Diffractive waveguides and near-eye display devices

Abstract

This application provides a diffractive waveguide and a near-eye display device. The diffractive waveguide includes a waveguide substrate, an insertion grating region, an exit grating region, and a transition grating region. The transition grating region includes a first transition grating region, a second transition grating region, and a third transition grating region. The first transition grating region is adjacent to the insertion grating region and the second transition grating region in a first direction, and the third transition grating region is adjacent to the first transition grating region, the second transition grating region, and the exit grating region in a second direction. After a first light ray is coupled into the waveguide substrate in the insertion grating region, the first light ray is transmitted to the exit grating region after passing through the first transition grating region and the third transition grating region in sequence, and then exits the waveguide substrate through the exit grating region. After a second light ray is coupled into the waveguide substrate in the insertion grating region, the second light ray is transmitted to the exit grating region after passing through the first transition grating region, the second transition grating region, and the third transition grating region in sequence, and then exits the waveguide substrate through the exit grating region.

Description

Technical Field

[0001] This application relates to the field of near-eye display technology, and more particularly to a diffractive waveguide and a near-eye display device. Background Technology

[0002] Near-eye display devices can include augmented reality (AR) devices, mixed reality (MR) devices, and so on. Near-eye display devices can utilize optical waveguides to achieve their near-eye display function. Optical waveguides can include diffractive waveguides. Related technologies utilize diffractive waveguides for full-color displays. However, due to the inherent dispersion characteristics of grating diffraction, light of different wavelengths will undergo dispersion after passing through the waveguide substrate coupled to the grating, meaning that different wavelengths of light will have different diffraction angles. This easily leads to differences in the total internal reflection angles of different wavelengths of light propagating within the waveguide substrate, resulting in differences in the number of reflections within the waveguide substrate. Ultimately, upon coupling out, the diffraction efficiency and pupil density of different wavelengths of light will differ. The greater the wavelength difference, the greater the difference in diffraction efficiency and pupil density, such as the significant difference between blue and red light. Therefore, when using diffractive waveguides for full-color displays, there is a problem of poor color uniformity. Summary of the Invention

[0003] This application provides a diffractive waveguide and a near-eye display device, which aims to improve the color uniformity when the diffractive waveguide performs full-color display.

[0004] In a first aspect, this application provides a diffractive optical waveguide, which includes a waveguide substrate, a coupling-in grating region, a coupling-out grating region, and a transition grating region.

[0005] The coupling-in grating region, the coupling-out grating region, and the turning grating region are disposed on the waveguide substrate;

[0006] The transition grating region includes a first transition grating region, a second transition grating region, and a third transition grating region; the first transition grating region is adjacent to the coupled-in grating region and the second transition grating region respectively in a first direction, and the third transition grating region is adjacent to the first transition grating region, the second transition grating region, and the coupled-out grating region respectively in a second direction; the first direction and the second direction are different;

[0007] After the first light ray is coupled into the waveguide substrate in the coupling grating region, the first light ray is transmitted to the coupling out grating region after passing through the first bend grating region and the third bend grating region in sequence, and is coupled out of the waveguide substrate through the coupling out grating region.

[0008] After the second light beam is coupled into the waveguide substrate in the coupling grating region, the second light beam is transmitted to the coupling out grating region after passing through the first bend grating region, the second bend grating region, and the third bend grating region in sequence, and is coupled out of the waveguide substrate through the coupling out grating region; the wavelength of the first light beam is less than the wavelength of the second light beam.

[0009] Secondly, this application provides a near-eye display device, which includes the aforementioned diffractive waveguide.

[0010] This application provides a diffractive waveguide and a near-eye display device. When the transition grating region of the diffractive waveguide includes a first transition grating region, a second transition grating region, and a third transition grating region, the first transition grating region can serve as a wavelength separation region, separating the propagation paths of a first light ray and a second light ray with different wavelengths. For example, the first light ray is transmitted to the third transition grating region after passing through the first transition grating region; the second light ray is transmitted to the second transition grating region after passing through the first transition grating region. Correspondingly, the first light ray transmitted to the third transition grating region can be processed by the third transition grating region to regulate the transmission diffraction efficiency of the first light ray, and then transmitted to the coupling grating region. The second light ray transmitted to the second transition grating region can be processed sequentially by the second transition grating region and the third transition grating region to regulate the transmission diffraction efficiency of the second light ray, and then transmitted to the coupling grating region. Based on this, the transmission diffraction efficiency of the first and second rays with different wavelengths can be adjusted differently, which helps to reduce the difference in transmission diffraction efficiency when the first and second rays are coupled out of the waveguide substrate through the coupling grating region, thereby improving the color uniformity when the diffracted waveguide is used for full-color display. Attached Figure Description

[0011] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a schematic diagram of the structure of a diffractive waveguide provided in an embodiment of this application;

[0013] Figure 2 This is a schematic diagram of the light transmission path of a diffractive waveguide according to an embodiment of this application;

[0014] Figure 3 This is a schematic diagram of the structure of a diffractive waveguide provided in another embodiment of this application;

[0015] Figure 4This is a schematic diagram of the light transmission path of a diffractive waveguide according to another embodiment of this application;

[0016] Figure 5 This is a schematic diagram of the structure of the diffractive waveguide involved in the related technology;

[0017] Figure 6 A full-color simulation diagram of the uniformity of the diffractive waveguide involved in the related technology;

[0018] Figure 7 This is a full-color simulation diagram of the uniformity of the diffractive waveguide involved in this application;

[0019] Figure 8 This is a schematic diagram of the structure of a near-eye display device provided in an embodiment of this application.

