A modulated optical waveguide and near-eye display device

Abstract

This application relates to the field of optical technology, specifically disclosing a modulated optical waveguide and a near-eye display device. The modulated optical waveguide includes a waveguide substrate, which includes an insertion region, a transition region, and an exit region. The transition region is used to receive and couple the image light from the insertion region. The transition region includes a transition sub-region and a transition transition region disposed between two adjacent transition sub-regions. The exit region is disposed on one side of the transition region and is used to receive the image light from the transition region and couple it out to the human eye. The exit region includes an exit sub-region and an exit transition region disposed between two adjacent exit sub-regions. The depth modulation speed and aspect ratio of the transition sub-region and the exit sub-region are progressively increased along the beam propagation direction. This modulated optical waveguide can eliminate the influence of interference fringes generated in the transition region on the uniformity and imaging quality of the image within the eye box, thereby improving the brightness uniformity and imaging quality within the eye box.

Description

Technical Field

[0001] This application relates to the field of optical technology, and in particular to a modulated optical waveguide and near-eye display device. Background Technology

[0002] Augmented Reality (AR) technology is a technology that integrates computer-generated virtual information with the real environment. It can dynamically overlay virtual information onto the real world in real time, thereby enhancing users' perception and understanding of the real world. In current AR display devices, diffractive waveguides based on surface relief gratings are the mainstream technical solution. On the one hand, it can achieve two-dimensional exit pupil expansion by allowing light beams to be transmitted through total internal reflection within the waveguide through the diffraction of the surface relief grating, thus realizing a larger eyebox. On the other hand, surface relief gratings can be replicated at low cost on a large scale based on mature semiconductor technology and nanoimprint technology. Therefore, it is widely used in AR glasses, AR helmets, or AR head-up display devices.

[0003] To achieve image uniformity at different locations within the eyebox generated by two-dimensional exit pupil expansion, related technologies modulate the transition region to achieve different diffraction efficiencies in the surface relief gratings of different areas of the optical waveguide. This ensures consistent image uniformity observed by the human eye at different locations within the eyebox during exit pupil expansion. However, in these technologies, the modulated optical waveguide experiences coherent or destructive interference at the transition region during beam expansion and propagation towards the coupling region, leading to significant changes in beam intensity. This, in turn, affects the brightness uniformity and image quality within the eyebox. Summary of the Invention

[0004] This application aims to provide a modulated optical waveguide and near-eye display device to at least solve the problem in the prior art where coherent or destructive interference occurs in the transition region when the light beam expands and propagates to the coupling region, resulting in significant changes in beam intensity and reduced brightness uniformity and imaging quality within the eye box.

[0005] In a first aspect, embodiments of this application provide a modulation optical waveguide, the modulation optical waveguide comprising a waveguide substrate, the waveguide substrate comprising:

[0006] A coupling region, wherein the coupling region is used to couple image rays into the waveguide substrate;

[0007] A transition region is provided on one side of the coupling region. The transition region is used to receive and couple the image light from the coupling region. The transition region includes at least two transition sub-regions and a transition transition region provided between two adjacent transition sub-regions.

[0008] A coupling region is disposed on one side of the turning region. The coupling region is used to receive image light from the turning region and couple it out to the human eye. The coupling region includes at least two coupling sub-regions and a coupling transition region disposed between two adjacent coupling sub-regions.

[0009] The depth modulation speed and aspect ratio of the at least two turning sub-regions and the at least two coupling sub-regions along the beam propagation direction are set to increase progressively.

[0010] In some embodiments, the transition sub-region and the transition transition region are alternately arranged along a first direction, and the coupling sub-region and the coupling transition region are alternately arranged along a second direction, wherein the first direction and the second direction intersect.

[0011] In some embodiments, the linewidth of the transition region is equal to the maximum linewidth of the two adjacent transition sub-regions, and the linewidth of the coupling transition region is equal to the maximum linewidth of the two adjacent coupling sub-regions.

