typically composed of a series of parallel lines or grooves. When image light passes through the grating, diffraction occurs, causing the image light to propagate according to a specific pattern and be guided from the inside of the light guide device to the outside.

[0280] In this embodiment, the coupling element 3 can be a metasurface structure, which is a two-dimensional artificial micro / nano structure that can manipulate the wavefront, phase, polarization, and intensity of light at the subwavelength scale. Compared with coupling gratings, metasurfaces have smaller size, higher integration, and greater design flexibility.

[0281] In one embodiment, the coupling element 3 is a two-dimensional grating.

[0282] In this embodiment, when the coupling element 3 is a grating structure, it is a two-dimensional grating. By adjusting the structural parameters of the two-dimensional grating (such as period and depth), the equivalent refractive index in the light guide device can be changed, thereby achieving modulation and control of the image light. Furthermore, the multi-directional diffraction characteristics of the two-dimensional grating enable it to process more dimensional information, achieving multi-angle imaging.

[0283] In one specific embodiment, the two-dimensional grating is a butterfly grating.

[0284] In this embodiment, defining the coupling element 3 as a butterfly grating simplifies the design requirements of the metasurface element 22 in the coupling region. Referring to Figures 7, 9, or 15, a coupling region is provided on the light guide device, and the butterfly grating is located in the coupling region.

[0285] Specifically, a butterfly grating is a two-dimensional grating with a special structure. By introducing periodic changes in refractive index, a grating structure is formed, thereby achieving feedback and selective amplification of specific wavelengths.

[0286] Because the butterfly grating has well-defined structural and performance parameters that have been optimized during the design and manufacturing process, the metasurface design in the coupling region can be based on the known parameters of the butterfly grating, thereby reducing the need for adjusting and optimizing the metasurface parameters.

[0287] Furthermore, the periodic structure of the butterfly grating enables it to efficiently couple image light of specific wavelengths. This characteristic allows for a greater focus on improving the coupling efficiency of the metasurface when designing the coupling end, without having to consider other complex factors.

[0288] In another specific embodiment, the coupling element 3 is a butterfly grating formed by combining two one-dimensional gratings.

[0289] In this embodiment, the coupling element 3 is a butterfly grating, specifically a butterfly grating formed by combining two one-dimensional gratings. Referring to Figures 13 and 17, the light guide device is provided with two coupling regions, which are arranged opposite to each other. One one-dimensional grating is disposed in one coupling region, and the other one-dimensional grating is disposed in the other coupling region.

[0290] In this embodiment, the butterfly grating combines the characteristics of two one-dimensional gratings. Through the interaction between the two one-dimensional gratings, the diffraction efficiency of the butterfly grating can be significantly improved. This means that more light can be effectively converted and utilized, reducing light energy loss.

[0291] Furthermore, the spectral characteristics of a butterfly grating can be optimized by adjusting the structural parameters of the two one-dimensional gratings, such as the grating period and duty cycle. This allows the butterfly grating to exhibit better performance within a specific spectral range, meeting the needs of specific applications.

[0292] In one embodiment, the two one-dimensional gratings include a first one-dimensional grating 31 and a second one-dimensional grating 32, wherein at least a portion of the projection of the first one-dimensional grating 31 in the thickness direction of the substrate 1 is located within the region where the second one-dimensional grating 32 is located. Referring to Figures 13 and 17, the light guide device is provided with two coupling regions, which are arranged opposite to each other. The first one-dimensional grating 31 may be located in the coupling region on the top surface of the light guide device, and the second one-dimensional grating 32 may be located in the coupling region on the bottom surface of the light guide device; or the first one-dimensional grating 31 may be located in the coupling region on the bottom surface of the light guide device, and the second one-dimensional grating 32 may be located in the coupling region on the top surface of the light guide device.

[0293] In this embodiment, since a portion of the projection of the first one-dimensional grating 31 overlaps with the second one-dimensional grating 32, the optical field overlap area between the two one-dimensional gratings is increased. This enhanced optical field overlap helps improve the overall coupling efficiency of the butterfly grating, allowing more light to be effectively transmitted between the two one-dimensional gratings.

[0294] The coupling efficiency of a butterfly grating can be further optimized by adjusting the overlap and structural parameters (such as grating period and duty cycle) of two one-dimensional gratings. This optimization enables the butterfly grating to exhibit higher coupling efficiency within a specific spectral range, meeting the needs of specific applications.

[0295] In one embodiment, the first one-dimensional grating 31 is either a reflective coupling element 3 or a transmissive coupling element 3, and the second one-dimensional grating 32 is either a reflective coupling element 3 or a transmissive coupling element 3.

