Optical waveguide device and display device

Abstract

The optical waveguide device comprises at least one optical waveguide, the optical waveguide comprises a coupling-in area, a coupling-out area and a propagation area located between the coupling-in area and the coupling-out area, the optical waveguide comprises an optical waveguide body, and the optical waveguide is used for receiving mixed light with image information and coupling target light into the optical waveguide body from the coupling-in area. The coupled-in target light is transmitted in the direction close to the coupling-out area in the transmission area in a total reflection mode, and finally the target light transmitted to the coupling-out area is coupled out of the optical waveguide. Wherein the optical waveguide body comprises a first surface and a second surface which are oppositely arranged, and target light is coupled from the first surface; the at least one optical waveguide further comprises a light extraction element, the light extraction element is arranged on the first surface and / or the second surface of the optical waveguide body, at least one part of the light extraction element is located in the propagation area, and the light extraction element is used for transmitting non-target light and reflecting target light.

Description

Technical Field

[0001] The utility model relates to the field of display technology, in particular to an optical waveguide device and a display device. Background Art

[0002] With the development of society and continuous innovation of technology, Augmented Reality (AR) has gradually entered people's lives. In the aspect of AR augmented reality, the optical waveguide technology is an essential step. It uses a flat optical waveguide sheet with a diffraction grating to transmit and expand the pupil of the image emitted by the light source component to the human eye, so that the user can observe the virtual image projected by the light source component superimposed on the real world while seeing the real world.

[0003] In a multi-sheet optical waveguide structure, different optical waveguides are used to transmit light of different wavelength bands. The device design needs to consider the influence of the grating diffraction effect on the photon path. Some light in non-target wavelength bands will be mis-guided into the target optical waveguide structure and merged with the light in the target wavelength band. This additional superposition will have an adverse effect on the final display effect.

[0004] The above information disclosed in this part is only used for understanding the background of the inventive concept of the utility model. Therefore, the above information may include information that does not constitute the prior art. Summary of the Utility Model

[0005] In one aspect, an optical waveguide device is provided. The optical waveguide device includes at least one optical waveguide. The optical waveguide includes an input region, an output region, and a propagation region located between the input region and the output region. The optical waveguide includes an optical waveguide body. The optical waveguide is configured to receive mixed light with image information and couple the target light into the optical waveguide body from the input region. The coupled target light propagates in the propagation region in the direction close to the output region in a total reflection manner, and finally couples the target light propagating to the output region out of the optical waveguide.

[0006] Wherein, the optical waveguide body includes a first surface and a second surface which are oppositely arranged, and the target light is coupled in from the first surface; and

[0007] At least one of the optical waveguides further includes a light extraction element. The light extraction element is disposed on the first surface and / or the second surface of the optical waveguide body. At least a part of the light extraction element is located in the propagation region. The light extraction element is configured to transmit non-target light and reflect target light.

[0008] According to some exemplary embodiments, the light extraction element includes a distributed Bragg reflector, and the distributed Bragg reflector is configured to transmit non-target light and reflect target light.

[0009] According to some exemplary embodiments, at least one of the optical waveguides further includes a light absorption element disposed on a side of the light extraction element away from the optical waveguide body, and the light absorption element is configured to absorb non-target light rays.

[0010] According to some exemplary embodiments, the material of the light absorption element includes a black matrix material.

[0011] According to some exemplary embodiments, the optical waveguide further includes a coupling grating, an output grating, and a turning grating disposed on the first surface of the optical waveguide body, the coupling grating is located in the coupling region, the output grating is located in the output region, and the turning grating is located in the propagation region;

[0012] Wherein, a positive projection of the turning grating on the optical waveguide body is located on one side of a positive projection of the coupling grating on the optical waveguide body along a second direction, and the positive projection of the turning grating on the optical waveguide body is located on one side of a positive projection of the output grating on the optical waveguide body along a first direction, and the first direction intersects with the second direction.

[0013] According to some exemplary embodiments, the light extraction element includes a first light extraction element and / or a second light extraction element;

[0014] Wherein, along the propagation direction of the target light ray, a positive projection of the first light extraction element on the optical waveguide body is located between a positive projection of the coupling grating on the optical waveguide body and a positive projection of the turning grating on the optical waveguide body; and

[0015] Along the propagation direction of the target light ray, a positive projection of the second light extraction element on the optical waveguide body is located between a positive projection of the output grating on the optical waveguide body and a positive projection of the turning grating on the optical waveguide body.

[0016] According to some exemplary embodiments, a positive projection of the first light extraction element on the optical waveguide body is tangent to a positive projection of the coupling grating on the optical waveguide body, and / or a positive projection of the first light extraction element on the optical waveguide body is tangent to a positive projection of the turning grating on the optical waveguide body; and

[0017] A positive projection of the second light extraction element on the optical waveguide body is tangent to a positive projection of the output grating on the optical waveguide body, and / or a positive projection of the second light extraction element on the optical waveguide body is tangent to a positive projection of the turning grating on the optical waveguide body.

[0018] According to some exemplary embodiments, the orthographic projection of the first light extraction element on the optical waveguide body is spaced apart from the orthographic projection of the coupling grating on the optical waveguide body, and / or, the orthographic projection of the first light extraction element on the optical waveguide body is spaced apart from the orthographic projection of the folding grating on the optical waveguide body; and

[0019] The orthographic projection of the second light extraction element on the optical waveguide body is spaced apart from the orthographic projection of the output coupling grating on the optical waveguide body, and / or, the orthographic projection of the second light extraction element on the optical waveguide body is spaced apart from the orthographic projection of the folding grating on the optical waveguide body.

[0020] According to some exemplary embodiments, the dimension of the orthographic projection of the first light extraction element on the optical waveguide body along the first direction is greater than or equal to the dimension of the orthographic projection of the coupling grating on the optical waveguide body along the first direction, and / or, the dimension of the orthographic projection of the first light extraction element on the optical waveguide body along the first direction is greater than or equal to the dimension of the orthographic projection of the folding grating on the optical waveguide body along the first direction; and

[0021] The dimension of the orthographic projection of the second light extraction element on the optical waveguide body along the second direction is greater than the dimension of the orthographic projection of the output coupling grating on the optical waveguide body along the second direction, and / or, the dimension of the orthographic projection of the second light extraction element on the optical waveguide body along the second direction is greater than the dimension of the orthographic projection of the folding grating on the optical waveguide body along the second direction.

[0022] According to some exemplary embodiments, in at least one optical waveguide, the coupling grating is configured to couple in target light and reflect non-target light.

[0023] According to some exemplary embodiments, the coupling grating includes a plurality of coupling grating bars arranged at intervals, the coupling grating bars have the structure of a distributed Bragg reflector, and the coupling grating bars are configured to reflect non-target light and transmit target light.