[0020] Explanation of reference numerals in the attached figures: 100, diffractive waveguide; 110, waveguide substrate; 120, coupling grating region; 130, coupling out grating region; 140, transition grating region; 141, first transition grating region; 142, second transition grating region; 143, third transition grating region; 1431, first transition grating sub-region; 1432, second transition grating sub-region. Detailed Implementation

[0021] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] The flowchart shown in the attached diagram is for illustrative purposes only and does not necessarily include all content and operations / steps, nor does it necessarily have to be performed in the order described. For example, some operations / steps can be broken down, combined, or partially merged, so the actual execution order may change depending on the actual situation.

[0023] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0024] Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of a diffractive waveguide 100 provided in an embodiment of this application.

[0025] like Figure 1 As shown, the diffractive waveguide 100 includes a waveguide substrate 110, a coupling grating region 120, a coupling out grating region 130, and a transition grating region 140.

[0026] The coupling-in grating region 120, the coupling-out grating region 130, and the turning grating region 140 are disposed on the waveguide substrate 110.

[0027] The transition grating region 140 includes a first transition grating region 141, a second transition grating region 142, and a third transition grating region 143. The first transition grating region 141 is adjacent to the coupled-in grating region 120 and the second transition grating region 142 in a first direction, and the third transition grating region 143 is adjacent to the first transition grating region 141, the second transition grating region 142, and the coupled-out grating region 130 in a second direction. The first direction is different from the second direction.

[0028] After the first light beam is coupled into the waveguide substrate 110 in the coupling grating region 120, the first light beam is transmitted to the coupling out grating region 130 after passing through the first bend grating region 141 and the third bend grating region 143 in sequence, and is coupled out of the waveguide substrate 110 through the coupling out grating region 130.

[0029] After the second light beam is coupled into the waveguide substrate 110 in the coupling grating region 120, the second light beam is transmitted to the coupling out grating region 130 after passing through the first bend grating region 141, the second bend grating region 142 and the third bend grating region 143 in sequence, and is then coupled out of the waveguide substrate 110 through the coupling out grating region 130.

[0030] The wavelength of the first ray is shorter than the wavelength of the second ray.

[0031] like Figure 1 As shown, when the first direction and the second direction are different, the first transition grating region 141 is adjacent to the coupled-in grating region 120 and the second transition grating region 142 in the first direction, similar to how the first transition grating region 141 is longitudinally adjacent to the coupled-in grating region 120 and the second transition grating region 142. The third transition grating region 143 is adjacent to the first transition grating region 141, the second transition grating region 142 and the coupled-out grating region 130 in the second direction, similar to how the third transition grating region 143 is laterally adjacent to the first transition grating region 141, the second transition grating region 142 and the coupled-out grating region 130.

[0032] For example, since the wavelength of the first ray is shorter than the wavelength of the second ray, the first ray can be classified as a short-wavelength ray and the second ray can be classified as a long-wavelength ray.

[0033] When the coupling grating region 120 couples light rays into the waveguide substrate 110, the light rays can include rays of different wavelengths, such as a first ray and a second ray. Therefore, the coupling grating region 120 can couple the first ray and the second ray into the waveguide substrate 110 respectively. Figure 2As shown, since the first bend grating region 141 is adjacent to the coupling grating region 120, both the first and second rays of the coupled waveguide substrate 110 can be transmitted to the first bend grating region 141. The first bend grating region 141 can serve as a wavelength separation region to separate the propagation paths of the first and second rays.

[0034] For example, when designing the first diffraction grating region 141, its properties can be set to: high diffraction efficiency for short-wavelength light and low diffraction efficiency for long-wavelength light. Figure 2 As shown, because the first diffraction grating region 141 has high diffraction efficiency for short-wavelength light and short-wavelength light has a short propagation step size, a large number of short-wavelength light rays, such as the first ray, will be diverted to the third diffraction grating region 143 after passing through the first diffraction grating region 141. Figure 2 As shown, since the first transition grating region 141 has a lower diffraction efficiency for long-wavelength light and the long-wavelength light has a longer propagation step size, a large amount of the long-wavelength light, such as the second light, will enter the second transition grating region 142 after passing through the first transition grating region 141. Based on this, the first transition grating region 141 can separate the propagation paths of the first light and the second light, which is beneficial for controlling light of different wavelengths in the same transition grating region 140.

[0035] For example, when designing the second transition grating region 142, its properties can be set to have high diffraction efficiency for long-wavelength light. Since short-wavelength light, such as the first light, largely propagates along the path of the third transition grating region 143, the characteristics of the second transition grating region 142 for short-wavelength light are not limited in its design; no restrictions are imposed here. The second transition grating region 142 can serve as an area for long-wavelength light, allowing for the control of the diffraction efficiency of long-wavelength light, such as the second light. Figure 2 As shown, after being acted upon by the second turning grating region 142, the second ray can enter the third turning grating region 143.