[0296] In this embodiment, the first one-dimensional grating 31 is a reflective coupling element 3, and the second one-dimensional grating 32 is a transmissive coupling element 3; or the first one-dimensional grating 31 is a transmissive coupling element 3, and the second one-dimensional grating 32 is a reflective coupling element 3. Thus, the butterfly grating composed of two one-dimensional gratings is a combined reflective and transmissive grating structure.

[0297] In this embodiment, the butterfly grating is a combined reflection and transmission grating structure. The reflective coupling element 3 and the transmission coupling element 3 each possess unique optical characteristics. The reflective coupling element 3 reflects light and disperses the spectrum, exhibiting high resolution and high spectral separation; while the transmission coupling element 3 transmits light and disperses the spectrum, exhibiting a wide wavelength range and high efficiency. Combining these two elements fully leverages their complementary advantages, improving optical coupling efficiency and flexibility.

[0298] Furthermore, the combined reflection and transmission grating structure can couple optical signals in multiple directions. This characteristic gives butterfly gratings greater flexibility and scalability when constructing complex light guide devices, meeting the needs of different application scenarios.

[0299] In this embodiment of the application, referring to Figures 9 and 12, a transition element 4 is also provided on the surface adjacent to the side surface 11 of the substrate 1, and the projection of the metasurface element 22 in the thickness direction of the substrate 1 is located within the transition element 4.

[0300] Referring to Figures 7 and 11, the light guide device does not have the deflection element 4, and the light transmission path within the light guide device is shown in Figure 11. The metasurface element 22 couples the image light emitted from the microdisplay component 21 into the substrate 1 (coupled into the substrate 1 at a large angle), and the light entering the substrate 1 is coupled out of the substrate 1 by the coupling element 3 after total internal reflection.

[0301] Referring to Figures 9 and 12, the light guide device is provided with a deflection element 4, and the light transmission path within the light guide device is shown in Figure 12. The metasurface element 22 couples the image light emitted from the microdisplay component 21 into the substrate 1 (coupled into the substrate 1 at a small angle). The light entering the substrate 1 is received by the deflection element 4 and deflected again for total internal reflection at a large angle, and then coupled out of the substrate 1 by the coupling element 3.

[0302] In this embodiment, the metasurface element 22 located in the coupling region implements small-angle encoding (modulation of light), while the transition element 4 converts the small-angle encoding back into a large angle, allowing it to be transmitted within the light guide device without light leakage. Simply put, the function of the transition element 4 is to reduce the design complexity of the overall light guide device.

[0303] Typically, metasurface elements 22, which are formed by combining multiple micro-nano structures, should be able to meet the conditions of 0-degree incident light and large-angle (no light leakage) light emission. If the processing difficulty of the metasurface material is too high and it cannot meet the condition of deflecting light into a large angle, then the deflection element 4 can be used as an auxiliary.

[0304] Theoretically, transition element 4 is not necessary. However, based on design experience, the processing of metasurface materials is very difficult. This auxiliary transition element 4 (such as a transition grating) can be used to help simplify the design of metasurface element 22.

[0305] Referring to Figures 9 and 12, the deflection element 4 is located on the opposite side of the metasurface element 22. This is because if the light emitted from the metasurface element 22 does not meet the TIR (total internal reflection) condition, the deflection element 4 is used to assist in refraction to increase the angle. The positions of all deflection elements 4 must cover the possible light emission direction. They are usually located on the opposite side of the coupling region, slightly larger than the coupling region, to be able to receive small-angle beams emitted from the metasurface.

[0306] For example, the type of transition element 4 can be a transition grating or a metasurface structure with a transition effect.

[0307] This application also provides a near-eye display device. The near-eye display device includes the aforementioned light guide device. A near-eye display device is a wearable device, typically designed to present images or information directly in front of a user's eyes without requiring the user to hold it or move it away from their eyes. The near-eye display device can be virtual reality (VR), augmented reality (AR), or mixed reality (MR).

[0308] Near-eye display devices

[0309] Traditional near-eye display modules typically include a traditional optical waveguide assembly and a corresponding traditional optical engine. The traditional optical waveguide assembly has an input grating region and an output grating region. The traditional optical engine is located in the input grating region and is used to output optical signals to the input grating region. The traditional optical waveguide assembly is configured to transmit the optical signals input to the input grating region by the traditional optical engine to the input grating region, so as to form outgoing light in the output grating region.

[0310] This shows that traditional near-eye display devices have a large overall size, which reduces user comfort when wearing them.

[0311] Therefore, embodiments of this application provide a novel near-eye display device.