[0012] In some embodiments, the depth modulation rate and aspect ratio of the at least two transition sub-regions along the first direction to the region adjacent to the coupling region are progressively increased, wherein the minimum depth modulation rate of the at least two transition sub-regions satisfies: ;

[0013] In the formula, k is the minimum depth modulation speed, Δh is the depth change value of the transition sub-region corresponding to the minimum modulation speed, and d is the minimum distance when the beams at different incident angles undergo total internal reflection transmission once in the optical waveguide.

[0014] In some embodiments, the depth modulation rate p of the transition region and the coupling transition region satisfies the following range: .

[0015] In some embodiments, the number of sub-regions in the transition region and the coupling region ranges from 5. In the formula, This represents the number of sub-regions within the transition region. The number of sub-regions in the coupled region.

[0016] In some embodiments, depth gradient modulation is used within the transition region and within individual sub-regions of the coupling region, and linewidth modulation is used between sub-regions.

[0017] In some embodiments, the aspect ratio λ of each sub-region in the transition region and the coupling region satisfies the following range: .

[0018] In some embodiments, the depth variation range of the transition region and each sub-region in the coupling region satisfies: .

[0019] Compared with the prior art, the technical solution provided in the first aspect of this application has at least the following beneficial effects or advantages:

[0020] The modulation waveguide of this application sets the transition region as multiple transition sub-regions and a transition transition region between two adjacent transition sub-regions, and sets the coupling region as multiple coupling sub-regions and a coupling transition region between two adjacent coupling sub-regions. The multiple transition sub-regions and multiple coupling sub-regions are configured with increasing depth modulation speed and aspect ratio along the beam propagation direction, improving the diffraction efficiency of the grating along the modulation direction. Simultaneously, in the transition region, when the beam interacts with the grating, the phase changes when the R0 and R1 orders of the beam meet again, preventing them from satisfying the Mach-Zehnder interference expansion or depletion conditions, thus making the light intensity entering the coupling region more uniform. The transition region connects two adjacent sub-regions, making the entire modulation region smoother and reducing the contrast between the two adjacent sub-regions. By controlling the modulation speed and aspect ratio of the transition region and coupling region, the influence of interference fringes generated in the transition region on the uniformity and imaging quality of the image within the eye box can be eliminated, and the brightness within the eye box can be significantly improved.

[0021] Secondly, embodiments of this application provide a near-eye display device, the near-eye display device including the modulation optical waveguide described in any of the first aspects above.

[0022] It is understandable that the beneficial effects of the second aspect mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here.

[0023] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of a modulation optical waveguide provided according to an embodiment of this application;

[0026] Figure 2This is yet another schematic diagram of a modulated optical waveguide provided according to an embodiment of this application;

[0027] Figure 3 It is a line graph showing the rate of change of depth in the transition region according to an embodiment of this application;

[0028] Figure 4 This is a line graph showing the rate of change of the depth of the coupling region according to an embodiment of this application;

[0029] Figure 5 It is a line graph showing the aspect ratio changes at different positions of the transition area according to the embodiments of this application;

[0030] Figure 6 It is a line graph showing the aspect ratio variation at different locations of the coupling region according to the embodiments of this application;

[0031] Figure 7 This is a schematic diagram of the modulated optical waveguide in use according to an embodiment of this application.

[0032] Figure label:

[0033] 100. Modulated optical waveguide; 101. Waveguide substrate;

[0034] 10. Coupling in region; 20. Turning point region; 21. Turning sub-region; 211. First turning sub-region; 212. Second turning sub-region; 213. Third turning sub-region; 22. Turning transition region; 221. First turning transition region; 222. Second turning transition region; 30. Coupling out region; 31. Coupling out sub-region; 311. First coupling out sub-region; 312. Second coupling out sub-region; 32. Coupling out transition region; 321. First coupling out transition region;

[0035] 200, Micro-optical machine; 300, Human eye; Y, First direction; X, Second direction. Detailed Implementation

[0036] The embodiments of this application are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. It should be understood that the specific embodiments described herein are merely for explaining this application and are not intended to limit this application.