[0024] On the other hand, a display device is provided, which includes an image source and the foregoing optical waveguide device;

[0025] wherein, the image source is configured to emit mixed light with image information; and

[0026] The optical waveguide device includes at least two optical waveguides, and the at least two optical waveguides are located on one side of the light-emitting surface of the image source and are arranged along the light-emitting direction of the image source.

[0027] According to some exemplary embodiments, the wavelengths of the target light rays coupled into different ones of the optical waveguides are different, and the wavelength of the target light ray coupled into the optical waveguide closer to the image source is shorter;

[0028] Among them, at least in the optical waveguide closest to the image source, the light extraction element is disposed on the optical waveguide body.

[0029] According to some exemplary embodiments, in the optical waveguide closest to the image source, the light extraction element is disposed on the first surface of the optical waveguide body; and / or

[0030] In the optical waveguide farthest from the image source, the light extraction element is disposed on the second surface of the optical waveguide body.

[0031] According to some exemplary embodiments, the optical waveguide includes a coupling grating disposed on the first surface of the optical waveguide body and located in the coupling region;

[0032] Among them, in the optical waveguide farthest from the image source, the coupling grating is configured to couple in the target light ray and reflect the non-target light ray. Description of the Drawings

[0033] Other objects and advantages of the present invention will be apparent from the following description with reference to the accompanying drawings, and will help to provide a comprehensive understanding of the present invention.

[0034] Figure 1 A side view of an optical waveguide device according to some embodiments of the present invention is schematically shown.

[0035] Figure 2 A top view of an optical waveguide device according to some embodiments of the present invention is schematically shown.

[0036] Figure 3 A side view of a light extraction element in an optical waveguide device according to some embodiments of the present invention is schematically shown.

[0037] Figure 4 A transmittance spectrum diagram of a distributed Bragg reflector in an optical waveguide device according to some embodiments of the present invention is schematically shown.

[0038] Figure 5 A side view of an optical waveguide device according to some other embodiments of the present invention is schematically shown.

[0039] Figure 6 A top view of an optical waveguide device according to some embodiments of the present invention is schematically shown.

[0040] Figure 7A top view of an optical waveguide device according to some other embodiments of the present invention is schematically shown.

[0041] Figure 8 A top view of an optical waveguide device according to still some other embodiments of the present invention is schematically shown.

[0042] Figure 9 A top view of an optical waveguide device according to yet some other embodiments of the present invention is schematically shown.

[0043] Figure 10 A side view of an optical waveguide device according to still some other embodiments of the present invention is schematically shown.

[0044] Figure 11 Schematically shown is Figure 10 an enlarged view of region S1 in

[0045] Figure 12 A side view of a display device according to some embodiments of the present invention is schematically shown.

[0046] Figure 13 A side view of a display device according to some other embodiments of the present invention is schematically shown.

[0047] Figure 14 A side view of a display device according to still some other embodiments of the present invention is schematically shown.

[0048] It should be noted that, for clarity, in the drawings used to describe the embodiments of the present invention, the dimensions of layers, structures or regions may be enlarged or reduced, that is, these drawings are not drawn to actual scale. Detailed implementation manners

[0049] In the following description, for the purpose of explanation, numerous specific details are set forth to provide a thorough understanding of various exemplary embodiments. However, it is obvious that various exemplary embodiments can be implemented without these specific details or with one or more equivalent arrangements. In other cases, well-known structures and devices are shown in block diagram form to avoid unnecessarily obscuring various exemplary embodiments. In addition, various exemplary embodiments may be different but not necessarily exclusive. For example, without departing from the inventive concept, the specific shapes, configurations and characteristics of an exemplary embodiment can be used or implemented in another exemplary embodiment.

[0050] In the drawings, for clarity and / or for descriptive purposes, the sizes and relative sizes of elements may be enlarged. Thus, the sizes and relative sizes of the individual elements need not be limited to the sizes and relative sizes shown in the figures. When exemplary embodiments can be implemented differently, the specific process sequences may be performed in a different order than the described order. For example, two consecutively described processes may be performed substantially simultaneously or in an order opposite to the described order. In addition, the same reference numerals denote the same elements.

[0051] When an element is described as being "on" another element, "connected to" another element, or "coupled to" another element, the element may be directly on the other element, directly connected to the other element, or directly coupled to the other element, or there may be intervening elements. However, when an element is described as being "directly on" another element, "directly connected to" another element, or "directly coupled to" another element, there are no intervening elements. Other terms and / or expressions used to describe the relationship between elements should be interpreted in a similar manner, e.g., "between" versus "directly between", "adjacent" versus "directly adjacent", or "on" versus "directly on", etc. In addition, the term "connected" may refer to a physical connection, an electrical connection, a communication connection, and / or a fluid connection. In addition, the X-axis, Y-axis, and Z-axis are not limited to the three axes of a rectangular coordinate system and may be interpreted in a broader sense. For example, the X-axis, Y-axis, and Z-axis may be perpendicular to each other, or may represent different directions that are not perpendicular to each other. For the purposes of the present utility model, "at least one of X, Y, and Z" and "at least one selected from the group consisting of X, Y, and Z" may be interpreted as only X, only Y, only Z, or any combination of two or more of X, Y, and Z such as XYZ, XY, YZ, and XZ. As used herein, the term "and / or" includes any combination and all combinations of one or more of the listed related items.

[0052] It should be understood that although the terms first, second, etc. may be used herein to describe different elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of the exemplary embodiments, the first element may be named the second element, and similarly, the second element may be named the first element.

[0053] Figure 1 A side view of an optical waveguide device according to some embodiments of the present utility model is schematically shown. Figure 2 A top view of an optical waveguide device according to some embodiments of the present utility model is schematically shown.

[0054] Referring to Figure 1 With Figure 2, The optical waveguide device includes at least one optical waveguide, and the optical waveguide includes an input region A1, an output region A3, and a propagation region A2 located between the input region A1 and the output region A3. The optical waveguide 100 includes an optical waveguide body 110. The optical waveguide 100 is configured to receive the mixed light with image information and screen the mixed light to couple the target light from the input region A1 into the optical waveguide body 110. The coupled target light propagates in the propagation region A2 towards the output region A3 in a total reflection manner, and finally couples the target light propagating to the output region A3 out of the optical waveguide 100.

[0055] Refer to Figure 1 , The optical waveguide body 110 is a light guide plate for guiding the target light in a total reflection manner. The optical waveguide body 110 can be made of a polymer material or an inorganic material with a relatively high refractive index. For example, the material of the optical waveguide body 110 is selected from glass with a refractive index greater than or equal to 1.5, but it is not limited thereto. The optical waveguide body 110 includes a first surface 110a and a second surface 110b arranged oppositely, and the target light is coupled into the optical waveguide body 110 from the first surface 110a.