[0312] In this embodiment of the application, referring to Figures 19 and 20, the near-eye display device includes: a frame module 5, used to provide wearing support for the target object;

[0313] A light guide device is disposed in the lens frame module 5;

[0314] The light guide device includes:

[0315] A substrate 1, wherein the substrate 1 is provided with a coupling-in region 61 and a coupling-out region 62;

[0316] The coupling region 61 is provided with a micro-display component 21 and a metasurface element 22, which are attached together along the light transmission direction;

[0317] The microdisplay component 21 is used to emit image light, and the metasurface element 22 is used to modulate the image light and couple the modulated image light into the substrate 1.

[0318] The coupling region 62 is provided with a coupling element 3, which is used to couple out the light propagating thereto.

[0319] In this embodiment, the near-eye display device is a wearable device, which can be a virtual reality (VR) device, an augmented reality (AR) device, or a mixed reality (MR) device. For example, the near-eye display device can specifically be AR glasses.

[0320] In this embodiment, the frame module 5 is used to provide wearing support for the target object. Taking AR glasses as an example of a near-eye display device, the target object refers to the wearer of the AR glasses, and the frame module 5 is adapted to the wearer's head to provide wearing support.

[0321] In this embodiment, the light guide device is disposed in the lens frame module 5, for example, the light guide device is disposed inside the lens frame module 5 or connected to the lens frame module 5. The main function of the light guide device is to couple the image light emitted from the micro-display component into the substrate through the metasurface element, and then guide it to the user's eyes through the coupling element.

[0322] Specifically, the light guide device includes a substrate 1, which has an insertion region 61 and an exit region 62. The substrate 1 serves as the carrier component of the light guide device and is embedded in the lens frame module 5.

[0323] For example, the material of the substrate 1 can be plastic, glass, lithium niobate, silicon carbide, or other high-transparency, low-light-absorption materials.

[0324] For example, the cross-sectional shape of the substrate 1 can be square, rectangle, ellipse, circle, or triangle. For practical purposes, the corners are usually rounded without affecting the overall optical path. The longitudinal section of the substrate 1 can be rectangular or arched. Among them, the cuboid structure is the most commonly used shape for the substrate 1.

[0325] In the design of traditional optical waveguide components, the function of the coupling region 61 is simply to guide external light into the interior of the light guide device.

[0326] However, in the embodiments of this application, we have innovatively designed the coupling region 61: integrating both the microdisplay component 21 and the metasurface element 22 into the coupling region 61. This region, through the design of the metasurface element 22, not only continues the original light coupling function of traditional optical waveguide components, but also, compared to traditional optical waveguide components, exhibits a higher degree of integration between the microdisplay component 21, the metasurface element 22, and the substrate 1, resulting in better light coupling efficiency for the metasurface element 22.

[0327] Furthermore, the light guide device provided in this embodiment also has other functions. First, the addition of the micro-display component 21 enables the coupling region 61 to autonomously generate image light rays. Second, the integration of the metasurface element 22 also endows the coupling region 61 with the ability to finely modulate the image light rays, thereby further improving the performance of the light guide device in terms of image quality and optical performance.

[0328] Therefore, in this embodiment, the coupling region 61 of the light guide device integrates multiple functions of light generation, coupling, and modulation. Furthermore, since both the microdisplay component 21 and the metasurface element 22 are integrated in the coupling region 61, the overall integration of the light guide device is higher, and the image light emitted from the microdisplay component 21 has better transmission efficiency.

[0329] In the design of traditional optical waveguide components, the function of the coupling region 62 relies on the coupling-in grating and coupling-out grating structures. The function of the coupling region 62 is to guide light, ensuring that the light rays propagating to the coupling region 62 can be coupled out of the substrate 1 as expected, thereby achieving efficient transmission and utilization of light.

[0330] However, in this embodiment, we have implemented a groundbreaking structural design for the coupling region 61 of the light guide device. Based on this structural design, the function of the light guide device in the coupling region 62 depends on the structural design of the metasurface element 22 and the coupling element 3 to achieve efficient light coupling. For example, the coupling region 62 of the light guide device is provided with a coupling element 3, which can be a grating or a metasurface material.

[0331] In this embodiment, a microdisplay component 21 and a metasurface element 22 are disposed in the coupling region 61 of the light guide device. The main function of the microdisplay component 21 in the light guide device is to emit image light. The image light emitted by the microdisplay component 21 can be collimated light (parallel light) or decollimated light.

[0332] When the image light emitted by the microdisplay component 21 is collimated, the complexity of light control and phase modulation of the metasurface element 22 is simplified, and the design difficulty of the metasurface element 22 is reduced.

[0333] When the image light of the microdisplay component 21 is non-collimated, it will increase the difficulty of designing the metasurface element 22, but it will not affect the overall architecture of the light guide device in this embodiment.

