Waveguide plate, optical waveguide structure, preparation method of optical waveguide structure and display device

Abstract

A waveguide sheet (100) and a preparation method thereof, an optical waveguide structure (200) and a preparation method thereof, and a display device (300), the waveguide sheet (100) comprising an optical waveguide body (101), the optical waveguide body (101) comprising a first main surface (101a) and a second main surface (101b) arranged opposite to each other, the first main surface (101a) being provided with a coupling-in grating (102) and a coupling-out grating (103), the second main surface (101b) being provided with a coupling-out grating (103), and the coupling-out grating (103) being provided with a coupling-in grating (102) and a coupling-out grating (103). And a polarization structure (104) disposed between the in-coupling grating (102) and the out-coupling grating (103); the coupling-in grating (102) is configured to couple a light beam into the optical waveguide body (101); the polarization structure (104) is configured to reflect light with a first polarization state included in the light beam, and enable the light with the first polarization state to be propagated in the optical waveguide body (101) in a total reflection mode; the coupling-out grating (103) is configured to couple the first color light transmitted to the coupling-out grating (103) out of the optical waveguide body (101), and the waveguide sheet (100) reflects the light with the first polarization state included in the light beam through the polarization structure (104) and makes the light with the first polarization state propagate in the optical waveguide body (101) in a total reflection mode. Therefore, the multilayer waveguide sheets (100) are arranged in a laminated manner, so that the problem of color cast caused by the response of the optical waveguide to the full wave band of visible light can be solved.

Description

Waveguide sheet, optical waveguide structure, preparation method thereof, and display device Technical Field

[0001] Embodiments of the present disclosure relate to a waveguide sheet and a method for manufacturing the same, an optical waveguide structure and 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 a waveguide plate and a method for manufacturing the same, an optical waveguide structure and a method for manufacturing the same, and a display device. The waveguide plate includes a polarization structure arranged between an in-coupling grating and an out-coupling grating. The polarization structure can reflect light with a first polarization state included in a light beam and cause the light with the first polarization state to propagate within the optical waveguide body by total reflection. Thus, stacking multiple layers of the above-mentioned waveguide plates can solve the problem of color deviation caused by the optical waveguide's response to the full band of visible light.

[0006] At least one embodiment of the present disclosure provides a waveguide sheet, which includes an optical waveguide body, wherein the optical waveguide body includes a first main surface and a second main surface arranged opposite to each other, and an in-coupling grating and an out-coupling grating are arranged on the first main surface, and a polarization structure is arranged between the in-coupling grating and the out-coupling grating; the in-coupling grating is configured to couple a light beam into the optical waveguide body; the polarization structure is configured to reflect light with a first polarization state included in the light beam and cause the light with the first polarization state to propagate in the optical waveguide body by total internal reflection; and the out-coupling grating is configured to couple the first color light transmitted to the out-coupling grating out of the optical waveguide body.

[0007] For example, the waveguide provided in at least one embodiment of the present disclosure further includes a folding grating arranged on the first main surface, wherein the folding grating is arranged between the coupling-in grating and the coupling-out grating, and the folding grating is configured to receive the light of the first polarization state transmitted from the coupling-in grating and perform pupil expansion transmission.

[0008] For example, in the waveguide plate provided in at least one embodiment of the present disclosure, the refractive index of the polarization structure is smaller than the refractive index of the optical waveguide body.

[0009] For example, in the waveguide provided in at least one embodiment of the present disclosure, the polarization structure includes at least one of a metal wire grid polarizer, a chemical reflective polarizer, and a metasurface structure.

[0010] For example, the waveguide plate provided in at least one embodiment of the present disclosure further includes a half-wave plate disposed on the first major surface or the second major surface of the optical waveguide body, wherein the orthographic projection of at least a portion of the half-wave plate on the optical waveguide body is located between the orthographic projection of the polarization structure on the optical waveguide body and the orthographic projection of the coupling grating on the optical waveguide body, the light beam first passes through the half-wave plate and then passes through the polarization structure, the half-wave plate is configured to deflect light in the first polarization state, and the reflectivity of the light in the first polarization state is greater than 90%.

