Optical waveguide structure, preparation method thereof and display device

Abstract

At least one embodiment of the present disclosure provides an optical waveguide structure and a preparation method thereof, and a display device, the optical waveguide structure comprising: a plurality of stacked waveguide sheets, the plurality of waveguide sheets comprising a first color waveguide sheet adjacent to a display and a second color waveguide sheet adjacent to the first color waveguide sheet, each waveguide sheet comprises a first main surface and a second main surface which are opposite to each other; a coupling-in grating and a coupling-out grating are arranged on the first main surface of each waveguide sheet, the coupling-in grating is configured to couple a light beam entering the coupling-in grating into the waveguide sheet, and the coupling-out grating is configured to couple a light beam transmitted to the coupling-out grating out of the waveguide sheet; a first filter layer is arranged on the first main surface or the second main surface of the first color waveguide sheet; the orthographic projection of the first filter layer on the first color waveguide sheet is between the orthographic projection of a coupling-in grating on the first color waveguide sheet and the orthographic projection of a coupling-out grating on the first color waveguide sheet; according to the optical waveguide structure, the first filter layer is arranged on the first main surface or the second main surface of the first color waveguide sheet, so that the problem of chromatic dispersion existing in color display can be remarkably solved; therefore, the formed optical module has an excellent color effect.

Description

Optical waveguide structure, manufacturing method thereof, and display device Technical Field

[0001] Embodiments of the present disclosure relate to an optical waveguide structure, a method for manufacturing the same, and a display device. Background Art

[0002] With the continuous advancement of technology, virtual reality (VR), augmented reality (AR), and mixed reality (MR) have gradually entered people's lives. For example, AR (Augmented Reality) technology, which integrates virtual information with the real world, is a technology represented by AR glasses. In the security and industrial fields, AR technology has demonstrated significant advantages, greatly improving the way information is interacted with.

[0003] Currently, augmented reality technologies mainly include prism technology, freeform surface technology, off-axis holographic lens technology, and lightguide technology. The equipment used in prism and freeform surface technology is relatively large, which limits its application in smart wearables, namely augmented reality glasses. Off-axis holographic lens technology utilizes the unique optical properties of holographic films and has the advantages of a large field of view (FOV) and a small size. However, due to the relatively small eye movement range, its large-scale mass production and large field of view are limited. Lightguide technology is currently the best solution for augmented reality glasses. Lightguide technology includes geometric waveguide technology, relief grating waveguide technology, and holographic waveguide technology. Geometric waveguide technology includes sawtooth structure waveguide and polarization film array reflector waveguide (referred to as polarization array waveguide). The current mainstream polarization film array reflector waveguide uses an array of partially transmissive and partially reflective thin film mirrors to display virtual information. Polarization array waveguide has the advantages of being light, thin, having a large eye movement range, and uniform color. Relief grating waveguide technology can be mass-produced using nanoimprinting technology, and has the advantages of a large field of view and a large eye movement range.

[0004] Summary of the Invention

[0005] At least one embodiment of the present disclosure provides an optical waveguide structure, a method for preparing the same, and a display device. The optical waveguide structure can significantly improve the dispersion problem existing in color display by providing a first filter layer on the first main surface or the second main surface of a first color waveguide plate, thereby enabling the optical module formed thereby to have an excellent color effect.

[0006] At least one embodiment of the present disclosure provides an optical waveguide structure, comprising: a plurality of stacked waveguide plates, wherein the plurality of waveguide plates include a first color waveguide plate disposed adjacent to a display, and a second color waveguide plate disposed adjacent to the first color waveguide plate, each of the waveguide plates including a first main surface and a second main surface facing each other; an in-coupling grating and an out-coupling grating disposed on the first main surface of each waveguide plate, the in-coupling grating being configured to couple a light beam incident thereon into the waveguide plate, and the out-coupling grating being configured to couple a light beam transmitted thereon out of the waveguide plate; a first filter layer being disposed on the first main surface or the second main surface of the first color waveguide plate, the orthographic projection of the first filter layer on the first color waveguide plate being between the orthographic projection of the in-coupling grating on the first color waveguide plate and the orthographic projection of the out-coupling grating on the first color waveguide plate, and the first filter layer being configured to remove light of other colors from the first color waveguide plate except the first color light.

[0007] For example, in the optical waveguide structure provided in at least one embodiment of the present disclosure, a first color interception layer is provided on the second major surface of the first color waveguide plate, an orthographic projection of the first color interception layer on the first color waveguide plate and an orthographic projection of the first filter layer on the first color waveguide plate do not overlap, and the first color interception layer is configured to intercept the first color light in the first color waveguide plate.

[0008] For example, in the optical waveguide structure provided by at least one embodiment of the present disclosure, the orthographic projection of the first color trapping layer on the first color waveguide plate overlaps with the orthographic projection of the coupling-in grating located on the first color waveguide plate on the first color waveguide plate.

[0009] For example, in the optical waveguide structure provided by at least one embodiment of the present disclosure, the first color intercepting layer is further configured to transmit light of other colors except the first color light incident from the incoupling grating into the first color waveguide plate to the second color waveguide plate.

[0010] For example, in the optical waveguide structure provided in at least one embodiment of the present disclosure, a second filter layer is provided on the first main surface or the second main surface of the second color waveguide plate, the orthographic projection of the second filter layer on the second color waveguide plate is between the orthographic projection of the coupling-in grating located on the second color waveguide plate on the second color waveguide plate and the orthographic projection of the coupling-out grating located on the second color waveguide plate on the second color waveguide plate, and the second filter layer is configured to remove light of other colors in the second color waveguide plate except the second color light.

[0011] For example, in the optical waveguide structure provided in at least one embodiment of the present disclosure, a second color interception layer is provided on the second major surface of the second color waveguide plate, an orthographic projection of the second color interception layer on the second color waveguide plate and an orthographic projection of the coupling-in grating located on the second color waveguide plate on the second color waveguide plate overlap, and the second color interception layer is configured to intercept the second color light in the second color waveguide plate.

[0012] For example, in the optical waveguide structure provided in at least one embodiment of the present disclosure, the plurality of waveguide plates further include a third color waveguide plate disposed adjacent to the second color waveguide plate; and the second color interception layer is further configured to transmit light of other colors except the second color light incident from the coupling-in grating into the second color waveguide plate to the third color waveguide plate.

[0013] For example, in the optical waveguide structure provided in at least one embodiment of the present disclosure, a folding grating is further provided on the first main surface of each of the waveguide plates, and in each of the waveguide plates, the folding grating is located between the coupling-in grating and the coupling-out grating, and the folding grating is configured to receive a light beam incoming from the coupling-in grating located in the same layer as the folding grating and perform pupil expansion transmission.

[0014] For example, in the optical waveguide structure provided in at least one embodiment of the present disclosure, the orthographic projection of the first filter layer on the first color waveguide plate is between the orthographic projection of the folding grating located on the first color waveguide plate on the first color waveguide plate and the orthographic projection of the coupling-in grating located on the first color waveguide plate on the first color waveguide plate, or, between the orthographic projection of the folding grating located on the first color waveguide plate on the first color waveguide plate and the orthographic projection of the coupling-out grating located on the first color waveguide plate on the first color waveguide plate, or, the orthographic projection of the first filter layer on the first color waveguide plate and the orthographic projection of the folding grating on the first color waveguide plate overlap.

[0015] For example, in the optical waveguide structure provided in at least one embodiment of the present disclosure, the orthographic projection of the second filter layer on the second color waveguide plate is between the orthographic projection of the folding grating located on the second color waveguide plate on the second color waveguide plate and the orthographic projection of the coupling-in grating located on the second color waveguide plate on the second color waveguide plate, or, between the orthographic projection of the folding grating located on the second color waveguide plate on the second color waveguide plate and the orthographic projection of the coupling-out grating located on the second color waveguide plate on the second color waveguide plate, or, the orthographic projection of the second filter layer on the second color waveguide plate and the orthographic projection of the folding grating on the second color waveguide plate overlap.

[0016] For example, in the optical waveguide structure provided by at least one embodiment of the present disclosure, the third color light is transmitted in the third color waveguide plate, and the first color waveguide plate is a blue waveguide plate, the second color waveguide plate is a green waveguide plate, and the third color waveguide plate is a red waveguide plate. Correspondingly, the first color light is blue light, the second color light is green light, and the third color light is red light; or, the third color light is transmitted in the third color waveguide plate, and the first color waveguide plate is a red waveguide plate, the second color waveguide plate is a blue waveguide plate, and the third color waveguide plate is a green waveguide plate. Correspondingly, the first color light is red light, the second color light is blue light, and the third color light is green light; or, the third color light is transmitted in the third color waveguide plate, and the first color waveguide plate is a red waveguide plate, the second color waveguide plate is a green waveguide plate, and the third color waveguide plate is a blue waveguide plate. Correspondingly, the first color light is red light, the second color light is green light, and the third color light is blue light.

[0017] For example, in the optical waveguide structure provided in at least one embodiment of the present disclosure, the first color waveguide plate is a blue-green waveguide plate, and the second color waveguide plate is a red waveguide plate. Correspondingly, the first color light is a mixture of green light and blue light, and light of other colors except the first color light is red light.

[0018] For example, in the optical waveguide structure provided in at least one embodiment of the present disclosure, the first color waveguide plate is a blue-green waveguide plate, and the second color waveguide plate is a red-green waveguide plate. Correspondingly, the first color light is blue light, and the light of other colors except the first color light is a mixture of red light and green light.

[0019] For example, in the optical waveguide structure provided in at least one embodiment of the present disclosure, the first filter layer includes a single-layer filter film, a filter grating structure, or a Bragg reflector.

[0020] For example, in the optical waveguide structure provided in at least one embodiment of the present disclosure, the coupling-in grating includes a transmissive-reflective coupling-in grating, so that the coupling-in grating couples the light beam incident thereon into the waveguide plate in both transmission and reflection forms.

[0021] For example, in the optical waveguide structure provided in at least one embodiment of the present disclosure, the coupling-in grating, the folding grating and the coupling-out grating respectively include a one-dimensional rectangular wire grating, a one-dimensional blazed wire grating, a one-dimensional tilted wire grating or a two-dimensional metasurface array.

[0022] For example, the optical waveguide structure provided by at least one embodiment of the present disclosure further includes a third color waveguide plate arranged on a side of the second color waveguide plate away from the first color waveguide plate, wherein a folding grating is further arranged on the first main surface of each of the waveguide plates, and in each of the waveguide plates, the folding grating is located between the coupling-in grating and the outcoupling grating, and the folding grating is configured to receive the light beam transmitted from the coupling-in grating located on the same layer as the folding grating and perform pupil expansion transmission; a first filter layer is provided on the first main surface of the first color waveguide plate, and the first filter layer is between the coupling-in grating and the folding grating located on the first color waveguide plate; a second filter layer is provided on the first main surface of the second color waveguide plate, and the second filter layer is between the coupling-in grating and the folding grating located on the second color waveguide plate; a third filter layer is provided on the first main surface of the third color waveguide plate, and the third filter layer is between the coupling-in grating and the folding grating located on the third color waveguide plate.

[0023] For example, the optical waveguide structure provided by at least one embodiment of the present disclosure further includes a first color filter film arranged between the first color waveguide plate and the second color waveguide plate, wherein the first color filter film includes a first color filter film body and a first color filter film arranged on the first color filter film body, and the orthographic projection of the first color filter film on the first color waveguide plate and the orthographic projection of the coupling grating on the first color waveguide plate on the first color waveguide plate overlap.

[0024] At least one embodiment of the present disclosure further provides a display device, which includes the optical waveguide structure described in any of the above embodiments.

