Diffractive optical structures, methods for controlling diffraction efficiency in the non-coupled region, and optical equipment.

Abstract

This application discloses a diffractive optical structure, a method for controlling the diffraction efficiency of the non-coupled region, and an optical device. The diffractive optical structure includes a substrate and at least one coupled region and at least one coupled-out region disposed on the substrate. The coupled region is used to couple external light into the substrate, and the coupled-out region is used to dilate the light and couple it out. The coupled-out region is provided with a coupled-out grating having a residual layer, and the residual layer has a set thickness variation trend at different positions of the coupled-out grating to control the coupled-out intensity of the light. The refractive index of the residual layer is different from that of the substrate, and the difference between the refractive indices is Δn, 0.1≤Δn≤0.8. The coupled-out region is configured to control the peak position of the diffraction efficiency curve of the coupled-out grating by the thickness variation trend of the residual layer during the transmission of light along the length direction of the diffractive optical structure.

Description

Technical Field

[0001] This application belongs to the field of augmented reality (AR) technology. Specifically, this application relates to a diffractive optical structure, a method for controlling the diffraction efficiency in the non-coupled region, and an optical device. Background Technology

[0002] With the continuous development of AR technology, the requirements for the optical efficiency of diffractive waveguides are increasing. In a diffractive waveguide, the coupling region is responsible for introducing external light into the waveguide, while the coupling region is responsible for expanding the pupil and coupling the light out. Among these, the diffraction efficiency control in the non-coupling region has become a key factor affecting the overall efficiency. Traditional control methods often struggle to achieve precise control of the diffraction efficiency curve, resulting in uneven light distribution in the coupling region and affecting the display effect of AR devices. Therefore, how to effectively control the diffraction efficiency of the non-coupling region to improve the overall efficiency and uniformity of the diffractive waveguide has become an urgent problem to be solved. Summary of the Invention

[0003] The purpose of this application is to provide a new technical solution for diffractive optical structures, a method for controlling the diffraction efficiency in the non-coupled region, and optical devices.

[0004] According to a first aspect of this application, an embodiment of this application provides a diffractive optical structure, the diffractive optical structure comprising a substrate and a component disposed on the substrate:

[0005] At least one coupling region is provided for coupling external light into the substrate;

[0006] At least one coupling region is provided for dilating and coupling out the light rays;

[0007] The coupling region is provided with a coupling grating with a residual layer, and the residual layer has a set thickness variation trend at different positions of the coupling grating to control the coupling intensity of light.

[0008] The residual layer has a different refractive index than the substrate, and the difference in refractive index between the two is Δn, where 0.1 ≤ Δn ≤ 0.8;

[0009] The coupling region is configured such that, during the transmission of light along the length of the diffraction optical structure, the peak position of the diffraction efficiency curve of the coupling grating is adjusted by the variation trend of the residual layer thickness, so as to achieve uniform coupling of light at different positions in the coupling region.

[0010] Optionally, the refractive index difference Δn between the residual layer and the substrate is: 0.2≤Δn≤0.5.

[0011] Optionally, as the light propagates along the length of the diffractive optical structure, the thickness of the residual layer gradually decreases, causing the peak position of the diffraction efficiency curve of the coupling grating to gradually shift from a large angle to a small angle along the propagation path of the light.

[0012] Optionally, the thickness of the residual layer is RSL, RSL*△n=C, where C is a constant and 2mm≤C≤60mm.

[0013] Optionally, the thickness of the residual layer is RSL, and 10nm≤RSL≤300nm.

[0014] Optionally, the residual layer is made of adhesive.

[0015] Optionally, the residual layer is made of an inorganic material, including titanium oxide, aluminum oxide, silicon oxide, or silicon nitride.

[0016] Optionally, within the coupling region, the coupling grating includes a front end, a middle part, and a rear end;

[0017] The thickness of the residual layer at the front end of the coupling grating is 100nm to 300nm, and the peak position of the diffraction efficiency curve of the coupling grating is between 65° and 85°.

[0018] The thickness of the residual layer in the middle of the coupling grating is 50 nm to 150 nm, and the peak position of the diffraction efficiency curve of the coupling grating is between 50° and 65°.

[0019] The thickness of the residual layer at the rear end of the coupling grating is 5nm to 15nm, and the peak position of the diffraction efficiency curve of the coupling grating is between 30° and 50°.

[0020] Optionally, the diffractive optical structure further includes a transition region disposed on the substrate and located between the optical paths of the coupling-in region and the coupling-out region, wherein the residual layer can extend from the coupling-out region to at least a portion of the transition region.

[0021] According to a second aspect of this application, embodiments of this application provide a method for controlling the diffraction efficiency of an uncoupled region. The method is used for a diffractive optical structure, which includes a substrate and at least one coupled region and at least one coupled region disposed on the substrate. The coupled region includes a coupled grating with a residual layer, and the refractive index of the residual layer is different from that of the substrate, with the refractive index difference between the two being Δn, where 0.1 ≤ Δn ≤ 0.8.

[0022] The methods for controlling the diffraction efficiency include:

[0023] Within the coupling region, the thickness variation trend of the residual layer at various positions of the coupling grating is determined according to the light transmission path and the required coupling angle, so as to control the peak position of the diffraction efficiency curve of the coupling grating.

[0024] External light is coupled into the substrate through the coupling region, and the light is transmitted to the coupling region by total internal reflection within the substrate.