[0011] For example, in the waveguide provided in at least one embodiment of the present disclosure, the coupling-in grating, the folding grating, and the coupling-out grating are all one-dimensional gratings, or are all two-dimensional gratings.

[0012] For example, in the waveguide provided in at least one embodiment of the present disclosure, the one-dimensional grating includes at least one of a one-dimensional rectangular wire grating, a one-dimensional blazed wire grating, and a one-dimensional tilted wire grating; the two-dimensional grating includes a two-dimensional metasurface array.

[0013] For example, in the waveguide 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 into the waveguide in both transmission and reflection forms.

[0014] For example, in the waveguide plate provided in at least one embodiment of the present disclosure, an extension direction of the grating lines of the in-coupling grating and an extension direction of the grating lines of the out-coupling grating intersect.

[0015] At least one embodiment of the present disclosure further provides an optical waveguide structure, which includes multiple layers of waveguide plates as described in any of the above embodiments, and the multiple layers of waveguide plates are stacked, and two adjacent layers of the waveguide plates are connected by sealing glue so that the multiple layers of waveguide plates form a whole.

[0016] For example, the optical waveguide structure provided by at least one embodiment of the present disclosure further includes a cover plate arranged on the outermost side of the multi-layered waveguide sheets, wherein the cover plate is a glass cover plate or a transparent resin cover plate.

[0017] At least one embodiment of the present disclosure further provides a display device, comprising the optical waveguide structure described in any of the above embodiments.

[0018] For example, the display device provided in at least one embodiment of the present disclosure further includes a projection structure, wherein the projection structure includes a display, and the display is used to emit a light beam having image information.

[0019] At least one embodiment of the present disclosure further provides a method for preparing a waveguide sheet, comprising: providing an optical waveguide body, wherein the optical waveguide body includes a first main surface and a second main surface arranged opposite to each other; forming an in-coupling grating, a polarization structure, and an out-coupling grating on the first main surface, wherein the polarization structure is between the in-coupling grating and the out-coupling grating.

[0020] For example, the preparation method provided by at least one embodiment of the present disclosure further includes: forming a folding grating on the first main surface, wherein the folding grating is between the coupling-in grating and the coupling-out grating, and the folding grating is configured to receive the light of the first polarization state transmitted from the coupling-in grating and perform pupil expansion transmission.

[0021] For example, the preparation method provided by at least one embodiment of the present disclosure further includes: forming a half-wave plate on the first main surface or the second main surface of the optical waveguide body, wherein the light beam first passes through the half-wave plate and then passes through the polarization structure, and the half-wave plate is configured to deflect the light of the first polarization state, and the reflectivity of the light of the first polarization state is greater than 90%.

[0022] For example, in the preparation method provided in at least one embodiment of the present disclosure, the polarization structure is a metal wire grid polarizer, and the coupling-in grating, the metal wire grid polarizer, the folding grating and the coupling-out grating are formed by nanoimprinting.

[0023] At least one embodiment of the present disclosure further provides a method for preparing an optical waveguide structure, comprising: providing a plurality of waveguide sheets as described in any of the above embodiments; stacking the plurality of waveguide sheets; and connecting two adjacent waveguide sheets with a sealing adhesive so that the plurality of waveguide sheets are integrated. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] 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.

[0025] FIG1 is a schematic diagram of a planar structure of a waveguide provided by at least one embodiment of the present disclosure;

[0026] FIG2 is a schematic diagram of a cross-sectional structure of a waveguide provided by at least one embodiment of the present disclosure;

[0027] FIG3 is a schematic diagram of a planar structure of another waveguide provided by at least one embodiment of the present disclosure;

[0028] FIG4 is a schematic diagram of a planar structure of another waveguide provided by at least one embodiment of the present disclosure;

[0029] FIG5 is a schematic diagram of a planar structure of another waveguide provided by at least one embodiment of the present disclosure;

[0030] FIG6 is a schematic diagram of a cross-sectional structure of another waveguide provided by at least one embodiment of the present disclosure;