[0334] Preferably, the microdisplay component 21 outputs highly collimated image light. For highly collimated image light, the light emitted from each pixel 210 in the microdisplay component 21 is emitted perpendicularly. The function of the metasurface element 22 is to refract the incident light from each pixel 210 to the corresponding angle of the light guide device, achieving a one-to-one correspondence. In other words, for traditional light guide devices, in order to couple external light into the substrate, the diffraction formula is satisfied, and the phase information is automatically coupled through the angle information. In this embodiment, the microdisplay component 21 and the metasurface element 22 are set in the coupling region 61 of the light guide device. The metasurface element 22 needs to modulate and refract the image light emitted from each pixel 210 in the microdisplay component 21 into the light guide device. It can also be understood that the metasurface element 22 performs point-to-point coupling of the image light emitted from the microdisplay component 21, realizing the light direction modulation at the pixel level, so that the coupling region 61 of the light guide device can achieve the function of a traditional optomechanical system and a traditional coupling grating.

[0335] In this embodiment, the microdisplay component 21 and the metasurface element 22 are attached together along the light transmission direction. This attachment ensures that the image light emitted from the microdisplay component 21 can be directly and efficiently transmitted to the metasurface element 22, reducing light loss and scattering and improving light transmission efficiency.

[0336] Furthermore, the metasurface element 22 can modulate the light incident upon it. For example, the metasurface element 22 can modulate the phase, polarization, amplitude, and other characteristics of the image light. The bonding arrangement between the microdisplay component 21 and the metasurface element 22 further ensures the accuracy of the modulation process and also guarantees that the light will not be subjected to additional interference during transmission.

[0337] Furthermore, the micro-display component 21 and the metasurface element 22 are attached along the light transmission direction, making the entire light guide device structure more compact. This helps to reduce the size and weight of the whole device and improve the portability and ease of use of the light guide device.

[0338] In this embodiment, the metasurface element 22 is composed of a metasurface structure. A metasurface structure is a structure including micro / nano structures 222. These micro / nano structures 222 are artificial layered material structures with dimensions at the subwavelength scale. These micro / nano structures 222 can achieve modulation of the polarization, amplitude, phase, and propagation characteristics of image light.

[0339] The metasurface element 22 modulates light through its micro / nano structures 222. When light is incident on the metasurface element 22, it interacts with these micro / nano structures 222, thereby changing the polarization, amplitude, phase, and propagation (direction and angle) properties of the light.

[0340] Referring to Figures 3a and 3b, an example structure of a metasurface element 22 is shown. The metasurface element 22 may include a substrate 221 and micro / nanostructures 222 located on the substrate 221. The micro / nanostructures 222 located on the substrate 221 may have the same or different shapes.

[0341] For example, referring to FIG5, another structure of the metasurface element 22 is shown. As shown in FIG3b and FIG5, the arrangement of the micro-nano structures 222 on the substrate 221 is not unique. Those skilled in the art can design the arrangement of the micro-nano structures 222 on the substrate 221 and the shape of each micro-nano structure according to the type of image light emitted from the micro-display component 21 and the type of optomechanical application to the light guide device.

[0342] In this embodiment, utilizing the structural features of the metasurface element 22, the microdisplay component 21 and the metasurface element 22 are bonded and disposed in the coupling region 61 of the light guide device. The metasurface element 22 has the function of modulating image light and coupling the modulated image light into the light guide device.

[0343] Specifically, in the embodiments of this application, the metasurface element 22 primarily functions to modulate image light. When image light emitted from the microdisplay component 21 shines onto the metasurface element 22, this light is modulated by the micro / nano structure 222 of the metasurface element 22.

[0344] Based on the micro / nano structure characteristics of the metasurface element 22, light undergoes changes in phase, amplitude, or polarization as it passes through, thereby achieving modulation of the light.

[0345] This part of the metasurface element 22 functions similarly to optical elements such as lenses in conventional optical engines. However, compared to conventional lenses, the metasurface element 22 has advantages such as being lighter, thinner, and easier to integrate.

[0346] For example, the material of metasurface element 22 is a metasurface material. Metasurface materials can encode the wavefront of light in a specific way to achieve the function of focusing or changing the direction of light. If you want to achieve the function of a lens, such as a focusing lens, you only need to map the phase information of the geometric lens to the phase information of the in-plane nanomaterial (the height and width of nanopillars, etc.). The encoded metasurface material can replicate the function of a traditional geometric lens, and the thickness is only a thin layer of nanomaterial.