[0036] For example, when designing the third diffraction grating region 143, its properties can be set to: high diffraction efficiency for short-wavelength light and low diffraction efficiency for long-wavelength light. Based on this, the third diffraction grating region 143 can serve as the area for short-wavelength light, generating the propagation path of short-wavelength light, such as the first light ray. Figure 2As shown, since both the first and second light rays can pass through the third transition grating region 143, the third transition grating region 143 can be used to perform secondary diffraction expansion on the first and second light rays. Correspondingly, since the third transition grating region 143 is adjacent to the coupling grating region 130, both the first and second light rays, after passing through the third transition grating region 143, can be transmitted to the coupling grating region 130 and coupled out of the waveguide substrate 110 through the coupling grating region 130. Furthermore, when the third transition grating region 143 has a lower diffraction efficiency for long-wavelength light rays such as the second light ray, it helps to reduce the loss of the second light ray during transmission in the third transition grating region 143, thereby ensuring that a large number of second light rays can enter the coupling grating region 130 through the third transition grating region 143.

[0037] After the first and second light rays are coupled into the waveguide substrate 110 through the coupling grating region 120, the first light ray can undergo multiple diffraction expansions through the first transition grating region 141 and the third transition grating region 143 in sequence, and the second light ray can undergo multiple diffraction expansions through the first transition grating region 141, the second transition grating region 142, and the third transition grating region 143 in sequence. This helps to improve the uniformity of the first and second light rays. With the improved uniformity of the first and second light rays, it is beneficial to improve the color uniformity when the diffracting waveguide 100 performs full-color display.

[0038] In related technologies, to improve the poor color uniformity of full-color displays using diffractive waveguides, multi-layer diffractive waveguides are often employed. This allows light of different wavelengths to propagate through different layers of the multi-layer waveguide, thereby enhancing color uniformity. However, multi-layer diffractive waveguides introduce a series of problems, including increased thickness, lower bonding yield, poor clarity, low transmittance, and optical crosstalk between different layers, making it difficult to improve the display effect. In contrast, the diffractive waveguide 100 described in this application is a single-layer diffractive waveguide. This means that this application can improve the color uniformity of the diffractive waveguide 100 during full-color displays while maintaining the overall display effect.

[0039] In one embodiment, the wavelength of the first light is greater than or equal to 440 nm and less than or equal to 480 nm; the wavelength of the second light is greater than or equal to 600 nm and less than or equal to 660 nm.

[0040] When the wavelength of the first ray is greater than or equal to 440 nm and less than or equal to 480 nm, the first ray can cover blue light. When the wavelength of the second ray is greater than or equal to 600 nm and less than or equal to 660 nm, the second ray can cover red light.

[0041] Based on this, after the blue light covered by the first ray is coupled into the waveguide substrate 110 via the coupling grating region 120, the blue light can be transmitted to the grating coupling region via the first transition grating region 141 and the third transition grating region 143 in sequence, and then coupled out of the waveguide substrate 110 via the grating coupling region. Correspondingly, after the red light covered by the second ray is coupled into the waveguide substrate 110 via the coupling grating region 120, the red light can be transmitted to the grating coupling region via the first transition grating region, the second transition grating region, and the third transition grating region 143 in sequence, and then coupled out of the waveguide substrate 110 via the grating coupling region. Since blue light can undergo multiple diffraction expansions sequentially through the first transition grating region 141 and the third transition grating region 143, and red light can undergo multiple diffraction expansions sequentially through the first transition grating region 141, the second transition grating region 142, and the third transition grating region 143, this helps to reduce the difference in diffraction efficiency between blue and red light, thereby improving the uniformity of blue and red light. Of course, the first ray can also cover light other than blue light, and the second ray can also cover light other than red light. Therefore, at least two of the first transition grating region 141, the second transition grating region 142, and the third transition grating region 143 can also be used to reduce the difference in diffraction efficiency between light other than blue light and light other than red light, thereby improving the uniformity of light other than blue light and light other than red light.

[0042] In one embodiment, the duty cycle of the first transition grating region 141 is greater than or equal to 0.2 and less than or equal to 0.6; the duty cycle of the second transition grating region 142 is greater than or equal to 0.6 and less than or equal to 0.8; and the duty cycle of the third transition grating region 143 is greater than or equal to 0.2 and less than or equal to 0.6.

[0043] The duty cycle of the first transition grating region 141 is determined based on the ratio of the tooth width within the grating period to the total period width. The duty cycle of the second transition grating region 142 is determined based on the ratio of the tooth width within the grating period to the total period width, and so on. The duty cycle can change the equivalent refractive index distribution of the first transition grating region 141, the second transition grating region 142, and the third transition grating region 143 to determine their respective diffraction efficiencies, thereby controlling the diffraction efficiency of light of different wavelengths.

[0044] When the duty cycle of the first transition grating region 141 is greater than or equal to 0.2 and less than or equal to 0.6, the first transition grating region 141 can improve the diffraction efficiency for short-wavelength light rays, such as the first light ray. For example, the first transition grating region 141 can improve the diffraction efficiency for blue light and reduce the diffraction efficiency for red light.