[0025] By controlling the peak position of the diffraction efficiency curve of the coupling grating through the residual layer, the peak value of the diffraction efficiency curve can change according to a predetermined trend as the light propagates along the length direction of the diffraction optical structure, thereby achieving uniform coupling at different positions in the coupling region.

[0026] According to a third aspect of this application, an embodiment of this application provides an optical device, the optical device comprising:

[0027] Image source; and

[0028] As described in the first aspect, the diffractive optical structure allows light emitted from the image source to enter the coupling region.

[0029] One beneficial effect of the embodiments of this application is that:

[0030] The diffractive optical structure provided in this application includes a substrate, a coupling region, a coupling region, and a residual layer for fabricating a grating. The residual layer is located in the coupling region on the substrate. By adjusting the refractive index difference between the residual layer and the substrate, the peak position of the diffraction efficiency curve of the coupling grating in the coupling region can be changed, thereby modulating the intensity of light coupling to achieve uniform light output.

[0031] The optical solution proposed in this application achieves the movement and control of the peak position of the diffraction efficiency curve of the coupling grating by adjusting the residual layer 4 in the non-coupled region. This technology not only improves the coupling efficiency but also provides a new solution for performance optimization of augmented reality (AR) optical display systems. The technical solution provided in this application can precisely control the transmission and coupling process of light, thereby meeting the requirements of AR optical display systems for high efficiency and high uniformity, and further promoting the development and application of AR technology.

[0032] Other features and advantages of this application will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0033] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the present application and, together with their description, serve to explain the principles of the present application.

[0034] Figure 1 This is a schematic diagram of the diffraction optical structure provided in the embodiments of this application;

[0035] Figure 2 This is a schematic diagram of the structure of the coupling region provided in an embodiment of this application;

[0036] Figure 3 This is one of the coupling efficiency curves of the diffraction optical structure provided in Embodiment 1 of this application;

[0037] Figure 4 This is the second coupling efficiency curve of the diffraction optical structure provided in Embodiment 1 of this application;

[0038] Figure 5 The third coupling efficiency curve of the diffraction optical structure provided in Embodiment 1 of this application;

[0039] Figure 6 This is one of the coupling efficiency curves of the diffraction optical structure provided in Embodiment 2 of this application;

[0040] Figure 7 This is the second coupling efficiency curve of the diffraction optical structure provided in Embodiment 2 of this application;

[0041] Figure 8 The third coupling efficiency curve of the diffraction optical structure provided in Embodiment 2 of this application.

[0042] Explanation of reference numerals in the attached figures:

[0043] 1. Substrate; 2. Coupling region; 3. Coupling out region; 4. Residual layer. Detailed Implementation

[0044] Various exemplary embodiments of the present 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 the present application.

[0045] 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.

[0046] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0047] 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.

[0048] 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.

[0049] The diffractive optical structure, the method for controlling the diffraction efficiency in the non-coupled region, and the optical device provided in the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0050] In diffractive optical structures, diffractive waveguide devices (or diffractive waveguide sheets) are a common form. In the following text, diffractive waveguide devices will be simply referred to as optical waveguides.

[0051] The overall optical performance of an optical waveguide depends primarily on two key factors: coupling efficiency and pupil-expanding coupling efficiency. Of these, the goal is to maximize coupling efficiency to ensure that as much external light as possible is captured and guided into the waveguide. The control mechanism for pupil-expanding coupling efficiency exhibits more complex and variable characteristics. In contrast, managing pupil-expanding coupling efficiency requires a more refined adjustment strategy based on the specific characteristics of light at different positions within the waveguide and its desired coupling angle.

[0052] by Figure 1 Taking the side view of the diffractive optical structure shown as an example, at the front end of the coupling region 3 (the part immediately adjacent to the coupling region 2), this region is relatively tolerant of the angle requirements of the incident light, and the coupling efficiency is generally maintained at a low level. This design is mainly to effectively couple out light rays with large total internal reflection angles, so its efficiency curve peak naturally falls within a large angle range. As the light gradually propagates from the front end to the rear end along the length direction of the substrate 1, the peak position of the diffraction efficiency curve also changes dynamically, showing a trend of smooth transition from large angles to small angles. To address this characteristic, this application proposes a diffractive optical structure design scheme aimed at optimizing the coupling efficiency of the optical waveguide.

[0053] According to one embodiment of this application, a diffractive optical structure is provided, see [link to relevant documentation]. Figure 1 and Figure 2The diffractive optical structure includes a substrate 1 and at least one coupling region 2 and at least one coupling region 3 disposed on the substrate 1. The coupling region 2 is used to couple external light into the substrate 1, and the coupling region 3 is used to dilate the light and couple it out. The coupling region 3 is provided with a coupling grating having a residual layer 4, and the residual layer 4 has a set thickness variation trend at different positions of the coupling grating to control the coupling intensity of the light. The refractive index of the residual layer 4 is different from that of the substrate 1, and the difference in refractive index between the two is Δn, 0.1≤Δn≤0.8. The coupling region 3 is configured such that, during the transmission of light along the length direction of the diffractive optical structure, the peak position of the diffraction efficiency curve of the coupling grating is controlled by the thickness variation trend of the residual layer 4 to achieve uniform coupling of light at different positions of the coupling region 3.