[0347] Furthermore, the metasurface element 22 can also achieve more complex optical functions, such as multifocal focusing, zooming, and polarization control, which are difficult to achieve with traditional lenses. In other words, in this embodiment, the light modulation effect of the metasurface element 22 is superior to the light modulation effect of optical elements such as lenses in traditional optomechanical systems.

[0348] Furthermore, the metasurface element 22 also has the function of coupling the modulated image light into the light guide device. The light modulated by the metasurface element 22 has its propagation direction and characteristics adjusted according to predetermined requirements, which makes it easier and more efficient for these lights to couple into the light guide device. Light guide devices are typically used to guide light along a specific path to achieve specific imaging or illumination effects.

[0349] This part of the metasurface functions similarly to the coupling element (e.g., a coupling grating) in a traditional optical waveguide assembly. A coupling grating is a component used to couple light into a light guide device; it typically has specific structures and parameters to achieve directional coupling of light. In this embodiment, the metasurface element 22 directly couples the modulated light into the light guide device.

[0350] Compared to traditional coupling gratings, metasurface elements 22 offer greater flexibility and customizability. By adjusting the microstructure and parameters of metasurface elements 22, image light emitted from them can be directly coupled into a light guide device without the need for a coupling grating, thus meeting a wider range of optical requirements. Furthermore, metasurface elements 22 also offer advantages such as being lighter, thinner, and easier to integrate.

[0351] In this embodiment, the light guide device disposed in the frame module 5 integrates the micro-display component, metasurface element and substrate into one unit, reducing the overall size of the near-eye display device and improving the user's comfort when wearing the near-eye display device.

[0352] In this embodiment of the application, referring to Figures 19 and 20, the frame module 5 includes a temple 51, and the micro-display component 21 and the metasurface element 22 are disposed close to the temple 51.

[0353] In this embodiment, the microdisplay component 21 and the metasurface element 22 are disposed in the coupling region 61 of the substrate 1, that is, in this embodiment, the coupling region 61 of the substrate 1 is disposed near the temple 51. Further, the coupling region 61 of the substrate 1 is disposed near the corner region of the temple 51.

[0354] In this embodiment, the coupling region 61 is positioned in the corner area near the temple 51, which allows for more efficient use of the overall space of the glasses. This layout avoids placing too many components in the center or front area of ​​the glasses, thereby reducing obstruction and interference with the line of sight.

[0355] In addition, placing the coupling area 61 in the corner area near the temple 51 can reduce the pressure on the bridge of the nose and around the eyes, thereby improving the user's wearing comfort.

[0356] Furthermore, the metasurface element 22 has the ability to control the propagation characteristics of light. By placing it in the coupling region 61 near the temple 51, light can be guided into the user's eyes more effectively, improving the clarity and brightness of the image.

[0357] In this embodiment of the application, referring to Figures 7, 9 and 19, the microdisplay component 21 and the metasurface element 22 are attached together along the thickness direction of the substrate 1, and the microdisplay component 21 and the metasurface element 22 are disposed away from the light-emitting side of the light guide device.

[0358] In this embodiment, by attaching the microdisplay component 21 and the metasurface element 22 to the substrate 1 and placing them in opposite directions on the light-emitting side of the light guide device, space can be greatly saved, making the overall structure more compact.

[0359] In this embodiment, the microdisplay component 21 is responsible for generating image light rays, while the metasurface element 22 can precisely control and couple these light rays. Positioning them away from the light-emitting side of the light guide ensures that, after being controlled and coupled by the metasurface element 22, the light rays are effectively guided to the user's eye. This arrangement helps reduce light loss and improve display efficiency.

[0360] Furthermore, the microdisplay components 21 may generate some heat during operation. Positioning them away from the light-emitting side of the light guide device allows for better thermal management. For example, a heat dissipation structure can be designed on the substrate 1, or airflow can be used to aid heat dissipation, thereby ensuring the stable operation of the microdisplay components 21.

[0361] In this embodiment of the application, referring to FIG9, when the microdisplay component 21 and the metasurface element 22 are attached together along the thickness direction of the substrate 1, the substrate 1 is further provided with a transition element 4, and the projection of the metasurface element 22 in the thickness direction of the substrate 1 is located within the transition element 4.

[0362] In this embodiment, referring to Figures 7 and 11, the light guide device does not have the turning element 4, and the light transmission path within the light guide device is shown in Figure 11. The metasurface element 22 couples the image light emitted from the microdisplay component 21 into the substrate 1 (coupled into the substrate 1 at a large angle), and the light entering the substrate 1 is coupled out of the substrate 1 by the coupling element 3 after total internal reflection.

