Optical waveguide and display device

Abstract

The utility model discloses an optical waveguide and a display device, and relates to the technical field of optical waveguides, the optical waveguide comprises a coupling-in area, a coupling-out area and first recovery areas, and the first recovery areas are arranged on the side, close to the coupling-in area, outside the coupling-out area and symmetrically arranged on the two sides of the coupling-in area. According to the invention, the first recovery region is used for diffracting the light diffracted and propagated out of the coupling-out region by the first coupling-out grating region, so that the propagation direction of the light is changed until the light is propagated to at least one of the second coupling-out grating region and the third coupling-out grating region to be coupled out, and the waveguide coupling-out efficiency is effectively improved; and meanwhile, the uniformity of the display brightness on one side, close to the coupling-in area, of the coupling-out area is also improved.

Description

Technical Field

[0001] The present application relates to the field of optical waveguide technology, and more specifically, to an optical waveguide and a display device. Background Art

[0002] With the development of augmented reality (AR) technology, AR displays are becoming more widely used in people's lives. Diffraction waveguides (DWGs), commonly used light propagation devices in displays, can confine light and transmit it through total internal reflection to achieve pupil expansion.

[0003] Currently, optical waveguides use coupling-in and coupling-out gratings to couple light in and out. However, due to the characteristics of light propagation through the grating structure, when light enters the coupling-out grating, a bifurcation phenomenon occurs, causing a portion of the energy of the light to be ejected out of the coupling-out grating and unable to exit the optical waveguide, resulting in low efficiency of existing optical waveguides. Utility Model Content

[0004] The present application proposes an optical waveguide and a display device to improve the above-mentioned defects.

[0005] In a first aspect, an embodiment of the present application provides an optical waveguide, comprising an in-coupling region and an out-coupling region, wherein light is coupled out from the out-coupling region after passing through the in-coupling region, and the out-coupling region comprises a first out-coupling grating region and a second out-coupling grating region and a third out-coupling grating region symmetrically arranged on both sides of the first out-coupling grating region. The light propagates from the in-coupling region to the first out-coupling grating region along a preset working order direction, and part of the light is diffracted by the first out-coupling grating region and then propagates along the first propagation direction to the second out-coupling grating region for out-coupling, and part of the light is diffracted by the first out-coupling grating region and then propagates along the second propagation direction to the third out-coupling grating region for out-coupling; the optical waveguide also comprises a first recycling region, which is arranged outside the out-coupling region on one side close to the in-coupling region and symmetrically arranged on both sides of the in-coupling region, and the first recycling region is used to diffract the light diffracted by the first out-coupling grating region and propagated outside the out-coupling region, so that the light changes its propagation direction and propagates to at least one of the second out-coupling grating region and the third out-coupling grating region for out-coupling.

[0006] Optionally, the first recycling region includes a first recycling grating region and a second recycling grating region, the first recycling grating region is arranged on a side outside the first out-coupling grating region close to the coupling-in region, and the second recycling grating region is arranged on a side outside the second out-coupling grating region close to the coupling-in region, and the first recycling grating region and the second recycling grating region are symmetrically arranged on both sides of the coupling-in region.

[0007] Optionally, the first recycling grating region and the second recycling grating region are both trapezoidal in shape.

[0008] Optionally, the grating parameters of the first recycling grating region are set so that the propagation direction of the first light incident on the first recycling grating region changes to the first propagation direction so as to enter the second outcoupling grating region along the first propagation direction and be coupled out; the grating parameters of the second recycling grating region are set so that the propagation direction of the second light incident on the second recycling grating region changes to the second propagation direction so as to enter the third outcoupling grating region along the second propagation direction and be coupled out.

[0009] Optionally, the first recycling region is used to diffract the light diffracted by the first out-coupling grating region and propagated outside the out-coupling region, so that the light propagates along a direction different from the first propagation direction and the second propagation direction to the second out-coupling grating region and the third out-coupling grating region away from the side of the in-coupling region and is coupled out; the optical waveguide also includes a second recycling region, which is arranged on a side of the out-coupling region away from the in-coupling region and symmetrically arranged on both sides of the first out-coupling grating region, and the second recycling region is used to couple out the light diffracted and propagated thereon by the first recycling grating region and the second recycling grating region, as well as the light propagating thereon along the first propagation direction and the second propagation direction.

[0010] Optionally, the grating parameters of the first recycling grating region are set so that the propagation direction of the first light incident on the first recycling grating region changes to a third propagation direction from the first recycling grating region to the side of the second out-coupling grating region away from the coupling-in region; the grating parameters of the second recycling grating region are set so that the propagation direction of the second light incident on the second recycling grating region changes to a fourth propagation direction from the second recycling grating region to the side of the third out-coupling grating region away from the coupling-in region.