[0056] Refer to Figure 2 , An input grating 140, a turning grating 150, and an output grating 160 are provided on the first surface 110a of the optical waveguide body 110. The input grating 140 is arranged in the input region A1, the turning grating 150 is arranged in the propagation region A2, and the output grating 160 is arranged in the output region A3. The orthographic projection of the turning grating 150 on the optical waveguide body 110 is located on one side of the orthographic projection of the input grating 140 on the optical waveguide body 110 along the second direction Y. The orthographic projection of the turning grating 150 on the optical waveguide body 110 is located on one side of the orthographic projection of the output grating 160 on the optical waveguide body 110 along the first direction X, and the first direction X intersects with the second direction Y. For example, the first direction X is perpendicular to the second direction Y.

[0057] It should be further noted that the input region A1 should be understood as the region where the target light is coupled into the optical waveguide body 110, and the region where the input grating 140 is provided is the input region A1. The output region A3 should be understood as the region where the target light is coupled out of the optical waveguide body 110, and the region where the output grating 160 is provided is the output region A3. The propagation region A2 has no specific division boundary, and the region through which the target light propagates from the input region A1 to the output region A3 is the propagation region A2. In theory, the region of the optical waveguide body 110 except for the input region A1 and the output region A3 can be used as the propagation region A2. However, in practical applications, in order to ensure that the target light can effectively propagate in the optical waveguide body 110, the setting range of the optical waveguide body 110 is slightly larger than the propagation region A2.

[0058] For example, the structure of the coupling grating 140 is set according to the wavelength band of the target light rays to be coupled. When the target light rays with wavelengths within the target wavelength band strike the coupling grating 140, diffraction occurs, the propagation direction of the target light rays changes, and they are coupled into the optical waveguide body 110 at a specific incident angle. By setting, the specific incident angle is greater than the critical angle for total internal reflection of the target light rays within the optical waveguide body 110. Therefore, after the target light rays are coupled into the optical waveguide body 110 through the coupling grating 140, they will propagate in the optical waveguide body 110 in the form of total internal reflection. When non-target light rays with wavelengths outside the target wavelength band strike the coupling grating 140, they will not be coupled into the optical waveguide body 110 by the coupling grating 140, but will pass through the coupling grating 140 and continue to propagate with the optical waveguide body 110.

[0059] For example, the folding grating 150 is configured to perform one-dimensional pupil expansion on the total internal reflection target light rays within the optical waveguide body 110, and divide the field of view angle. Generally, the left field of view angle and the right field of view angle are propagated in two directions, thereby increasing the field of view angle.

[0060] For example, the output grating 160 is used to change the propagation direction of the target light rays propagating into the output region A3, so that the target light rays do not continue to perform total internal reflection in the optical waveguide body 110, but exit from the optical waveguide body 110 at a predetermined exit angle. The target light rays are expanded along the propagation direction, and after exiting from the optical waveguide body 110, they enter the human eye, achieving the purpose of exit pupil expansion.

[0061] It should be supplemented that the target light rays should be understood as the set of all light rays with wavelengths within the target wavelength band, and the non-target light rays should be understood as the set of all light rays with wavelengths outside the target wavelength band. The target wavelength band of the target wavelength is set according to actual display requirements. For example, when the optical waveguide is used to conduct blue light, the target wavelength band of the optical waveguide can be set to 440 - 480 nm. Then, the non-target light rays are light rays with wavelengths greater than 480 nm and wavelengths less than 440 nm. When the optical waveguide device has multiple optical waveguides, the wavelength bands of the target light rays of different optical waveguides may not overlap, that is, different optical waveguides are used to conduct light rays of different wavelengths.

[0062] With reference to Figure 1 and Figure 2 , at least one optical waveguide 100 further includes a light extraction element 120. The light extraction element 120 can be disposed on the first surface 110a of the optical waveguide body 110, or the light extraction element 120 can be disposed on the second surface 110b of the optical waveguide body 110, or the first surface 110a and the second surface 110b of the optical waveguide body 110 are respectively provided with light extraction elements. Figure 1Schematically shows a situation where the light extraction element 120 can be disposed on the second surface 110b of the optical waveguide body 110. The light extraction element 120 is used to transmit non-target light rays and reflect target light rays, and at least a part of the light extraction element 120 is located in the propagation region A2. With this arrangement, the target light rays coupled into the optical waveguide body 110 are reflected when propagating to the light extraction element 120 and continue to propagate within the optical waveguide body 110, while the non-target light rays coupled by the coupling grating 140 are transmitted through the light extraction element 120 and exit outside the optical waveguide body 110 when propagating to the light extraction element 120, that is, the non-target light rays are extracted by the light extraction element 120 and do not continue to propagate, thereby improving the color purity of the light rays propagating within the optical waveguide.

[0063] It should be understood that theoretically, only the target light rays with wavelengths within the target wavelength band will be coupled into the optical waveguide body by the coupling grating. However, due to factors such as the manufacturing precision of the coupling grating, a small amount of non-target light rays will still be coupled into the optical waveguide body by the coupling grating. By providing the light extraction element, this part of non-target light rays can be effectively extracted from the optical waveguide body, thereby improving the color purity of the light rays propagating within the optical waveguide, and further improving the display effect of the display device fabricated with the optical waveguide device.

[0064] According to some exemplary embodiments, the light extraction element 120 includes a distributed Bragg reflector, and the distributed Bragg reflector is used to transmit non-target light rays and reflect target light rays. Of course, the light extraction element 120 can also be other optical devices having the ability to selectively reflect light rays of a specific wavelength band, and the embodiments of the present invention do not limit this.

[0065] Figure 3 Schematically shows a side view of the light extraction element in an optical waveguide device according to some embodiments of the present invention.

[0066] For example, referring to Figure 3 , using a distributed Bragg reflector as the light extraction element, the light extraction element includes a high refractive index film layer 121 and a low refractive index film layer 122 that are alternately arranged perpendicular to the surface of the optical waveguide body. By comprehensively setting the refractive indices, thicknesses of the high refractive index film layer 121 and the low refractive index film layer 122, and the number of layers of the high refractive index film layer 121 and the low refractive index film layer 122, the light extraction element can transmit non-target light rays and reflect target light rays.

[0067] It should be further noted that the distributed Bragg reflector described in the embodiments of the present utility model is an artificial microstructured material formed by stacking at least two media with different refractive indices in a certain period. The media are periodically and orderly arranged, so that moving photons are modulated to form an energy band structure. When the structural parameters are appropriate, there may be a photonic bandgap structure similar to the electronic energy band between the photonic energy bands. Therefore, the distributed Bragg reflector can be used to regulate the transmission of light. By adjusting the structure, light in some wavelength bands cannot propagate in the distributed Bragg reflector, thereby realizing the regulation and control of the light propagation.