[0045] When the duty cycle of the second transition grating region 142 is greater than or equal to 0.6 and less than or equal to 0.8, the second transition grating region 142 can improve the diffraction efficiency for long-wavelength light rays, such as the second light ray. For example, the second transition grating region 142 can improve the diffraction efficiency for red light.

[0046] When the duty cycle of the third transition grating region 143 is greater than or equal to 0.2 and less than or equal to 0.6, the third transition grating region 143 can improve the diffraction efficiency for short-wavelength light, such as the first light. For example, the third transition grating region 143 can improve the diffraction efficiency for blue light and reduce the diffraction efficiency for red light.

[0047] When the first transition grating region 141 and the third transition grating region 143 can improve the diffraction efficiency for short-wavelength light rays, such as the first light ray, they can also reduce the diffraction efficiency for long-wavelength light rays, such as the second light ray. Correspondingly, when the second transition grating region 142 can improve the diffraction efficiency for long-wavelength light rays, such as the second light ray, it can also reduce the diffraction efficiency for short-wavelength light rays, such as the first light ray.

[0048] By designing the duty cycles of the first transition grating region 141, the second transition grating region 142, and the third transition grating region 143, the first and second light rays, after being coupled into the waveguide substrate 110 via the coupling grating region 120, can have their diffraction efficiency adjusted by at least two of the three regions (first transition grating region 141, second transition grating region 142, and third transition grating region 143) within the transition grating region 140. This reduces the difference in diffraction efficiency between the first and second light rays, thereby improving their uniformity. Improved uniformity between the first and second light rays enhances the color uniformity of the diffraction waveguide 100 during full-color display.

[0049] In one embodiment, the grating depth of the first transition grating region 141 is greater than or equal to 25 nm and less than or equal to 50 nm; the grating depth of the second transition grating region 142 is greater than or equal to 60 nm and less than or equal to 100 nm; and the grating depth of the third transition grating region 143 is greater than or equal to 25 nm and less than or equal to 50 nm.

[0050] The grating depth can be used to indicate the vertical height of the grating etching trenches in the first transition grating region 141, the second transition grating region 142, and the third transition grating region 143, i.e., the depth difference from the surface of the waveguide substrate 110 to the bottom of the trench. The grating depth can affect the diffraction efficiency of the first transition grating region 141, the second transition grating region 142, and the third transition grating region 143, thereby controlling the diffraction efficiency of light of different wavelengths.

[0051] When the grating depth of the first transition grating region 141 is greater than or equal to 25 nm and less than or equal to 50 nm, the first transition grating region 141 can improve the diffraction efficiency for short-wavelength light, such as the first light ray. For example, the first transition grating region 141 can improve the diffraction efficiency for blue light and reduce the diffraction efficiency for red light.

[0052] When the grating depth of the second transition grating region 142 is greater than or equal to 60 nm and less than or equal to 100 nm, the second transition grating region 142 can improve the diffraction efficiency for long-wavelength light, such as the second light ray. For example, the second transition grating region 142 can improve the diffraction efficiency for red light.

[0053] When the grating depth of the third transition grating region 143 is greater than or equal to 25 nm and less than or equal to 50 nm, the third transition grating region 143 can improve the diffraction efficiency for short-wavelength light, such as the first light. For example, the third transition grating region 143 can improve the diffraction efficiency for blue light and reduce the diffraction efficiency for red light.

[0054] By designing the grating depths of the first transition grating region 141, the second transition grating region 142, and the third transition grating region 143, the first and second rays, after being coupled into the waveguide substrate 110 via the coupling grating region 120, can have their diffraction efficiency adjusted by at least two of the three regions included in the transition grating region 140: the first transition grating region 141, the second transition grating region 142, and the third transition grating region 143. This reduces the difference in diffraction efficiency between the first and second rays, thereby improving their uniformity. Improved uniformity between the first and second rays enhances the color uniformity of the diffractive waveguide 100 during full-color display.

[0055] In one embodiment, the tilt angle of the grating ridge sidewall corresponding to the first folding grating region 141, the second folding grating region 142, and the third folding grating region 143 is greater than or equal to 0° and less than or equal to 50°.

[0056] The tilt angle of the grating ridge sidewall can be used to indicate the angle between the grating ridge sidewall and the waveguide substrate 110 plane. The tilt angle of the grating ridge sidewall can change the equivalent refractive index distribution of the first bend grating region 141, the second bend grating region 142, and the third bend grating region 143, thereby controlling the diffraction efficiency of light of different wavelengths.

[0057] When the tilt angles of the grating ridge sidewalls corresponding to the first transition grating region 141, the second transition grating region 142, and the third transition grating region 143 are all greater than or equal to 0° and less than or equal to 50°, after the first light ray and the second light ray are coupled into the waveguide substrate 110 through the coupling grating region 120, their diffraction efficiency can be adjusted by at least two of the first transition grating region 141, the second transition grating region 142, and the third transition grating region 143 included in the transition grating region 140. This reduces the difference in diffraction efficiency between the first light ray and the second light ray, thereby improving the uniformity between the first light ray and the second light ray. When the uniformity between the first light ray and the second light ray is improved, it is beneficial to improve the color uniformity when the diffraction waveguide 100 performs full-color display.