[0011] Optionally, the second recycling region includes a third recycling grating region and a fourth recycling grating region, the third recycling grating region is arranged on a side of the second outcoupling grating away from the coupling-in region, the fourth recycling grating region is arranged on a side of the third outcoupling grating away from the coupling-in region, and the third recycling grating region and the fourth recycling grating region are symmetrically arranged on both sides of the first outcoupling grating region; the third recycling grating region is used to couple out light propagating thereon along the third propagation direction and along the first propagation direction; the fourth recycling grating region is used to couple out light propagating thereon along the fourth propagation direction and along the second propagation direction.

[0012] Optionally, the grating parameters of the first recycling grating region are set so that the propagation direction of the first light incident on the first recycling grating region becomes a fifth propagation direction pointing from the first recycling grating region to the third out-coupling grating region away from the coupling-in region; the grating parameters of the second recycling grating region are set so that the propagation direction of the second light incident on the second recycling grating region becomes a sixth propagation direction pointing from the second recycling grating region to the second out-coupling grating region away from the coupling-in region.

[0013] Optionally, the second recycling region includes a fifth recycling grating region and a sixth recycling grating region, the fifth recycling grating region is arranged on a side of the second outcoupling grating away from the coupling-in region, the sixth recycling grating region is arranged on a side of the third outcoupling grating away from the coupling-in region, and the fifth recycling grating region and the sixth recycling grating region are symmetrically arranged on both sides of the first outcoupling grating region; the fifth recycling grating region is used to couple out light propagating thereon along the sixth propagation direction and along the first propagation direction; the sixth recycling grating region is used to couple out light propagating thereon along the fifth propagation direction and along the second propagation direction.

[0014] In a second aspect, an embodiment of the present application further provides a display device, comprising light and the optical waveguide as described above, wherein the light is used to emit the light, and the image light is transmitted through the optical waveguide and then emitted toward an observation area.

[0015] Therefore, the present application provides an optical waveguide and a display device, wherein the optical waveguide includes an in-coupling region and an out-coupling region, wherein the out-coupling region includes a first out-coupling grating region, a second out-coupling grating region, and a third out-coupling grating region. The optical waveguide also includes a first recovery region, which is used to diffract the light that is incident on the first out-coupling grating region and is diffracted outside the out-coupling region and then is recovered to the second out-coupling grating region and the third out-coupling grating region, so that this part of the light can also be coupled out on the out-coupling region, which not only effectively improves the waveguide out-coupling efficiency, but also improves the uniformity of the display brightness on the side of the out-coupling region close to the in-coupling region.

[0016] Other features and advantages of the embodiments of the present application will be described in the following description and, in part, will become apparent from the description or be understood by practicing the embodiments of the present application. The objectives and other advantages of the embodiments of the present application can be achieved and obtained through the structures particularly pointed out in the written description, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 shows a schematic diagram of light propagation in a diffraction optical waveguide;

[0019] Figure 2 A schematic structural diagram of an optical waveguide proposed in an embodiment of the present application is shown;

[0020] Figure 3 A schematic diagram of a K-vector circle of light propagating in an optical waveguide according to an embodiment of the present application is shown;

[0021] Figure 4 A schematic diagram of a grating structure of a first recycling grating region and a second recycling grating region in an embodiment of the present application is shown;

[0022] Figure 5 A schematic diagram of a grating structure of a first recycling grating region and a second recycling grating region in another embodiment of the present application is shown;

[0023] Figure 6 A schematic structural diagram of another optical waveguide proposed in an embodiment of the present application is shown;

[0024] Figure 7 A schematic diagram of a K-vector circle of another optical waveguide propagating light proposed in an embodiment of the present application is shown;

[0025] Figure 8 A schematic diagram of a grating structure of a third recycling grating region in an embodiment of the present application is shown;

[0026] Figure 9 A schematic diagram of a grating structure of a third recycling grating region in another embodiment of the present application is shown;

[0027] Figure 10 A schematic diagram of a grating structure of a third recycling grating region in another embodiment of the present application is shown;

[0028] Figure 11 A schematic diagram of a grating structure of a third recycling grating region in another embodiment of the present application is shown;

[0029] Figure 12 A schematic structural diagram of another optical waveguide proposed in an embodiment of the present application is shown;

[0030] Figure 13A schematic diagram of a K-vector circle of light propagating in another optical waveguide proposed in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application for which protection is claimed, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work fall within the scope of protection of the present application.

