Diffractive optical waveguide structure and near-eye display device

Abstract

The utility model relates to optical diffraction technical field provides diffraction light waveguide structure and near eye display device, diffraction light waveguide structure includes: waveguide base, in -coupling grating and out -coupling grating, in -coupling grating and out -coupling grating set up in waveguide base surface, in -coupling grating is used for with incident light line in -coupling to waveguide base, out -coupling grating is used for with the diffraction light line conduction in waveguide base out -coupling, wherein, out -coupling grating is provided with a plurality of periodic arrangement's base element, base element is used for introducing the asymmetry of out -coupling grating along x direction, and base element is divided into first base element area and second base element area according to the central axis, the shape structure of first base element area and the shape structure of second base element area are not same, through above -mentioned diffraction light waveguide structure, the utility model can reduce the light leakage of grating waveguide out -coupling area, improve the efficiency of grating waveguide.

Description

Technical Field

[0001] This utility model relates to the field of optical diffraction technology, and in particular to diffractive waveguide structures and near-eye display devices. Background Technology

[0002] Augmented Reality (AR) technology is a technology that integrates computer-generated virtual information with the real world. Near-eye display devices, exemplified by AR glasses, transmit images from a microdisplay to the human eye through a series of optical imaging elements. Their perspective properties allow real-world scenes to simultaneously appear in the eye, greatly enhancing the immersive experience. Currently, mature optical imaging solutions include prisms, freeform surfaces, off-axis holographic lenses, arrayed waveguides, volume holographic waveguides, and diffractive waveguides. Among these, diffractive waveguides primarily utilize photolithography to create surface relief gratings on the waveguide surface to achieve image coupling and decoupling. They offer a large field of view, are lightweight, and their manufacturing process is compatible with mature semiconductor manufacturing technologies, resulting in high yield rates for mass production. Therefore, diffractive waveguides are a highly favored optical imaging solution for AR displays.

[0003] Diffractive waveguides employ grating regions such as coupling-in gratings, deflection gratings, and coupling-out gratings to achieve the function of image light extension and coupling-out. However, one problem for augmented reality users using diffractive waveguides in social interactions is light leakage or eye-emitting effect at the coupling-out grating region. This refers to the light coupled outward from the waveguide directly leaking into the environment. This light leakage not only weakens the efficiency of the waveguide but also makes the user's eyes appear unnatural and leads to privacy issues, greatly hindering the user's interaction with the real world. Utility Model Content

[0004] This invention provides a diffractive waveguide structure and a near-eye display device. By optimizing the waveguide grating structure, the light leakage effect at the coupling grating region can be reduced or eliminated.

[0005] This invention provides a diffractive waveguide structure, comprising: a waveguide substrate, an insertion grating, and an exit grating, wherein the insertion grating and the exit grating are disposed on the surface of the waveguide substrate; the insertion grating is used to couple incident light into the waveguide substrate, and the exit grating is used to couple diffracted light propagating within the waveguide substrate out; wherein the exit grating is provided with a plurality of periodically arranged primitives; the primitives are used to introduce the asymmetry of the exit grating along the x-direction, and the primitives are divided into a first primitive region and a second primitive region according to the central axis; the shape and structure of the first primitive region and the shape and structure of the second primitive region are different.

[0006] According to the present invention, a diffractive waveguide structure is provided, wherein the basic element includes multiple sub-units; at least two of the multiple sub-units have different heights and / or widths.

[0007] According to the present invention, the cross-sectional shape of the sub-unit along the vertical direction is rectangular or triangular.

[0008] According to the present invention, a diffractive waveguide structure includes two blazed gratings of different heights, and the cross-sectional shape of the two blazed gratings along the vertical direction is a right triangle.

[0009] According to the present invention, the diffractive waveguide structure has a basic element with a cross-sectional shape of a combination of rectangle and triangle along the vertical direction.

[0010] According to the present invention, a diffractive waveguide structure includes multiple sub-units, including a first sub-unit, a second sub-unit, and a third sub-unit arranged sequentially at intervals. The first and second sub-units have the same height, while the second and third sub-units have different heights. The first and second sub-units also have different widths, as do the second and third sub-units.

[0011] According to the diffractive waveguide structure provided by this utility model, the highest height of the shape structure in the first element region is greater than the highest height of the shape structure in the second element region; or, the lowest height of the shape structure in the first element region is greater than the lowest height of the shape structure in the second element region.