[0054] The diffractive optical structure provided in this application embodiment aims to optimize the coupling efficiency of light through a carefully designed residual layer 4, thereby achieving uniform coupling of light in the coupling region 3.

[0055] The diffractive optical structure provided in the embodiments of this application is described in [reference]. Figure 1 and Figure 2 It mainly consists of four parts: substrate 1, coupling region 2, coupling region 3, and residual layer 4 remaining on substrate 1 and at least located in coupling region 3.

[0056] The substrate 1 serves as the support for the entire diffractive optical structure, and it houses the other functional areas. The coupling region 2 is responsible for coupling external light (such as projected light from an image source) into the substrate 1; it is the primary channel for light to enter the diffractive optical structure. The coupling region 3 is responsible for dilating and coupling out the light; it is the key area for light to leave the diffractive optical structure and enter the human eye.

[0057] It is worth noting that a coupling grating is provided in the coupling region 3. Unlike traditional technology, the coupling grating of this application has a key residual layer 4, and the residual layer 4 has a specific thickness variation trend at different positions of the coupling grating. This is the key to achieving uniform light coupling.

[0058] In the diffractive optical structure provided in the embodiments of this application, the residual layer 4 is an important component. It is located on the substrate 1, especially in the coupling region 3, and has a decisive influence on the coupling efficiency of light.

[0059] The residual layer 4 is made of a different material than the substrate material to ensure a significant difference in refractive index between the two. This difference in refractive index is the basis for controlling the peak position of the diffraction efficiency curve of the coupling grating by adjusting the thickness of the residual layer 4. Specifically, the difference between the refractive index of the residual layer 4 and the refractive index of the substrate 1 is constrained to the range of 0.1 to 0.8. This range ensures the effectiveness of diffraction efficiency control while avoiding the increased difficulty of control or performance instability caused by excessive refractive index difference.

[0060] One of the key characteristics of the residual layer 4 is that its thickness exhibits a specific variation trend at different locations of the coupling grating. This thickness variation trend is specifically designed to achieve uniform coupling of light at different locations within the coupling region 3 by altering the peak position of the diffraction efficiency curve during light transmission through the diffraction optical structure. As light propagates along the length of the diffraction optical structure of this application, the change in the thickness of the residual layer 4 will cause a corresponding shift in the peak position of the diffraction efficiency curve of the coupling grating, thereby achieving fine control over the light coupling intensity.

[0061] In this application, the material selection for the residual layer 4 is diverse. For example, the residual layer 4 can be an organic material such as adhesive, achieved through spin coating or inkjet processes. Alternatively, the residual layer 4 can be an inorganic material such as titanium oxide, alumina, or silicon oxide, prepared using processes such as PVD, CVD, or ALD. The choice of these materials depends on the specific application scenario and performance requirements to ensure that the residual layer 4 meets optical, mechanical, and other requirements.

[0062] The residual layer 4, as a key part of the diffractive optical structure in this application embodiment, achieves precise control of light coupling efficiency through its thickness variation trend and refractive index difference, providing strong support for improving the overall optical efficiency and uniformity of coupled light intensity of the diffractive optical structure.

[0063] Regarding the residual layer 4 mentioned in this application, it should be noted that it is intentionally retained as a direct product of the manufacturing process of the diffractive optical structure, especially when constructing the coupling grating of the coupling region 3, thus constituting at least one layer of critical material. Specifically, when the coupling grating is fabricated on the substrate 1 using specific techniques such as etching or deposition, due to limitations in the process conditions or design considerations, a layer of material that is not completely removed may remain on the substrate portion of the coupling grating; this is the so-called residual layer 4.

[0064] In other words, the presence of the residual layer 4 in this application is by no means accidental. In this application, the residual layer 4 plays an important role in adjusting the diffraction efficiency curve of the coupling grating in the coupling region 3. By rationally designing the thickness of the residual layer 4 in different regions of the coupling grating, the coupling efficiency and direction of the light within the coupling grating can be finely adjusted, thereby achieving a more precise and flexible control effect on the coupled light.

[0065] The residual layer 4 is a key material layer that is naturally generated and deliberately retained during the fabrication of the coupling region 3. It plays a crucial role in the fabrication and performance optimization of the diffractive optical structure. By managing the thickness of the residual layer 4, this application achieves a significant improvement in the ability to control light, laying a solid foundation for the advancement and application of augmented reality (AR) optical systems.

[0066] The diffractive optical structure provided in this application embodiment can control the diffraction efficiency curve of the coupling grating. Specifically, during the propagation of light along the length of the diffractive optical structure, the thickness variation trend of the residual layer 4 can effectively control the peak position of the diffraction efficiency curve of the coupling grating. This control mechanism allows the coupling intensity of light at different positions to be adjusted, thereby avoiding the problems of local over-coupling or under-coupling.

[0067] The diffractive optical structure provided in this application embodiment can achieve uniform light coupling. Specifically, by controlling the thickness variation trend of the residual layer 4 and the refractive index difference between the residual layer 4 and the substrate 1, the diffractive optical structure can achieve uniform light coupling at different positions in the coupling region. This improves the overall optical efficiency of the diffractive optical structure and enhances the visual experience of optical devices.

[0068] The diffractive optical structure provided in this application embodiment is particularly suitable for diffractive waveguide technology in the field of augmented reality (AR). It can significantly improve the efficiency and uniformity of AR optical solutions, and provide strong support for the lightweighting, miniaturization and high performance of AR devices.