[0025] For example, the display device provided by at least one embodiment of the present disclosure further includes a projection structure, wherein the projection structure includes the display and a collimating component, the display is used to emit a light beam with image information, and the collimating component is used to collimate the light beam emitted by the display to form parallel light coupled into the optical waveguide structure.

[0026] At least one embodiment of the present disclosure further provides a method for preparing an optical waveguide structure, the method comprising: providing a plurality of stacked waveguide sheet bodies, wherein the plurality of waveguide sheet bodies include a first color waveguide sheet body disposed adjacent to a display, and a second color waveguide sheet body disposed adjacent to the first color waveguide sheet body, each of the waveguide sheet bodies including a first main surface and a second main surface opposite to each other; forming an in-coupling grating and an out-coupling grating on the first main surface of each of the waveguide sheet bodies; and forming a first filter layer on the first main surface or the second main surface of the first color waveguide sheet body, wherein an orthographic projection of the first filter layer on the first color waveguide sheet body is between an orthographic projection of the in-coupling grating on the first color waveguide sheet body and an orthographic projection of the out-coupling grating on the first color waveguide sheet body, and the first filter layer is configured to remove light of other colors from the first color waveguide sheet body except the first color light.

[0027] For example, in the preparation method provided in at least one embodiment of the present disclosure, the coupling-in grating and the coupling-out grating are formed on the first main surface of the first color waveguide sheet body by a nanoimprint method, a protective layer is formed on the first main surface having the coupling-in grating and the coupling-out grating, and the first filter layer is formed on the second main surface of the first color waveguide sheet body; alternatively, the first filter layer is formed on the second main surface of the first color waveguide sheet body, a protective layer is formed on the second main surface having the first filter layer, and the coupling-in grating and the coupling-out grating are formed on the first main surface of the first color waveguide sheet body by a nanoimprint method; and the protective layer is removed to form the first color waveguide sheet.

[0028] For example, in the preparation method provided in at least one embodiment of the present disclosure, after forming the first filter layer on the second main surface of the first color waveguide sheet body and before removing the protective layer, or, forming the first filter layer on the second main surface of the first color waveguide sheet body and before forming the protective layer on the second main surface having the first filter layer, the method further includes: forming a first color interception layer on the second main surface of the first color waveguide sheet body and spaced apart from the first filter layer.

[0029] For example, in the preparation method provided in at least one embodiment of the present disclosure, the coupling-in grating and the coupling-out grating are formed on the first main surface of the first color waveguide body by a nanoimprinting method; the first filter layer is formed on the first main surface having the coupling-in grating and the coupling-out grating; and a protective layer is formed on the first main surface having the coupling-in grating, the coupling-out grating and the first filter layer.

[0030] For example, the preparation method provided by at least one embodiment of the present disclosure further includes: forming a first color retention layer on the second main surface of the first color waveguide sheet body, wherein the orthographic projection of the first color retention layer on the first color waveguide sheet body and the orthographic projection of the coupling-in grating located on the first color waveguide sheet body on the first color waveguide sheet body overlap; and removing the protective layer to form the first color waveguide sheet.

[0031] For example, in the preparation method provided in at least one embodiment of the present disclosure, in the process of forming the coupling-in grating and the coupling-out grating on the first main surface of the first color waveguide sheet body by the nanoimprint method, the method also includes forming a folding grating on the first main surface of the first color waveguide sheet body by the nanoimprint method, and the folding grating is located between the coupling-in grating and the coupling-out grating, and the folding grating is configured to receive the light beam transmitted from the coupling-in grating located in the same layer as the folding grating and perform pupil expansion transmission.

[0032] For example, the preparation method provided by at least one embodiment of the present disclosure further includes: forming the coupling-in grating and the coupling-out grating on the first main surface of the second color waveguide sheet body; forming a second filter layer on the first main surface or the second main surface of the second color waveguide sheet body, wherein the orthographic projection of the second filter layer on the second color waveguide sheet body is between the orthographic projection of the coupling-in grating located on the second color waveguide sheet body on the second color waveguide sheet body and the orthographic projection of the coupling-out grating located on the second color waveguide sheet body on the second color waveguide sheet body, and the second filter layer is configured to remove light of other colors in the second color waveguide sheet body except the second color light.

[0033] For example, in the preparation method provided in at least one embodiment of the present disclosure, the coupling-in grating and the coupling-out grating are formed on the first main surface of the second color waveguide sheet body by a nanoimprint method, a protective layer is formed on the first main surface having the coupling-in grating and the coupling-out grating, and a second filter layer is formed on the second main surface of the second color waveguide sheet body; alternatively, the second filter layer is formed on the second main surface of the second color waveguide sheet body, a protective layer is formed on the second main surface having the second filter layer, and the coupling-in grating and the coupling-out grating are formed on the first main surface of the second color waveguide sheet body by a nanoimprint method; and the protective layer is removed to form the second color waveguide sheet.

[0034] For example, in the preparation method provided in at least one embodiment of the present disclosure, after forming the second filter layer on the second main surface of the second color waveguide sheet body and before removing the protective layer, or after forming the second filter layer on the second main surface of the second color waveguide sheet body and before forming the protective layer on the second main surface having the second filter layer, the method further includes: forming a second color interception layer on the second main surface of the second color waveguide sheet body and spaced apart from the second filter layer.

[0035] For example, in the preparation method provided in at least one embodiment of the present disclosure, the coupling-in grating and the coupling-out grating are formed on the first main surface of the second color waveguide body by a nanoimprinting method; the second filter layer is formed on the first main surface having the coupling-in grating and the coupling-out grating; and a protective layer is formed on the first main surface having the coupling-in grating, the coupling-out grating and the second filter layer.

[0036] For example, the preparation method provided in at least one embodiment of the present disclosure further includes: forming a second color retention layer on the second main surface of the second color waveguide sheet body, wherein the orthographic projection of the second color retention layer on the second color waveguide sheet body and the orthographic projection of the coupling-in grating located on the second color waveguide sheet body on the second color waveguide sheet body overlap; and removing the protective layer to form the second color waveguide sheet.

[0037] For example, in the preparation method provided in at least one embodiment of the present disclosure, in the process of forming the coupling-in grating and the coupling-out grating on the first main surface of the second color waveguide sheet body by the nanoimprint method, the method also includes forming a folding grating on the first main surface of the second color waveguide sheet body by the nanoimprint method, and the folding grating is located between the coupling-in grating and the coupling-out grating, and the folding grating is configured to receive the light beam transmitted from the coupling-in grating located in the same layer as the folding grating and perform pupil expansion transmission.

[0038] For example, in the preparation method provided in at least one embodiment of the present disclosure, the plurality of waveguide plates further include a third color waveguide plate body arranged adjacent to the second color waveguide plate body, and the preparation method further includes: forming the coupling-in grating and the coupling-out grating on the first main surface of the third color waveguide plate body by a nanoimprinting method.

[0039] For example, in the preparation method provided in at least one embodiment of the present disclosure, the process of forming the coupling-in grating and the coupling-out grating on the first main surface of the third color waveguide sheet body by the nanoimprint method also includes: forming a folding grating located between the coupling-in grating and the coupling-out grating by the nanoimprint method. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present disclosure, rather than limiting the present disclosure.

[0041] FIG1 is a schematic cross-sectional view of an optical waveguide structure provided by at least one embodiment of the present disclosure;

[0042] FIG2 is a schematic diagram of the three-dimensional structure of a first color waveguide provided by at least one embodiment of the present disclosure;

[0043] FIG3 is a schematic diagram of the three-dimensional structure of a second color waveguide provided by at least one embodiment of the present disclosure;

[0044] FIG4 is a schematic diagram of the three-dimensional structure of a third color waveguide plate provided by at least one embodiment of the present disclosure;

[0045] FIG5 is a schematic cross-sectional view of another optical waveguide structure provided by at least one embodiment of the present disclosure;

[0046] FIG6 is a schematic cross-sectional view of another optical waveguide structure provided by at least one embodiment of the present disclosure;

[0047] FIG7 is a schematic cross-sectional view of another optical waveguide structure provided by at least one embodiment of the present disclosure;

[0048] FIG8 is a schematic cross-sectional view of another optical waveguide structure provided by at least one embodiment of the present disclosure;

[0049] FIG9 is a schematic cross-sectional view of another optical waveguide structure provided by at least one embodiment of the present disclosure;

[0050] FIG10 is a schematic cross-sectional view of another optical waveguide structure provided by at least one embodiment of the present disclosure;

[0051] FIG11 is a schematic cross-sectional view of another optical waveguide structure provided by at least one embodiment of the present disclosure;

[0052] FIG12 is a schematic cross-sectional view of another optical waveguide structure provided by at least one embodiment of the present disclosure;

[0053] FIG13 is a schematic cross-sectional view of another optical waveguide structure provided by at least one embodiment of the present disclosure;

[0054] FIG14 is an exploded view of another optical waveguide structure provided by at least one embodiment of the present disclosure;

[0055] FIG15 is a schematic diagram of the cross-sectional structure of the optical waveguide structure shown in FIG14;

[0056] FIG16 is an exploded view of another optical waveguide structure provided by at least one embodiment of the present disclosure;

[0057] FIG17 is a schematic diagram of the cross-sectional structure of the optical waveguide structure shown in FIG16;

[0058] FIG18 is a schematic cross-sectional view of a display device provided by at least one embodiment of the present disclosure;

[0059] FIG19 is a flow chart of a method for preparing an optical waveguide structure according to at least one embodiment of the present disclosure;

[0060] 20 to 22 are process diagrams of a method for preparing an optical waveguide structure according to at least one embodiment of the present disclosure; and

[0061] 23 to 25 are process diagrams of another method for preparing an optical waveguide structure provided by at least one embodiment of the present disclosure. DETAILED DESCRIPTION

[0062] To make the purpose, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0063] Unless otherwise defined, the technical or scientific terms used in this disclosure should have the usual meanings understood by persons of ordinary skill in the field to which this disclosure belongs. The words "first", "second" and similar terms used in this disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0064] Unless otherwise defined, the features such as "parallel", "perpendicular" and "same" used in the embodiments of the present invention include the situations of "parallel", "perpendicular", "same" in a strict sense, as well as the situations of "approximately parallel", "approximately perpendicular", "approximately the same" and the like that contain certain errors. For example, the above-mentioned "approximately" may mean that the difference between the compared objects is 10% of the average value of the compared objects, or within 5%. When the number of a component or element is not specifically indicated below in the embodiments of the present invention, it means that the component or element may be one or more, or may be understood as at least one. "At least one" refers to one or more, and "multiple" refers to at least two. The "same-layer setting" in the embodiments of the present invention refers to the relationship between multiple layers formed by the same material after the same step (for example, a one-step patterning process). The "same layer" here does not always mean that the thickness of multiple layers is the same or the height of multiple layers in the cross-sectional view is the same.

[0065] For example, a waveguide near-eye display system based on optical waveguide technology generally consists of a microdisplay, a collimating eyepiece assembly, a waveguide substrate, an input coupling grating, and an output coupling grating. The input coupling grating and output coupling grating are located on the same transparent waveguide substrate. The basic principle of a waveguide near-eye display system based on optical waveguide technology is that the microdisplay outputs the required virtual image information. The collimating eyepiece assembly collimates this image information, converting light rays from various viewing angles into parallel light rays. The input coupling grating of the waveguide structure changes the propagation direction of the light rays so that they enter the waveguide substrate. The parallel light rays from various viewing angles meet the conditions of total internal reflection in the waveguide substrate and propagate laterally along the waveguide to reach the output coupling grating. The output coupling grating also changes the propagation direction of the light rays, causing them to no longer meet the conditions of total internal reflection within the waveguide substrate. As a result, the light rays exit the waveguide structure, expand along the propagation direction, and after coupling out of the waveguide substrate, enter the observer's eye, achieving the purpose of pupil expansion. To better promote augmented reality (AR) glasses to the consumer market, one important direction is color AR. Current color AR displays typically include three waveguides, each of which can transmit light of a mixed color of the three primary colors, and finally the light is output at the output coupling grating of each waveguide for fusion, thereby achieving a color effect. The response wavelength bandwidth of the input coupling grating of the monochrome waveguide is very large, basically responding to the three colors R, G, and B. This also results in the multi-wavelength incident light of the color light machine entering the monochrome waveguide, and the color of the light finally emitted from its output coupling grating is not monochrome, but uneven color. In addition, after different monochrome waveguides are superimposed, the final color will become even more uneven, and the chromaticity uniformity will also be very poor. For color AR with diffraction light waveguides, one of the main reasons for its poor color effect is that the response wavelength bandwidth of the grating is very large.