[0012] This invention also provides a near-eye display device, including the above-described diffractive waveguide structure.

[0013] According to the present invention, a near-eye display device further includes a microdisplay; the microdisplay is used to output image light as incident light in a diffractive waveguide structure.

[0014] This invention provides a diffractive waveguide structure and a near-eye display device. The diffractive waveguide structure includes a waveguide substrate, an insertion grating, and an exit grating, which are disposed on the surface of the waveguide substrate. The insertion grating couples incident light rays into the waveguide substrate, and the exit grating couples exit diffracted light rays propagating within the waveguide substrate. The exit grating has multiple periodically arranged primitives. These primitives introduce asymmetry in the x-direction of the exit grating, and are divided into a first primitive region and a second primitive region along the central axis. The shapes of the first and second primitive regions are different. Through this diffractive waveguide structure, this invention can reduce light leakage in the exit region of the grating waveguide and improve its efficiency. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the principle of a grating waveguide display device in the existing technology.

[0017] Figure 2 This is a schematic diagram of the structure of a one-dimensional grating waveguide in the prior art.

[0018] Figure 3 This is one of the schematic diagrams of the diffractive waveguide structure provided in the embodiments of this utility model.

[0019] Figure 4 Based on Figure 3 A schematic diagram showing the diffraction efficiencies of (1,0)R and (1,0)T as a function of the incident angle, calculated from the structure.

[0020] Figure 5 Based on Figure 3 Structure and Figure 4 A schematic diagram of the R / T ratio calculated from the diffraction efficiency.

[0021] Figure 6 Based on Figure 3 A schematic diagram showing the diffraction efficiencies of (1,0)R and (1,0)T as a function of incident wavelength, calculated from the structure.

[0022] Figure 7 Based on Figure 3 Structure and Figure 6 A schematic diagram of the R / T ratio calculated from the diffraction efficiency.

[0023] Figure 8 This is the second schematic diagram of the diffractive waveguide structure provided in this embodiment of the present invention.

[0024] Figure 9 Based on Figure 8 A schematic diagram showing the diffraction efficiencies of (1,0)R and (1,0)T as a function of the incident angle, calculated from the structure.

[0025] Figure 10 Based on Figure 8 Structure and Figure 9 A schematic diagram of the R / T ratio calculated from the diffraction efficiency.

[0026] Figure 11 Based on Figure 8A schematic diagram showing the diffraction efficiencies of (1,0)R and (1,0)T as a function of incident wavelength, calculated from the structure.

[0027] Figure 12 Based on Figure 8 Structure and Figure 11 A schematic diagram of the R / T ratio calculated from the diffraction efficiency.

[0028] Figure 13 This is the third schematic diagram of the diffractive waveguide structure provided in this embodiment of the present invention.

[0029] Figure 14 Based on Figure 13 A schematic diagram showing the diffraction efficiencies of (1,0)R and (1,0)T as a function of the incident angle, calculated from the structure.

[0030] Figure 15 Based on Figure 13 Structure and Figure 14 A schematic diagram of the R / T ratio calculated from the diffraction efficiency.

[0031] Figure 16 Based on Figure 13 A schematic diagram showing the diffraction efficiencies of (1,0)R and (1,0)T as a function of incident wavelength, calculated from the structure.

[0032] Figure 17 Based on Figure 13 Structure and Figure 16 A schematic diagram of the R / T ratio calculated from the diffraction efficiency. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0034] In the description of the embodiments of this utility model, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this utility model 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. Therefore, they should not be construed as limitations on the embodiments of this utility model. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0035] In the description of the embodiments of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this utility model based on the specific circumstances.

[0036] In this embodiment of the utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0037] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "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 the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0038] Please see Figure 1 , Figure 1This is a schematic diagram of the principle of a prior art grating waveguide display device. The grating waveguide display device consists of a microdisplay 110, from which light carrying image information is output; and an optical waveguide sheet 100.

[0039] in, Figure 1 In the Cartesian coordinate system, x and z represent the x-axis and z-axis, respectively.