[0363] Referring to Figures 9 and 12, the light guide device is provided with a deflection element 4, and the light transmission path within the light guide device is shown in Figure 12. The metasurface element 22 couples the image light emitted from the microdisplay component 21 into the substrate 1 (coupled into the substrate 1 at a small angle). The light entering the substrate 1 is received by the deflection element 4 and deflected again for total internal reflection at a large angle, and then coupled out of the substrate 1 by the coupling element 3.

[0364] In this embodiment, the metasurface element 22 located in the coupling region 61 implements small-angle encoding (modulation of light), while the transition element 4 converts the small-angle encoding back into a large angle, allowing it to be transmitted within the light guide device without light leakage. Simply put, the function of the transition element 4 is to reduce the design complexity of the overall light guide device.

[0365] Typically, metasurface elements 22 formed by combining multiple micro / nano structures 222 should be able to meet the conditions of 0-degree incident light and large-angle (no light leakage) light emission. If the processing difficulty of the metasurface material is too high and it cannot meet the condition of deflecting light into a large angle, then the use of a deflection element 4 can be considered as an auxiliary.

[0366] Theoretically, transition element 4 is not necessary. However, based on design experience, the processing of metasurface materials is very difficult. This auxiliary transition element 4 (such as a transition grating) can be used to help simplify the design of metasurface element 22.

[0367] Referring to Figures 9 and 12, the deflection element 4 is located on the opposite side of the metasurface element 22. This is because if the light emitted from the metasurface element 22 does not meet the TIR (total internal reflection) condition, the deflection element 4 is used to assist in refraction to increase the angle. The positions of all deflection elements 4 must cover the possible light emission directions. They are usually located on the opposite side of the coupling region 61, slightly larger than the coupling region 61, to be able to receive small-angle beams emitted from the metasurface.

[0368] In this embodiment of the application, referring to Figures 15 and 17, and referring to Figure 20, the microdisplay component 21 and the metasurface element 22 are disposed on the surface 11 of the side end of the substrate 1, and the surface 11 of the side end is a vertical plane or an inclined plane.

[0369] In this embodiment, the coupling region 61 is designed on the surface 11 of the side end of the substrate 1. This means that light does not enter the substrate 1 from the top or bottom, but from the surface 11 of the side end.

[0370] With the microdisplay component 21 and the metasurface element 22 disposed on the surface 11 of the side end of the substrate 1, the coupling-out region 62 is located adjacent to the coupling-in region 61, and the coupling-out region 62 is located on another surface in contact with the side end surface 11. This surface can be the top, bottom, or other side of the substrate 1, depending on the overall design and application requirements. The coupling-out region 62 is responsible for effectively guiding the light that has been internally transmitted and modulated out of the substrate 1 for subsequent use or observation.

[0371] For example, the light guide device may include a coupling region 62, which may be located on the top, bottom or other side of the substrate 1.

[0372] For example, the light guide device may include two coupling regions 62, which may be located on two surfaces adjacent to and opposite to the substrate 1.

[0373] Referring to Figures 15 and 16, the coupling region 61 is located on the surface 11 of the side end of the substrate 1, the micro-display component 21 and the metasurface element 22 are attached along the length direction of the substrate 1 (X direction in the figure), and the coupling region 62 is located on the surface of the top of the substrate 1.

[0374] Referring to Figures 17 and 18, the coupling region 61 is located on the surface 11 at the side end of the substrate 1. The surface 11 at the side end is a slope, and the micro-display component 21 and the metasurface element 22 are disposed on the slope.

[0375] In this embodiment, the two key components, the microdisplay component 21 and the metasurface element 22, are bonded together in a direction perpendicular to the direction of the side surface 11. This means that the bonding direction of the two components forms a right angle with the side surface 11, and they work together to influence light. The microdisplay component 21 is responsible for generating image light, while the metasurface element 22 precisely modulates this light to meet specific optical requirements. This perpendicular bonding arrangement helps ensure efficient light transmission and modulation while reducing unnecessary losses and interference.

[0376] Furthermore, in this embodiment, for the substrate 1, the image light entering the substrate 1 from the side must satisfy the condition of no light leakage. The condition of TIR (Total Internal Reflection) is the requirement for the light guide device to not leak light, which mainly depends on the refractive index of the substrate 1. By designing and optimizing the metasurface element 22, when the angle of the light within the substrate 1 is greater than the total internal reflection angle of the substrate 1, no light leakage will occur.

[0377] Furthermore, in this embodiment, the coupling element 3 and the metasurface element 22 are designed as a pair, and need to be able to couple normally at the required FOV angle in the coupling region 62, which depends on the specific design requirements. The metasurface element 22 is located in the coupling region 61, which typically receives light incident at 0 degrees or light incident from a lattice pattern with a small dispersion angle, that is, the coupling region 61 typically receives light incident at a small angle.