[0037] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0039] In current AR display devices, diffractive waveguides based on surface relief gratings are the mainstream technical solution. In current diffractive waveguide display devices, in order to achieve the uniformity of the image at different positions within the Eyebox generated by the two-dimensional exit pupil expansion, the surface relief gratings in different areas of the waveguide need to achieve different diffraction efficiencies. This ensures that the image observed by the human eye at different positions within the Eyebox has consistent uniformity when achieving exit pupil expansion.

[0040] One current approach to achieving consistent image uniformity across different locations within the eyebox involves discretizing the transition and coupling regions along the expansion direction and modulating grating parameters (such as depth and duty cycle) within each region to alter the diffraction efficiency of the gratings in different areas, thereby improving image uniformity. However, the inventors have discovered that this approach, due to the discretization of the transition region and the uniformity of grating parameters within each region, exhibits a Mach-Zehnder interference-like optical path during expansion and propagation towards the coupling region. This results in destructive or constructive interference of the beam reaching the coupling region, ultimately leading to interference effects within the eyebox. This reduces brightness uniformity and image resolution within the eyebox. Furthermore, the discretized modulation also increases the contrast between the diffracted waveguide structure and the unstructured region.

[0041] In another technical solution, perturbation patterns are added to the grating in the transition region, such as a structure with a period much larger than that of the extended grating, to disrupt the coherence or destructive conditions of the beams in the interference. However, the inventors found that the transition region contains two grating structures, which increases the difficulty of processing. Furthermore, the introduced perturbation structure causes stray light to exist inside the eyebox, reducing the imaging resolution and imaging contrast.

[0042] Based on this, the inventors propose a modulated optical waveguide that solves the problem that when the beam expands and propagates to the coupling region, the beam undergoes coherent or destructive interference in the turning region, resulting in significant changes in beam intensity, which in turn affects the brightness uniformity and imaging quality within the eyebox. It also addresses the problem that when the diffractive optical waveguide performs discrete partitioning modulation in the turning and coupling regions, the discrete changes in parameters between the grating regions lead to excessively high contrast between the regions and between the grating and non-grating regions.

[0043] Please see Figure 1 This embodiment provides a modulation optical waveguide 100, which includes a waveguide substrate 101. The waveguide substrate 101 includes a coupling-in region 10, a transition region 20, and a coupling-out region 30. The coupling-in region 10 is used to couple image light into the waveguide substrate 101. The transition region 20 is disposed on one side of the coupling-in region 10 and is used to receive and couple the image light from the coupling-in region 10. The transition region 20 includes at least two transition sub-regions 21 and a transition transition region 22 disposed between two adjacent transition sub-regions 21. The coupling-out region 30 is disposed on one side of the transition region 20 and is used to receive the image light from the transition region 20 and couple it out to the human eye. The coupling-out region 30 includes at least two coupling-out sub-regions 31 and a coupling-out transition region 32 disposed between two adjacent coupling sub-regions 31. The depth modulation speed and aspect ratio of the at least two transition sub-regions 21 and the at least two coupling-out sub-regions 31 along the beam propagation direction are progressively increased.

[0044] It should be noted that the optical waveguide substrate 101 of the modulation optical waveguide 100 can be a single or multiple substrate structure. The substrate can be glass, resin, plastic, transparent ceramic, or a combination thereof. In this embodiment, the beam propagation direction is not the same in the turning region 20 and the coupling region 30. The turning sub-region 21 and the turning transition region 22 are alternately arranged along the first direction Y, and the coupling sub-region 31 and the coupling transition region 32 are alternately arranged along the second direction X. The first direction Y and the second direction X intersect. Figure 1 For ease of description, the dividing direction along the transition region 20 is defined as the first direction Y, and the dividing direction along the coupling region 30 is defined as the second direction X. One end of the transition region 20 is set close to the coupling region 10, and the other end extends away from the coupling region 10 along the first direction Y. That is, the beam expansion direction in the transition region 20 is the first direction Y. In the coupling region 30, one end of the coupling region 30 is set close to the transition region 20, and the other end extends away from the transition region 20 along the second direction X. That is, the beam expansion direction in the coupling region 30 is the second direction X.