[0069] The diffractive optical structure provided in this application embodiment achieves uniform coupling of light in the coupling region 3 through the design of the residual layer 4, which has significant technical effects and broad application prospects.

[0070] In the diffractive optical structure of this application embodiment, a coupling grating is provided in the coupling region 3.

[0071] The coupling grating in the coupling region 3 can be a one-dimensional grating or a two-dimensional grating.

[0072] In some examples of this application, the refractive index difference Δn between the residual layer 4 and the substrate 1 is: 0.2≤Δn≤0.5.

[0073] The diffractive optical structure provided in this application adjusts the peak position of the grating diffraction efficiency curve by changing the thickness of the residual layer in the non-coupled region grating structure, thereby optimizing the coupling efficiency of the grating at different positions. The key here lies in the refractive index difference between the residual layer 4 and the substrate 1, which directly affects the movement and adjustment of the peak position of the diffraction efficiency curve.

[0074] In this example of the application, the refractive index difference Δn between the residual layer 4 and the substrate 1 is controlled between 0.2 and 0.5. When the refractive index difference Δn is within this range, the change in the thickness of the residual layer 4 can sensitively and stably control the peak position of the diffraction efficiency curve.

[0075] When 0.2 ≤ Δn ≤ 0.5, even a small change in the thickness of the residual layer 4 can lead to a significant shift in the peak position of the diffraction efficiency curve, making the control process both sensitive and stable. Furthermore, by precisely controlling the thickness of the residual layer 4, the coupled light at different positions of the coupling grating can be optimized, resulting in a more uniform light output. This is crucial for improving the overall efficiency of AR optical solutions and enhancing the user experience.

[0076] When the refractive index difference is too small, such as less than 0.1, the change in the thickness of the residual layer 4 has an insufficient effect on the diffraction efficiency curve; however, when the refractive index difference is too large, such as greater than 0.8, the change in the thickness of the residual layer 4 becomes too sensitive, leading to instability during the control process. Therefore, the selection of a range of 0.2 ≤ Δn ≤ 0.5 avoids these extreme cases.

[0077] It should be noted that when the refractive index difference Δn is less than 0.2, the thickness of the residual layer 4 has a relatively weak impact on the diffraction efficiency curve of the coupling grating. This means that even if the thickness of the residual layer 4 changes significantly, the peak position of the diffraction efficiency curve may only shift slightly. In this case, controlling the coupling efficiency by adjusting the thickness of the residual layer 4 becomes more difficult because the sensitivity of the adjustment is greatly reduced.

[0078] When the refractive index difference Δn is greater than 0.5 but less than 0.8, changes in the thickness of the residual layer 4 may have an overly sensitive effect on the diffraction efficiency curve. This means that even a small change in the thickness of the residual layer 4 can cause a significant shift in the peak position of the diffraction efficiency curve. In this case, the control process may become unstable, making it difficult to achieve stable control of the coupling efficiency.

[0079] When the refractive index difference Δn is greater than or equal to 0.8, the effect of changes in the thickness of the residual layer 4 on the diffraction efficiency curve can become very sensitive and unstable. In this case, even a slight adjustment to the residual layer 4 can lead to drastic changes in the diffraction efficiency curve, making the adjustment process difficult to control. This can severely affect the performance of the AR optical display system.

[0080] In summary, the range of refractive index difference Δn proposed in this example, i.e., 0.2 ≤ Δn ≤ 0.5, is determined based on a deep understanding of the efficiency curve shifting characteristics and optimization requirements in diffraction waveguide technology. This choice not only achieves stable and sensitive control of the diffraction efficiency curve but also optimizes the coupling efficiency and avoids extreme cases, thereby improving the overall efficiency of the AR optical solution and the user's visual experience.

[0081] In some examples of this application, as the light propagates along the length of the diffractive optical structure, the thickness of the residual layer 4 gradually decreases, causing the peak position of the diffraction efficiency curve of the coupling grating to gradually shift from a large angle to a small angle along the propagation path of the light.

[0082] As light propagates along the length of the diffractive optical structure, the thickness of the residual layer 4 gradually decreases, causing the peak position of the diffraction efficiency curve of the coupling grating in the coupling region 3 to gradually shift from a large angle to a small angle. This control process ensures that the coupling angle can be precisely controlled according to the different light angle requirements during the propagation of light in the diffractive optical structure.

[0083] By adjusting the thickness of the residual layer 4 at different positions of the coupling grating, the coupling efficiency can be controlled. At different stages of light transmission, the coupling efficiency can be optimized by adjusting the thickness of the residual layer 4 according to the required light angle, thereby further improving the effective coupling efficiency.

[0084] By adjusting the thickness of the residual layer 4, the diffraction efficiency curve of the coupling grating can be adaptively adjusted according to the light angle requirements at different positions, thereby achieving a more uniform light output effect. This helps to improve the overall efficiency of the diffractive optical structure, while also improving image quality and user visual experience.

[0085] In some examples of this application, the thickness of the residual layer 4 is RSL, RSL*△n=C, C is a constant, and 2mm≤C≤60mm.

[0086] The relationship between the thickness RSL of the residual layer 4 and the refractive index difference Δn can be controlled by using the C value (between 2 mm and 60 mm). This relationship allows for precise control of the diffraction efficiency curve of the uncoupled region, such as the coupled-out grating, by fine-tuning the thickness of the residual layer 4 during manufacturing.