[0032] It should be noted that similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings. At the same time, in the description of this application, the terms "first", "second", etc. are only used to distinguish the description and should not be understood as indicating or implying relative importance.

[0033] See also Figure 1 , Figure 1 Figure 2 shows a schematic diagram of light propagation in a diffraction waveguide. Figure 1 As shown, the diffraction waveguide 100 includes an in-coupling grating 101 and an out-coupling grating 102. Generally, the out-coupling grating 102 is often designed as a two-dimensional grating to achieve the pupil expansion effect of the diffraction waveguide. Due to the diffraction characteristics of the two-dimensional grating structure unit, the light will be diffracted by the out-coupling grating 102 and will go towards Figure 1 In order to make the overall outcoupling efficiency of the diffraction waveguide higher within the user's observable range, the outcoupling grating 102 is usually designed to concentrate the diffraction energy on the forward propagation and forward bifurcation orders (corresponding to Figure 1 However, it is difficult to eliminate the redundant propagation and bifurcation orders (corresponding to Figure 1 Therefore, when light propagates to the outcoupling grating 102, the light propagating along the light propagation directions x4 and x5 diffracted by the outcoupling grating 102 will be ejected outside the outcoupling grating 102. These ejected light rays cannot be received by the human eye, thereby losing a lot of light energy and resulting in a low efficiency of the diffraction optical waveguide.

[0034] Therefore, see Figure 2 , Figure 2A schematic structural diagram of an optical waveguide proposed in an embodiment of the present application is shown. The optical waveguide 200 includes a coupling-in region 210 and a coupling-out region 220. After light L is coupled into the optical waveguide by the coupling-in region 210, it is coupled out of the optical waveguide from the coupling-out region 220. Specifically, the coupling-out region 220 includes a first coupling-out grating region 221 and a second coupling-out grating region 222 and a third coupling-out grating region 223 symmetrically arranged on both sides of the first coupling-out grating region 221. After light is coupled into the optical waveguide 200 through the coupling-in region 210, it will propagate from the coupling-in region 210 to the first coupling-out grating region 221 along a preset working level direction.

[0035] In some embodiments, the coupling-in region 210 is a one-dimensional grating, and the preset working order direction of the light is the working order direction of the coupling-in region 210. Furthermore, the working order direction of the coupling-in region 210 is the direction from the coupling-in region 210 to the first outcoupling grating region 221. Specifically, after light is incident on the grating, it undergoes multiple orders of diffraction. For example, taking the incident grating as monochromatic light, after the light is incident on the grating, it is diffracted into several different directions (i.e., diffraction orders). Among these diffraction orders, a non-zero diffraction order (e.g., +1 order) satisfies the total internal reflection condition of the waveguide layer and thus enters the waveguide layer for total internal reflection propagation. Therefore, this diffraction order is the working order of the grating, and the working order direction of the grating is the propagation direction of the light of this diffraction order in the waveguide layer.

[0036] In some embodiments, the first outcoupling grating region 221 is a two-dimensional grating, and the second outcoupling grating region 222 and the third outcoupling grating region 223 are one-dimensional gratings. Furthermore, the grating parameters of the first outcoupling grating region 221 are designed so that the light incident on the first outcoupling grating region 221 is partially diffracted to propagate along the first propagation direction L1 to the second outcoupling grating region 222 and is coupled out by the second outcoupling grating region 222, and the light incident on the first outcoupling grating region 221 is partially diffracted to propagate along the second propagation direction L2 to the third outcoupling grating region 223 and is coupled out by the third outcoupling grating region 223.

[0037] Further, see Figure 3 , Figure 3 A schematic diagram of a K-vector circle for propagating light in an optical waveguide proposed in an embodiment of the present application is shown. Specifically, the K vector shown in the K-vector circle is used to characterize its ability to change the distribution of the light wave vector. Light whose wave vector is in the inner area of the small circle will be transmitted on the surface of the optical waveguide, and light whose wave vector is in the area between the small circle and the large circle will be totally reflected and propagated in the optical waveguide. In addition, the propagation direction of the light in the optical waveguide is related to the distribution position of the light wave vector in the K-vector circle. The propagation direction is the direction from the center of the K-vector circle to the distribution position of the light wave vector. For example, Figure 3The K0 vector shown represents the grating vector of the coupling region 210, which is used to move the light wave vector from the center of the circle to the position indicated by the vector arrow. Combined with the above description, it can be seen that the propagation direction of the light after diffraction by the coupling region 210 is from the center of the circle to the position where the K0 vector arrow is located, which is consistent with the Figure 2 Therefore, when the grating vector of the coupling region 210 is designed to be Figure 3 When the vector K0 is shown, the requirement that light is incident on the first outcoupling grating region 221 after being coupled in from the incoupling region 210 can be met. Similarly, when the first outcoupling grating region 221 is designed to have at least the grating vectors shown by the vectors K1 and K2, the requirement that part of the light incident on the first outcoupling grating region 221 propagates along the first propagation direction L1 to the second outcoupling grating region 222, and part of the light incident on the first outcoupling grating region 221 propagates along the second propagation direction L2 to the third outcoupling grating region 223 can be met. The grating vector of the second outcoupling grating region 222 is designed to be vector K5, so that the light incident on the second outcoupling grating region 222 can be coupled out of the optical waveguide 200. The grating vector of the third outcoupling grating region 223 is designed to be vector K6, so that the light incident on the third outcoupling grating region 223 can be coupled out of the optical waveguide 200.