[0066] However, the inventors of the present disclosure have found that AR glasses based on diffraction optical waveguides generally have problems such as dispersion, which leads to poor color display effects. The inventors of the present disclosure have considered that a suitable filter layer can be set on a single-layer waveguide plate. The filter layer filters the light of colors other than those transmitted by the waveguide plate itself, so that the waveguide plate only transmits light of one color. The waveguide structure designed and manufactured in this way can significantly improve the dispersion problem of color display, so that the optical module formed therefrom has excellent color display effects.

[0067] At least one embodiment of the present disclosure provides an optical waveguide structure, which includes: a plurality of stacked waveguide plates, the plurality of waveguide plates including a first color waveguide plate disposed adjacent to a display, and a second color waveguide plate disposed adjacent to the first color waveguide plate, each waveguide plate including a first main surface and a second main surface opposite to each other; an in-coupling grating and an out-coupling grating are disposed on the first main surface of each waveguide plate, the in-coupling grating being configured to couple a light beam incident thereon into the waveguide plate, and the out-coupling grating being configured to couple a light beam transmitted thereon out of the waveguide plate; on the first main surface or the second main surface of the first color waveguide plate, A first filter layer is provided, and the orthographic projection of the first filter layer on the first color waveguide plate is between the orthographic projection of the coupling-in grating located on the first color waveguide plate on the first color waveguide plate and the orthographic projection of the coupling-out grating located on the first color waveguide plate on the first color waveguide plate, and the first filter layer is configured to remove light of other colors in the first color waveguide plate except the first color light. By arranging the first filter layer on the first main surface or the second main surface of the first color waveguide plate, the optical waveguide structure can significantly improve the dispersion problem existing in color display, so that the optical module formed thereby has excellent color effect.

[0068] For example, Figure 1 is a schematic diagram of the cross-sectional structure of an optical waveguide structure provided in at least one embodiment of the present disclosure, Figure 2 is a schematic diagram of the three-dimensional structure of a first color waveguide plate provided in at least one embodiment of the present disclosure, Figure 3 is a schematic diagram of the three-dimensional structure of a second color waveguide plate provided in at least one embodiment of the present disclosure, and Figure 4 is a schematic diagram of the three-dimensional structure of a third color waveguide plate provided in at least one embodiment of the present disclosure. As shown in Figures 1, 2, 3 and 4, the optical waveguide structure 100 includes: a plurality of stacked waveguide plates 101, the plurality of waveguide plates 101 including a first color waveguide plate 1011 disposed adjacent to the display 300, and a second color waveguide plate 2011 disposed adjacent to the first color waveguide plate 1011, each waveguide plate 101 including a first main surface 101a and a second main surface 101b opposite to each other; an in-coupling grating 102 and an out-coupling grating 103 are disposed on the first main surface 101a of each waveguide plate 101, the in-coupling grating 102 being configured to couple a light beam incident thereon into the waveguide plate 101, and the out-coupling grating 103 being configured to couple a light beam transmitted thereon out of the waveguide plate 101; A first filter layer 1013 is provided on 11b. The orthographic projection of the first filter layer 1013 on the first color waveguide plate 1011 is between the orthographic projection of the in-coupling grating 102 located on the first color waveguide plate 1011 on the first color waveguide plate 1011 and the orthographic projection of the out-coupling grating 103 located on the first color waveguide plate 1011 on the first color waveguide plate 1011. The first filter layer 1013 is configured to remove light of other colors in the first color waveguide plate 1011 except the first color light. By providing the first filter layer 1013 on the first main surface 1011a or the second main surface 1011b of the first color waveguide plate 1011, the optical waveguide structure 100 can significantly improve the dispersion problem existing in color display, so that the optical module formed thereby has excellent color effect.

[0069] For example, as shown in Figures 1 and 2, a first color interception layer 1014 is provided on the second major surface 1011b of the first color waveguide plate 1011. The orthographic projection of the first color interception layer 1014 on the first color waveguide plate 1011 and the orthographic projection of the first filter layer 1013 on the first color waveguide plate 1011 do not overlap, and the first color interception layer 1014 is configured to intercept the first color light in the first color waveguide plate 1011 to prevent the first color light from being emitted from the first color waveguide plate 1011, thereby ensuring the effective utilization of the first color light. For example, the first color intercepting layer 1014 and the first filter layer 1013 are spaced apart from each other and can be formed in the same process step. The first color intercepting layer 1014 can retain the light of the first color in the first color waveguide plate 1011, but a portion of light of other colors also propagates in the first color waveguide plate 1011. The light is then further filtered by the first filter layer 1013, so that only light of the first color remains in the light propagating in the first color waveguide plate 1011, and light of other colors is absorbed by the first filter layer 1013. As a result, the light ultimately emitted from the first color waveguide plate 1011 is monochromatic light of the first color with a relatively high purity.

[0070] For example, in one embodiment, the first color interception layer 1014 can transmit a portion of light of other colors except the first color light incident from the coupling-in grating 102 into the first color waveguide plate 1011 to the second color waveguide plate 2011, and another portion of light of other colors except the first color light retained in the first color waveguide plate 1011 is transmitted to the first filter layer 1013 and then absorbed by the first filter layer 1013, so that only the first color light remains in the light propagating in the first color waveguide plate 1011.

[0071] 1 , the orthographic projection of the first color trapping layer 1014 on the first color waveguide plate 1011 overlaps with the orthographic projection of the incoupling grating 102 located on the first color waveguide plate 1011. For example, in one embodiment, the orthographic projection of the first color trapping layer 1014 on the first color waveguide plate 1011 and the orthographic projection of the incoupling grating 102 located on the first color waveguide plate 1011 on the first color waveguide plate 1011 coincide with each other, or the orthographic projection of the incoupling grating 102 located on the first color waveguide plate 1011 on the first color waveguide plate 1011 is within the orthographic projection of the first color trapping layer 1014 on the first color waveguide plate 1011. This allows all light passing through the incoupling grating 102 to be transmitted to the first color trapping layer 1014, thereby improving the filtering efficiency of the input light.

[0072] For example, as shown in FIG1 and FIG3 , a second filter layer 2013 may be provided on the first main surface 2011a or the second main surface 2011b of the second color waveguide plate 2011. As shown in FIG1 , a second filter layer 2013 is provided on the second main surface 2011b of the second color waveguide plate 2011. The orthographic projection of the second filter layer 2013 on the second color waveguide plate 2011 is between the orthographic projection of the in-coupling grating 102 on the second color waveguide plate 2011 and the orthographic projection of the out-coupling grating 103 on the second color waveguide plate 2011. The second filter layer 2013 is configured to remove light of other colors except the second color light from the second color waveguide plate 2011. That is, the second filter layer 2013 can absorb light of other colors except the second color light from the second color waveguide plate 2011. In this way, the second filter layer 2013 can further purify the light propagating in the second color waveguide plate 2011, so that only the second color light remains in the light propagating in the second color waveguide plate 2011, and the light of other colors is absorbed by the second filter layer 2013, so that the light finally emitted from the second color waveguide plate 2011 is monochromatic light with a relatively high purity.

[0073] For example, as shown in FIG1 , a second color interception layer 2014 is provided on the second major surface 2011b of the second color waveguide plate 2011. The second color interception layer 2014 is configured to intercept the second color light in the second color waveguide plate 2011 to prevent the second color light from being emitted from the second color waveguide plate 2011, thereby ensuring the effective utilization of the second color light.

[0074] For example, in one embodiment, the orthographic projection of the second color intercepting layer 2014 on the second color waveguide plate 2011 overlaps with the orthographic projection of the coupling-in grating 102 located on the second color waveguide plate 2011 on the second color waveguide plate 2011. This allows the second color intercepting layer 2014 to be more efficient in purifying the light incident from the coupling-in grating 102 into the second color waveguide plate 2011.

[0075] For example, as shown in FIG1 , the second color intercepting layer 2014 and the second filter layer 2013 are spaced apart from each other and can be formed in the same process step. The second color intercepting layer 2014 can retain the second color light within the second color waveguide plate 2011, but a portion of light of other colors also propagates through the second color waveguide plate 2011. The light is then further filtered by the second filter layer 2013, so that only the second color light remains in the second color waveguide plate 2011, while light of other colors is absorbed by the second filter layer 2013. As a result, the light ultimately emitted from the second color waveguide plate 2011 is monochromatic light of the second color with a relatively high purity.

[0076] For example, in one embodiment, the second color interception layer 2014 can transmit a portion of light of other colors except the second color light incident from the coupling-in grating 102 into the second color waveguide plate 2011 to the third color waveguide plate 3011, and another portion of light of other colors except the second color light retained in the second color waveguide plate 2011 is transmitted to the second filter layer 2013 and then absorbed by the second filter layer 2013, so that only the second color light remains in the light propagating in the second color waveguide plate 2011.

[0077] 1 , the orthographic projection of the second color trapping layer 2014 on the second color waveguide plate 2011 overlaps with the orthographic projection of the incoupling grating 102 located on the second color waveguide plate 2011. For example, in one embodiment, the orthographic projection of the second color trapping layer 2014 on the second color waveguide plate 2011 and the orthographic projection of the incoupling grating 102 located on the second color waveguide plate 2011 on the second color waveguide plate 2011 coincide with each other, or the orthographic projection of the incoupling grating 102 located on the second color waveguide plate 2011 on the second color waveguide plate 2011 is within the orthographic projection of the second color trapping layer 2014 on the second color waveguide plate 2011. This allows all light passing through the incoupling grating 102 to be transmitted to the second color trapping layer 2014, thereby improving the filtering efficiency of the input light.

[0078] For example, as shown in Figures 1 and 4, the multiple waveguide plates 101 also include a third color waveguide plate 3011 arranged adjacent to the second color waveguide plate 2011, and the second color retention layer 2014 is further configured to transmit a portion of light of other colors except the second color light incident from the coupling-in grating 102 to the third color waveguide plate 3011. For the three primary colors of light emitted by the optical machine (for example, the display 300) including only red light, green light and blue light, the light transmitted to the third color waveguide plate 3011 is monochromatic light, so the light emitted from the coupling-out grating 103 after total reflection is also monochromatic light.

[0079] For example, as shown in Figures 1, 2, 3 and 4, a folding grating 104 is also provided on the first principal surface 101a of each waveguide plate 101, and in each waveguide plate 101, the folding grating 104 is located between the coupling-in grating 102 and the coupling-out grating 103, and the folding grating 104 is configured to receive the light beam incoming from the coupling-in grating 102 located in the same layer as the folding grating 104 and perform pupil expansion transmission.