[0045] The division of transition sub-regions 21 and 22 in transition region 20, and the division of coupling sub-regions 31 and 32 in coupling region 30, can be achieved by using multi-field input and optical field tracing to obtain thermal maps of the transition region 20 and coupling region 30 of the optical waveguide, and by using the thermal map index (hot map index). The region is divided using the index. It should be explained that multi-field input refers to inputting light rays from multiple different angles (fields of view) into the waveguide during optical simulation or testing, simulating the scene observed by the user's eye at different positions in real-world applications. Multi-field input can comprehensively evaluate the waveguide's performance across the entire field of view. Optical field tracing differs from traditional ray tracing (which only tracks the geometric path). Optical field tracing is a simulation method that simultaneously calculates the amplitude, phase, polarization, and propagation direction of light. Based on wave optics theory, it more accurately simulates the interference and diffraction behavior of light waves in microstructures. The thermal index is a threshold index for quantifying energy distribution. Boundary values ​​can be set empirically, and the transition region 20 and coupling region 30 are divided into sub-regions and transition regions based on the boundary values ​​and the thermal index.

[0046] It should also be noted that, for the transition sub-region 21 of the transition region 20, depth gradient modulation is used within a single transition sub-region 21, that is, the modulation speed in each sub-region along the first direction Y is progressively increased; linewidth modulation is used between each sub-region, and for the linewidth data value of each sub-region, the ratio of the maximum depth of each sub-region to its corresponding linewidth, that is, the depth-to-width ratio H / L, needs to gradually increase; for the coupling sub-region 31 of the coupling region 30, depth gradient modulation is used within a single coupling sub-region 31, and the modulation speed in each sub-region along the second direction X is progressively increased; linewidth modulation is used between each sub-region, and the ratio of the maximum depth of each sub-region to its corresponding linewidth, that is, the depth-to-width ratio H / L, needs to gradually increase.

[0047] In this embodiment, the modulated optical waveguide 100 is configured by setting the transition region 20 as a plurality of transition sub-regions 21 and a transition transition region 22 between two adjacent transition sub-regions 21, and by setting the coupling region 30 as a plurality of coupling sub-regions 31 and a coupling transition region 32 between two adjacent coupling sub-regions 31. The depth modulation speed and aspect ratio of the plurality of transition sub-regions 21 and the plurality of coupling sub-regions 31 are progressively increased along the beam propagation direction, thereby improving the diffraction efficiency of the grating along the modulation direction. Simultaneously, the transition region 20 enables the beam to... When interacting with the grating, the phase changes when the R0 and R1 orders meet again, causing them to no longer satisfy the Mach-Zehnder interference expansion or depletion conditions, thus making the light intensity entering the coupling region 30 more uniform. By setting a transition region to connect two adjacent sub-regions, the entire modulation region becomes smoother and the contrast between the two adjacent sub-regions is reduced. By controlling the modulation speed and aspect ratio, the transition region 20 and the coupling region 30 can eliminate the influence of interference fringes generated by the transition region 20 on the uniformity and imaging quality of the image inside the eye box, and can also significantly improve the brightness inside the eye box.

[0048] In some embodiments, the number of sub-regions in the transition region 20 and the coupling region 30 must satisfy the following range: 5 In the formula, This represents the number of sub-regions within transition region 20. This refers to the number of sub-regions in the coupling region 30. For example, the transition sub-region 21 in the transition region 20 can be divided into two, three, or four sub-regions. Similarly, the coupling sub-region 31 in the coupling region 30 can also be divided into two, three, or four sub-regions. The specific value within this range can be selected according to actual needs.