[0087] When the value of C is fixed, as long as the constant of C remains unchanged in each manufacturing process, a relatively consistent and stable control effect can be achieved. This helps to improve production efficiency and product quality, and reduce performance fluctuations caused by inconsistent control.

[0088] Controlling the thickness of the residual layer 4 is crucial for optimizing the overall optical performance of the diffractive optical structure. By adjusting the thickness of the residual layer 4, the peak position of the diffraction efficiency curve of the coupling grating can be controlled, thereby optimizing the coupling efficiency of light, reducing light loss, and improving image quality and visual experience.

[0089] Different material systems may have different refractive indices, and the design of the C value allows for precise control of the peak position of the diffraction efficiency curve in the non-coupled region under different material systems.

[0090] In this application, the thickness RSL of the residual layer 4 is inversely proportional to the difference Δn between the refractive index of the substrate 1 and the residual layer 4.

[0091] The diffractive optical structure provided in this application aims to improve the diffraction efficiency and uniformity of the diffraction optical structure by controlling the diffraction efficiency of the non-coupled region. Based on this, this example proposes a key technical innovation: the inverse relationship between the thickness RSL of the residual layer 4 and the refractive index difference Δn between the substrate 1 and the residual layer 4.

[0092] The inverse relationship between the thickness RSL of the residual layer 4 and the refractive index difference Δn indicates that as the refractive index difference Δn increases, the thickness RSL of the residual layer 4 needs to decrease accordingly to maintain the same diffraction effect. Conversely, when the refractive index difference Δn decreases, the thickness RSL of the residual layer 4 can increase accordingly.

[0093] The magnitude of the refractive index difference Δn directly affects the propagation behavior of light between the substrate 1 and the residual layer 4. By adjusting this difference value, the propagation path and diffraction efficiency of light can be controlled.

[0094] To satisfy this inverse relationship, the material of the residual layer 4 needs to have an adjustable refractive index and be able to achieve the required thickness through appropriate processing methods (such as spin coating, inkjet, PVD, CVD or ALD).

[0095] According to the design scheme proposed in this example of the application, the diffraction efficiency curve of a coupling grating can be adjusted by controlling the thickness RSL of the residual layer 4 and the refractive index difference Δn. This helps to optimize the coupling efficiency, making the transmission of light in the diffractive optical structure more efficient and uniform.

[0096] In some examples of this application, the thickness of the residual layer 4 is RSL, and 10nm≤RSL≤300nm.

[0097] The thickness RSL of the residual layer 4 is limited to 10 nm to 300 nm. This setting is based on the need to control the diffraction efficiency of the uncoupled region and considerations for the manufacturing process.

[0098] The variation in the thickness of the residual layer 4 directly affects the diffraction efficiency curve of devices such as coupling gratings. In this application, by adjusting the thickness of the residual layer 4 to between 10 nm and 300 nm, the peak position of the diffraction efficiency curve can be shifted and controlled, thereby optimizing the coupling efficiency.

[0099] By limiting the thickness RSL of the residual layer 4 to between 10 nm and 300 nm, the diffraction efficiency curve of the uncoupled region, such as the coupling-out grating, can be controlled. This setting allows the technical solution to flexibly adjust the thickness of the residual layer 4 according to different application scenarios and requirements, thereby optimizing the coupling efficiency and improving the efficiency and uniformity of the waveguide.

[0100] By adjusting the thickness range of the residual layer 4, different application scenarios and requirements can be flexibly addressed. For example, in applications requiring higher resolution or a wider field of view, better performance can be achieved by adjusting the thickness of the residual layer 4.

[0101] Of course, the thickness of the residual layer 4 can also be in the range of 0-500 nm, and this application does not impose any specific limitations on this.

[0102] For example, the thickness of the residual layer 4 is in the range of 0-10 nm. Since the residual layer is very thin, it has little effect on the regulation of the diffraction efficiency curve.

[0103] Within the range of 300nm-500nm, the increase in the thickness of the residual layer 4 has a significant impact on the peak position of the diffraction efficiency curve.

[0104] Achieving precise thickness control on thinner residual layers (close to 0 nm) may be more challenging, as even minute thickness variations can significantly impact performance. For thicker residual layers, material selection and manufacturing process optimization must be considered to ensure stability and reliability.

[0105] An expanded thickness range can provide more options for different application scenarios and needs. For example, in certain specific scenarios, a thicker residual layer may be required to achieve specific diffraction effects.

[0106] The diffractive optical structure provided in this application allows for adjustment of the light coupling efficiency at the coupling grating by controlling the thickness of the residual layer 4 at different positions of the coupling grating. This enables the light to be controlled at different positions and angles. This design significantly improves the overall optical efficiency of the diffractive optical structure and allows light to be coupled out in a more uniform and stable manner, thereby greatly improving the imaging quality and user experience of augmented reality (AR) optical systems.

[0107] In some examples of this application, the residual layer 4 is made of adhesive.

[0108] As an organic material, glue typically has a low refractive index.

[0109] Optionally, the adhesive can be applied to a suitable location on the substrate 1 by spin coating or inkjet to create a grating structure to form the coupling region 2 and / or the coupling region 3.