[0080] For example, in combination with Figures 1 and 2, the orthographic projection of the first filter layer 1013 on the first color waveguide plate 1011 is between the orthographic projection of the folding grating 104 located on the first color waveguide plate 1011 on the first color waveguide plate 1011 and the orthographic projection of the coupling-in grating 102 located on the first color waveguide plate 1011 on the first color waveguide plate 1011, or, between the orthographic projection of the folding grating 104 located on the first color waveguide plate 1011 on the first color waveguide plate 1011 and the orthographic projection of the coupling-out grating 103 located on the first color waveguide plate 1011 on the first color waveguide plate 1011, or, the orthographic projection of the first filter layer 1013 on the first color waveguide plate 1011 and the orthographic projection of the folding grating 104 on the first color waveguide plate 1011 overlap, so that the first filter layer 1013 can remove light of other colors except the first color in the optical path of light transmission.

[0081] 2 , the orthographic projection of the first filter layer 1013 on the first color waveguide plate 1011 is located within the orthographic projection of the folding grating 104 on the first color waveguide plate 1011. In another example, the orthographic projection of the first filter layer 1013 on the first color waveguide plate 1011 and the orthographic projection of the folding grating 104 on the first color waveguide plate 1011 may overlap.

[0082] For example, as shown in Figures 1 and 3, the orthographic projection of the second filter layer 2013 on the second color waveguide plate 2011 is between the orthographic projection of the folding grating 104 located on the second color waveguide plate 2011 on the second color waveguide plate 2011 and the orthographic projection of the coupling-in grating 102 located on the second color waveguide plate 2011 on the second color waveguide plate 2011, or, between the orthographic projection of the folding grating 104 located on the second color waveguide plate 2011 on the second color waveguide plate 2011 and the orthographic projection of the coupling-out grating 103 located on the second color waveguide plate 2011 on the second color waveguide plate 2011, or, the orthographic projection of the second filter layer 2013 on the second color waveguide plate 2011 and the orthographic projection of the folding grating 104 on the second color waveguide plate 2011 overlap, so that the second filter layer 2013 can remove light of other colors except the second color in the optical path of light transmission.

[0083] 3 , the orthographic projection of the second filter layer 2013 on the second color waveguide plate 2011 is within the orthographic projection of the folding grating 104 on the second color waveguide plate 2011. In another example, the orthographic projection of the second filter layer 2013 on the second color waveguide plate 2011 and the orthographic projection of the folding grating 104 on the second color waveguide plate 2011 may overlap.

[0084] For example, as shown in FIG4 , the third color light is transmitted in the third color waveguide plate 3011, and a coupling-in grating 102, a coupling-out grating 103, and a folding grating 104 spaced apart from each other are provided on the first main surface 3011a of the third color waveguide plate 3011, and no other structures are provided on the second main surface 3011b of the third color waveguide plate 3011.

[0085] For example, as shown in Figure 1, the light emitted from the external display 300 is three primary colors of red, green and blue light. The first color waveguide plate 1011 is a blue waveguide plate, the second color waveguide plate 2011 is a green waveguide plate, and the third color waveguide plate 3011 is a red waveguide plate. Correspondingly, the first color light is blue light, the second color light is green light, and the third color light is red light. For example, in the cross-sectional structure shown in FIG1 , the blue waveguide plate is arranged at the top layer, which is closest to the external display 300. A first filter layer 1013 and a first color interception layer 1014 are provided on the second main surface 1011b of the blue waveguide plate, which are spaced apart from each other. The first filter layer 1013 is a red-green filter film, that is, it can absorb the red light and green light transmitted thereto, so that the light finally emitted from the outcoupling grating 103 of the blue waveguide plate is blue light. The first color interception layer 1014 is a blue light filter film, which can intercept all blue light in the blue waveguide plate and only transmit light of other colors except blue light to the second color waveguide plate 2011, so as to improve the utilization rate of blue light. The green waveguide is positioned in the middle layer. A second filter layer 2013 and a second color interception layer 2014 are spaced apart from each other on the second major surface 2011b of the green waveguide. The second filter layer 2013 is a red filter film that absorbs red light transmitted therethrough, resulting in green light ultimately emitted from the outcoupling grating 103 on the green waveguide. The second color interception layer 2014 is a green filter film that intercepts green light within the green waveguide, thereby improving the utilization rate of green light. The red waveguide is positioned in the bottom layer. An unfiltered structure is provided on the second major surface 3011b of the red waveguide. Only red light remains within the red waveguide, which is then transmitted through the red waveguide by total internal reflection and ultimately emitted from the outcoupling grating 103 on the red waveguide.

[0086] For example, in the structures shown in FIG. 1 to FIG. 4 , the coupling-in grating 102 includes a transmissive-reflective coupling-in grating 102 , so that the coupling-in grating 102 couples the incident light beam thereon into the waveguide plate in both the transmission and reflection forms, thereby improving the utilization rate of light.

[0087] For example, in the structures shown in Figures 1 to 4, the coupling-in grating 102, the folding grating 104 and the coupling-out grating 103 all include one-dimensional rectangular wire gratings, but the embodiments of the present disclosure are not limited to this. The coupling-in grating 102, the folding grating 104 and the coupling-out grating 103 may also respectively include one-dimensional blazed wire gratings, one-dimensional tilted wire gratings or two-dimensional metasurface arrays, and the embodiments of the present disclosure are not limited to this.

[0088] It should be noted that, although the cross-sectional structure shown in FIG1 shows that the first filter layer 1013 and the first color intercepting layer 1014 are provided on the second main surface 1011b of the first color waveguide plate 1011, and the second filter layer 2013 and the second color intercepting layer 2014 are provided on the second main surface 2011b of the second color waveguide plate 2011, the embodiments of the present disclosure are not limited thereto. It is possible that only the first filter layer 1013 is provided on the second main surface 1011b of the first color waveguide plate 1011, and only the second filter layer 2013 is provided on the second main surface 2011b of the second color waveguide plate 2011; it is also possible that the first filter layer 1013 and the first color intercepting layer 1014 are provided on the second main surface 1011b of the first color waveguide plate 1011, and the second filter layer 2014 is provided on the second main surface 2011b of the second color waveguide plate 2011. Only the second filter layer 2013 is provided; alternatively, only the first filter layer 1013 may be provided on the second major surface 1011b of the first color waveguide plate 1011, and a second filter layer 2013 and a second color interception layer 2014 spaced apart from each other may be provided on the second major surface 2011b of the second color waveguide plate 2011. This is not limited in the embodiments of the present disclosure.

[0089] Figure 5 is a schematic diagram of the cross-sectional structure of another optical waveguide structure provided by at least one embodiment of the present disclosure. The light emitted from the external display 300 is three primary colors of light consisting of red, green and blue light. The first color waveguide plate 1011 is a red waveguide plate, the second color waveguide plate 2011 is a green waveguide plate, and the third color waveguide plate 3011 is a blue waveguide plate. Correspondingly, the first color light is red, the second color light is green, and the third color light is blue. For example, in the cross-sectional structure shown in FIG5 , the red waveguide plate is arranged at the top layer, which is closest to the external display 300. A first filter layer 1013 and a first color interception layer 1014 are provided on the second main surface 1011b of the red waveguide plate, which are spaced apart from each other. The first filter layer 1013 is a blue-green filter film, that is, it can absorb the blue light and the green light transmitted thereto, so that the light finally emitted from the outcoupling grating 103 of the red waveguide plate is red light. The first color interception layer 1014 is a red filter film, which can intercept all the red light in the red waveguide plate and only transmit the light of other colors except the red light to the second color waveguide plate 2011, so as to improve the utilization rate of the red light. The green waveguide is positioned in the middle layer. A second filter layer 2013 and a second color interception layer 2014 are spaced apart from each other on the second major surface 2011b of the green waveguide. The second filter layer 2013 is a blue filter film that absorbs blue light transmitted therethrough, resulting in green light ultimately emitted from the outcoupling grating 103 on the green waveguide. The second color interception layer 2014 is a green filter film that intercepts green light within the green waveguide, thereby improving the utilization of green light. The blue waveguide is positioned in the bottom layer. An unfiltered structure is provided on the second major surface 3011b of the blue waveguide. Only blue light remains within the blue waveguide, which is then transmitted through the blue waveguide by total internal reflection and ultimately emitted from the outcoupling grating 103 on the blue waveguide. The basic structure shown in FIG5 can be found in the relevant description of FIG1 and will not be repeated here.

[0090] Figure 6 is a schematic diagram of the cross-sectional structure of another optical waveguide structure provided by at least one embodiment of the present disclosure. The light emitted from the external display 300 is three primary colors of light consisting of red, green and blue light. The first color waveguide plate 1011 is a red waveguide plate, the second color waveguide plate 2011 is a blue waveguide plate, and the third color waveguide plate 3011 is a green waveguide plate. Correspondingly, the first color light is red, the second color light is blue, and the third color light is green. For example, in the cross-sectional structure shown in FIG6 , the red waveguide plate is arranged at the top layer, which is closest to the external display 300. A first filter layer 1013 and a first color interception layer 1014 are provided on the second main surface 1011 b of the red waveguide plate, which are spaced apart from each other. The first filter layer 1013 is a blue-green filter film, that is, it can absorb the blue light and the green light transmitted thereto, so that the light finally emitted from the outcoupling grating 103 of the red waveguide plate is red light. The first color interception layer 1014 is a red filter film, which can intercept all the red light in the red waveguide plate and only transmit the light of other colors except the red light to the second color waveguide plate 2011, so as to improve the utilization rate of the red light. The blue waveguide is positioned in the middle layer. A second filter layer 2013 and a second color interception layer 2014 are spaced apart from each other on the second major surface 2011b of the blue waveguide. The second filter layer 2013 is a green filter film that absorbs green light transmitted therethrough, resulting in blue light being emitted from the outcoupling grating 103 on the blue waveguide. The second color interception layer 2014 is a blue filter film that intercepts blue light within the blue waveguide, thereby improving the utilization of blue light. The green waveguide is positioned in the bottom layer. An unfiltered structure is disposed on the second major surface 3011b of the green waveguide. Only green light remains within the green waveguide, which is then transmitted through the green waveguide by total internal reflection and ultimately emitted from the outcoupling grating 103 on the green waveguide. The basic structure shown in FIG6 can be found in the relevant description of FIG1 and will not be repeated here.

[0091] For example, in the structures shown in Figures 1 to 6, the first filter layer 1013, the second filter layer 2013, the first color interception layer 1014 and the second color interception layer 2014 are all layer structures formed of organic materials, which can be formed by full-surface coating and then a photolithography process.

[0092] For example, FIG7 is a schematic diagram of the cross-sectional structure of another optical waveguide structure provided in at least one embodiment of the present disclosure. The structure shown in FIG7 differs from the structure shown in FIG1 in that the first filter layer 1013, the second filter layer 2013, the first color interception layer 1014, and the second color interception layer 2014 are all grating structures, i.e., filter grating structures that match the other structures on each waveguide plate 101. The filter grating structure is a nanograting, each nanograting having a period of 200 nm to 600 nm, a height of 50 nm to 400 nm, and a duty cycle of 0.2 to 0.8. The material of the nanograting may include any one of a polymer, an inorganic film layer, and a metal element or alloy, or may be a composite layer formed of these materials. For other structures of the waveguide plates shown in FIG7, please refer to the relevant description of FIG1 and will not be repeated here.

[0093] For example, in the structure shown in FIG7 , the first filter layer 1013 and the first color interception layer 1014 can be formed in the same process step by nanoimprinting, and the second filter layer 2013 and the second color interception layer 2014 can be formed in the same process step by nanoimprinting.