[0049] With this configuration, if the number of sub-regions divided into the transition region 20 or the coupling region 30 is less than two, discrete gradient modulation cannot be achieved. At the same time, this design is actually a continuous gradient modulation. When the beam expands and is transmitted to the coupling region 30, the beam undergoes coherent or destructive interference in the transition region 20, resulting in a significant change in beam intensity, which in turn affects the brightness uniformity and imaging quality within the eyebox. If the number of sub-regions is greater than five, there will be too many transition regions, leading to increased manufacturing difficulty and performance saturation.

[0050] Meanwhile, the number of sub-regions divided into transition region 20 and coupling region 30 can be the same or different. For transition transition region 22 and coupling transition region 32, they are respectively set between two transition sub-regions 21 or two coupling sub-regions 31. For example, when there are two transition sub-regions 21 or coupling sub-regions 31, there is one transition transition region 22 or coupling transition region 32. When there are three transition sub-regions 21 or coupling sub-regions 31, there are two transition transition regions 22 or coupling transition regions 32. That is, if transition region 20 is divided into M sub-regions, it should contain M-1 transition transition regions 22. Similarly, if coupling region 30 is divided into N sub-regions, it should contain N-1 coupling transition regions.

[0051] The setting of transition region 22 or coupling transition region 32 can connect two adjacent sub-regions, making the entire modulation area smoother and reducing the contrast between the two adjacent sub-regions. Specifically, in discrete partition modulation, the sub-regions of transition region 20 and coupling region 30 need to have their grating parameters (such as depth and linewidth) set independently. If there is no transition region between sub-regions, the parameters will change at the boundary, resulting in a sudden change in the aspect ratio (H / L). This sudden change will significantly amplify the visual contrast between the grating structure area and the unstructured area, affecting the image quality. The transition region achieves a smooth transition through linewidth modulation and depth gradient, ensuring continuous change in aspect ratio and avoiding obvious color difference or light-dark boundary lines at the boundary.

[0052] In some embodiments, the linewidth setting of the transition region 22 needs to satisfy the condition that it is equal to the maximum linewidth of the two adjacent transition sub-regions 21, and the linewidth setting of the coupling transition region 32 needs to satisfy the condition that it is equal to the maximum linewidth of the two adjacent coupling sub-regions 31; for example, assuming that the linewidths of the two adjacent transition sub-regions 21 are L1 and L2 respectively, then the linewidth L of the transition region 22 of the two adjacent transition sub-regions 21 is set to... 12 =(L 1， Similarly, assuming the line widths of two adjacent coupling sub-regions 31 are L3 and L4 respectively, then the line width L of the transition region 22 of the two adjacent transition sub-regions 21 is set to... 34 =(L 3， L4), by limiting the linewidth of the transition region, the rate of change can be effectively reduced, and a smoother gradient of parameters and light field can be achieved between adjacent sub-regions with different optical parameters (especially linewidth, depth modulation speed, and aspect ratio).

[0053] Meanwhile, based on actual production and processing considerations, the size of the transition region 22 or the coupling transition region 32 along the first direction Y (beam expansion direction) can be set between 0.5mm and 2mm, depending on actual needs. However, it should be noted that for the transition region 20 or the coupling region 30, if the number of sub-regions is smaller and the size of the sub-regions along the expansion direction is larger, the size of the transition region along the expansion direction needs to be increased to make the transition smoother.

[0054] In some embodiments, the depth modulation speed and aspect ratio of at least two transition sub-regions 21 to the adjacent coupling region 10 along the first direction Y are progressively increased, wherein the minimum depth modulation speed of at least two transition sub-regions 21 satisfies: (1);

[0055] In the formula, k is the minimum depth modulation speed, Δh is the depth change value of the transition sub-region 21 corresponding to the minimum modulation speed, and d is the minimum distance when the beams at different incident angles undergo total internal reflection transmission once in the optical waveguide.