[0040] The optical waveguide 100 typically consists of a waveguide substrate 111 and a coupling grating 120 and a coupling grating 140 located on the surface of the waveguide substrate 111. Light 101 output from the microdisplay 110 is incident on the coupling grating 120 of the optical waveguide 100 and diffracts to generate diffracted light 102. The diffracted light 102 is propagated towards the coupling grating 140 via total internal reflection within the waveguide. Upon reaching the region of the coupling grating 140, it diffracts again to generate diffracted light 103, 104, and 105, which are propagated towards the human eye 160 and enter the human eye 160 for imaging. Simultaneously, diffracted light 106, 107, and 108 are generated and coupled outwards from the waveguide, entering the external environment. This diffracted light cannot be received by the human eye 160, resulting in energy waste. Furthermore, this diffracted light entering the external environment can be seen by other users, causing privacy breaches.

[0041] The energies of the diffracted light 103, 104, and 105 generated by the existing grating waveguide are nearly the same as those of the diffracted light 106, 107, and 108. This is because the symmetry of the coupling grating structure along the x-direction cannot distinguish between the energies of the reflected and transmitted light.

[0042] Please see Figure 2 , Figure 2 This is a schematic diagram of a one-dimensional grating waveguide in the prior art. The one-dimensional grating waveguide includes three grating regions: a coupling grating 120, a turning grating 130, and a coupling grating 140.

[0043] in, Figure 2 In the Cartesian coordinate system, x and y represent the x-axis and y-axis, respectively.

[0044] The deflection grating 130 can deflect the light beam at a specific angle in the waveguide substrate 111, but light leakage still occurs in the coupling grating region.

[0045] Therefore, to reduce and eliminate light leakage at the coupling grating region, this invention provides a diffractive waveguide structure. The diffractive waveguide structure may include: a waveguide substrate, an input grating, and an output grating.

[0046] The coupling grating and the coupling grating are disposed on the surface of the waveguide substrate; the coupling grating is used to couple the incident light into the waveguide substrate, and the coupling grating is used to couple the diffracted light propagating in the waveguide substrate out.

[0047] Optionally, the waveguide substrate material can be glass, silicon carbide, polymer, or other materials that are transparent to visible light, and it is in the form of a flat plate with two smooth surfaces.

[0048] Optionally, the coupling grating and the coupling grating can be located on the same surface or different surfaces of the waveguide substrate, and can be fabricated by photolithography or nanoimprint technology.

[0049] Alternatively, the coupling grating can be a one-dimensional blazed grating or a tilted grating.

[0050] The coupling grating has multiple periodically arranged primitives. The primitives are used to introduce the asymmetry of the coupling grating along the x-direction. The primitives are divided into a first primitive region and a second primitive region according to the central axis. The shape and structure of the first primitive region and the second primitive region are different. The different shape and structure will lead to different scattering, reflection and transmission characteristics of light in the two regions.

[0051] The difference in shape structure between the first primitive region and the second primitive region can be represented by height. For example, the highest height of the shape structure in the first primitive region can be greater than the highest height of the shape structure in the second primitive region; or, the lowest height of the shape structure in the first primitive region can be greater than the lowest height of the shape structure in the second primitive region.

[0052] In this embodiment, the periodically arranged primitives of the coupling grating can provide specific phase modulation for the light wave. Specifically, the primitives are used to introduce asymmetry in the coupling grating along the x-direction. The asymmetric structure can change the distribution and propagation characteristics of the light field. The asymmetry along the x-direction makes the coupling process of light in this direction no longer symmetrical, thereby enabling control over the polarization state of the light or the energy of the beam.

[0053] In some embodiments, the grating can be made to have inclined sidewalls by changing the etching direction of the grating, thereby forming an asymmetric structure.

[0054] In some embodiments, an asymmetric structure can be formed by adjusting the tooth shape or groove shape of the grating to give it a certain blaze angle.

[0055] In some embodiments, a stepped grating structure can be used to achieve asymmetry.

[0056] In some embodiments, a bottom reflective layer can be added below the coupling grating. The reflective layer alters the propagation path and phase relationship of the light, thereby achieving asymmetric coupling. When light is reflected back from the bottom reflective layer, it interferes with the directly transmitted light. Based on the parameters of the grating and the characteristics of the reflective layer, the light intensity enhancement in a specific direction can be controlled to improve the coupling efficiency.