[0068] The width and position of the photonic bandgap of the distributed Bragg reflector are affected by the stacking period and the stacking thickness. When the optical thickness of a single-layer medium is λ0 / 4, the transmittance minimum value of the photonic bandgap will appear at λ0. At this time, λ0 is defined as the central wavelength of the photonic bandgap. According to formula (1-1), the width of the photonic bandgap can be calculated, where n H is the refractive index of the high-refractive-index film layer, and n L is the refractive index of the low-refractive-index film layer.

[0069]

[0070] It can be seen from formula (1-1) that the greater the difference in refractive indices of the materials, the greater the width of the photonic bandgap Δλ. For example, the material of the high-refractive-index film layer 121 includes Nb2O5, and the material of the low-refractive-index film layer 122 includes SiO2.

[0071] Exemplarily, an optical waveguide is used to conduct blue light, that is, the wavelength of the target light conducted by the optical waveguide is 440nm - 480nm. However, in actual use, the optical waveguide will couple in green light and red light with wavelengths greater than or equal to 510nm. Calculated in combination with the following formula (1-2), the light with a wavelength of 480nm will propagate in the optical waveguide body at an angle of 59° due to the diffraction effect of the coupling grating of the optical waveguide, and the light with a wavelength of 510nm will propagate in the optical waveguide body at an angle of 65° due to the diffraction effect of the coupling grating of the optical waveguide.

[0072] The following formula (1-2) is the grating equation, where n0 is the refractive index of the grating medium, n1 is the refractive index of the grating, θ0 is the incident angle, θ1 is the diffraction angle, λ is the wavelength, d is the grating constant, and m is the diffraction order.

[0073]

[0074] According to formula (1-2), for the same input grating, when the incident angle is fixed, the longer the wavelength, the larger the diffraction angle. Therefore, the diffraction angle of the target light coupled into the optical waveguide body by the input grating is less than or equal to 59°, and the diffraction angle of the non-target light coupled into the optical waveguide body by the input grating is greater than 65°. According to the maximum diffraction angle of 59° of the target light, the minimum diffraction angle of 65° of the non-target light, and the wavelength range of 440nm - 480nm of the target light, a specific distributed Bragg reflector is designed as the light extraction element of the optical waveguide, and the transmittance of the distributed Bragg reflector for all visible light band light with an incident angle of 59° and all visible light band light with an incident angle of 65° is simulated and analyzed. The obtained transmittance spectrogram is shown in Figure 4 . It can be seen from Figure 4 that the transmittance of the light with an incident angle of 59° is almost 0% at a wavelength of 480nm, that is, the blue light with a wavelength of 480nm and a diffraction angle of 59° will be reflected when it hits the distributed Bragg reflector. The diffraction angles of other target lights with wavelengths less than 480nm are less than 59°. The transmittance spectrogram of the light with an angle less than 59° will shift towards a longer wavelength compared to the transmittance spectrogram of the 59° light. Obviously, the transmittance in the blue light band of the shifted spectrogram is almost 0. Therefore, almost all the target lights in the target band will be reflected by the distributed Bragg reflector. The transmittance of the light with an incident angle of 65° is almost 100% at a wavelength of 510nm, that is, the green light with a wavelength of 510nm and a diffraction angle of 65° will transmit through the distributed Bragg reflector. The diffraction angles of other target lights with wavelengths greater than 510nm are greater than 65°. The transmittance spectrogram of the light with an angle greater than 65° will shift towards a shorter wavelength compared to the transmittance spectrogram of the 65° light. Obviously, the transmittance spectrogram after shifting has a high transmittance in both the green light band and the red light band. Therefore, almost all the target lights in the non-target band will be transmitted by the distributed Bragg reflector.

[0075] It should be understood that the above only exemplarily illustrates the design principle of the distributed Bragg reflector by combining a specific optical waveguide to design a specific distributed Bragg reflector, and does not represent that the transmittance spectrogram of the distributed Bragg reflector in actual application must be as Figure 4 shown.

[0076] Figure 5 Schematically shows a side view of an optical waveguide device according to some other embodiments of the present invention.

[0077] According to some exemplary embodiments, referring to Figure 5, at least one optical waveguide further includes a light absorption element 130 disposed on a side of the light extraction element 120 away from the optical waveguide body 110, and the light absorption element 130 is configured to absorb non-target light rays. That is, the non-target light rays extracted by the light extraction element 120 are absorbed by the light absorption element 130 after being incident on the light absorption element 130. With this arrangement, when there are multiple optical waveguides in the optical waveguide device, the problem of light crosstalk caused by the non-target light rays being extracted and then incident on adjacent optical waveguides again can be effectively avoided.

[0078] According to some exemplary embodiments, referring to Figure 5 , in order to ensure that the non-target light rays extracted by the light extraction element 120 are fully absorbed by the light absorption element 130, the light absorption element 130 is arranged to cover the surface of the light extraction element 120 away from the optical waveguide body 110, that is, the orthographic projection of the light absorption element 130 on the optical waveguide body 110 covers the orthographic projection of the light extraction element 120 on the optical waveguide body 110.

[0079] According to some exemplary embodiments, the material of the light absorption element 130 may include a light-absorbing material that has a specific absorption effect on non-target light rays, or the material of the light absorption element 130 may include a light-absorbing material that has an absorption effect on light rays in the entire visible light band. For example, the material of the light absorption element 130 may include a black matrix material, which is a material commonly used in the display field, with low cost and mature preparation process.

[0080] Figure 6 The top view of the optical waveguide device according to some embodiments of the present invention is schematically shown.

[0081] According to some exemplary embodiments, referring to Figure 6 , the light extraction element 120 includes a first light extraction element 121. Along the propagation direction of the target light rays, the orthographic projection of the first light extraction element 121 on the optical waveguide body 110 is located between the orthographic projection of the coupling grating 140 on the optical waveguide body 110 and the orthographic projection of the folding grating 150 on the optical waveguide body 110. With this arrangement, during the process of the target light rays doped with non-target light rays propagating from the coupling grating 140 to the folding grating 150, they will be incident on the interface between the optical waveguide body 110 and the first light extraction element 121. The target light rays incident on this interface are reflected and continue to propagate in the optical waveguide body 110, while the non-target light rays incident on this interface are transmitted out of the optical waveguide body 110 through the first light extraction element 121, that is, the first light extraction element 121 can effectively extract the non-target light rays from the optical waveguide body 110.