[0056] It should be explained that, in this embodiment, the depth modulation speed and aspect ratio of the multiple transition sub-regions 21 set from the near coupling region 10 along the first direction Y are progressively set. By adopting discrete partitioned gradual depth modulation, since the energy of the beam gradually attenuates during total internal reflection transmission in the waveguide, the progressive aspect ratio design makes the diffraction efficiency of the subsequent sub-regions higher, offsetting the energy loss and enhancing the interaction intensity between the light wave and the micro-nano structure, thereby significantly improving the diffraction efficiency. It can obtain better brightness uniformity in the Eyebox while ensuring that there are no interference fringes in the transition region 20, which can significantly improve the brightness of the user's eyes when using the diffractive waveguide.

[0057] During the modulation process in the transition region 20 of the related technology, when the beam expands and propagates to the coupling region 30, Mach-Zehnder interference (MZI) is induced due to the consistency of the partition parameters. Specifically, the phase difference between the R0 order (zero-order reflection) and the R1 order (first-order diffraction) optical paths is fixed, resulting in destructive interference (dark area) or diffraction (bright area), causing brightness fluctuations and resolution reduction within the Eyebox (the intensity changes are caused by coherent or destructive interference of the beam). The R0 order refers to the beam or order that exits along the specular reflection direction after the beam illuminates the periodic structure (such as a grating); the R1 order refers to the beam or order that deviates from the specular reflection direction after the beam illuminates the periodic structure and is its lowest non-zero diffraction order (positive first or negative first order).

[0058] And through the minimum depth modulation speed of the transition sub-region 21 closest to the coupling region 10 To impose restrictions, that is The minimum value needs to satisfy greater than When the depth modulation speed satisfies formula (1), the phase of the beam changes when the R0 order and R1 order meet again when the beam interacts with the grating, so that the conditions for Mach-Zehnder interference are not met, thus avoiding the beam reaching the coupling region 30 from exhibiting destructive or constructive interference, so that the light intensity entering the coupling region 30 is more uniform; thus improving the brightness uniformity and image resolution within the Eyebox.

[0059] In some embodiments, the depth modulation rate p of the transition region 22 and the coupling transition region 32 satisfies the following range: (2) Unlike the transition sub-region 21 and the coupling sub-region 31, the depth modulation speed of the transition region 22 and the coupling transition region 32 needs to satisfy the above interval (2), wherein, if If the phase perturbation is insufficient, the R0 and R1 order beams will have residual destructive interference at the sub-region boundary, leading to a decrease in brightness uniformity within the eyebox. Based on the current process conditions, due to the small transition zone, a rapid change in the rate will significantly increase the process difficulty, thereby affecting production efficiency and increasing production difficulty.

[0060] In some embodiments, depth gradient modulation is used within a single sub-region of the transition region 20 and the coupling region 30, and linewidth modulation is used between sub-regions. The range of the depth-to-width ratio λ of each sub-region of the transition region 20 and the coupling region 30 satisfies: The depth h of each sub-region in the transition region 20 and the coupling region 30 varies within the range that satisfies: .

[0061] It should be noted that the aspect ratio settings for each transition sub-region 21 and coupling sub-region 31 in the transition region 20 and coupling region 30 are as follows: This ensures the structure has sufficient "depth" to generate the required phase modulation or diffraction effects, thus maintaining the diffraction efficiency needed for critical waveguide, deflection, and coupling functions. If H / L is too small (e.g., close to 0), the structure height is too shallow, and its modulation capability will drop sharply (diffraction efficiency is too low), making it unable to effectively deflect or couple light rays. This design avoids excessively "deep and steep" structures that would lead to increased light scattering on their sidewalls. In other words, the aspect ratio within this range reduces visual interference from the grating structure when the user observes the external environment. This reduces the contrast between the structured and unstructured areas (i.e., reduces the visibility of the grating) while maintaining modulation effects. Furthermore, the depth h of each sub-region in the transition region 20 and the coupling region 30 varies within a range of 15nm-80nm, effectively reducing the contrast between the structured and unstructured areas.