[0094] For example, FIG8 is a schematic cross-sectional view of another optical waveguide structure provided by at least one embodiment of the present disclosure. The structure shown in FIG8 differs from the structure shown in FIG1 in that the first filter layer 1013, the second filter layer 2013, the first color trapping layer 1014, and the second color trapping layer 2014 are all Bragg reflectors (DBRs), i.e., DBRs that match the other structures on each waveguide plate 101. The light filtering or light trapping functions of the first filter layer 1013, the second filter layer 2013, the first color trapping layer 1014, and the second color trapping layer 2014 are achieved by the DBRs, which are formed by stacking a film layer formed of a material having a high refractive index and a film layer formed of a material having a low refractive index. For example, the high refractive index material and the low refractive index material can both be inorganic materials. For example, the material with a high refractive index may include silicon nitride or silicon dioxide, and the material with a low refractive index may be silicon oxide. A layer of the high refractive index material and a layer of the low refractive index material stacked together form a stacked structure, forming a pair of stacked layers. The first filter layer 1013, the second filter layer 2013, the first color intercepting layer 1014, and the second color intercepting layer 2014 may each include 2 to 32 stacked layers to form an integrated structure. For other structures of the waveguides shown in FIG8 , refer to the description of FIG1 and are not further elaborated here.

[0095] For example, in the structure shown in FIG8 , the first filter layer 1013 , the second filter layer 2013 , the first color interception layer 1014 and the second color interception layer 2014 may be formed by full-surface coating and then photolithography.

[0096] For example, FIG9 is a schematic diagram of the cross-sectional structure of another optical waveguide structure provided by at least one embodiment of the present disclosure. The difference between the structure shown in FIG9 and the structure shown in FIG1 is that the coupling-in grating 102 and the coupling-out grating 103 provided on the first main surface 101a of each waveguide plate 101 are both tilted gratings. The cross-sectional shape of the tilted grating is a parallelogram. Compared with the rectangular grating shown in FIG1, the tilted grating can further improve the optical efficiency. The period of the tilted grating is 200nm to 500nm, the height of each tilted grating is 50nm to 500nm, the duty cycle of each tilted grating is 0.2 to 0.8, and the tilt angle of each tilted grating relative to the waveguide plate body is 30 to 80 degrees. ° It should be noted that although the folded grating is not shown in FIG9 , the folded grating can have the same range of period, height, duty cycle, and tilt angle relative to the waveguide plate body as the in-coupling grating 102 and the out-coupling grating 103, and the embodiments of the present disclosure are not limited to this. For other structures of the waveguide plates shown in FIG9 , please refer to the relevant description of FIG1 and will not be repeated here.

[0097] For example, FIG10 is a schematic diagram of the cross-sectional structure of another optical waveguide structure provided by at least one embodiment of the present disclosure. The difference between the structure shown in FIG10 and the structure shown in FIG1 is that the coupling-in grating 102 and the coupling-out grating 103 provided on the first main surface 101a of each waveguide plate 101 are both blazed gratings, and the cross-sectional shape of the blazed grating is triangular. Compared with the rectangular grating shown in FIG1, the blazed grating can further improve the optical efficiency. The period of the blazed grating is 200nm to 500nm, the height of each blazed grating is 50nm to 500nm, the duty cycle of each blazed grating is 0.2 to 0.8, and the inclination angle of the longest side of each blazed grating relative to the waveguide plate body is 30 to 80 degrees. ° It should be noted that although the folded grating is not shown in FIG10 , the folded grating can have the same range of period, height, duty cycle, and tilt angle of the longest side relative to the waveguide plate body as the in-coupling grating 102 and the out-coupling grating 103, and the embodiments of the present disclosure are not limited to this. For other structures of the waveguide plates shown in FIG10 , please refer to the relevant description of FIG1 , and will not be repeated here.

[0098] For example, FIG11 is a schematic diagram of the cross-sectional structure of another optical waveguide structure provided by at least one embodiment of the present disclosure. The difference between the structure shown in FIG11 and the structure shown in FIG1 is that the coupling-in grating 102 and the coupling-out grating 103 provided on the first main surface 101a of each waveguide plate 101 are both metasurface gratings. The cross-sectional shapes of the coupling-in grating 102 and the coupling-out grating 103 are both rectangular, but the embodiments of the present disclosure are not limited thereto and can also be parallelograms or triangles, etc. Compared with the rectangular grating shown in FIG1 , this metasurface grating can further improve the light efficiency and the uniformity of the output light. The period of the metasurface grating is 200 to 500 nm, the height of the metasurface grating is 50 to 500 nm, and the gradient duty cycle of the metasurface grating is 0.2 to 0.8. The metasurface structure of the metasurface grating can be a transmission-type structure or a geometric structure, or a composite structure of the two. It should be noted that although the folded grating is not shown in FIG11 , the folded grating can have the same range of period, height, duty cycle, and tilt angle of the longest side relative to the waveguide plate body as the in-coupling grating 102 and the out-coupling grating 103, and the embodiments of the present disclosure are not limited thereto. For other structures of the waveguide plates shown in FIG11 , please refer to the relevant description of FIG1 , and will not be repeated here.

[0099] For example, in the optical waveguide structures shown in Figures 1 to 11, each optical waveguide structure includes three stacked layers of waveguide plates. In other examples, the number of stacked layers of waveguide plates included in the optical waveguide structure can also be 2 layers, 4 layers, or 5 layers, etc. The number of stacked layers of waveguide plates can be adjusted according to actual needs, and the embodiments of the present disclosure are not limited to this.

[0100] For example, FIG12 is a schematic diagram of the cross-sectional structure of another optical waveguide structure provided in at least one embodiment of the present disclosure. The structure shown in FIG12 differs from the structure shown in FIG1 in that the optical waveguide structure 100 includes two stacked waveguide plates 101. For example, in FIG12 , an in-coupling grating 102, an out-coupling grating 103, and a folding grating (not shown in FIG12 ) are provided on each waveguide plate 101. The structures and materials of the in-coupling grating 102, the out-coupling grating 103, and the folding grating can be found in the relevant description of any of the above embodiments and will not be repeated here.

[0101] For example, as shown in FIG12 , the light emitted from the external display 300 is three primary colors of red, green, and blue, the first color waveguide plate 1011 is a blue-green waveguide plate, and the second color waveguide plate 2011 is a red waveguide plate. Correspondingly, the first color light is a mixture of blue and green light, the light of other colors except the first color light is red light, and the second color light is red light. For example, in the cross-sectional structure shown in FIG12 , the cyan waveguide plate is disposed at the top layer, which is closest to the external display 300. A first filter layer 1013 and a first color interception layer 1014 are provided on the second main surface 1011 b of the cyan waveguide plate, which are spaced apart from each other. The first filter layer 1013 is a red filter film, which can absorb the red light transmitted thereto, so that the light ultimately emitted from the outcoupling grating 103 of the cyan waveguide plate is a mixture of blue and green light. The first color interception layer 1014 is a cyan filter film, which can intercept all blue and green light in the cyan waveguide plate, and only transmit light of other colors except blue and green light to the second color waveguide plate 2011, so as to improve the utilization rate of blue and green light. The red waveguide is disposed in the lower layer, and a non-filtering structure is disposed on the second major surface 2011b of the red waveguide. As a result, only red light remains within the red waveguide, which is then transmitted by total internal reflection within the red waveguide before exiting the outcoupling grating 103 on the red waveguide. The basic structure shown in FIG12 can be found in the description of FIG1 and will not be further elaborated here.

[0102] It should be noted that in the embodiments of the present disclosure, the light of the first color, the light of the second color, and the light of the third color are not limited to light of only one color, that is, they do not refer to monochromatic light, but can also be mixed light formed by mixing lights of multiple colors.

[0103] For example, FIG13 is a schematic diagram of the cross-sectional structure of another optical waveguide structure provided in at least one embodiment of the present disclosure. The structure shown in FIG13 differs from the structure shown in FIG1 in that the optical waveguide structure 100 includes two stacked waveguide plates 101. For example, in FIG13 , an in-coupling grating 102, an out-coupling grating 103, and a folding grating (not shown in FIG12 ) are provided on each waveguide plate 101. The structures and materials of the in-coupling grating 102, the out-coupling grating 103, and the folding grating can be found in the relevant description of any of the above embodiments and will not be repeated here.

[0104] For example, as shown in FIG13 , the light emitted from the external display 300 is three primary colors of red, green, and blue. The first color waveguide plate 1011 is a blue-green waveguide plate, and the second color waveguide plate 2011 is a red-green waveguide plate. Correspondingly, the first color light is blue, and the light of other colors except the first color light is a mixture of red and green. For example, in the cross-sectional structure shown in FIG13 , the cyan waveguide plate is disposed on the uppermost layer, which is closest to the external display 300. A first filter layer 1013 and a first color interception layer 1014 are disposed on the second major surface 1011 b of the cyan waveguide plate, spaced apart from each other. The first filter layer 1013 is a red filter film, that is, it can absorb red light transmitted thereto, so that the light ultimately emitted from the outcoupling grating 103 of the cyan waveguide plate is a mixture of blue and green light. The first color interception layer 1014 is a blue filter film, which can intercept all blue light in the cyan waveguide plate, but can also intercept part of the green light and part of the red light in the first color waveguide plate. After the blue light, part of the green light, and part of the red light pass through the first filter layer 1013, the red light is absorbed, and the light emitted from the outcoupling grating 103 of the first color waveguide plate is only blue light and green light, thereby improving the utilization rate of the blue and green light. The red and green waveguide plates are disposed in the lower layer, and a non-filtering structure is disposed on the second major surface 2011b of the red and green waveguide plates. Light transmitted into the red and green waveguide plates includes red and green light. These red and green light rays are transmitted through the red and green waveguide plates by total internal reflection and ultimately emerge from the outcoupling grating 103 on the red and green waveguide plates. The basic structure shown in FIG13 can be found in the description of FIG1 and will not be repeated here.

[0105] For example, FIG14 is an exploded view of another optical waveguide structure provided by at least one embodiment of the present disclosure, and FIG15 is a schematic diagram of a cross-sectional structure of the optical waveguide structure shown in FIG14. As shown in FIG14 and FIG15 , the optical waveguide structure 100 includes: a plurality of stacked waveguide sheets 101, the plurality of waveguide sheets 101 including a first color waveguide sheet 1011 disposed adjacent to the display 300, a second color waveguide sheet 2011 disposed adjacent to the first color waveguide sheet 1011, and a third color waveguide sheet 301 disposed adjacent to the second color waveguide sheet 2011. 1. Each waveguide plate 101 includes a first main surface 101a and a second main surface 101b opposite to each other; an in-coupling grating 102, an out-coupling grating 103, and a folding grating 104 are provided on the first main surface 101a of each waveguide plate 101. The in-coupling grating 102 is configured to couple a light beam incident thereon into the waveguide plate 101, the out-coupling grating 103 is configured to couple a light beam transmitted thereon out of the waveguide plate 101, and the folding grating 104 is configured to receive a light beam transmitted from the in-coupling grating 102 located on the same layer as the folding grating 104 and perform pupil expansion transmission. A first filter layer 1013 is also provided on the first major surface 1011a of the first color waveguide plate 1011. The first filter layer 1013 is located between the coupling grating 102 and the folding grating 104. The first filter layer 1013 is configured to remove light of other colors from the first color waveguide plate 1011 except for the first color light. By providing the first filter layer 1013 on the first major surface 1011a of the first color waveguide plate 1011, the optical waveguide structure 100 can significantly improve the dispersion problem existing in color display, thereby making the optical module formed thereby have excellent color effects.

[0106] For example, as shown in Figures 14 and 15, a second filter layer 2013 is further provided on the first major surface 2011a of the second color waveguide plate 2011. The second filter layer 2013 is between the coupling grating 102 and the folding grating 104, and the second filter layer 2013 is configured to remove light of other colors in the second color waveguide plate 2011 except the second color light.