[0110] Using adhesive as the material for the residual layer 4 in this application facilitates adjustments to thickness and uniformity during manufacturing, thereby enabling precise control of the diffraction efficiency curve of the coupling grating. Furthermore, the adhesive material is relatively inexpensive, contributing to reduced overall manufacturing costs.

[0111] Because the adhesive has a low refractive index, the difference in refractive index between it and the substrate 1 can be more easily controlled within the required range (e.g., 0.1 < Δn < 0.8, or 0.2 < Δn < 0.5), thereby achieving effective light control.

[0112] In some examples of this application, the residual layer 4 is made of an inorganic material, including titanium oxide, aluminum oxide, silicon oxide, or silicon nitride.

[0113] The inorganic materials proposed in this example, such as titanium oxide, aluminum oxide, silicon oxide, or silicon nitride, mostly have high refractive indices. These inorganic materials can be deposited on the substrate 1 at suitable locations (such as the coupling region 3) by processes such as PVD, CVD, or ALD.

[0114] The high refractive index of inorganic materials allows for a larger refractive index difference Δn between the residual layer 4 and the substrate 1, thereby enhancing the ability to control light. Furthermore, inorganic materials exhibit better thermal and chemical stability, contributing to the long-term stability of the diffractive optical structure.

[0115] It should be noted that adhesives typically have a low refractive index, while inorganic materials typically have a high refractive index. Therefore, when selecting the material for the residual layer 4, the most suitable material can be chosen based on the required range of refractive index differences.

[0116] The choice of material for the residual layer 4 has a significant impact on the control of the grating diffraction efficiency curve in the non-coupled region. Adhesive, as a low-cost and easily processed material, is suitable for applications requiring flexible adjustment of the diffraction efficiency curve; while inorganic materials, with their high refractive index, good stability, and performance optimization capabilities, are more suitable for applications with higher optical performance requirements. In practical applications, the most suitable residual layer material can be selected based on specific needs and manufacturing conditions.

[0117] In some examples of this application, within the coupling region 3, the coupling grating includes a front end, a middle part, and a rear end; the thickness of the residual layer 4 at the front end of the coupling grating is 100 nm to 300 nm, and the peak position of the diffraction efficiency curve of the coupling grating is between 65° and 85°; the thickness of the residual layer 4 at the middle part of the coupling grating is 50 nm to 150 nm, and the peak position of the diffraction efficiency curve of the coupling grating is between 50° and 65°; the thickness of the residual layer 4 at the rear end of the coupling grating is 5 nm to 15 nm, and the peak position of the diffraction efficiency curve of the coupling grating is between 30° and 50°.

[0118] The diffractive optical structure provided in this application embodiment has a coupling-in region 2 and a coupling-out region 3 on its substrate 1. The coupling-in region 2 is responsible for coupling external light into the substrate 1, and the coupling-out region 3 is responsible for dilating the light and coupling it out of the substrate 1. By adjusting the thickness of the residual layer 4 at different positions at the bottom of the coupling-out region 3, the peak position of the diffraction efficiency curve can be controlled.

[0119] In one example, see Figures 3 to 5 The substrate 1 of the diffractive optical structure has a refractive index of 1.9, and the residual layer 4 has a refractive index of 2.4, with a refractive index difference Δn of 0.5. This refractive index difference Δn has a direct impact on the performance of the coupling grating.

[0120] See Figure 3 In the initial state, when the residual layer thickness is 100 nm, the peak value of the diffraction efficiency curve of the coupling grating appears at a large angle of 84°. This indicates that under the condition of a thicker residual layer, the diffraction effect of light in the coupling grating causes the peak value of the diffraction efficiency to be biased towards a large angle.

[0121] See Figure 4As light propagates towards the rear end within the coupling grating, the peak position of the diffraction efficiency curve of the coupling grating changes. Specifically, when the thickness of the residual layer 4 decreases, the peak diffraction efficiency shifts towards a smaller angle. This phenomenon demonstrates the close relationship between the thickness of the residual layer 4 and the peak angle of the diffraction efficiency curve.

[0122] To further verify this relationship, experimental adjustments were made. When the thickness of the residual layer 4 was reduced to 50 nm, the peak value of the diffraction efficiency curve shifted to 62°, indicating that by adjusting the thickness of the residual layer 4, the peak position of the efficiency curve of the coupling grating can be effectively controlled.

[0123] See Figure 5 Finally, the thickness of the residual layer 4 was further reduced to explore its further impact on the peak angle of the diffraction efficiency curve. When the thickness of the residual layer 4 was reduced to only 10 nm, the peak angle of the diffraction efficiency curve shifted to 36°, further confirming the negative correlation between the thickness of the residual layer 4 and the peak angle of the diffraction efficiency. This relationship is of great significance for optimizing the grating design in the uncoupled region and improving light transmission efficiency.

[0124] In summary, by controlling the thickness of the residual layer 4, the peak position of the diffraction efficiency curve of the uncoupled grating can be effectively adjusted, thereby meeting the needs of different application scenarios.

[0125] In another example, see Figures 6 to 8 The substrate 1 of the diffractive optical structure has a refractive index of 1.7, and the residual layer 4 has a refractive index of 1.9, with a refractive index difference Δn of 0.2. This refractive index difference Δn has a direct impact on the performance of the coupling grating.

[0126] See Figure 6 When the thickness of the residual layer 4 is 300 nm, the peak of the diffraction efficiency curve of the coupled grating appears at a large angle position of 66°.