[0062] Please see Figures 2 to 6 To verify the effect of the structural arrangement in the modulated optical waveguide 100 in the above embodiments, this embodiment proposes a modulated optical waveguide 100 based on the above embodiments. In the waveguide substrate 101 of the modulated optical waveguide 100, the sub-regions divided by the transition region 20 include a first transition sub-region 211, a second transition sub-region 212, and a third transition sub-region 213. Simultaneously, a first transition transition region 221 is provided between the first transition sub-region 211 and the second transition sub-region 212, and a second transition transition region 222 is provided between the second transition sub-region 212 and the third transition sub-region 213. The first transition sub-region 211, the first transition transition region 221, the second transition region 212, the second transition transition region 222, and the third transition sub-region 213 are arranged along the first direction Y. Figure 3 The depth change rates of the first transition sub-region 211, the first transition transition region 221, the second transition sub-region 212, the second transition transition region 222, and the third transition sub-region 213 are k11, p1-12, k12, p1-23, and k23, respectively, where: k11=1.2nm / mm, p1-12=5.7nm / mm, k12=1.67nm / mm, p1-23=4.5nm / mm, and k13=1.78nm / mm.

[0063] The sub-regions of the coupling region 30 include a first coupling sub-region 311 and a second coupling sub-region 31. A first coupling transition region 321 is set between the first coupling sub-region 311 and the second coupling sub-region 31. The first coupling sub-region 311, the first coupling transition region 321, and the second coupling sub-region 31 are arranged along the second direction X. Figure 4 The coupling region 30 is discretely divided into three line segments: the first coupling sub-region 311, the first coupling transition region 321, and the second coupling sub-region 31. The depth change rates are k21=1.15nm / mm, p2-12=16nm / mm, and k23=2nm / mm from left to right.

[0064] Meanwhile, for the three discrete regions in the transition region 20, the linewidths L1 of the first transition sub-region 211, the second transition sub-region 212, and the third transition sub-region 213 are 129nm, 150nm, and 106nm, respectively. Therefore, the aspect ratios corresponding to each position of the first transition sub-region 211, the second transition sub-region 212, and the third transition sub-region 213 in the first direction Y can be found in [reference needed]. Figure 5As shown, for the two discrete regions in the coupling region 30, the linewidths L2 of the first coupling sub-region 311 and the second coupling sub-region 31 are 182nm and 138nm, respectively. Therefore, the aspect ratio of each position in the first coupling sub-region 311 and the second coupling sub-region 31 along the second direction X can be found in [reference needed]. Figure 6 As shown.

[0065] In this embodiment, the modulation waveguide 100 configured in the aforementioned transition region 20 and coupling region 30 was used to conduct experimental tests on the light intensity at different Pupil locations within the Eyebox. The obtained light intensity data is shown in Table (1). It should be noted that the data in Table (1) represents the average light intensity within each of the 6x4 sub-regions of the entire Eyebox, used to evaluate the uniformity and efficiency within the Eyebox. It can be concluded that good brightness uniformity (minimum light intensity / maximum light intensity) and average light intensity are achieved within the Eyebox. The brightness uniformity within the entire Eyebox is 88%, and the average light intensity is 0.01 (V / m). 2 .

[0066] Table (1) shows the light intensity at different locations of the Pupil within the EyeBox optical waveguide in this implementation.

[0067]

[0068] Similarly, for optical waveguides using traditional modulation methods, the light intensity at different Pupil locations within the Eyebox was experimentally tested as a comparative example. The obtained light intensity data is shown in Table (2). It should be noted that the data in Table (2) represents the average light intensity within each of the 6x4 sub-regions of the entire Eyebox region, used to evaluate the uniformity and efficiency within the Eyebox. It can be concluded that the brightness uniformity reaches 87%, but the average light intensity is only 0.0063 (V / m). 2 .