[0038] However, according to the relevant description in the background art, it is difficult to eliminate the grating vector of the first out-coupling grating region 221 propagating and bifurcating toward the in-coupling grating 210 in the two-dimensional grating design. In other words, the first out-coupling grating region 221 will still have the superposition and appear as follows: Figure 3 The grating vectors K3 and K4 (dashed lines) shown in FIG. 2 are the grating vectors. When light enters the first outcoupling grating region 221, a portion of the light will be affected by the vectors K3 and K4 and diffracted to the outside of the outcoupling region 220, which is reflected in FIG. Figure 2 In the figure, the light diffracted by the vector K3 is Figure 2 The first light L3 shown in FIG is diffracted by the vector K4. Figure 2 Therefore, in this embodiment, the optical waveguide further includes a first recycling region 230, which is disposed outside the outcoupling region 220 and close to the incoupling region 210, and is symmetrically disposed on both sides of the incoupling region 210. Furthermore, the first recycling region 230 is configured to diffract the first light L3 and the second light L4 diffracted and propagated outside the outcoupling region 220 by the first outcoupling grating region 221, so as to change their propagation directions and propagate to at least one of the second outcoupling grating region 222 and the third outcoupling grating region 223 for outcoupling.

[0039] In some embodiments, the first recycling region 230 includes a first recycling grating region 231 and a second recycling grating region 232. The first recycling grating region 231 is arranged on a side of the first outcoupling grating region 221 close to the coupling-in region 210, and the second recycling grating region 232 is arranged on a side of the second outcoupling grating region 222 close to the coupling-in region 210. In addition, the first recycling grating region 231 and the second recycling grating region 232 are symmetrically arranged on both sides of the coupling-in region 210. Furthermore, the grating parameters of the first recycling grating region 231 are set so that the propagation direction of the first light L3 incident on the first recycling grating region 231 changes to the first propagation direction L1 so as to be incident on the second outcoupling grating region 222 along the first propagation direction L1 and be coupled out. The grating parameters of the second recycling grating region 232 are set so that the propagation direction of the second light L4 incident on the second recycling grating region 232 changes to the second propagation direction L2 so as to be incident on the third outcoupling grating region 223 along the second propagation direction L2 and be coupled out. Specifically, reference may still be made to Figure 3 According to the above description of the grating vector, when the grating parameters of the first recycling grating area 231 are set so that the grating vector of the first recycling grating area 231 is as follows: Figure 3 When the vector K7 is shown, it can be ensured that the first recycling grating area 231 can change the propagation direction of the first light L3 incident on the first recycling grating area 231 to the first propagation direction L1, so that it propagates to the second outcoupling grating area 222 and is coupled out by the action of the grating vector K5; similarly, when the grating parameters of the second recycling grating area 232 are set so that the grating vector of the second recycling grating area 232 is as follows Figure 3 When the vector K8 is shown, it can ensure that the second recycling grating area 232 can change the propagation direction of the second light L4 incident on the second recycling grating area 232 to the second propagation direction L2, so that it propagates to the third outcoupling grating area 223 and is coupled out by the grating vector K6.

[0040] In some embodiments, the first recycling grating region 231 and the second recycling grating region 232 may be one-dimensional gratings. Alternatively, the first recycling grating region 231 and the second recycling grating region 232 may also be two-dimensional gratings. Figure 4 , Figure 4 A schematic diagram of the grating structure of a first recycling grating region and a second recycling grating region in an embodiment of the present application is shown, wherein: Figure 4 The first recycling grating region and the second recycling grating region are shown as one-dimensional gratings. Figure 5 The figure shows the case where the first recycling grating region and the second recycling grating region are two-dimensional gratings. The grating size and direction of the first recycling grating region 231 and the second recycling grating region 232 are designed. Furthermore, for a one-dimensional grating, the grating shape can be a straight grating, a tilted grating, and a blazed grating. For a two-dimensional grating, the grating unit of the two-dimensional grating can be an ellipse, a diamond, a rectangle, etc. Figure 4 and Figure 5 The cases where the one-dimensional grating is a straight grating and the grating unit is an ellipse are respectively shown.