[0127] See Figure 7 As light travels from the front end to the rear end of the coupling grating, the peak position of the efficiency curve of the coupling grating shifts. Specifically, the peak diffraction efficiency shifts towards a smaller angle as the thickness of the residual layer 4 decreases.

[0128] To more intuitively illustrate this change, further experimental adjustments were made. When the thickness of the residual layer 4 was reduced to 150 nm, the peak value of the diffraction efficiency curve of the coupling grating shifted to approximately 50°. This result further reinforces the negative correlation between the thickness of the residual layer 4 and the peak angle of the diffraction efficiency curve.

[0129] See Figure 8 When the thickness of the residual layer 4 was further reduced to only 10 nm, the peak angle of the efficiency curve of the coupling grating shifted to a position less than 30°. This confirms the ability of the thickness of the residual layer 4 to control the peak position of the diffraction efficiency curve.

[0130] In summary, by adjusting the thickness of the residual layer 4, the peak position of the coupling grating efficiency curve in the coupling region 3 can be flexibly adjusted, thereby meeting the diverse requirements for light transmission efficiency in practical applications.

[0131] In some examples of this application, the diffractive optical structure further includes a transition region disposed on the substrate 1 and located between the optical paths of the coupling-in region 2 and the coupling-out region 3, wherein the residual layer 4 can extend from the coupling-out region 3 to at least a portion of the transition region.

[0132] In this example of the application, the diffractive optical structure not only includes the coupling-in region 2 and the coupling-out region 3, but also adds a transition region ( Figure 1 (Not shown in the image). Specifically, this transition zone is disposed on the substrate 1 and located between the optical paths of the coupling-in zone 2 and the coupling-out zone 3. More uniquely, the design of the residual layer 4 is also extended in this example, covering not only the bottom of the coupling-out zone 3 but also extending further to the bottom of the transition zone.

[0133] The introduction of the transition region provides a more flexible and diverse path for light transmission in the diffractive optical structure. By designing the shape and size of the transition region, precise control of the light transmission direction can be achieved, allowing the light to enter the coupling region 3 at the expected angle and direction, thereby further improving the performance and efficiency of the optical system.

[0134] By adjusting parameters such as the thickness and refractive index of the residual layer 4 at the bottom of the transition zone, further control and optimization of light transmission in the transition zone can be achieved, thereby further improving the overall optical performance.

[0135] According to another embodiment of this application, a method for controlling the diffraction efficiency in the non-coupled region is provided for use in diffractive optical structures. See [link to relevant documentation]. Figure 1 The diffractive optical structure includes a substrate 1 and at least one coupling region 2 and at least one coupling region 3 disposed on the substrate 1. The coupling region 3 includes a coupling grating with a residual layer 4, and the refractive index of the residual layer 4 is different from that of the substrate 1, and the difference in refractive index between the two is Δn, 0.1≤Δn≤0.8.

[0136] The method for controlling the diffraction efficiency includes the following steps S100 to S300:

[0137] Step S100: Within the coupling region 3, based on the light transmission path and the required coupling angle, determine the thickness variation trend of the residual layer 4 at each position of the coupling grating, so as to control the peak position of the diffraction efficiency curve of the coupling grating.

[0138] Step S200: External light is coupled into the substrate 1 through the coupling region 2, and the light is transmitted to the coupling region 3 by total internal reflection within the substrate 1.

[0139] Step S300: By adjusting the peak position of the diffraction efficiency curve of the coupling grating through the residual layer 4, the peak value of the diffraction efficiency curve can change according to a predetermined trend during the transmission of light along the length direction of the diffraction optical structure, thereby uniformly coupling out at different positions in the coupling region 3.

[0140] According to step S100 above, this step is the core preprocessing stage of the control method of this application. It requires first clarifying the transmission path of light in the diffractive optical structure and the required light coupling angle at each position. Based on this information, the ideal thickness variation trend of the residual layer 4 at different positions of the coupling grating is calculated.

[0141] According to step S200 above, this step is the actual transmission process of light. The coupling region 2 allows external light to enter the substrate 1. The light is transmitted inside the substrate 1 by total internal reflection, which minimizes light loss and effectively guides the light to the coupling region 3. The realization of this step depends on the optical properties of the substrate material and the structural design of the coupling region.

[0142] According to step S300 above, the design and fabrication of the residual layer 4 allows the peak position of the diffraction efficiency curve of the coupling grating to vary according to the predetermined trend determined in step S100. This variation ensures that light can be uniformly coupled out at different positions in the coupling region 3 as it propagates along the length of the diffractive optical structure. This uniform coupling is crucial for improving the overall efficiency and performance of the diffractive optical structure.

[0143] As light continues to propagate within the coupling region 3, the peak position of the diffraction efficiency curve of the coupling grating changes accordingly due to the variation in the thickness of the residual layer 4. This variation ensures that light can be coupled out at appropriate angles at different positions, thereby achieving efficient and uniform light output from the entire diffractive optical structure.

[0144] By implementing the above steps S100 to S300, the method for controlling the diffraction efficiency in the uncoupled entry region provided in this application achieves the following technical effects:

[0145] (1) Improved diffraction efficiency: By precisely controlling the thickness variation trend of the residual layer 4, the control method of this application can control the peak position of the diffraction efficiency curve of the coupling grating, thereby realizing the uniform coupling of light in the coupling region 3 and improving the diffraction efficiency.