[0107] For example, as shown in Figures 14 and 15, a third filter layer 3013 is further provided on the first major surface 3011a of the third color waveguide plate 3011. The third filter layer 3013 is between the coupling grating 102 and the folding grating 104, and the third filter layer 3013 is configured to remove light of other colors in the third color waveguide plate 3011 except the third color light.

[0108] For example, the structural and material characteristics of the first filter layer 1013 , the second filter layer 2013 , and the third filter layer 3013 can be found in the above descriptions and will not be repeated here.

[0109] For example, in one embodiment, the light emitted from the external display 300 is three primary colors of light, namely red, green, and blue. The first color waveguide plate 1011 is a blue waveguide plate, the second color waveguide plate 2011 is a green waveguide plate, and the third color waveguide plate 3011 is a red waveguide plate. Accordingly, the first color light is blue, the second color light is green, and the third color light is red. For example, in the cross-sectional structure shown in FIG15 , the blue waveguide plate is disposed at the top layer, closest to the external display 300. A first filter layer 1013 is disposed on the first major surface 1011a of the blue waveguide plate. The first filter layer 1013 can absorb the red and green light transmitted thereto, so that the light ultimately emitted from the outcoupling grating 103 of the blue waveguide plate is blue light. The green waveguide plate is disposed in the middle layer, with a second filter layer 2013 disposed on its first major surface 2011a. This second filter layer 2013 absorbs red and blue light rays transmitted therethrough, resulting in green light rays ultimately emitted from the outcoupling grating 103 of the green waveguide plate. The red waveguide plate is disposed in the bottom layer, with a third filter layer 3013 disposed on its first major surface 3011a. This third filter layer 3013 absorbs green and blue light rays transmitted therethrough, resulting in red light rays ultimately emitted from the outcoupling grating 103 of the red waveguide plate. The basic structures shown in Figures 14 and 15 can be found in the relevant description of Figure 1 and will not be repeated here.

[0110] For example, in another example, the first color waveguide plate 1011 can be a blue waveguide plate, the second color waveguide plate 2011 can be a red waveguide plate, and the third color waveguide plate 3011 can be a green waveguide plate. The corresponding first filter layer 1013 can absorb red light and green light, the second filter layer 2013 can absorb blue light and green light, and the third filter layer 3013 can absorb red light and blue light.

[0111] For example, in another example, the first color waveguide plate 1011 can be a green waveguide plate, the second color waveguide plate 2011 can be a blue waveguide plate, and the third color waveguide plate 3011 can be a red waveguide plate. The corresponding first filter layer 1013 can absorb red light and blue light, the second filter layer 2013 can absorb red light and green light, and the third filter layer 3013 can absorb green light and blue light.

[0112] For example, in another example, the first color waveguide plate 1011 can be a red waveguide plate, the second color waveguide plate 2011 can be a blue waveguide plate, and the third color waveguide plate 3011 can be a green waveguide plate. The corresponding first filter layer 1013 can absorb blue light and green light, the second filter layer 2013 can absorb red light and green light, and the third filter layer 3013 can absorb red light and blue light.

[0113] For example, FIG16 is an exploded view of another optical waveguide structure provided by at least one embodiment of the present disclosure, and FIG17 is a schematic diagram of a cross-sectional structure of the optical waveguide structure shown in FIG16. As shown in FIG16 and FIG17, the optical waveguide structure 100 includes: a plurality of stacked waveguide sheets 101, the plurality of waveguide sheets 101 including a first color waveguide sheet 1011 disposed adjacent to the display 300, a first color filter sheet 210 disposed on a side of the first color waveguide sheet 1011 away from the display 300, a second color waveguide sheet 2011 disposed on a side of the first color filter sheet 210 away from the first color waveguide sheet 1011, and a A third color waveguide plate 3011 is provided on the side of 2011 away from the first color waveguide plate 1011, and each waveguide plate 101 includes a first main surface 101a and a second main surface 101b relative to each other; a coupling-in grating 102, a coupling-out grating 103 and a folding grating 104 are provided on the first main surface 101a of each waveguide plate 101, the coupling-in grating 102 is configured to couple the light beam incident thereon into the waveguide plate 101, the coupling-out grating 103 is configured to couple the light beam transmitted thereto out of the waveguide plate 101, and the folding grating 104 is configured to receive the light beam transmitted from the coupling-in grating 102 located on the same layer as the folding grating 104 and perform pupil expansion transmission. A first filter layer 1013 is also provided on the first major surface 1011a of the first color waveguide plate 1011. The first filter layer 1013 is located between the coupling grating 102 and the folding grating 104. The first filter layer 1013 is configured to remove light of other colors from the first color waveguide plate 1011 except for the first color light. By providing the first filter layer 1013 on the first major surface 1011a of the first color waveguide plate 1011, the optical waveguide structure 100 can significantly improve the dispersion problem existing in color display, thereby making the optical module formed thereby have excellent color effects.

[0114] For example, as shown in Figures 16 and 17, the first color filter film 210 includes a first color filter film body 211 and a first color filter film 212 disposed on the first color filter film body 211. The orthographic projection of the first color filter film 212 on the first color waveguide plate 1011 and the orthographic projection of the coupling grating 102 on the first color waveguide plate 1011 on the first color waveguide plate 1011 overlap. The first color filter film 210 can absorb or reflect the first color light incident thereon, so that the first color light is not included in the light incident on the second color waveguide plate 2011, or the amount of light incident on the second color waveguide plate 2011 is reduced to a minimum.

[0115] For example, as shown in Figures 16 and 17, a second filter layer 2013 is further provided on the first major surface 2011a of the second color waveguide plate 2011. The second filter layer 2013 is between the coupling grating 102 and the folding grating 104, and the second filter layer 2013 is configured to remove light of other colors in the second color waveguide plate 2011 except the second color light.

[0116] For example, as shown in Figures 16 and 17, a third filter layer 3013 is further provided on the first major surface 3011a of the third color waveguide plate 3011. The third filter layer 3013 is between the coupling grating 102 and the folding grating 104, and the third filter layer 3013 is configured to remove light of other colors in the third color waveguide plate 3011 except the third color light.

[0117] For example, the structural and material characteristics of the first filter layer 1013 , the second filter layer 2013 , and the third filter layer 3013 can be found in the above descriptions and will not be repeated here.

[0118] For example, in one embodiment, the light emitted from the external display 300 is three primary colors of light, namely red, green, and blue. The first color waveguide plate 1011 is a blue waveguide plate, the second color waveguide plate 2011 is a green waveguide plate, and the third color waveguide plate 3011 is a red waveguide plate. Accordingly, the first color light is blue, the second color light is green, and the third color light is red. For example, in the cross-sectional structure shown in FIG17 , the blue waveguide plate is disposed at the top layer, closest to the external display 300. A first filter layer 1013 is disposed on the first major surface 1011a of the blue waveguide plate. The first filter layer 1013 can absorb the red and green light transmitted thereto, so that the light ultimately emitted from the outcoupling grating 103 of the blue waveguide plate is blue light. The first color filter 212 disposed on the first color filter body 211 can absorb blue light or reflect it back toward the blue waveguide, resulting in only red and green light entering the green waveguide. A second filter layer 2013 is disposed on the first major surface 2011a of the green waveguide. This second filter layer 2013 absorbs red light transmitted therethrough, resulting in green light ultimately exiting the outcoupling grating 103 of the green waveguide. The red waveguide is disposed at the bottom layer, and a third filter layer 3013 is disposed on the first major surface 3011a of the red waveguide. This third filter layer 3013 absorbs green light transmitted therethrough, resulting in red light ultimately exiting the outcoupling grating 103 of the red waveguide. The basic structures shown in Figures 16 and 17 can be found in the relevant description of Figure 1 and will not be further elaborated here.

[0119] For example, in another example, the first color waveguide plate 1011 can be a blue waveguide plate, the second color waveguide plate 2011 can be a red waveguide plate, and the third color waveguide plate 3011 can be a green waveguide plate. The corresponding first filter layer 1013 can absorb red light and green light, the first color filter film 210 can absorb or reflect red light, the second filter layer 2013 can absorb green light, and the third filter layer 3013 can absorb red light.

[0120] For example, in another example, the first color waveguide plate 1011 can be a green waveguide plate, the second color waveguide plate 2011 can be a blue waveguide plate, and the third color waveguide plate 3011 can be a red waveguide plate. The corresponding first filter layer 1013 can absorb red light and blue light, the first color filter film 210 can absorb or reflect green light, the second filter layer 2013 can absorb red light, and the third filter layer 3013 can absorb blue light.

[0121] For example, in another example, the first color waveguide plate 1011 can be a red waveguide plate, the second color waveguide plate 2011 can be a blue waveguide plate, and the third color waveguide plate 3011 can be a green waveguide plate. The corresponding first filter layer 1013 can absorb blue light and green light, the first color filter film 210 can absorb or reflect red light, the second filter layer 2013 can absorb green light, and the third filter layer 3013 can absorb blue light.

[0122] At least one embodiment of the present disclosure further provides a display device. For example, FIG18 is a schematic diagram of the cross-sectional structure of a display device provided by at least one embodiment of the present disclosure. As shown in FIG18 , the display device 400 includes the optical waveguide structure 100 of any of the above-mentioned embodiments. FIG18 is taken as an example for explaining the optical waveguide structure 100 as the optical waveguide shown in FIG1 . The display device 400 further includes a projection structure 401. The projection structure 401 includes a display 300 and a collimating component 403. The display 300 is used to emit a light beam having image information. The collimating component 403 is used to collimate the light beam emitted by the display 300 to form parallel light coupled into the optical waveguide structure 100.

[0123] For example, other structures included in the display device 400 can refer to conventional designs and will not be described in detail here.

[0124] At least one embodiment of the present disclosure further provides a method for preparing an optical waveguide structure. For example, FIG19 is a flow chart of a method for preparing an optical waveguide structure provided by at least one embodiment of the present disclosure. As shown in FIG19 , the preparation method includes the following steps.

[0125] Step S101: Provide a plurality of stacked waveguide sheet bodies, wherein the plurality of waveguide sheet bodies include a first color waveguide sheet body arranged adjacent to the display, and a second color waveguide sheet body arranged adjacent to the first color waveguide sheet body, and each waveguide sheet body includes a first main surface and a second main surface relative to each other.

[0126] Step S102: forming an in-coupling grating and an out-coupling grating on the first main surface of each waveguide body.

[0127] Step S103: forming a first filter layer on the first main surface or the second main surface of the first color waveguide sheet body, wherein the orthographic projection of the first filter layer on the first color waveguide sheet body is between the orthographic projection of the in-coupling grating located on the first color waveguide sheet body on the first color waveguide sheet body and the orthographic projection of the out-coupling grating located on the first color waveguide sheet body on the first color waveguide sheet body, and the first filter layer is configured to remove light of other colors in the first color waveguide sheet body except the first color light.

[0128] The optical waveguide structure prepared by this preparation method can significantly improve the dispersion problem of color display by forming a first filter layer on the first main surface or the second main surface of the first color waveguide plate, so that the optical module formed therefrom has excellent color effect.