[0041] In some embodiments, the shapes of the first recycling grating region 231 and the second recycling grating region 232 include but are not limited to regular rectangles, circles, triangles, trapezoids, etc., and may also be irregular shapes. In particular, the shapes of the first recycling grating region 231 and the second recycling grating region 232 are both trapezoidal to distinguish them from the coupling-in region 210 and the coupling-out region 220.

[0042] Therefore, an embodiment of the present application provides an optical waveguide, which includes a coupling-in region and a coupling-out region, wherein the coupling-out region includes a first coupling-out grating region, a second coupling-out grating region, and a third coupling-out grating region. The optical waveguide also includes a first recycling region, which is used to diffract the light that is incident on the first coupling-out grating region and is diffracted outside the coupling-out region and then recycled to the second coupling-out grating region and the third coupling-out grating region, so that this part of the light can also be coupled out on the coupling-out region, which not only effectively improves the waveguide coupling efficiency, but also improves the uniformity of the display brightness on the side of the coupling-out region close to the coupling-in region.

[0043] See also Figure 6 , Figure 6 The structure diagram of another optical waveguide proposed in an embodiment of the present application is shown. Among them, the optical waveguide 300 includes a coupling-in region 310 and a coupling-out region 320. After the light L is coupled into the optical waveguide by the coupling-in region 310, it is coupled out of the optical waveguide from the coupling-out region 320. Specifically, the coupling-out region 320 includes a first coupling-out grating region 311 and a second coupling-out grating region 312 and a third coupling-out grating region 323 symmetrically arranged on both sides of the first coupling-out grating region 311. After the light is coupled into the optical waveguide 300 through the coupling-in region 310, it will propagate from the coupling-in region 310 to the first coupling-out grating region 311 along a preset working order direction. The optical waveguide 300 also includes a first recycling region 330. The first recycling region 330 includes a first recycling grating region 331 and a second recycling grating region 332 for diffracting the light L coupled into the optical waveguide 300 by the coupling-in region 310. The grating region 321 diffracts the light propagating out of the outcoupling region 320, causing it to propagate along a direction different from the first propagation direction L1 and the second propagation direction L2 to the second outcoupling grating region 322 and the third outcoupling grating region 323 on a side away from the coupling-in region 310 for coupling out. Furthermore, the optical waveguide 300 also includes a second recycling region 340, which is arranged on a side of the outcoupling region 320 away from the coupling-in region 310 and is symmetrically arranged on both sides of the first outcoupling grating region 321, for coupling out the light diffracted and propagated thereon by the first recycling grating region 331 and the second recycling grating region 332, as well as coupling out the light propagating thereon along the first propagation direction L1 and the second propagation direction L2.

[0044] In some embodiments, see Figure 7 , Figure 7 A schematic diagram of a K-vector circle for propagating light in another optical waveguide proposed in an embodiment of the present application is shown, wherein, when the grating vector of the coupling-in region 310 is designed to be vector K0, and the first outcoupling grating region 321 is designed to have at least grating vectors as shown by vectors K1 and K2, the requirements are met that after light enters the coupling-in region 310, it enters the first outcoupling grating region 321 along a preset propagation direction, and part of the light entering the first outcoupling grating region 321 propagates to the second outcoupling grating region 322 along the first propagation direction L1, and part of the light entering the first outcoupling grating region 321 propagates to the third outcoupling grating region 323 along the second propagation direction L2; the grating vector of the second outcoupling grating region 322 is designed to be vector K7, so that the light entering the second outcoupling grating region 322 can be coupled out of the optical waveguide 300; the grating vector of the third outcoupling grating region 323 is designed to be vector K8, so that the light entering the third outcoupling grating region 323 can be coupled out of the optical waveguide 300. According to the above analysis, the first outcoupling grating region 321 will also have the following superposition: Figure 7 As shown in the grating vectors of vectors K3 and K4 (shown by dotted lines), when light enters the first out-coupling grating area 321, a portion of the light will be affected by the vectors K3 and K4 and diffracted to the outside of the out-coupling area 320, forming the corresponding first light L3 and second light L4.