[0082] According to some exemplary embodiments, referring to Figure 2, the optical extraction element 120 includes a second optical extraction element 122. Along the propagation direction of the target light ray, the orthographic projection of the second optical extraction element 122 on the optical waveguide body 110 is located between the orthographic projection of the outcoupling grating 160 on the optical waveguide body 110 and the orthographic projection of the turning grating 150 on the optical waveguide body 110. With this arrangement, when the target light ray doped with non-target light rays propagates from the turning grating 150 to the in-coupling grating 140, it will hit the interface between the optical waveguide body 110 and the second optical extraction element 122. The target light ray hitting this interface is reflected and continues to propagate within the optical waveguide body 110, while the non-target light ray hitting this interface will transmit out of the optical waveguide body 110 through the second optical extraction element 122. That is, the second optical extraction element 122 can effectively extract the non-target light rays from the optical waveguide body 110.

[0083] Figure 7 Schematically shows a top view of an optical waveguide device according to some other embodiments of the present invention.

[0084] According to some exemplary embodiments, refer to Figure 7 , the optical extraction element 120 includes a first optical extraction element 121 and a second optical extraction element 122. That is, an optical extraction element 120 is provided both between the in-coupling grating 140 and the turning grating 150, and between the turning grating 150 and the outcoupling grating 160. With this arrangement, during the propagation process from the in-coupling grating 140 to the turning grating 150 and the propagation process from the turning grating 150 to the outcoupling grating 160, the non-target light rays doped in the target light rays can be extracted, thereby increasing the extraction rate of the non-target light rays from the optical waveguide body 110.

[0085] According to some exemplary embodiments, refer to Figure 6 and Figure 7 , the orthographic projection of the first optical extraction element 121 on the optical waveguide body 110 is spaced apart from the orthographic projection of the in-coupling grating 140 on the optical waveguide body 110, and the orthographic projection of the first optical extraction element 121 on the optical waveguide body 110 is spaced apart from the orthographic projection of the turning grating 150 on the optical waveguide body 110.

[0086] According to some exemplary embodiments, refer to Figure 2 and Figure 7 , the orthographic projection of the second optical extraction element 122 on the optical waveguide body 110 is spaced apart from the orthographic projection of the outcoupling grating 160 on the optical waveguide body 110, and the orthographic projection of the second optical extraction element 122 on the optical waveguide body 110 is spaced apart from the orthographic projection of the turning grating 150 on the optical waveguide body 110.

[0087] Figure 8 Schematically shows a top view of an optical waveguide device according to still some other embodiments of the present invention.

[0088] According to some exemplary embodiments, with reference to Figure 8 , the orthographic projection of the first light extraction element 121 on the optical waveguide body 110 is tangent to the orthographic projection of the coupling grating 140 on the optical waveguide body 110, and the orthographic projection of the first light extraction element 121 on the optical waveguide body 110 is spaced apart from the orthographic projection of the turning grating 150 on the optical waveguide body 110.

[0089] Of course, according to actual requirements, it can also be set that the orthographic projection of the first light extraction element on the optical waveguide body is tangent to the orthographic projection of the turning grating on the optical waveguide body, or the orthographic projection of the first light extraction element on the optical waveguide body is respectively tangent to the orthographic projection of the turning grating on the optical waveguide body and the orthographic projection of the coupling grating on the optical waveguide body. The size of the first light extraction element in the propagation direction of the target light between the coupling grating and the turning grating can be set according to actual process requirements. Theoretically, the larger this size is, the higher the extraction rate of non-target light is. That is, when the orthographic projection of the first light extraction element on the optical waveguide body is respectively tangent to the orthographic projection of the turning grating on the optical waveguide body and the orthographic projection of the coupling grating on the optical waveguide body, it is more conducive to extracting non-target light from the optical waveguide body.

[0090] It should be further noted that the "tangency" of the orthographic projections of the two structures mentioned in the embodiments of the present invention should be understood as: a part of the edge of the orthographic projection of one structure substantially coincides with a part of the edge of the orthographic projection of the other structure, and the orthographic projections of the other parts of one structure do not overlap with the orthographic projections of the other parts of the other structure.

[0091] Figure 9 Schematically shows a top view of an optical waveguide device according to still some other embodiments of the present invention.

[0092] According to some exemplary embodiments, with reference to Figure 9 , the orthographic projection of the second light extraction element 122 on the optical waveguide body 110 is tangent to the orthographic projection of the turning grating 150 on the optical waveguide body 110, and the orthographic projection of the second light extraction element 122 on the optical waveguide body 110 is spaced apart from the orthographic projection of the output grating 160 on the optical waveguide body 110.

[0093] Of course, according to actual requirements, it can also be set such that the orthographic projection of the second light extraction element on the optical waveguide body is tangent to the orthographic projection of the output grating on the optical waveguide body, or the orthographic projection of the first light extraction element on the optical waveguide body is respectively tangent to the orthographic projection of the turning grating on the optical waveguide body and the orthographic projection of the output grating on the optical waveguide body. The size of the second light extraction element in the propagation direction of the target light between the output grating and the turning grating can be set according to actual process requirements. In theory, the larger this size is, the higher the extraction rate of non-target light is. That is, when the orthographic projection of the second light extraction element on the optical waveguide body is respectively tangent to the orthographic projection of the turning grating on the optical waveguide body and the orthographic projection of the output grating on the optical waveguide body, it is more conducive to extracting non-target light from the optical waveguide body.

[0094] According to some exemplary embodiments, the larger the size of the orthographic projection of the first light extraction element on the optical waveguide body in the first direction is, the higher the extraction rate of non-target light is. In order to make the extraction rate of non-target light meet the process requirements, the size of the orthographic projection of the first light extraction element on the optical waveguide body in the first direction can be set according to the sizes of the orthographic projections of the input grating and the turning grating on the optical waveguide body in the first direction. For example, the size of the orthographic projection of the first light extraction element on the optical waveguide body in the first direction is greater than or equal to the size of the orthographic projection of the input grating on the optical waveguide body in the first direction, or the size of the orthographic projection of the first light extraction element on the optical waveguide body in the first direction is greater than or equal to the size of the orthographic projection of the turning grating on the optical waveguide body in the first direction, or the size of the orthographic projection of the first light extraction element on the optical waveguide body in the first direction is greater than or equal to the size of the orthographic projection of the input grating on the optical waveguide body in the first direction and the size of the orthographic projection of the first light extraction element on the optical waveguide body in the first direction is greater than or equal to the size of the orthographic projection of the turning grating on the optical waveguide body in the first direction.

[0095] Schematically, referring to Figure 6 , the size of the orthographic projection of the first light extraction element 121 on the optical waveguide body 110 in the first direction X is equal to the size of the orthographic projection of the input grating 140 on the optical waveguide body 110 in the first direction X, and the size of the orthographic projection of the first light extraction element 121 on the optical waveguide body 110 in the first direction X is greater than the size of the orthographic projection of the turning grating 150 on the optical waveguide body 110 in the first direction X.