[0057] In this embodiment, the structural difference between the first and second primitive regions creates a composite optical effect, causing light to undergo complex optical processes at the coupling grating. This can be used to achieve multi-order diffraction of light and control the intensity distribution of different diffraction orders. By rationally designing the shape and structure of the first and second primitive regions, the performance of the coupling grating can be optimized, light leakage in the coupling region of the grating waveguide can be reduced, and the efficiency of the grating waveguide can be improved.

[0058] In some embodiments, the diffractive waveguide structure of the present invention may further include a folding grating.

[0059] In this invention, the basic unit can be a single, integral structure or a structure comprising multiple sub-units.

[0060] Optionally, the height parameter of the primitive is in the range of 20~200nm, the width parameter of the primitive is in the range of 100~500nm, and the periodic arrangement parameter of the primitive is in the range of 200~1500nm.

[0061] In some embodiments, the primitive includes multiple sub-units; at least two of the multiple sub-units have different heights and / or widths.

[0062] In some embodiments, the cross-sectional shape of the sub-unit along the vertical direction is rectangular or triangular.

[0063] Optionally, multiple sub-units can have the same shape but different sizes, or they can have both different shapes and sizes.

[0064] For example, the sub-units in the first primitive region can be rectangular structures with a specific width, which will produce a certain reflection and refraction of light; while the sub-units in the second primitive region can be triangular structures, which act on light in a different way than the rectangular structures.

[0065] In some embodiments, the plurality of sub-units includes a first sub-unit, a second sub-unit, and a third sub-unit arranged sequentially at intervals. The first sub-unit and the second sub-unit have the same height, while the second sub-unit and the third sub-unit have different heights. The first sub-unit and the second sub-unit have different widths, while the second sub-unit and the third sub-unit have different widths.

[0066] Please see Figure 3 , Figure 3 This is one of the schematic diagrams of the diffractive waveguide structure provided in the embodiments of this utility model.

[0067] In the diffractive waveguide structure 300 of this embodiment, the basic unit is composed of sub-units with different widths and heights to introduce the asymmetry of the coupling grating along the x-direction. Figure 3 In the Cartesian coordinate system, x and z represent the x-axis and z-axis, respectively.

[0068] The incident light enters the waveguide substrate and is propagated towards the coupling grating via total internal reflection. Upon reaching the coupling grating region, diffraction occurs, generating diffracted light beams 303, 304, 305, 306, 307, and 308. Diffracted light beams 303, 304, and 305 propagate towards the human eye and are used for image formation. Diffracted light beams 306, 307, and 308 are coupled outwards from the waveguide substrate and enter the external environment, where they cannot be received by the human eye.

[0069] Figure 4 Based on Figure 3 A schematic diagram showing the diffraction efficiencies of (1,0)R and (1,0)T as a function of the incident angle, calculated from the structure. Figure 5 Based on Figure 3 Structure and Figure 4 A schematic diagram of the R / T ratio calculated from the diffraction efficiency.

[0070] When the incident angles are 40°, 60°, and 80°, the ratios of (1,0)R and (1,0)T are 0.7, 25.96, and 11.39, respectively. When the incident angle is greater than 46°, the diffraction efficiency of (1,0)R is always greater than that of (1,0)T, and the ratio of (1,0)R to (1,0)T is greater than 3. This indicates that the light energy coupled towards the human eye is enhanced, while the light energy coupled towards the external environment is weakened, thus reducing the intensity of leaked light.

[0071] Figure 6 Based on Figure 3 A schematic diagram showing the diffraction efficiencies of (1,0)R and (1,0)T as a function of incident wavelength, calculated from the structure. Figure 7 Based on Figure 3 Structure and Figure 6 A schematic diagram of the R / T ratio calculated from the diffraction efficiency.

[0072] When the incident wavelengths are 460nm, 530nm, and 620nm, the ratios of (1,0)R and (1,0)T are 2.32, 25.96, and 1.7, respectively. When the incident wavelength is in the range of 480nm to 580nm, the ratio of (1,0)R to (1,0)T is greater than 3, indicating that more light energy is coupled out towards the human eye. It can be seen that when the coupling grating is composed of rectangular structures with different widths and heights, the light leakage effect is achieved by increasing the light energy of diffracted light 303, 304, and 305 that is conducted towards the human eye and enters the eye for imaging, while reducing the light energy coupled out of diffracted light 306, 307, and 308 to the external environment.

[0073] In some embodiments, the primitive includes two blazed gratings of different heights, and the cross-sectional shape of the two blazed gratings along the vertical direction is a right triangle.