[0058] In one embodiment, the projected area of ​​the third folding grating region 143 on the waveguide substrate 110 is greater than or equal to the projected area of ​​the first folding grating region 141 on the waveguide substrate 110, and the projected area of ​​the third folding grating region 143 on the waveguide substrate 110 is greater than or equal to the projected area of ​​the second folding grating region 142 on the waveguide substrate 110.

[0059] like Figure 1 as well as Figure 2 As shown, the projected area of ​​the third transition grating region 143 on the waveguide substrate 110 is greater than or equal to the projected areas of the first transition grating region 141 and the second transition grating region 142 on the waveguide substrate 110. In an exemplary embodiment, the projected area of ​​the third transition grating region 143 on the waveguide substrate 110 is greater than or equal to the sum of the projected areas of the first transition grating region 141 and the second transition grating region 142 on the waveguide substrate 110. However, this is not a limitation; for example, the projected area of ​​the second transition grating region 142 on the waveguide substrate 110 may be greater than or equal to the projected area of ​​the first transition grating region 141 on the waveguide substrate 110. This is not a limitation in this context.

[0060] When the projected area of ​​the third transition grating region 143 on the waveguide substrate 110 is greater than or equal to the projected areas of the first transition grating region 141 and the second transition grating region 142 on the waveguide substrate 110, the third transition grating region 143 can have a wider area to allow for secondary diffraction expansion of the first and second rays passing through the third transition grating, thereby reducing the difference in diffraction efficiency between the first and second rays and improving the uniformity between the first and second rays. Improved uniformity between the first and second rays is beneficial for enhancing the color uniformity of the diffraction waveguide 100 during full-color display.

[0061] In one embodiment, the third folding grating region 143 includes a first folding grating sub-region 1431 and a second folding grating region 1432.

[0062] The first fold grating sub-region 1431 is adjacent to the second fold grating sub-region 1432 in the first direction, and the first fold grating sub-region 1431 is adjacent to the first fold grating region 141 and the coupling grating region 130 in the second direction, respectively.

[0063] The second fold grating sub-region 1432 is adjacent to the second fold grating region 142 and the coupling grating region 130 in the second direction, respectively.

[0064] After the first light beam is coupled into the waveguide substrate 110 in the coupling grating region 120, the first light beam is transmitted to the coupling out grating region 130 after passing through the first bend grating region 141, the first bend grating sub-region 1431 and the second bend grating sub-region 1432 in sequence, and is then coupled out of the waveguide substrate 110 through the coupling out grating region 130.

[0065] After the second light beam is coupled into the waveguide substrate 110 in the coupling grating region 120, the second light beam is transmitted to the coupling out grating region 130 after passing through the first bending grating region 141, the second bending grating region 142 and the second bending grating sub-region 1432 in sequence, and is then coupled out of the waveguide substrate 110 through the coupling out grating region 130.

[0066] like Figure 3 as well as Figure 4 As shown, when the first direction and the second direction are different, the first folding grating sub-region 1431 is adjacent to the second folding grating sub-region 1432 in the first direction, similar to how the first folding grating sub-region 1431 and the second folding grating sub-region 1432 are longitudinally adjacent. In the second direction, the first folding grating sub-region 1431 is adjacent to both the first folding grating region 141 and the coupling grating region 130, similar to how the first folding grating sub-region 1431 is laterally adjacent to both the first folding grating region 141 and the coupling grating region 130. By analogy, it can be determined that the second folding grating region 1432 is laterally adjacent to both the second folding grating region 142 and the coupling grating region 130.

[0067] Since the third transition grating region 143 includes the first transition grating sub-region 1431 and the second transition grating sub-region 1432, the design method of the first transition grating sub-region 1431 and the second transition grating sub-region 1432 can refer to the design method of the third transition grating region 143.

[0068] In one embodiment, the duty cycle of the first lattice grating sub-region 1431 is greater than or equal to 0.2 and less than or equal to 0.6; the duty cycle of the second lattice grating sub-region 1432 is greater than or equal to 0.2 and less than or equal to 0.6.

[0069] In one embodiment, the grating depth of the first transition grating sub-region 1431 is greater than or equal to 25 nm and less than or equal to 50 nm; the grating depth of the second transition grating sub-region 1432 is greater than or equal to 25 nm and less than or equal to 50 nm.

[0070] In one embodiment, the tilt angle of the grating ridge sidewall corresponding to the first fold grating sub-region 1431 and the second fold grating sub-region 1432 is greater than or equal to 0° and less than or equal to 50°.

[0071] The descriptions of the first transition grating sub-region 1431 and the second transition grating sub-region 1432 can be referred to the description of the third transition grating region 143 mentioned above, and will not be repeated here.

[0072] For example, when designing the first bend grating sub-region 1431, its properties can be set to have high diffraction efficiency for short-wavelength light. Correspondingly, when designing the second bend grating sub-region 1432, its properties can be set to have high diffraction efficiency for short-wavelength light and low diffraction efficiency for long-wavelength light. Figure 4 As shown, since the main propagation path of long-wavelength light does not pass through the first turning grating sub-region 1431, when designing the first turning grating sub-region 1431, it is not necessary to limit the characteristics of the first turning grating sub-region 1431 for long-wavelength light, and no restrictions are imposed here.