[0096] It should be further noted that the dimension of the orthographic projection in the first direction in the embodiments of the present invention should be understood as the maximum dimension of the orthographic projection in the first direction. For example, when the orthographic projection is equally wide in the direction perpendicular to the first direction, the dimensions of any position of the orthographic projection in the first direction are the same, and this dimension is the dimension of the orthographic projection in the first direction. When the orthographic projection is not equally wide in the direction perpendicular to the first direction, the width at the widest part of the orthographic projection in the direction perpendicular to the first direction is the dimension of the orthographic projection in the first direction.

[0097] According to some exemplary embodiments, the larger the dimension of the orthographic projection of the second light extraction element on the optical waveguide body in the second direction, the higher the extraction rate of non-target light. In order to make the extraction rate of non-target light meet the process requirements, the dimension of the orthographic projection of the second light extraction element on the optical waveguide body in the second direction can be set according to the dimensions of the coupling grating and the turning grating in the second direction on the optical waveguide body. For example, the dimension of the orthographic projection of the second light extraction element on the optical waveguide body in the second direction is greater than or equal to the dimension of the coupling grating in the second direction on the optical waveguide body, or the dimension of the orthographic projection of the second light extraction element on the optical waveguide body in the second direction is greater than or equal to the dimension of the turning grating in the second direction on the optical waveguide body, or the dimension of the orthographic projection of the second light extraction element on the optical waveguide body in the second direction is greater than or equal to the dimension of the coupling grating in the second direction on the optical waveguide body and the dimension of the orthographic projection of the second light extraction element on the optical waveguide body in the second direction is greater than or equal to the dimension of the turning grating in the second direction on the optical waveguide body.

[0098] Exemplarily, referring to Figure 9 , the dimension of the orthographic projection of the second light extraction element 120 on the optical waveguide body 110 in the second direction Y is greater than the dimension of the coupling grating 160 in the second direction Y on the optical waveguide body 110, and the dimension of the orthographic projection of the second light extraction element 120 on the optical waveguide body 110 in the second direction Y is equal to the dimension of the turning grating 150 in the second direction Y on the optical waveguide body 110.

[0099] It should be further noted that the dimension of the orthographic projection in the second direction in the embodiments of the present invention should be understood as the maximum dimension of the orthographic projection in the second direction. For example, when the orthographic projection is equally wide in the direction perpendicular to the second direction, the dimensions of any position of the orthographic projection in the second direction are the same, and this dimension is the dimension of the orthographic projection in the second direction. When the orthographic projection is not equally wide in the direction perpendicular to the second direction, the width at the widest part of the orthographic projection in the direction perpendicular to the second direction is the dimension of the orthographic projection in the second direction.

[0100] According to some exemplary embodiments, a plurality of first light extraction elements arranged at intervals may be provided between the coupling grating and the deflecting grating. The plurality of first light extraction elements may be arranged in a first direction, and the plurality of first light extraction elements may also be arranged in a second direction.

[0101] According to some exemplary embodiments, a plurality of second light extraction elements arranged at intervals may be provided between the output grating and the deflecting grating. The plurality of second light extraction elements may be arranged in a first direction, and the plurality of second light extraction elements may also be arranged in a second direction.

[0102] According to some exemplary embodiments, the shape of the orthographic projection of the light extraction element on the optical waveguide body may be a rectangle, a parallelogram, a trapezoid, an ellipse, or the like.

[0103] Figure 10 A side view of an optical waveguide device according to still other embodiments of the present invention is schematically shown.

[0104] According to some exemplary embodiments, referring to Figure 10 , in at least one optical waveguide, the coupling grating 140 is used to couple in the target light and reflect the non-target light. Through the design of the coupling grating 140, the coupling grating 140 has a specific reflection effect on the non-target light, that is, the non-target light incident on the coupling grating 140 will be reflected and will not be coupled into the optical waveguide body 110, thereby improving the color purity of the light coupled into the optical waveguide body 110.

[0105] Figure 11 Schematically shown is Figure 10 an enlarged view of the region S1 in

[0106] According to some exemplary embodiments, with reference to Figure 10 and Figure 11 , the coupling grating 140 includes a plurality of coupling grating bars 141 arranged at intervals. The coupling grating bars 141 have the structure of a distributed Bragg reflector, that is, the coupling grating bars 141 include high-refractive-index grating sub-bars 141a and low-refractive-index grating sub-bars 141b alternately stacked in a direction perpendicular to the first surface 110a. The refractive index of the high-refractive-index grating sub-bars 141a is greater than that of the low-refractive-index grating sub-bars 141b. According to the wavelength band of the non-target light to be reflected, the refractive index, thickness, and number of layers of the high-refractive-index grating sub-bars 141a and the low-refractive-index grating sub-bars 141b are designed so that the coupling grating bars 141 can transmit the target light and reflect the non-target light.

[0107] In the actual manufacturing process, a complete distributed Bragg reflector can be prepared in the coupling region on the first surface of the optical waveguide body, and then the distributed Bragg reflector is etched to form a plurality of parallel slits, that is, a coupling grating with a distributed Bragg reflector structure is formed.

[0108] According to some exemplary embodiments, a display device is provided. The display device includes an image source and the above-mentioned optical waveguide device. The image source is configured to emit mixed light with image information. The optical waveguide device includes at least two optical waveguides. The at least two optical waveguides are located on one side of the light-emitting surface of the image source and are arranged along the light-emitting direction of the image source. The wavelengths of the target light rays coupled into different optical waveguides are different, and the wavelength of the target light ray coupled into the optical waveguide closer to the image source is shorter. At least in the optical waveguide closest to the image source, a light extraction element is provided on the optical waveguide body.

[0109] For example, the image source can be a micro display such as a Micro LED display substrate or a Micro-OLED display substrate.

[0110] Figure 12 A side view of a display device according to some embodiments of the present invention is schematically shown.

[0111] According to some exemplary embodiments, referring to Figure 12 , the optical waveguide device includes a first optical waveguide 100a, a second optical waveguide 100b, and a third optical waveguide 100c. The first optical waveguide 100a is located on one side of the light-emitting surface of the image source 200. The second optical waveguide 100b is located on the side of the first optical waveguide 100a away from the image source 200. The third optical waveguide 100c is located on the side of the second optical waveguide 100b away from the image source 200.