[0074] Please see Figure 8 , Figure 8 This is the second schematic diagram of the diffractive waveguide structure provided in this embodiment of the present invention.

[0075] In the diffractive waveguide structure 400 of this embodiment, the basic element consists of two blazed gratings of different heights to introduce the asymmetry of the coupling grating along the x-direction. Figure 8 In the Cartesian coordinate system, x and z represent the x-axis and z-axis, respectively.

[0076] The incident light enters the waveguide substrate and is propagated towards the coupling grating via total internal reflection. Upon reaching the coupling grating region, diffraction occurs, generating diffracted light beams 403, 404, 405, 406, 407, and 408. Diffracted light beams 403, 404, and 405 propagate towards the human eye and are used for image formation, while diffracted light beams 406, 407, and 408 are coupled outwards from the waveguide substrate and enter the external environment, where they cannot be received by the human eye.

[0077] Figure 9 Based on Figure 8 A schematic diagram showing the diffraction efficiencies of (1,0)R and (1,0)T as a function of the incident angle, calculated from the structure. Figure 10 Based on Figure 8 Structure and Figure 9 A schematic diagram of the R / T ratio calculated from the diffraction efficiency.

[0078] When the incident angles are 40°, 60° and 80°, the ratios of (1,0)R and (1,0)T are 2.75, 3.8 and 1.37, respectively. The diffraction efficiency of (1,0)R is always greater than that of (1,0)T, and the ratio of (1,0)R to (1,0)T is greater than 1.

[0079] Figure 11 Based on Figure 8 A schematic diagram showing the diffraction efficiencies of (1,0)R and (1,0)T as a function of incident wavelength, calculated from the structure. Figure 12 Based on Figure 8 Structure and Figure 11 A schematic diagram of the R / T ratio calculated from the diffraction efficiency.

[0080] When the incident wavelengths are 460nm, 530nm, and 620nm, the ratios of (1,0)R and (1,0)T are 3.63, 3.8, and 3.53, respectively. It can be seen that when the coupling grating consists of two blazed grating structures with different heights, the light leakage effect is achieved by increasing the light energy of diffracted light 403, 404, and 405 transmitted towards the human eye and entering the eye for imaging, while simultaneously decreasing the light energy of diffracted light 406, 407, and 408 coupled out to the external environment.

[0081] In some embodiments, the cross-sectional shape of the primitive along the vertical direction is a combination of a rectangle and a triangle. Optionally, the height of the rectangle and the height of the triangle can be the same, or the height of the rectangle can be greater than the height of the triangle.

[0082] Please see Figure 13 , Figure 13 This is the third schematic diagram of the diffractive waveguide structure provided in this embodiment of the present invention.

[0083] In the diffractive waveguide structure 500 of this embodiment, the basic element is composed of a highly modulated grating structure to introduce the asymmetry of the coupling grating along the x-direction. Figure 13 In the Cartesian coordinate system, x and z represent the x-axis and z-axis, respectively.

[0084] The incident light enters the waveguide substrate and is propagated towards the coupling grating via total internal reflection. Upon reaching the coupling grating region, diffraction occurs, generating diffracted light beams 503, 504, 505, 506, 507, and 508. Diffracted light beams 503, 504, and 505 propagate towards the human eye and are used for image formation, while diffracted light beams 506, 507, and 508 are coupled outwards from the waveguide substrate and enter the external environment, where they cannot be received by the human eye.

[0085] Figure 14 Based on Figure 13 A schematic diagram showing the diffraction efficiencies of (1,0)R and (1,0)T as a function of the incident angle, calculated from the structure. Figure 15 Based on Figure 13 Structure and Figure 14 A schematic diagram of the R / T ratio calculated from the diffraction efficiency.

[0086] When the incident angles are 40°, 60° and 80°, the ratios of (1,0)R and (1,0)T are 2.9, 4.7 and 4.43, respectively. The diffraction efficiency of (1,0)R is always greater than that of (1,0)T, and when the incident angle is >42°, the ratio of (1,0)R and (1,0)T is greater than 3.

[0087] Figure 16 Based on Figure 13 A schematic diagram showing the diffraction efficiencies of (1,0)R and (1,0)T as a function of incident wavelength, calculated from the structure. Figure 17 Based on Figure 13 Structure and Figure 16 A schematic diagram of the R / T ratio calculated from the diffraction efficiency.