[0073] like Figure 4 As shown, after the first and second light rays are coupled into the waveguide substrate 110 in the coupling grating region 120, the first light ray can undergo multiple diffraction expansions sequentially through the first transition grating region 141, the first transition grating sub-region 1431, and the second transition grating sub-region 1432. Similarly, the second light ray can undergo multiple diffraction expansions through the first transition grating region 141, the second transition grating region 142, and the second transition grating sub-region 1432. This improves the uniformity of the first and second light rays. Improved uniformity of the first and second light rays enhances the color uniformity of the diffractive waveguide 100 during full-color display.

[0074] In one embodiment, the projected area of ​​the first bend grating sub-region 1431 on the waveguide substrate 110 is greater than or equal to the projected area of ​​the first bend grating region 141 on the waveguide substrate 110; the projected area of ​​the second bend grating sub-region 1432 on the waveguide substrate 110 is greater than or equal to the projected area of ​​the second bend grating region 142 on the waveguide substrate 110. However, this is not a limitation; for example, if the projected area of ​​the second bend grating region 142 on the waveguide substrate 110 is greater than or equal to the projected area of ​​the first bend grating region 141 on the waveguide substrate 110, then the projected area of ​​the second bend grating sub-region 1432 on the waveguide substrate 110 is greater than or equal to the projected area of ​​the first bend grating region 1431 on the waveguide substrate 110. No limitation is imposed here.

[0075] When the projected area of ​​the first bend grating sub-region 1431 on the waveguide substrate 110 is greater than or equal to the projected area of ​​the first bend grating region 141 on the waveguide substrate 110, and the projected area of ​​the second bend grating sub-region 1432 on the waveguide substrate 110 is greater than or equal to the projected area of ​​the second bend grating region 142 on the waveguide substrate 110, the first bend grating sub-region 1431 and the second bend grating region 1432 can have a relatively wide area to allow for corresponding orders of diffraction expansion of the first ray passing through the first bend grating region 1431, the first ray passing through the second bend grating region 1432, and the second ray, thereby reducing the difference in diffraction efficiency between the first ray and the second ray and improving the uniformity between the first ray and the second ray. With the improved uniformity between the first ray and the second ray, it is beneficial to improve the color uniformity when the diffracted waveguide 100 performs full-color display.

[0076] In one embodiment, the diffractive waveguide 100 includes one of a transmission diffractive waveguide 100 and a reflection diffractive waveguide 100.

[0077] When the diffractive waveguide 100 includes a transmission diffractive waveguide 100, the coupling-in grating region 120, the coupling-out grating region 130, and the transition grating region 140 can all perform transmission diffraction on light rays, such as at least one of the first light ray and the second light ray. Correspondingly, the transition grating region 140, including the first transition grating region 141, the second transition grating region 142, and the third transition grating region 143, can all perform transmission diffraction on light rays, such as at least one of the first light ray and the second light ray. By analogy, the third transition grating region 143, including the first transition grating sub-region 1431 and the second transition grating sub-region 1432, can also perform transmission diffraction on light rays, such as at least one of the first light ray and the second light ray.

[0078] When the diffractive waveguide 100 includes a reflective diffractive waveguide 100, the coupling-in grating region 120, the coupling-out grating region 130, and the transition grating region 140 can all reflect and diffract light rays, such as at least one of the first light ray and the second light ray. Correspondingly, the transition grating region 140, including the first transition grating region 141, the second transition grating region 142, and the third transition grating region 143, can all reflect and diffract light rays, such as at least one of the first light ray and the second light ray. By analogy, the third transition grating region 143, including the first transition grating sub-region 1431 and the second transition grating sub-region 1432, can also reflect and diffract light rays, such as at least one of the first light ray and the second light ray.

[0079] When the diffractive waveguide 100 includes either a transmission diffractive waveguide 100 or a reflection diffractive waveguide 100, it is beneficial to improve the color uniformity of the diffractive waveguide 100 when performing full-color display, while also increasing the design flexibility of the diffractive waveguide 100.

[0080] In one embodiment, the coupled grating region 120 includes any one of a straight tooth grating, a helical tooth grating, and a blazed grating; the coupled grating region 130 includes any one of a straight tooth grating, a helical tooth grating, and a stepped grating; and the transition grating region 140 includes at least one of a straight tooth grating, a helical tooth grating, and a blazed grating.

[0081] For example, when the transition grating region 140 includes a first transition grating region 141, a second transition grating region 142, and a third transition grating region 143, the first transition grating region 141, the second transition grating region 142, and the third transition grating region 143 can adopt the same grating type, such as one of a straight-tooth grating, a helical-tooth grating, or a blazed grating. Alternatively, they can adopt different grating types, such as the first transition grating adopting one of a straight-tooth grating, a helical-tooth grating, or a blazed grating, the second transition grating adopting another of a straight-tooth grating, a helical-tooth grating, or a blazed grating, and the third transition grating adopting one of a straight-tooth grating, a helical-tooth grating, or a blazed grating, etc. There are no restrictions here.