[0112] The mixed light emitted by the image source 200 includes a first target light ray, a second target light ray, and a third target light ray. For example, the first target light ray includes blue light, the second target light ray includes green light, and the third target light ray includes red light. The first optical waveguide 100a includes a first optical waveguide body 111. The first optical waveguide 100a is configured to couple the first target light ray into the first optical waveguide body 111. The second optical waveguide 100b includes a second optical waveguide body 112. The second optical waveguide 100b is configured to couple the second target light ray into the second optical waveguide body 112. The third optical waveguide 100c includes a third optical waveguide body 113. The third optical waveguide 100c is configured to couple the third target light ray into the third optical waveguide body 113.

[0113] In order to improve the color purity of the light rays propagating in each optical waveguide in the optical waveguide device, a light extraction element can be provided in at least one optical waveguide, or light extraction elements can be provided in each optical waveguide respectively. For example, continue to refer to Figure 12, the first optical waveguide 100a further includes a first light extraction element 121 disposed on the first optical waveguide body 111. The first light extraction element 121 is configured to transmit the second target light ray and the third target light ray and reflect the first target light ray. The second optical waveguide 100b further includes a second light extraction element 122 disposed on the second optical waveguide body 112. The second light extraction element 122 is configured to transmit the first target light ray and the third target light ray and reflect the second target light ray.

[0114] According to some exemplary embodiments, the non-target light rays coupled into the third optical waveguide that is farthest from the image source are fewer than those in the second optical waveguide and the first optical waveguide. From the perspective of cost control, the third optical waveguide may not be provided with a light extraction element. Of course, according to actual process requirements, a third light extraction element may also be provided on the third optical waveguide body. The third light extraction element is configured to transmit the first target light ray and the second target light ray and reflect the third target light ray.

[0115] According to some exemplary embodiments, referring to Figure 12 , the first light extraction element 121 may be disposed on the second surface 111b of the first optical waveguide body 111, or the first light extraction element 121 may also be disposed on the first surface 111a of the first optical waveguide body 111. Alternatively, the first light extraction element 121 is disposed on both the first surface 111a and the second surface 111b.

[0116] According to some exemplary embodiments, referring to Figure 12 , the second light extraction element 122 may be disposed on the second surface 112b of the second optical waveguide body 112, or the second light extraction element 122 may be disposed on the first surface 112a of the second optical waveguide body 112. Alternatively, the second light extraction element 122 is disposed on both the first surface 112a and the second surface 112b.

[0117] According to some exemplary embodiments, referring to Figure 12 , the display device further includes a collimating lens group 300 located between the image source 200 and the optical waveguide device. The collimating lens group 300 is configured to collimate the mixed light rays with image information emitted by the image source 200 and convert the light rays at each field of view angle into parallel light.

[0118] Figure 13 Schematically shows a side view of a display device according to other embodiments of the present invention.

[0119] According to some exemplary embodiments, referring to Figure 13, the first optical waveguide 100a is the optical waveguide closest to the image source 200. The first light extraction element 121 in the first optical waveguide 100a can be disposed on the first surface 111a of the first optical waveguide body 111, that is, the first light extraction element 121 is disposed on the side of the first optical waveguide body 111 away from the second optical waveguide 100b and the third optical waveguide 100c, so as to avoid the light extracted by the first light extraction element 121 from being incident on the second optical waveguide 100b and the third optical waveguide 100c again and causing interference.

[0120] Similarly, when a light extraction element is disposed in the optical waveguide farthest from the image source, the light extraction element can be disposed on the second surface of the optical waveguide body away from the image source.

[0121] According to some exemplary embodiments, referring back to Figure 12 , the coupling grating 140 of the third optical waveguide 100c can be configured to reflect the first target light and the second target light and couple the third target light into the third optical waveguide body 113. For example, the coupling grating bars of the coupling grating 140 of the third optical waveguide 100c have the structure of a distributed Bragg reflector. By designing the distributed Bragg reflector, the coupling grating 140 of the third optical waveguide 100c can be made to reflect the first target light and the second target light and transmit the third target light.

[0122] It should be understood that the coupling grating can be configured to reflect non-target light only in the optical waveguide farthest from the image source, which can improve the color purity of the optical waveguide without affecting the display effect of the display device.

[0123] Figure 14 Schematically shows a side view of a display device according to still other embodiments of the present invention.

[0124] According to some exemplary embodiments, referring to Figure 14 , the optical waveguide device includes a first optical waveguide 100a and a second optical waveguide 100b. The first optical waveguide 100a is located on one side of the light-emitting surface of the image source 200, and the second optical waveguide 100b is located on the side of the first optical waveguide 100a away from the image source 200.

[0125] The mixed light emitted by the image source 200 includes a first target light and a second target light. For example, the first target light includes blue light and a part of the green light in a certain wavelength band, and the second target light includes the remaining green light and red light in the wavelength band. The first optical waveguide 100a includes a first optical waveguide body 111, and the first optical waveguide 100a is configured to couple the first target light into the first optical waveguide body 111. The second optical waveguide 100b includes a second optical waveguide body 112, and the second optical waveguide 100b is configured to couple the second target light into the second optical waveguide body 112.

[0126] In order to separately improve the color purity of the light transmitted in the first optical waveguide 100a and the second optical waveguide 100b, the first optical waveguide 100a further includes a first light extraction element 121 disposed on the first optical waveguide body 111. The first light extraction element 121 is configured to reflect a first target light ray and project a second target light ray. The coupling grating 140 of the second optical waveguide 100b has a structure of a distributed Bragg reflector. The coupling grating 140 of the second optical waveguide 100b is configured to couple in the second target light ray and reflect the first target light ray.

[0127] According to some exemplary embodiments, the display device is a head-mounted display device. For example, the display device is an augmented reality glasses.

[0128] The display device provided according to the embodiments of the present invention has a wide range of application fields. For example, it can be applied to the field of mass consumption. By combining the head-mounted display device with mobile Internet data, positioning information can be obtained, enabling people to more conveniently obtain service information related to the surrounding life, and even big data social relationships in interpersonal interactions. For example, it can be applied to the medical field. Doctors can wear the head-mounted display device to create virtual coordinates at the surgical site of the patient for precise positioning of the surgical site. For example, it can be applied to the field of entertainment games. Players can wear the head-mounted display device, enabling players located at different locations to combine GPS and gyroscopes, using the real world as the game background and adding virtual elements to make the game a combination of virtual and real.

[0129] It should be understood that the display device according to some exemplary embodiments of the present invention has all the features and advantages of the above-described optical waveguide device. These features and advantages can be referred to the description of the optical waveguide device above and will not be repeated here.

[0130] As used herein, the terms "substantially", "about", "approximately" and other similar terms are used as approximate terms rather than terms of degree, and they are intended to explain the inherent deviations of measured or calculated values that would be recognized by a person of ordinary skill in the art. Considering factors such as process fluctuations, measurement problems, and errors related to the measurement of a specific quantity (i.e., limitations of the measurement system), "about" or "approximately" as used herein includes the stated value and represents within an acceptable deviation range for a specific value determined by a person of ordinary skill in the art. For example, "about" can mean within one or more standard deviations, or within ±10% or ±5% of the stated value.