[0129] For example, Figures 20 to 22 are process diagrams of a method for preparing an optical waveguide structure provided by at least one embodiment of the present disclosure. Figures 20, 21 and 22 respectively show the process diagrams of preparing the first color waveguide sheet, the second color waveguide sheet and the third color waveguide sheet. In combination with Figures 20 to 22, the preparation method includes: providing a plurality of stacked waveguide sheet bodies 500, wherein the plurality of waveguide sheet bodies 500 include a first color waveguide sheet body 501 adjacent to a display (not shown in the figure), a second color waveguide sheet body 502 adjacent to the first color waveguide sheet body 501, and a third color waveguide sheet body 503 adjacent to the second color waveguide sheet body 502, each waveguide sheet body 500 includes a first main surface 500a and a second main surface 500b opposite to each other. An in-coupling grating 102 and an out-coupling grating 103 are formed on the first principal surface 500a of each waveguide body 500; a first filter layer 1013 is formed on the first principal surface 501a or the second principal surface 501b of the first color waveguide body 501. FIG20 shows an example of the first filter layer 1013 being formed on the second principal surface 501b of the first color waveguide body 501. The orthographic projection of the first filter layer 1013 on the first color waveguide body 501 is between the orthographic projection of the in-coupling grating 102 on the first color waveguide body 501 and the orthographic projection of the out-coupling grating 103 on the first color waveguide body 501. The first filter layer 1013 is configured to remove light of other colors from the first color waveguide body 501 except the first color light.

[0130] For example, as shown in FIG20 , the in-coupling grating 102 and the out-coupling grating 103 are formed on the first major surface 501a of the first color waveguide body 501 using a nanoimprint method, a protective layer 512 is formed on the first major surface 501a having the in-coupling grating 102 and the out-coupling grating 103, and then the first color trapping layer 1014 is formed on the second major surface 501b of the first color waveguide body 501, and then the first filter layer 1013 is formed. That is, the first color trapping layer 1014 is formed after the first filter layer 1013 is formed on the second major surface 501b of the first color waveguide body 501 and before the protective layer 512 is removed.

[0131] For example, in another embodiment, the coupling-in grating 102 and the coupling-out grating 103 may be formed on the first main surface 501a of the first color waveguide sheet body 501 by a nanoimprint method; a first filter layer 1013 may be formed on the first main surface 501a having the coupling-in grating 102 and the coupling-out grating 103; a protective layer 512 may be formed on the first main surface 501a having the coupling-in grating 102, the coupling-out grating 103, and the first filter layer 1013; and a first color interception layer 1014 may be formed on the second main surface 501b of the first color waveguide sheet body 501, wherein the orthographic projection of the first color interception layer 1014 on the first color waveguide sheet body 501 overlaps with the orthographic projection of the coupling-in grating 102 located on the first color waveguide sheet body 501 on the first color waveguide sheet body 501; and finally, the protective layer 512 may be removed to form the first color waveguide sheet.

[0132] For example, as shown in Figure 20, in the process of forming the coupling-in grating 102 and the coupling-out grating 103 on the first main surface 501a of the first color waveguide sheet body 501 by the nanoimprint method, it also includes forming the folding grating 104 on the first main surface 501a of the first color waveguide sheet body 501 by the nanoimprint method. The folding grating 104 is located between the coupling-in grating 102 and the coupling-out grating 103. The folding grating 104 is configured to receive the light beam transmitted from the coupling-in grating 102 located on the same layer as the folding grating 104 and perform pupil expansion transmission.

[0133] For example, the structures and materials of the first filter layer 1013 and the first color interception layer 1014 can refer to the relevant descriptions in the above embodiments, which will not be repeated here.

[0134] For example, as shown in Figure 21, an in-coupling grating 102 and an out-coupling grating 103 are formed on the first main surface 502a of the second color waveguide sheet body 502; a second filter layer 2013 is formed on the first main surface 502a or the second main surface 502b of the second color waveguide sheet body 502. Figure 21 takes the formation of the second filter layer 2013 on the second main surface 502b of the second color waveguide sheet body 502 as an example. The orthographic projection of the second filter layer 2013 on the second color waveguide sheet body 502 is between the orthographic projection of the in-coupling grating 102 located on the second color waveguide sheet body 502 on the second color waveguide sheet body 502 and the orthographic projection of the out-coupling grating 103 located on the second color waveguide sheet body 502 on the second color waveguide sheet body 502, and the second filter layer 2013 is configured to remove light of other colors in the second color waveguide sheet body 502 except the second color light.

[0135] For example, as shown in FIG21 , a coupling-in grating 102 and a coupling-out grating 103 are formed on the first main surface 502a of the second color waveguide body 502 by a nanoimprinting method, a protective layer 512 is formed on the first main surface 502a having the coupling-in grating 102 and the coupling-out grating 103, a second color intercepting layer 2014 is formed on the second main surface 502b of the second color waveguide body 502, and then a second filter layer 2013 is formed. That is, after the second filter layer 2013 is formed on the second main surface 502b of the second color waveguide body 502 and before the protective layer 512 is removed, the method further includes: forming a second color intercepting layer 2014 on the second main surface 502a of the second color waveguide body 502 and spaced from the second filter layer 2013.

[0136] For example, in another embodiment, the steps may be as follows: forming the in-coupling grating 102 and the out-coupling grating 103 on the first main surface 502a of the second color waveguide sheet body 502 by a nanoimprint method; forming the second filter layer 2013 on the first main surface 502a having the in-coupling grating 102 and the out-coupling grating 103; forming the protective layer 512 on the first main surface 502a having the in-coupling grating 102, the out-coupling grating 103, and the second filter layer 2013; and then forming the second color intercepting layer 2014 on the second main surface 502b of the second color waveguide sheet body 502, wherein the orthographic projection of the second color intercepting layer 2014 on the second color waveguide sheet body 502 overlaps with the orthographic projection of the in-coupling grating 102 located on the second color waveguide sheet body 502 on the second color waveguide sheet body 502; and finally, removing the protective layer 512 to form the second color waveguide sheet.

[0137] For example, as shown in Figure 21, in the process of forming the coupling-in grating 102 and the coupling-out grating 103 on the first main surface 502a of the second color waveguide sheet body 502 by the nanoimprint method, it also includes forming the folding grating 104 on the first main surface 502a of the second color waveguide sheet body 502 by the nanoimprint method. The folding grating 104 is located between the coupling-in grating 102 and the coupling-out grating 103. The folding grating 104 is configured to receive the light beam transmitted from the coupling-in grating 102 located on the same layer as the folding grating 104 and perform pupil expansion transmission.

[0138] For example, as shown in FIG22 , the preparation method of the third color waveguide sheet body 503 includes: forming the in-coupling grating 102 and the out-coupling grating 103 on the first main surface 503 a of the third color waveguide sheet body 503 by nanoimprinting.

[0139] For example, the process of forming the coupling-in grating 102 and the coupling-out grating 103 on the first main surface 503a of the third color waveguide body 503 by the nanoimprint method further includes: forming the folding grating 104 located between the coupling-in grating 102 and the coupling-out grating 103 by the nanoimprint method.

[0140] For example, Figures 23 to 25 are process diagrams of another method for preparing an optical waveguide structure provided by at least one embodiment of the present disclosure. Figures 23, 24 and 25 respectively show the process diagrams of preparing the first color waveguide sheet, the second color waveguide sheet and the third color waveguide sheet.

[0141] For example, as shown in FIG23 , a first color intercepting layer 1014 is formed on the second main surface 501 b of the first color waveguide sheet body 501, and then a first filter layer 1013 is formed. A protective layer 512 is formed on the second main surface 501 b having the first filter layer 1013 and the first color intercepting layer 1014. The sheet is then flipped over, and a coupling-in grating 102 and a coupling-out grating 103 are formed on the first main surface 501 a of the first color waveguide sheet body 501 using a nanoimprint method. The protective layer 512 is removed to form the first color waveguide sheet.

[0142] For example, as shown in FIG24 , a second color intercepting layer 2014 is formed on the second main surface 502b of the second color waveguide sheet body 502, and then a second filter layer 2013 is formed. A protective layer 512 is formed on the second main surface 502b having the second filter layer 2013 and the second color intercepting layer 2014. The sheet is then flipped over, and an in-coupling grating 102 and an out-coupling grating 103 are formed on the first main surface 502a of the second color waveguide sheet body 502 using a nanoimprint method. The protective layer 512 is removed to form the second color waveguide sheet.

[0143] For example, as shown in FIG25 , the preparation method of the third color waveguide sheet body 503 includes: forming the coupling-in grating 102 and the coupling-out grating 103 on the first main surface 503 a of the third color waveguide sheet body 503 by nanoimprinting.

[0144] The optical waveguide structure, preparation method thereof, and display device provided in at least one embodiment of the present disclosure have at least the following beneficial technical effects: the optical waveguide structure provided in at least one embodiment of the present disclosure can significantly improve the dispersion problem existing in color display by providing a first filter layer on the first main surface or the second main surface of the first color waveguide plate, thereby making the optical module formed thereby have excellent color effects.

[0145] There are a few points to note:

[0146] (1) The drawings of the embodiments of the present disclosure only relate to the structures related to the embodiments of the present disclosure. Other structures may refer to conventional designs.

[0147] (2) For the sake of clarity, in the drawings used to describe the embodiments of the present disclosure, the thickness of layers or regions is exaggerated or reduced, that is, these drawings are not drawn according to the actual scale.

[0148] (3) In the absence of conflict, the embodiments of the present disclosure and the features therein may be combined with each other to form new embodiments.

[0149] The above description is only a specific embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto. The protection scope of the present disclosure shall be based on the protection scope of the claims.

Claims

1. An optical waveguide structure, comprising: A plurality of waveguide plates arranged in a stacked manner, wherein the plurality of waveguide plates include a first color waveguide plate arranged adjacent to the display, and a second color waveguide plate arranged adjacent to the first color waveguide plate, and each of the waveguide plates includes a first main surface and a second main surface opposite to each other; An in-coupling grating and an out-coupling grating are arranged on the first main surface of each of the waveguide plates, wherein the in-coupling grating is configured to couple a light beam incident thereon into the waveguide plate, and the out-coupling grating is configured to couple a light beam transmitted thereon out of the waveguide plate; A first filter layer is arranged on the first main surface or the second main surface of the first color waveguide plate, and the orthographic projection of the first filter layer on the first color waveguide plate is between the orthographic projection of the coupling-in grating located on the first color waveguide plate on the first color waveguide plate and the orthographic projection of the coupling-out grating located on the first color waveguide plate on the first color waveguide plate, and the first filter layer is configured to remove light of other colors in the first color waveguide plate except the first color light.

2. The optical waveguide structure according to claim 1, wherein: A first color interception layer is disposed on the second major surface of the first color waveguide plate, the orthographic projection of the first color interception layer on the first color waveguide plate and the orthographic projection of the first filter layer on the first color waveguide plate do not overlap, and the first color interception layer is configured to intercept the first color light in the first color waveguide plate.

3. The optical waveguide structure according to claim 2, wherein: An orthographic projection of the first color trapping layer on the first color waveguide plate overlaps with an orthographic projection of the incoupling grating located on the first color waveguide plate on the first color waveguide plate.

4. The optical waveguide structure according to claim 3, wherein: The first color intercepting layer is further configured to transmit light rays of other colors except the first color light rays incident from the incoupling grating into the first color waveguide plate to the second color waveguide plate.

5. The optical waveguide structure according to any one of claims 1 to 4, wherein: A second filter layer is arranged on the first main surface or the second main surface of the second color waveguide plate, the orthographic projection of the second filter layer on the second color waveguide plate is between the orthographic projection of the coupling-in grating located on the second color waveguide plate on the second color waveguide plate and the orthographic projection of the coupling-out grating located on the second color waveguide plate on the second color waveguide plate, and the second filter layer is configured to remove light of other colors in the second color waveguide plate except the second color light.

6. The optical waveguide structure according to claim 5, wherein: A second color interception layer is disposed on the second major surface of the second color waveguide plate, an orthographic projection of the second color interception layer on the second color waveguide plate overlaps with an orthographic projection of the coupling-in grating located on the second color waveguide plate on the second color waveguide plate, and the second color interception layer is configured to intercept the second color light in the second color waveguide plate.