[0082] Based on this, it is beneficial to improve the design flexibility of the coupling grating region 120, coupling out grating region 130 and turning grating region 140 in the diffractive waveguide 100.

[0083] Please see Figure 5 , Figure 5 This is a schematic diagram of the structure of a diffractive optical waveguide involved in the related technology. Figure 5 It is known that the diffractive waveguide in the related technology may include an input grating section, an output grating section, and multiple transition grating sections, with the multiple transition grating sections arranged adjacent to each other in the first direction.

[0084] like Figure 6 As shown, Figure 6 This is a full-color uniformity simulation image of the diffractive waveguide involved in the related technology. In the related technology, the color uniformity value of the diffractive waveguide is duv > 0.15. Figure 6 It is known that when the diffractive waveguide in the related technology is used for full-color display, obvious color cast can be seen, that is, the color uniformity of the diffractive waveguide in the related technology is poor when used for full-color display.

[0085] Please see Figure 7 , Figure 7 This is a full-color uniformity simulation image of the diffractive waveguide 100 involved in this application. The color uniformity value of the diffractive waveguide 100 in this application is duv < 0.1. Figure 7 It can be seen that the diffractive waveguide 100 in this application does not have obvious color shift when displaying in full color, that is, the diffractive waveguide 100 in this application has good color uniformity when displaying in full color.

[0086] Based on the design of the transition grating region 140 in the diffractive waveguide 100 of this application, the diffractive waveguide 100 of this application can effectively improve the color uniformity of a single-layer diffractive waveguide.

[0087] The diffractive waveguide 100 provided in the above embodiment comprises a coupling-in grating region 120, a coupling-out grating region 130, and a transition grating region 140 disposed on the waveguide substrate 110 of the diffractive waveguide 100. The transition grating region 140 includes a first transition grating region 141, a second transition grating region 142, and a third transition grating region 143. The first transition grating region 141 is adjacent to the coupling-in grating region 120 and the second transition grating region 142 in a first direction, and the third transition grating region 143 is adjacent to the first transition grating region 141, the second transition grating region 142, and the coupling-out grating region 130 in a second direction. The second direction is different; after the first light beam is coupled into the waveguide substrate 110 in the coupling grating region 120, the first light beam is transmitted to the coupling grating region 130 after passing through the first bend grating region 141 and the third bend grating region 143 in sequence, and is coupled out of the waveguide substrate 110 through the coupling grating region 130; after the second light beam is coupled into the waveguide substrate 110 in the coupling grating region 120, the second light beam is transmitted to the coupling grating region 130 after passing through the first bend grating region 141, the second bend grating region 142 and the third bend grating region 143 in sequence, and is coupled out of the waveguide substrate 110 through the coupling grating region 130; the wavelength of the first light beam is smaller than the wavelength of the second light beam. In the case where the transition grating region 140 of the diffractive waveguide 100 includes a first transition grating region 141, a second transition grating region 142, and a third transition grating region 143, the first transition grating region 141 can serve as a wavelength separation region, separating the propagation paths of the first light rays and the second light rays with different wavelengths. For example, the first light ray is transmitted to the third transition grating region 143 after passing through the first transition grating region 141; the second light ray is transmitted to the second transition grating region 142 after passing through the first transition grating region 141. Correspondingly, the first light ray transmitted to the third transition grating region 143 can be processed by the third transition grating region 143 to regulate the transmission diffraction efficiency of the first light ray, and then transmitted to the coupling grating region 130. The second light ray transmitted to the second transition grating region 142 can be processed sequentially by the second transition grating region 142 and the third transition grating region 143 to regulate the transmission diffraction efficiency of the second light ray, and then transmitted to the coupling grating region 130. Based on this, the transmission diffraction efficiency of the first and second rays with different wavelengths can be adjusted differently, which helps to reduce the difference in transmission diffraction efficiency when the first and second rays are coupled out of the waveguide substrate 110 through the coupling grating region 130, thereby improving the color uniformity of the diffraction waveguide 100 when performing full-color display.

[0088] Please see Figure 8 , Figure 8 This is a schematic diagram of the structure of a near-eye display device provided in an embodiment of this application.

[0089] In one embodiment, the near-eye display device includes a diffractive waveguide 100 as provided in any of the embodiments described above.

[0090] It should be understood that the diffractive waveguide 100 provided in any of the above embodiments can couple the first light beam and the second light beam into the waveguide substrate 110 via the coupling grating region 120 provided on the waveguide substrate 110, and then transmit the first light beam and the second light beam to the coupling grating region 130 via the transition grating region 140 provided on the waveguide substrate 110, respectively, and then couple the first light beam and the second light beam out of the waveguide substrate 110 via the coupling grating region 130, thereby enabling the user to see the full-color image displayed by the diffractive waveguide 100. Specifically, the first light beam is transmitted to the coupling grating region 130 after passing through the first transition grating region 141 and the third transition grating region 143 of the transition grating region 140 in sequence, and the second light beam is transmitted to the coupling grating region 130 after passing through the first transition grating region 141, the second transition grating region 142, and the third transition grating region 143 in sequence. Since the first and second light rays have different propagation paths in the diffractive waveguide 100, the diffractive waveguide 100 can use the transition grating region 140 to control the transmission diffraction efficiency of the first and second light rays with different wavelengths differently. This helps to reduce the difference in transmission diffraction efficiency when the first and second light rays are coupled out of the waveguide substrate 110 through the coupling grating region 130, thereby improving the color uniformity of the diffractive waveguide 100 in full-color display. The specific structure and implementation principle of the diffractive waveguide 100 included in the near-eye display device can be found in the previous text and will not be described again here.