[0045] Furthermore, the first recycling grating region 331 and the second recycling grating region 332 are used to recycle the first light L3 and the second light L4. Specifically, the grating parameters of the first recycling grating region 331 are set so that the propagation direction of the first light L3 incident on the first recycling grating region 331 changes to a third propagation direction L5 pointing from the first recycling grating region 331 to the second out-coupling grating region 322 away from the coupling-in region 330. The grating parameters of the second recycling grating region 332 are set so that the propagation direction of the second light L4 incident on the second recycling grating region 332 changes to a fourth propagation direction L6 pointing from the second recycling grating region 332 to the third out-coupling grating region 323 away from the coupling-in region 330. Figure 7 , that is, the first recycling grating region 331 has Figure 7 The grating vector of vector K5 is shown, and the second recycling grating area 332 has a Figure 7 The raster vector of vector K6 is shown.

[0046] Correspondingly, the second recycling region 340 includes a third recycling grating region 341 and a fourth recycling grating 342. The third recycling grating region 341 is arranged on a side of the second outcoupling grating 322 away from the coupling-in region 310, and the fourth recycling grating region 342 is arranged on a side of the third outcoupling grating 323 away from the coupling-in region 310. The third recycling grating region 341 and the fourth recycling grating 342 are symmetrically arranged on both sides of the first outcoupling grating region 321. In addition, the third recycling grating region 341 is used to couple out light propagating thereon along the third propagation direction L5 and along the first propagation direction L1, and the fourth recycling grating region 342 is used to couple out light propagating thereon along the fourth propagation direction L6 and along the second propagation direction L2. For example, in combination Figure 7 The grating parameters of the third recycling grating region 341 are set so that the third recycling grating region 341 has a grating vector as shown by vector K7 and vector K9, and the grating parameters of the fourth recycling grating region 342 are set so that the fourth recycling grating region 342 has a grating vector as shown by vector K8 and vector K10, wherein vector K7 is used to couple out light propagating along the first propagation direction L1 to the third recycling grating region 341, vector K9 is used to couple out light propagating along the third propagation direction L5 to the third recycling grating region 341, vector K8 is used to couple out light propagating along the second propagation direction L2 to the fourth recycling grating region 342, and vector K10 is used to couple out light propagating along the fourth propagation direction L6 to the fourth recycling grating region 342.

[0047] In some embodiments, the third recycling grating region 341 and the fourth recycling grating 342 may be a one-dimensional grating or a two-dimensional grating. Figure 7 , Figure 7 FIG. 1 shows a schematic diagram of the grating structure of the third recycling grating region in an embodiment of the present application, wherein: Figures 8-10 Schematic diagram of the grating structure when the third recycling grating area is a one-dimensional grating. When the third recycling grating area 341 is a one-dimensional grating, in order to ensure that the third recycling grating area 341 can have two different grating vectors K7 and K9, it is necessary to set the grating structure staggered distribution in the third recycling grating area 341, such as Figure 10 As shown, the unshaded grating structure has Figure 8 The grating vector K7 shown in FIG. 1 has a shaded grating structure with a Figure 9 The grating vector K9 shown; wherein, Figure 11 is a schematic diagram of the grating structure when the third recycling grating area is a two-dimensional grating. The grating unit can be elliptical, diamond, rectangular, etc. Figure 11 The grating unit is shown as a rectangle. It is understood that the grating structure of the fourth recycling grating region 342 is similar to that of the third recycling grating region 341, and will not be described in detail here.

[0048] In some embodiments, the shapes of the third recycling grating region 341 and the fourth recycling grating region 342 include but are not limited to regular rectangles, circles, triangles, trapezoids, etc., and may also be irregular shapes. In particular, the shapes of the third recycling grating region 341 and the fourth recycling grating region 342 are both trapezoidal, and are combined with the second outcoupling grating region 322 and the third outcoupling grating region 323 to form a complete rectangle.

[0049] In some embodiments, see Figure 12 , Figure 12 A schematic diagram of the structure of another optical waveguide proposed in an embodiment of the present application is shown. The grating parameters of the first recycling grating region 331 are set so that the propagation direction of the first light ray L3 incident on the first recycling grating region 331 changes to a fifth propagation direction L7, which is directed from the first recycling grating region 331 to the side of the third outcoupling grating region 323 away from the incoupling region 310. The grating parameters of the second recycling grating region 332 are set so that the propagation direction of the second light ray L4 incident on the second recycling grating region 332 changes to a sixth propagation direction L8, which is directed from the second recycling grating region 332 to the side of the second outcoupling grating region 322 away from the incoupling region 310. Correspondingly, the second recycling region 340 includes a fifth recycling grating region 343 and a sixth recycling grating 344. The fifth recycling grating region 343 is disposed on a side of the second outcoupling grating 322 away from the incoupling region 310, and the sixth recycling grating 344 is disposed on a side of the third outcoupling grating 323 away from the incoupling region 310. The fifth recycling grating region 343 and the sixth recycling grating 344 are symmetrically disposed on either side of the first outcoupling grating region 321. Furthermore, the fifth recycling grating region 343 is configured to decouple light propagating along the sixth propagation direction L8 and the first propagation direction L1, while the sixth recycling grating 344 is configured to decouple light propagating along the fifth propagation direction L7 and the second propagation direction L2.