[0146] (2) Enhanced performance of optical structure: The control method of this application optimizes the transmission path and coupling process of light in the diffractive optical structure, reduces light loss, and thus enhances the overall performance of the optical structure.

[0147] In summary, the method for controlling the diffraction efficiency in the non-coupled region provided in this application achieves efficient and uniform coupling of light in the diffractive optical structure by precisely controlling the thickness and refractive index difference of the residual layer, thereby improving the overall performance and efficiency of the optical structure.

[0148] According to another embodiment of this application, an optical device is also provided. The optical device includes an image source and a diffractive optical structure as described above, wherein light emitted from the image source can be incident on a coupling region of the diffractive optical structure.

[0149] The image source is, for example, a projection optical engine.

[0150] The diffractive optical structure is, for example, a diffractive waveguide.

[0151] The diffractive optical structure can be configured in two parts: one diffractive optical structure corresponds to the user's left eye, and the other diffractive optical structure corresponds to the user's right eye.

[0152] The optical device provided in this application embodiment is, for example, an AR optical display device. Further, the AR optical display device may be, for example, AR smart glasses or an AR smart helmet.

[0153] The specific implementation of the optical device in this application can refer to the above-described embodiments of the diffractive optical structure. Therefore, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, and will not be described in detail here.

[0154] 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.

[0155] 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 diffractive optical structure, characterized in that, Includes a substrate (1) and a component disposed on the substrate (1): At least one coupling region (2) is used to couple external light into the substrate (1); At least one coupling region (3) is used to dilate and couple the light beam; The coupling region (3) is provided with a coupling grating having a residual layer (4), and the residual layer (4) has a set thickness variation trend at different positions of the coupling grating to control the coupling intensity of light. The refractive index of the residual layer (4) is different from that of the substrate (1), and the difference in refractive index between the two is Δn, 0.1≤Δn≤0.8; The coupling region (3) is configured such that, during the transmission of light along the length direction of the diffraction optical structure, the peak position of the diffraction efficiency curve of the coupling grating is controlled by the thickness variation trend of the residual layer (4) so ​​as to achieve uniform coupling of light at different positions in the coupling region (3). As the light propagates along the length of the diffractive optical structure, the thickness of the residual layer (4) gradually decreases, causing the peak position of the diffraction efficiency curve of the coupling grating to gradually shift from a large angle to a small angle along the propagation path of the light. The thickness of the residual layer (4) is RSL, RSL*△n=C, C is a constant, and 2mm≤C≤60mm.

2. The diffractive optical structure according to claim 1, characterized in that, The refractive index difference Δn between the residual layer (4) and the substrate (1) is: 0.2≤Δn≤0.

5.

3. The diffractive optical structure according to claim 1, characterized in that, The thickness of the residual layer (4) is RSL, and 10nm≤RSL≤300nm.

4. The diffractive optical structure according to claim 1, characterized in that, The residual layer (4) is made of glue.

5. The diffractive optical structure according to claim 1, characterized in that, The residual layer (4) is made of inorganic materials, including titanium oxide, aluminum oxide, silicon oxide or silicon nitride.

6. The diffractive optical structure according to claim 1, characterized in that, Within the coupling region (3), the coupling grating includes a front end, a middle part, and a rear end; The thickness of the residual layer (4) at the front end of the coupling grating is 100nm to 300nm, and the peak position of the diffraction efficiency curve of the coupling grating is 65° to 85°. The thickness of the residual layer (4) in the middle of the coupling grating is 50 nm to 150 nm, and the peak position of the diffraction efficiency curve of the coupling grating is between 50° and 65°. The thickness of the residual layer (4) at the rear end of the coupling grating is 5nm to 15nm, and the peak position of the diffraction efficiency curve of the coupling grating is between 30° and 50°.

7. The diffractive optical structure according to any one of claims 1-6, characterized in that, The diffractive optical structure further includes a transition region, which is disposed on the substrate (1) and located between the optical paths of the coupling-in region (2) and the coupling-out region (3), and the residual layer (4) can extend from the coupling-out region (3) to at least part of the transition region.

8. A method for controlling the diffraction efficiency in the non-coupled region, used in diffractive optical structures, characterized in that, The diffractive optical structure includes a substrate (1) and at least one coupling region (2) and at least one coupling region (3) disposed on the substrate (1). The coupling region (3) includes a coupling grating with a residual layer (4). The residual layer (4) has a different refractive index than the substrate (1), and the difference in refractive index between the two is Δn, 0.1≤Δn≤0.

8. The methods for controlling the diffraction efficiency include: Within the coupling region (3), the thickness variation trend of the residual layer (4) at each position of the coupling grating is determined according to the light transmission path and the required coupling angle, so as to control the peak position of the diffraction efficiency curve of the coupling grating. The light from the outside is coupled into the substrate (1) through the coupling region (2), and the light is transmitted to the coupling region (3) by total internal reflection within the substrate (1). By controlling the peak position of the diffraction efficiency curve of the coupling grating through the residual layer (4), the peak value of the diffraction efficiency curve can change according to a predetermined trend during the transmission of light along the length direction of the diffraction optical structure, thereby uniformly coupling out at different positions in the coupling region (3).

9. An optical device, characterized in that, include: Image source; and According to any one of claims 1-7, the diffractive optical structure, the light emitted from the image source can be incident on the coupling region (2).

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