[0378] To further optimize light output, the coupling element 3 can be designed as a butterfly grating. This design not only expands the image light rays in a two-dimensional angle, but also ensures that the light rays can be accurately coupled to the predetermined angle, thereby greatly improving the overall optical performance and user experience.

[0379] In this embodiment of the application, the coupling element 3 of the coupling region 62 is disposed on the surface of the substrate 1 opposite to the wearer's eye, and the coupling element 3 is a reflective coupling element 3.

[0380] In this embodiment, the reflective coupling element 3 can change the direction of light propagation, allowing the light to be coupled out of the light guide device more effectively and directed towards the wearer's eyes. This design ensures that the light maintains high brightness and contrast even after multiple reflections and refractions, thereby improving the display effect.

[0381] Furthermore, placing the coupling element 3 on the surface of the substrate 1 facing away from the wearer's eyes allows for a simpler overall structural design. This layout avoids placing too many complex components in the area near the eyes, thereby reducing obstruction and interference with vision.

[0382] In this embodiment of the application, the coupling element 3 of the coupling region 62 is disposed on a surface of the substrate 1 near the wearer's eye, and the coupling element 3 is a transmissive coupling element 3.

[0383] In this embodiment, the transmissive coupling element 3 allows light to pass directly through and be projected into the wearer's eyes without undergoing additional reflection or refraction. This reduces light loss during transmission and provides a more direct and clearer visual experience.

[0384] Since the light is directly transmitted through the coupling element 3, the light emitted by the microdisplay component 21 can be utilized more effectively, improving luminous efficiency and brightness. This is especially important for using near-eye display devices in low-light environments, ensuring users receive a bright and clear display.

[0385] Furthermore, transmissive coupling elements are typically thinner and lighter than reflective elements because they do not require additional reflective surfaces or structures to guide light. This helps reduce the weight and thickness of the entire near-eye display device, making it lighter and more comfortable.

[0386] In this embodiment, regardless of whether the coupling element 3 is a reflective coupling element 3 or a transmissive coupling element 3, the type of the coupling element 3 is a two-dimensional grating.

[0387] In this embodiment, when the coupling element 3 is a grating structure, it is a two-dimensional grating. By adjusting the structural parameters of the two-dimensional grating (such as period and depth), the equivalent refractive index in the light guide device can be changed, thereby achieving modulation and control of the image light. Furthermore, the multi-directional diffraction characteristics of the two-dimensional grating enable it to process more dimensional information, achieving multi-angle imaging.

[0388] Furthermore, the two-dimensional grating is a butterfly grating. Defining the coupling element 3 as a butterfly grating simplifies the design requirements of the metasurface element 22 in the coupling region 61. Referring to Figures 7, 9, or 15, a coupling region 62 is provided on the light guide device, and the butterfly grating is located in this coupling region 62.

[0389] Specifically, a butterfly grating is a two-dimensional grating with a special structure. By introducing periodic changes in refractive index, a grating structure is formed, thereby achieving feedback and selective amplification of specific wavelengths.

[0390] Since the butterfly grating has well-defined structural and performance parameters that have been optimized during the design and manufacturing process, the metasurface element 22 in the coupling region 61 can be designed and optimized based on the known parameters of the butterfly grating, thereby reducing the need for adjustment and optimization of the metasurface parameters.

[0391] Furthermore, the periodic structure of the butterfly grating enables it to efficiently couple image light of specific wavelengths. This characteristic allows for a greater focus on improving the coupling efficiency of the metasurface when designing the coupling end, without having to consider other complex factors.

[0392] In this embodiment of the application, referring to Figures 13 and 17, the coupling element 3 is composed of two one-dimensional gratings. The two one-dimensional gratings include a first one-dimensional grating 31 and a second one-dimensional grating 32. The first one-dimensional grating 31 is disposed on a surface of the substrate 1 close to the wearer's eye, and the second one-dimensional grating 32 is disposed on a surface of the substrate 1 away from the wearer's eye. The first one-dimensional grating 31 is a transmissive coupling element 3, and the second one-dimensional grating 32 is a reflective coupling element 3.

[0393] In this embodiment, the first one-dimensional grating 31 serves as a transmissive coupling element 3, allowing light to pass directly through and be projected into the wearer's eyes, providing a direct and clear viewing experience. Simultaneously, it can also adjust the light as needed, such as adjusting the direction and intensity of the light, to meet different display requirements.

[0394] The second one-dimensional grating 32, acting as a reflective coupling element 3, can reflect and control light from other directions. This design allows light to maintain high brightness and contrast even after multiple reflections and transmissions, thereby improving the display effect.