[0050] For example, Figure 13A schematic diagram of a K-vector circle for light propagation in another optical waveguide according to an embodiment of the present application is shown. Specifically, when the grating vector of the coupling-in region 310 is designed to be vector K0, and the first outcoupling grating region 321 is designed to have at least grating vectors such as vectors K1 and K2, the following requirements are met: after light enters the coupling-in region 310, it enters the first outcoupling grating region 321 along a preset propagation direction, and a portion of the light entering the first outcoupling grating region 321 propagates along the first propagation direction L1 to the second outcoupling grating region 322, and a portion of the light entering the first outcoupling grating region 321 propagates along the second propagation direction L2 to the third outcoupling grating region 323; the grating vector of the second outcoupling grating region 322 is designed to be vector K7, so that light entering the second outcoupling grating region 322 can be coupled out of the optical waveguide 300; and the grating vector of the third outcoupling grating region 323 is designed to be vector K8, so that light entering the third outcoupling grating region 323 can be coupled out of the optical waveguide 300. According to the above analysis, the first outcoupling grating region 321 will also have the following superposition: Figure 12 As shown in the grating vectors of vectors K3 and K4 (shown by dotted lines), when light enters the first out-coupling grating area 321, a portion of the light will be affected by the vectors K3 and K4 and diffracted to the outside of the out-coupling area 320, forming the corresponding first light L3 and second light L4.

[0051] Combining the above description, it can be seen that the first recycling grating area 331 has the following Figure 13 The grating vector of vector K5 is shown, and the second recycling grating area 332 has a Figure 13 The raster vector of vector K6 is shown. Figure 7 The grating parameters of the fifth recycling grating region 343 are set so that the fifth recycling grating region 343 has a grating vector as shown by vector K7 and vector K9, and the grating parameters of the sixth recycling grating region 344 are set so that the sixth recycling grating region 344 has a grating vector as shown by vector K8 and vector K10, wherein vector K7 is used to couple out the light propagating along the first propagation direction L1 to the fifth recycling grating region 343, vector K9 is used to couple out the light propagating along the sixth propagation direction L8 to the fifth recycling grating region 343, vector K8 is used to couple out the light propagating along the second propagation direction L2 to the sixth recycling grating region 344, and vector K10 is used to couple out the light propagating along the fifth propagation direction L7 to the sixth recycling grating region 344.

[0052] In some embodiments, the fifth recycling grating region 343 and the sixth recycling grating region 344 may be one-dimensional gratings or two-dimensional gratings. The specific grating structure can refer to the relevant description of the third recycling grating region 341 and the fourth recycling grating region 342 in the above embodiments and will not be described again here.

[0053] In some embodiments, the shapes of the fifth recycling grating region 343 and the sixth recycling grating region 344 include but are not limited to regular rectangles, circles, triangles, trapezoids, etc., and may also be irregular shapes. In particular, the shapes of the fifth recycling grating region 343 and the sixth recycling grating region 344 are both trapezoidal, and are combined with the second outcoupling grating region 322 and the third outcoupling grating region 323 to form a complete rectangle.

[0054] Therefore, this embodiment adds a second recycling area on the side of the outcoupling area away from the coupling-in area, so that the recycled light is coupled out on the side of the outcoupling area away from the coupling-in area, effectively improving the light outcoupling energy in this area and improving the uniformity of the light brightness.

[0055] As an embodiment, the present application further provides a display device comprising a light source and the aforementioned optical waveguide. The light source is configured to emit light, which is then transmitted through the optical waveguide and directed toward an observation area. As a result, the light transmission efficiency of the display device and the brightness uniformity of the output image are significantly improved, thereby enhancing the user experience.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements 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 the present application.

Claims

1. An optical waveguide comprising an incoupling region and an outcoupling region, wherein light is coupled into the incoupling region and then coupled out from the outcoupling region, wherein: The outcoupling region includes a first outcoupling grating region and a second outcoupling grating region and a third outcoupling grating region symmetrically arranged on both sides of the first outcoupling grating region. The light propagates from the incoupling region to the first outcoupling grating region along a preset working order direction, and part of the light is diffracted by the first outcoupling grating region and then propagates along the first propagation direction to the second outcoupling grating region for outcoupling. Part of the light is diffracted by the first outcoupling grating region and then propagates along the second propagation direction to the third outcoupling grating region for outcoupling. The optical waveguide also includes a first recycling region, which is arranged on a side outside the outcoupling region close to the incoupling region and symmetrically arranged on both sides of the incoupling region. The first recycling region is used to diffract the light diffracted by the first outcoupling grating region and propagated outside the outcoupling region, so that the light changes its propagation direction and propagates to at least one region of the second outcoupling grating region and the third outcoupling grating region for outcoupling.