[0088] When the incident wavelengths are 460nm, 530nm, and 620nm, the ratios of (1,0)R and (1,0)T are 4.83, 4.7, and 3.83, respectively. This indicates that the light energy coupled towards the human eye is enhanced, while the light energy coupled towards the external environment is weakened, thus reducing the intensity of light leakage. It can be seen that when the coupling grating is composed of a highly modulated grating structure, the light leakage is reduced by increasing the light energy of diffracted beams 503, 504, and 505 that is conducted towards the human eye and enters the eye for imaging, while simultaneously reducing the light energy coupled outwards from diffracted beams 506, 507, and 508 to the external environment.

[0089] Furthermore, this invention also provides a near-eye display device, including the aforementioned diffractive waveguide structure. Since the near-eye display device of this invention includes the aforementioned diffractive waveguide structure, it has similar technical effects to the above embodiments, and will not be described again here.

[0090] A near-eye display device is a display device worn on the user's eyes and can take the form of glasses or a helmet. For example, a near-eye display device may include AR glasses, etc.

[0091] In some embodiments, the near-eye display device further includes a microdisplay; the microdisplay is used to output image light as incident light in a diffractive waveguide structure.

[0092] In summary, this invention provides a diffractive waveguide structure and a near-eye display device. The diffractive waveguide structure includes a waveguide substrate, an insertion grating, and an exit grating, which are disposed on the surface of the waveguide substrate. The insertion grating couples incident light rays into the waveguide substrate, and the exit grating couples exit diffracted light rays propagating within the waveguide substrate. The exit grating has multiple periodically arranged primitives. These primitives introduce asymmetry in the x-direction of the exit grating, and are divided into a first primitive region and a second primitive region along the central axis. The shapes of the first and second primitive regions are different. Through this diffractive waveguide structure, this invention can reduce light leakage in the exit region of the grating waveguide and improve the efficiency of the grating waveguide.

[0093] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A diffractive optical waveguide structure, characterized in that, include: A waveguide substrate, a coupling grating, and a coupling grating are provided, wherein the coupling grating and the coupling grating are disposed on the surface of the waveguide substrate; the coupling grating is used to couple incident light into the waveguide substrate, and the coupling grating is used to couple out diffracted light propagating within the waveguide substrate; The coupled grating is provided with a plurality of periodically arranged primitives; The primitive is used to introduce the asymmetry of the coupling grating along the x-direction. The primitive is divided into a first primitive region and a second primitive region according to the central axis. The shape and structure of the first primitive region and the shape and structure of the second primitive region are different.

2. The diffractive waveguide structure according to claim 1, characterized in that, The primitive comprises multiple sub-units; at least two of the multiple sub-units have different heights and / or widths.

3. The diffractive waveguide structure according to claim 2, characterized in that, The cross-sectional shape of the sub-unit along the vertical direction is rectangular or triangular.

4. The diffractive waveguide structure according to claim 2, characterized in that, The multiple sub-units are arranged at intervals or consecutively.

5. The diffractive waveguide structure according to claim 1, characterized in that, The element comprises two blazed gratings of different heights, and the cross-sectional shape of the two blazed gratings along the vertical direction is a right triangle.

6. The diffractive waveguide structure according to claim 1, characterized in that, The cross-sectional shape of the basic element along the vertical direction is a combination of rectangle and triangle.

7. The diffractive waveguide structure according to claim 3, characterized in that, The plurality of sub-units includes a first sub-unit, a second sub-unit, and a third sub-unit arranged at intervals in sequence. The first sub-unit and the second sub-unit have the same height, while the second sub-unit and the third sub-unit have different heights. The first sub-unit and the second sub-unit have different widths, and the second sub-unit and the third sub-unit have different widths.

8. The diffractive waveguide structure according to any one of claims 1 to 7, characterized in that, The highest height of the shape structure in the first primitive region is greater than the highest height of the shape structure in the second primitive region; or, the lowest height of the shape structure in the first primitive region is greater than the lowest height of the shape structure in the second primitive region.

9. A near-eye display device, characterized in that, Including the diffractive waveguide structure as described in any one of claims 1 to 8.

10. The near-eye display device according to claim 9, characterized in that, It also includes a microdisplay; the microdisplay is used to output image light as incident light in the diffractive waveguide structure.

Images