[0069]

[0070] The light intensity results measured at different Pupil locations within the EyeBox in two sets of experiments show that the modulated optical waveguide 100 in this implementation, by adopting discrete partitioned gradient depth modulation, can achieve better brightness uniformity within the Eyebox while ensuring no interference fringes in the transition region 20, and its evaluated light intensity can be increased by more than 50%, which can significantly improve the brightness entering the eye when the user uses the diffractive optical waveguide.

[0071] Please see Figure 7In some embodiments, a near-eye display device is also provided, which includes the modulation waveguide 100 described in any of the above embodiments. Specifically, the micro-optomechanical system 200 in the near-eye display device emits image light. The coupling region 10 of the modulation waveguide 100 is used to couple the image light into the waveguide substrate 101. The turning region 20 receives the image light from the coupling region 10 and couples it to the output region 30. The output region 30 then receives the image light from the turning region 20 and couples it out to the human eye 300, enabling the user to observe real-world scenes with a wide field of view and obtain better brightness uniformity and imaging quality within the Eyebox.

[0072] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the invention.

[0073] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0074] Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. The reference to "embodiment" herein means that a specific feature, structure, or characteristic described in connection with an embodiment can be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily indicate the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0075] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A modulated optical waveguide, characterized in that, The modulated optical waveguide includes a waveguide substrate, and the waveguide substrate includes: A coupling region, wherein the coupling region is used to couple image rays into the waveguide substrate; A transition region is provided on one side of the coupling region. The transition region is used to receive and couple the image light from the coupling region. The transition region includes at least two transition sub-regions and a transition transition region provided between two adjacent transition sub-regions. A coupling region is disposed on one side of the turning region. The coupling region is used to receive image light from the turning region and couple it out to the human eye. The coupling region includes at least two coupling sub-regions and a coupling transition region disposed between two adjacent coupling sub-regions. The depth modulation speed and aspect ratio along the beam propagation direction between the at least two turning sub-regions and between the at least two coupling sub-regions are set to increase sequentially. The linewidth of the transition region is equal to the maximum linewidth of the two adjacent transition sub-regions, and the linewidth of the coupling transition region is equal to the maximum linewidth of the two adjacent coupling sub-regions.

2. The modulated optical waveguide according to claim 1, characterized in that, The transition sub-region and the transition transition region are alternately arranged along a first direction, and the coupling sub-region and the coupling transition region are alternately arranged along a second direction, wherein the first direction and the second direction intersect.

3. The modulated optical waveguide according to claim 2, characterized in that, The depth modulation speed and aspect ratio of the at least two transition sub-regions along the first direction to the region near the coupling region are progressively increased, wherein the minimum depth modulation speed of the at least two transition sub-regions satisfies: ; In the formula, k is the minimum depth modulation speed, Δh is the depth change value of the transition sub-region corresponding to the minimum modulation speed, and d is the minimum distance when the beams at different incident angles undergo total internal reflection transmission once in the optical waveguide.

4. The modulation optical waveguide according to any one of claims 1-2, characterized in that, The range of values ​​for the depth modulation speed p of the transition region and the coupling transition region satisfies: .

5. The modulated optical waveguide according to claim 1, characterized in that, The number of sub-regions in the transition region and the coupling region ranges from 5. In the formula, This represents the number of sub-regions within the transition region. The number of sub-regions in the coupled region.

6. The modulated optical waveguide according to claim 1, characterized in that, Depth gradient modulation is used within the transition region and within individual sub-regions of the coupling region, while linewidth modulation is used between sub-regions.

7. The modulated optical waveguide according to claim 1, characterized in that, The range of the aspect ratio λ of the turning region and each sub-region in the coupling region satisfies: .

8. The modulated optical waveguide according to claim 1, characterized in that, The depth variation range of the turning region and each sub-region of the coupling region satisfies: .

9. A near-eye display device, characterized in that, The near-eye display device includes the modulation optical waveguide as described in any one of claims 1-8.

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