[0131] Although some embodiments in accordance with the general inventive concept of the present invention have been illustrated and described, those of ordinary skill in the art will understand that changes can be made to these embodiments without departing from the principles and spirit of the general inventive concept of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. An optical waveguide device, wherein: The optical waveguide device comprises at least one optical waveguide, wherein the optical waveguide comprises an incoupling region, an outcoupling region and a propagation region between the incoupling region and the outcoupling region, and the optical waveguide comprises an optical waveguide body, wherein the optical waveguide is used to receive mixed light with image information and couple target light from the incoupling region into the optical waveguide body, wherein the coupled target light propagates in the propagation region toward a direction close to the outcoupling region in a total reflection manner, and finally the target light propagated to the outcoupling region is coupled out of the optical waveguide; The optical waveguide body comprises a first surface and a second surface arranged opposite to each other, and the target light is coupled in from the first surface; and At least one of the optical waveguides also includes a light extraction element, which is arranged on the first surface and / or the second surface of the optical waveguide body, at least a portion of the light extraction element is located in the propagation area, and the light extraction element is used to transmit non-target light and reflect target light.

2. The optical waveguide device according to claim 1, wherein The light extraction element includes a distributed Bragg reflector configured to transmit non-target light and reflect target light.

3. The optical waveguide device according to claim 1, wherein: At least one of the optical waveguides further includes a light absorbing element disposed on a side of the light extraction element away from the optical waveguide body, and the light absorbing element is used to absorb non-target light.

4. The optical waveguide device according to claim 2, wherein: At least one of the optical waveguides further includes a light absorbing element disposed on a side of the light extraction element away from the optical waveguide body, and the light absorbing element is used to absorb non-target light.

5. The optical waveguide device according to claim 3 or 4, wherein: The material of the light absorbing element includes a black matrix material.

6. The optical waveguide device according to any one of claims 1 to 4, wherein: The optical waveguide further comprises an in-coupling grating, an out-coupling grating and a folding grating arranged on the first surface of the optical waveguide body, the in-coupling grating is located in the in-coupling region, the out-coupling grating is located in the out-coupling region, and the folding grating is located in the propagation region; The orthographic projection of the folding grating on the optical waveguide body is located on one side of the orthographic projection of the coupling-in grating on the optical waveguide body along the second direction, and the orthographic projection of the folding grating on the optical waveguide body is located on one side of the orthographic projection of the coupling-out grating on the optical waveguide body along the first direction, and the first direction intersects the second direction.

7. The optical waveguide device according to claim 6, wherein: The light extraction element includes a first light extraction element and / or a second light extraction element; Wherein, along the propagation direction of the target light, the orthographic projection of the first light extraction element on the optical waveguide body is located between the orthographic projection of the coupling grating on the optical waveguide body and the orthographic projection of the folding grating on the optical waveguide body; and Along the propagation direction of the target light, the orthographic projection of the second light extraction element on the optical waveguide body is located between the orthographic projection of the outcoupling grating on the optical waveguide body and the orthographic projection of the folding grating on the optical waveguide body.

8. The optical waveguide device according to claim 7, wherein: The orthographic projection of the first light extraction element on the optical waveguide body is tangent to the orthographic projection of the coupling grating on the optical waveguide body, and / or the orthographic projection of the first light extraction element on the optical waveguide body is tangent to the orthographic projection of the folding grating on the optical waveguide body; as well as The orthographic projection of the second light extraction element on the optical waveguide body is tangent to the orthographic projection of the outcoupling grating on the optical waveguide body, and / or the orthographic projection of the second light extraction element on the optical waveguide body is tangent to the orthographic projection of the folding grating on the optical waveguide body.

9. The optical waveguide device according to claim 7, wherein: The orthographic projection of the first light extraction element on the optical waveguide body is spaced from the orthographic projection of the coupling grating on the optical waveguide body, and / or the orthographic projection of the first light extraction element on the optical waveguide body is spaced from the orthographic projection of the folding grating on the optical waveguide body; as well as The orthographic projection of the second light extraction element on the optical waveguide body is spaced apart from the orthographic projection of the outcoupling grating on the optical waveguide body, and / or the orthographic projection of the second light extraction element on the optical waveguide body is spaced apart from the orthographic projection of the folding grating on the optical waveguide body.

10. The optical waveguide device according to any one of claims 7 to 9, wherein: The size of the orthographic projection of the first light extraction element on the optical waveguide body along the first direction is greater than or equal to the size of the orthographic projection of the coupling grating on the optical waveguide body along the first direction, and / or the size of the orthographic projection of the first light extraction element on the optical waveguide body along the first direction is greater than or equal to the size of the orthographic projection of the folding grating on the optical waveguide body along the first direction; as well as The size of the orthographic projection of the second light extraction element on the optical waveguide body along the second direction is larger than the size of the orthographic projection of the outcoupling grating on the optical waveguide body along the second direction, and / or the size of the orthographic projection of the second light extraction element on the optical waveguide body along the second direction is larger than the size of the orthographic projection of the folding grating on the optical waveguide body along the second direction.

11. The optical waveguide device according to claim 6, wherein: In at least one optical waveguide, the coupling grating is used to couple target light and reflect non-target light.

12. The optical waveguide device according to claim 11, wherein The coupling-in grating comprises a plurality of coupling-in grating strips arranged at intervals, the coupling-in grating strips have a distributed Bragg reflector structure, and the coupling-in grating strips are used to reflect non-target light and transmit target light.

13. A display device, wherein: The display device comprises an image source and an optical waveguide device according to any one of claims 1 to 12; Wherein, the image source is used to emit mixed light with image information; and The optical waveguide device includes at least two optical waveguides, and the at least two optical waveguides are located on one side of the light emitting surface of the image source and are arranged along the light emitting direction of the image source.

14. The display device according to claim 13, wherein: The wavelengths of the target light coupled into different optical waveguides are different, and the wavelength of the target light coupled into the optical waveguide closer to the image source is shorter; At least in the optical waveguide closest to the image source, the light extraction element is provided on the optical waveguide body.

15. The display device according to claim 13 or 14, wherein: In the optical waveguide closest to the image source, the light extraction element is disposed on the first surface of the optical waveguide body; and / or In the optical waveguide farthest from the image source, the light extraction element is disposed on the second surface of the optical waveguide body.

16. The display device according to claim 13 or 14, wherein: The optical waveguide comprises an incoupling grating disposed on the first surface of the optical waveguide body and located in the incoupling region; Wherein, in the optical waveguide farthest from the image source, the coupling grating is used to couple in the target light and reflect the non-target light.

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