2. The optical waveguide according to claim 1, wherein The first recycling region includes a first recycling grating region and a second recycling grating region. The first recycling grating region is arranged on a side outside the first out-coupling grating region close to the coupling-in region, and the second recycling grating region is arranged on a side outside the second out-coupling grating region close to the coupling-in region. The first recycling grating region and the second recycling grating region are symmetrically arranged on both sides of the coupling-in region.

3. The optical waveguide according to claim 2, wherein The first recycling grating region and the second recycling grating region are both trapezoidal in shape.

4. The optical waveguide according to claim 2, wherein: The grating parameters of the first recycling grating region are set to change the propagation direction of the first light incident on the first recycling grating region to the first propagation direction so as to be incident on the second outcoupling grating region along the first propagation direction and be coupled out; The grating parameters of the second recycling grating region are set to change the propagation direction of the second light incident on the second recycling grating region to the second propagation direction so as to be incident on the third outcoupling grating region along the second propagation direction and be coupled out.

5. The optical waveguide according to claim 2, wherein The first recycling region is used to diffract the light diffracted by the first outcoupling grating region and propagated outside the outcoupling region, so that the light propagates along a direction different from the first propagation direction and the second propagation direction to the second outcoupling grating region and the third outcoupling grating region away from the incoupling region and is coupled out; The optical waveguide also includes a second recycling region, which is arranged on a side of the out-coupling region away from the in-coupling region and symmetrically arranged on both sides of the first out-coupling grating region. The second recycling region is used to couple out the light diffracted and propagated thereon by the first recycling grating region and the second recycling grating region, and to couple out the light propagated thereon along the first propagation direction and the second propagation direction.

6. The optical waveguide according to claim 5, wherein: The grating parameters of the first recycling grating region are set so that the propagation direction of the first light incident on the first recycling grating region changes to a third propagation direction from the first recycling grating region to the side of the second outcoupling grating region away from the incoupling region; The grating parameters of the second recycling grating region are set to change the propagation direction of the second light incident on the second recycling grating region to a fourth propagation direction from the second recycling grating region to the side of the third outcoupling grating region away from the coupling-in region.

7. The optical waveguide according to claim 6, wherein The second recycling region includes a third recycling grating region and a fourth recycling grating region, the third recycling grating region is arranged on a side of the second outcoupling grating away from the incoupling region, the fourth recycling grating region is arranged on a side of the third outcoupling grating away from the incoupling region, and the third recycling grating region and the fourth recycling grating region are symmetrically arranged on both sides of the first outcoupling grating region; The third recycling grating region is used to couple out the light propagating along the third propagation direction and the light propagating thereto along the first propagation direction; The fourth recycling grating region is used to couple out the light propagating thereon along the fourth propagation direction and the light propagating thereon along the second propagation direction.

8. The optical waveguide according to claim 5, wherein: The grating parameters of the first recycling grating region are set so that the propagation direction of the first light incident on the first recycling grating region changes to a fifth propagation direction from the first recycling grating region to the side of the third outcoupling grating region away from the incoupling region; The grating parameters of the second recycling grating region are set to change the propagation direction of the second light incident on the second recycling grating region into a sixth propagation direction from the second recycling grating region to the side of the second outcoupling grating region away from the coupling-in region.

9. The optical waveguide according to claim 8, wherein The second recycling region includes a fifth recycling grating region and a sixth recycling grating region, the fifth recycling grating region is arranged on a side of the second outcoupling grating away from the incoupling region, the sixth recycling grating region is arranged on a side of the third outcoupling grating away from the incoupling region, and the fifth recycling grating region and the sixth recycling grating region are symmetrically arranged on both sides of the first outcoupling grating region; The fifth recycling grating region is used to couple out the light propagating along the sixth propagation direction and the light propagating thereto along the first propagation direction; The sixth recycling grating region is used to couple out the light propagating thereon along the fifth propagation direction and along the second propagation direction.

10. A display device, characterized in that: The optical waveguide comprises a light source and the optical waveguide according to any one of claims 1 to 9, wherein the light source is used to emit the light, and the light is transmitted through the optical waveguide and then emitted to the observation area.

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