[0091] For example, near-eye display devices include AR devices, such as AR glasses, AR helmets, etc.; near-eye display devices may also include mixed reality (MR) devices, such as MR glasses, MR helmets, etc., without limitation.

[0092] It should be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0093] It should also be understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. It should be noted that, herein, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0094] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. The above descriptions are merely specific implementations of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A diffractive optical waveguide, characterized in that, The diffractive waveguide includes a waveguide substrate, a coupling grating region, a coupling out grating region, and a transition grating region. The coupling-in grating region, the coupling-out grating region, and the turning grating region are disposed on the waveguide substrate; The transition grating region includes a first transition grating region, a second transition grating region, and a third transition grating region; the first transition grating region is adjacent to the coupled-in grating region and the second transition grating region respectively in a first direction, and the third transition grating region is adjacent to the first transition grating region, the second transition grating region, and the coupled-out grating region respectively in a second direction; the first direction and the second direction are different; After the first light ray is coupled into the waveguide substrate in the coupling grating region, the first light ray is transmitted to the coupling out grating region after passing through the first bend grating region and the third bend grating region in sequence, and is coupled out of the waveguide substrate through the coupling out grating region. After the second light beam is coupled into the waveguide substrate in the coupling grating region, the second light beam is transmitted to the coupling out grating region after passing through the first bend grating region, the second bend grating region, and the third bend grating region in sequence, and is coupled out of the waveguide substrate through the coupling out grating region; the wavelength of the first light beam is less than the wavelength of the second light beam.

2. The diffractive waveguide according to claim 1, characterized in that, The wavelength of the first light is greater than or equal to 440 nm and less than or equal to 480 nm; The wavelength of the second light is greater than or equal to 600 nm and less than or equal to 660 nm.

3. The diffractive waveguide according to claim 2, characterized in that, The duty cycle of the first transition grating region is greater than or equal to 0.2 and less than or equal to 0.6; The duty cycle of the second transition grating region is greater than or equal to 0.6 and less than or equal to 0.8; The duty cycle of the third transition grating region is greater than or equal to 0.2 and less than or equal to 0.

6.

4. The diffractive waveguide according to claim 2, characterized in that, The grating depth of the first transition grating region is greater than or equal to 25 nm and less than or equal to 50 nm; The grating depth of the second transition grating region is greater than or equal to 60 nm and less than or equal to 100 nm; The grating depth of the third transition grating region is greater than or equal to 25 nm and less than or equal to 50 nm.

5. The diffractive waveguide according to claim 2, characterized in that, The tilt angle of the grating ridge sidewall corresponding to the first transition grating region, the second transition grating region, and the third transition grating region is greater than or equal to 0° and less than or equal to 50°.

6. The diffractive waveguide according to claim 1, characterized in that, The projected area of ​​the third transition grating region on the waveguide substrate is greater than or equal to the projected area of ​​the first transition grating region on the waveguide substrate, and the projected area of ​​the third transition grating region on the waveguide substrate is greater than or equal to the projected area of ​​the second transition grating region on the waveguide substrate.

7. The diffractive waveguide according to any one of claims 1 to 6, characterized in that, The third folding grating region includes a first folding grating sub-region and a second folding grating region; The first folding grating sub-region is adjacent to the second folding grating sub-region in the first direction, and the first folding grating sub-region is adjacent to both the first folding grating region and the coupling grating region in the second direction. The second folding grating sub-region is adjacent to the second folding grating region and the coupling grating region in the second direction, respectively; After the first light beam is coupled into the waveguide substrate in the coupling grating region, the first light beam is transmitted to the coupling out grating region after passing through the first bend grating region, the first bend grating sub-region and the second bend grating sub-region in sequence, and is coupled out of the waveguide substrate through the coupling out grating region. After the second light beam is coupled into the waveguide substrate in the coupling grating region, the second light beam is transmitted to the coupling out grating region after passing through the first bend grating region, the second bend grating region, and the second bend grating sub-region in sequence, and is coupled out of the waveguide substrate through the coupling out grating region.

8. The diffractive waveguide according to any one of claims 1 to 6, characterized in that, The diffractive waveguide includes one of the following: a transmission diffractive waveguide and a reflection diffractive waveguide.

9. The diffractive waveguide according to any one of claims 1 to 6, characterized in that, The coupled grating region includes any one of straight-tooth gratings, helical-tooth gratings, and blazed gratings; The coupled-out grating region includes any one of straight-tooth gratings, helical-tooth gratings, and stepped gratings; The transition grating region includes at least one of straight tooth grating, oblique tooth grating, and blazed grating.

10. A near-eye display device, characterized in that, Includes the diffractive waveguide as described in any one of claims 1 to 9.

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