[0395] By combining transmissive and reflective one-dimensional gratings, the light emitted by the light source can be utilized more effectively. Transmissive gratings directly transmit light, while reflective gratings can reflect and control the light. The combined effect of the two can improve light utilization and display efficiency.

[0396] In this embodiment of the application, the projection of the second one-dimensional grating 32 onto the thickness direction of the substrate 1 is located within the area where the first one-dimensional grating 31 is located.

[0397] In this embodiment, when light propagates within the substrate, it first encounters the second one-dimensional grating 32. Because the second one-dimensional grating 32 has a specific grating structure, it can process the light through reflection or diffraction. The light processed by the second one-dimensional grating 32 is then received by the first one-dimensional grating 31. Because the first one-dimensional grating 31 also has a specific grating structure, it can further manipulate the light, such as through transmission, focusing, or dispersion.

[0398] Since the projection of the second one-dimensional grating 32 overlaps with the first one-dimensional grating 31, the light, after being reflected by the second one-dimensional grating 32, can be directly captured by the first one-dimensional grating 31 and transmitted to the wearer's eye.

[0399] This arrangement reduces light loss during transmission because the light does not need to undergo multiple reflections or refractions within the substrate 1 or at the interface between the substrate 1 and the air, thus avoiding light loss caused by these processes. Therefore, more light reaches the wearer's eyes, improving light utilization and device display brightness.

[0400] The above embodiments mainly describe the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. For the sake of brevity, they will not be elaborated here.

[0401] While specific embodiments of this application have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of this application. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of this application. The scope of this application is defined by the appended claims.

Claims

1. A light guide device, wherein, The light guide device includes: A substrate having an insertion region and an exit region; The coupling region is provided with a micro-display component and a metasurface element, and the micro-display component and the metasurface element are attached together along the light transmission direction; The microdisplay component is used to emit image light, and the metasurface element is used to modulate the image light and couple the modulated image light into the substrate. The coupling region is provided with a coupling element, which is used to couple out the light propagating thereto.

2. The light guide device according to claim 1, wherein, The microdisplay component and the metasurface element are bonded together, and the bonding air gap between the microdisplay component and the metasurface element is less than 1 μm; or, The metasurface element is bonded to the substrate on the side opposite to the microdisplay component, and the refractive index of the bonding layer between the metasurface element and the substrate matches the refractive index of the substrate material; or The metasurface element is formed in the coupling region of the substrate.

3. The light guide device according to claim 1 or 2, wherein, The metasurface element is composed of subwavelength micro-nano structures, and each micro-nano structure in the metasurface element corresponds one-to-one with a pixel in the micro-display component. The micro-nano structure modulates and refracts the light emitted from its corresponding pixel into the light guide device.

4. The light guide device according to claim 3, wherein, The metasurface element includes a dielectric layer formed by arranging multiple subwavelength micro / nano structures along the light transmission direction. This dielectric layer is configured to modulate the image light and couple the modulated image light into the substrate; or The metasurface element includes a first part and a second part along the light transmission direction, and both the first part and the second part include a dielectric layer formed by the arrangement of multiple subwavelength-sized micro-nano structures; The first portion is configured to modulate the image light, and the second portion is configured to couple the modulated image light into the substrate.

5. The light guide device according to claim 1, wherein, The coupling region is located on the surface of the side end of the substrate, the coupling region is located on the surface adjacent to the surface of the side end, and the microdisplay component and the metasurface element are attached in a direction perpendicular to the direction of the surface of the side end.

6. The light guide device according to claim 5, wherein, The surface of the side end is arranged vertically, and the microdisplay component and the metasurface element are attached horizontally; or The surface of the side end is inclined, and the micro-display component and the metasurface element are attached to each other in the normal direction of the inclined surface.

7. The light guide device according to claim 1, wherein, Both the coupling-in region and the coupling-out region are located on surfaces adjacent to the side end of the substrate, and the microdisplay component and the metasurface element are attached to each other along the thickness direction of the substrate.

8. The light guide device according to claim 1, wherein, The coupling element is a two-dimensional butterfly grating or the coupling element is a butterfly grating formed by combining two one-dimensional gratings.

9. The light guide device according to claim 8, wherein, The two one-dimensional gratings include a first one-dimensional grating and a second one-dimensional grating. The first one-dimensional grating is either a reflective coupling element or a transmissive coupling element, and the second one-dimensional grating is either a reflective coupling element or a transmissive coupling element.

10. The light guide device according to claim 5, wherein, A transition element is also provided on the surface adjacent to the side end of the substrate, and the projection of the metasurface element in the thickness direction of the substrate is located within the transition element.

11. A near-eye display device, wherein, The near-eye display device includes a light guide device as described in any one of claims 1-10.

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