7. The optical waveguide structure according to claim 6, wherein: The plurality of waveguide plates further include a third color waveguide plate disposed adjacent to the second color waveguide plate; The second color intercepting layer is further configured to transmit light rays of other colors except the second color light rays incident from the incoupling grating into the second color waveguide plate to the third color waveguide plate.

8. The optical waveguide structure according to claim 7, wherein: A folding grating is also arranged on the first main surface of each of the waveguide plates, and in each of the waveguide plates, the folding grating is located between the coupling-in grating and the out-coupling grating, and the folding grating is configured to receive a light beam incoming from the coupling-in grating located at the same layer as the folding grating and perform pupil expansion transmission.

9. The optical waveguide structure according to claim 8, wherein: The orthographic projection of the first filter layer on the first color waveguide plate is between the orthographic projection of the folding grating on the first color waveguide plate and the orthographic projection of the coupling-in grating on the first color waveguide plate, or between the orthographic projection of the folding grating on the first color waveguide plate and the orthographic projection of the coupling-out grating on the first color waveguide plate, or the orthographic projection of the first filter layer on the first color waveguide plate and the orthographic projection of the folding grating on the first color waveguide plate overlap.

10. The optical waveguide structure according to claim 8, wherein: The orthographic projection of the second filter layer on the second color waveguide plate is between the orthographic projection of the folding grating on the second color waveguide plate and the orthographic projection of the coupling-in grating on the second color waveguide plate, or between the orthographic projection of the folding grating on the second color waveguide plate and the orthographic projection of the coupling-out grating on the second color waveguide plate, or the orthographic projection of the second filter layer on the second color waveguide plate and the orthographic projection of the folding grating on the second color waveguide plate overlap.

11. The optical waveguide structure according to any one of claims 6 to 10, wherein: A third color light is transmitted in the third color waveguide sheet, and the first color waveguide sheet is a blue waveguide sheet, the second color waveguide sheet is a green waveguide sheet, and the third color waveguide sheet is a red waveguide sheet. Correspondingly, the first color light is a blue light, the second color light is a green light, and the third color light is a red light; or, The third color light is transmitted in the third color waveguide sheet, and the first color waveguide sheet is a red waveguide sheet, the second color waveguide sheet is a blue waveguide sheet, and the third color waveguide sheet is a green waveguide sheet. Correspondingly, the first color light is a red light, the second color light is a blue light, and the third color light is a green light; or, The third color light is transmitted in the third color waveguide plate, and the first color waveguide plate is a red waveguide plate, the second color waveguide plate is a green waveguide plate, and the third color waveguide plate is a blue waveguide plate. Correspondingly, the first color light is red light, the second color light is green light, and the third color light is blue light.

12. The optical waveguide structure according to claim 4, wherein: The first color waveguide plate is a cyan waveguide plate, and the second color waveguide plate is a red waveguide plate. Correspondingly, the first color light is a mixture of green light and blue light, and the light of other colors except the first color light is red light.

13. The optical waveguide structure according to claim 4, wherein: The first color waveguide plate is a blue-green waveguide plate, and the second color waveguide plate is a red-green waveguide plate. Correspondingly, the first color light is a blue light, and the light of other colors except the first color light is a mixture of red light and green light.

14. The optical waveguide structure according to any one of claims 1 to 13, wherein: The first filter layer includes a single-layer filter film, a filter grating structure or a Bragg reflector.

15. The optical waveguide structure according to any one of claims 1 to 13, wherein: The coupling-in grating comprises a transmissive-reflective coupling-in grating, so that the coupling-in grating couples the light beam incident thereon into the waveguide plate in the form of transmission and reflection.

16. The optical waveguide structure according to any one of claims 8 to 10, wherein: The coupling-in grating, the folding grating and the coupling-out grating respectively include a one-dimensional rectangular wire grating, a one-dimensional blazed wire grating, a one-dimensional inclined wire grating or a two-dimensional metasurface array.

17. The optical waveguide structure according to claim 1, further comprising a third color waveguide sheet disposed on a side of the second color waveguide sheet away from the first color waveguide sheet, wherein: A folding grating is also provided on the first main surface of each of the waveguide sheets, and in each of the waveguide sheets, the folding grating is located between the coupling-in grating and the coupling-out grating, and the folding grating is configured to receive a light beam transmitted from the coupling-in grating located at the same layer as the folding grating and perform pupil expansion transmission; A first filter layer is disposed on the first main surface of the first color waveguide plate, and the first filter layer is between the coupling grating and the folding grating located on the first color waveguide plate; A second filter layer is disposed on the first main surface of the second color waveguide plate, and the second filter layer is between the coupling grating and the folding grating on the second color waveguide plate; A third filter layer is disposed on the first major surface of the third color waveguide plate, and the third filter layer is between the coupling-in grating and the folding grating on the third color waveguide plate.

18. The optical waveguide structure according to claim 17, further comprising a first color filter film disposed between the first color waveguide plate and the second color waveguide plate, wherein: The first color filter film includes a first color filter film body and a first color filter film arranged on the first color filter film body, and the orthographic projection of the first color filter film on the first color waveguide plate and the orthographic projection of the coupling grating on the first color waveguide plate on the first color waveguide plate overlap.

19. A display device comprising the optical waveguide structure according to any one of claims 1 to 18.

20. The display device according to claim 19, further comprising a projection structure, wherein: The projection structure comprises the display and a collimating component, wherein the display is used to emit a light beam having image information, and the collimating component is used to collimate the light beam emitted by the display to form parallel light coupled into the optical waveguide structure.

21. A method for preparing an optical waveguide structure, comprising: Providing a plurality of waveguide sheet bodies stacked in layers, wherein the plurality of waveguide sheet bodies include a first color waveguide sheet body disposed adjacent to the display, and a second color waveguide sheet body disposed adjacent to the first color waveguide sheet body, each of the waveguide sheet bodies including a first main surface and a second main surface opposite to each other; forming an in-coupling grating and an out-coupling grating on the first main surface of each of the waveguide sheet bodies; A first filter layer is formed on the first main surface or the second main surface of the first color waveguide sheet body, wherein the orthographic projection of the first filter layer on the first color waveguide sheet body is between the orthographic projection of the coupling-in grating located on the first color waveguide sheet body on the first color waveguide sheet body and the orthographic projection of the coupling-out grating located on the first color waveguide sheet body on the first color waveguide sheet body, and the first filter layer is configured to remove light of other colors except the first color light in the first color waveguide sheet body.

22. The preparation method according to claim 21, wherein The coupling-in grating and the coupling-out grating are formed on the first main surface of the first color waveguide sheet body by a nanoimprinting method, a protective layer is formed on the first main surface having the coupling-in grating and the coupling-out grating, and the first filter layer is formed on the second main surface of the first color waveguide sheet body, or forming the first filter layer, forming a protective layer on the second main surface having the first filter layer, and forming the coupling-in grating and the coupling-out grating on the first main surface of the first color waveguide body by a nano-imprinting method; The protective layer is removed to form a first color waveguide plate.

23. The preparation method according to claim 22, wherein: After forming the first filter layer on the second main surface of the first color waveguide sheet body and before removing the protective layer, or, forming the first filter layer on the second main surface of the first color waveguide sheet body and before forming the protective layer on the second main surface having the first filter layer, it also includes: forming a first color retention layer on the second main surface of the first color waveguide sheet body and spaced apart from the first filter layer.

24. The preparation method according to claim 21, wherein Forming the coupling-in grating and the coupling-out grating on the first main surface of the first color waveguide sheet body by a nano-imprinting method; forming the first filter layer on the first main surface having the coupling-in grating and the coupling-out grating; A protective layer is formed on the first major surface having the in-coupling grating, the out-coupling grating and the first filter layer.

25. The preparation method according to claim 24, further comprising: forming a first color interception layer on the second main surface of the first color waveguide sheet body, wherein an orthographic projection of the first color interception layer on the first color waveguide sheet body overlaps with an orthographic projection of the coupling-in grating located on the first color waveguide sheet body on the first color waveguide sheet body; The protective layer is removed to form a first color waveguide plate.

26. The preparation method according to claim 22 or 24, wherein: In the process of forming the coupling-in grating and the coupling-out grating on the first main surface of the first color waveguide sheet body by the nanoimprint method, it also includes forming a folding grating on the first main surface of the first color waveguide sheet body by the nanoimprint method, the folding grating is located between the coupling-in grating and the coupling-out grating, and the folding grating is configured to receive a light beam transmitted from the coupling-in grating located on the same layer as the folding grating and perform pupil expansion transmission.

27. The preparation method according to claim 26, further comprising: forming the coupling-in grating and the coupling-out grating on the first main surface of the second color waveguide sheet body; A second filter layer is formed on the first main surface or the second main surface of the second color waveguide sheet body, wherein the orthographic projection of the second filter layer on the second color waveguide sheet body is between the orthographic projection of the coupling-in grating located on the second color waveguide sheet body on the second color waveguide sheet body and the orthographic projection of the coupling-out grating located on the second color waveguide sheet body on the second color waveguide sheet body, and the second filter layer is configured to remove light of other colors except the second color light in the second color waveguide sheet body.

28. The preparation method according to claim 27, wherein The coupling-in grating and the coupling-out grating are formed on the first main surface of the second color waveguide sheet body by a nanoimprint method, a protective layer is formed on the first main surface having the coupling-in grating and the coupling-out grating, and a second filter layer is formed on the second main surface of the second color waveguide sheet body; or, the second filter layer is formed on the second main surface of the second color waveguide sheet body, a protective layer is formed on the second main surface having the second filter layer, and the coupling-in grating and the coupling-out grating are formed on the first main surface of the second color waveguide sheet body by a nanoimprint method; The protective layer is removed to form a second color waveguide plate.

29. The preparation method according to claim 28, wherein After forming the second filter layer on the second main surface of the second color waveguide sheet body and before removing the protective layer, or, forming the second filter layer on the second main surface of the second color waveguide sheet body and before forming the protective layer on the second main surface having the second filter layer, it also includes: forming a second color retention layer on the second main surface of the second color waveguide sheet body and spaced apart from the second filter layer.

30. The preparation method according to claim 27, wherein: Forming the coupling-in grating and the coupling-out grating on the first main surface of the second color waveguide sheet body by a nano-imprinting method; forming the second filter layer on the first main surface having the coupling-in grating and the coupling-out grating; A protective layer is formed on the first major surface having the in-coupling grating, the out-coupling grating and the second filter layer.

31. The preparation method according to claim 30, further comprising: forming a second color interception layer on the second main surface of the second color waveguide sheet body, wherein an orthographic projection of the second color interception layer on the second color waveguide sheet body overlaps with an orthographic projection of the coupling-in grating located on the second color waveguide sheet body on the second color waveguide sheet body; The protective layer is removed to form a second color waveguide plate.

32. The preparation method according to claim 28 or 30, wherein: In the process of forming the coupling-in grating and the coupling-out grating on the first main surface of the second color waveguide sheet body by the nanoimprint method, it also includes forming a folding grating on the first main surface of the second color waveguide sheet body by the nanoimprint method, the folding grating is located between the coupling-in grating and the coupling-out grating, and the folding grating is configured to receive a light beam transmitted from the coupling-in grating located on the same layer as the folding grating and perform pupil expansion transmission.

33. The preparation method according to claim 21, wherein The plurality of waveguide plates further include a third color waveguide plate body disposed adjacent to the second color waveguide plate body, and the preparation method further includes: forming the coupling-in grating and the coupling-out grating on the first main surface of the third color waveguide plate body by a nanoimprinting method.

34. The preparation method according to claim 33, wherein: The process of forming an in-coupling grating and an out-coupling grating on the first main surface of the third color waveguide sheet body by nanoimprinting also includes: forming a folding grating located between the in-coupling grating and the out-coupling grating by nanoimprinting.

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