[0031] FIG7 is a schematic diagram of the optical paths of light of various colors passing through a half-wave plate and a polarization structure according to at least one embodiment of the present disclosure;

[0032] FIG8 is a schematic diagram of a cross-sectional structure of another waveguide provided by at least one embodiment of the present disclosure;

[0033] FIG9 is a schematic diagram of a cross-sectional structure of another waveguide provided by at least one embodiment of the present disclosure;

[0034] FIG10 is a schematic diagram of a cross-sectional structure of another waveguide provided by at least one embodiment of the present disclosure;

[0035] FIG11 is a schematic diagram of a cross-sectional structure of another waveguide provided by at least one embodiment of the present disclosure;

[0036] FIG12 is a schematic diagram of a cross-sectional structure of another waveguide provided by at least one embodiment of the present disclosure;

[0037] FIG13 is a schematic diagram of a cross-sectional structure of another waveguide provided by at least one embodiment of the present disclosure;

[0038] FIG14 is a schematic diagram of a cross-sectional structure of another waveguide provided by at least one embodiment of the present disclosure;

[0039] FIG15 is a schematic diagram of a three-dimensional structure of an optical waveguide body and an in-coupling grating provided in at least one embodiment of the present disclosure;

[0040] FIG16 is a schematic cross-sectional view of an optical waveguide structure provided by at least one embodiment of the present disclosure;

[0041] FIG17 is a schematic diagram of a light path propagating in an optical waveguide structure provided by at least one embodiment of the present disclosure;

[0042] FIG18 is a schematic diagram of another light path propagating in an optical waveguide structure provided by at least one embodiment of the present disclosure;

[0043] FIG19 is a schematic diagram of another light path propagating in an optical waveguide structure provided by at least one embodiment of the present disclosure;

[0044] FIG20 is a schematic diagram of another light path propagating in an optical waveguide structure provided by at least one embodiment of the present disclosure;

[0045] FIG21 is a block diagram of a display device provided by at least one embodiment of the present disclosure;

[0046] FIG22 is a schematic cross-sectional view of a display device according to at least one embodiment of the present disclosure;

[0047] FIG23 is a flow chart of a method for preparing a waveguide according to at least one embodiment of the present disclosure;

[0048] FIG24 is a flow chart of a method for preparing a waveguide according to at least one embodiment of the present disclosure;

[0049] FIG25 is a flow chart of another method for preparing a waveguide according to at least one embodiment of the present disclosure;

[0050] FIG26 is a process diagram of a method for preparing a waveguide sheet according to at least one embodiment of the present disclosure; and

[0051] FIG27 is a flow chart of a method for preparing an optical waveguide structure provided by at least one embodiment of the present disclosure. DETAILED DESCRIPTION

[0052] 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.

[0053] 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.

[0054] 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 which 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. "Same-layer arrangement" in the embodiments of the present invention refers to the relationship between multiple film 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 film layers is the same or the height of multiple film layers in the cross-sectional view is the same.

[0055] Since the concept of the "metaverse" was proposed, augmented reality (AR) technology has also received more attention. A large number of technology companies have increased their research and development efforts, hoping to develop related products for consumer applications as soon as possible. Currently, the most popular AR field is AR glasses. AR glasses are predicted to become the "third screen" for humans and can be applied in military, education, medical and industrial fields, with very broad development prospects. The implementation methods of AR include geometric optics and diffraction optics. Among the diffraction optics solutions, the surface relief grating (SRG) diffraction waveguide has attracted much attention because it is more suitable for mass production.

[0056] Due to the diffraction optical properties of the surface relief grating (SRG), the grating responds to the entire visible light band (380nm to 780nm). The total reflection angle and step size of light in the waveguide are related to the wavelength of the light. Therefore, for a waveguide with a single wavelength, the different light output of the three colors of red light (R), green light (G), and blue light (B) will cause color deviation. Therefore, it is currently very difficult to achieve color AR display using a waveguide grating. The current mainstream method in the industry is to use two or three waveguides to superimpose to achieve color augmented reality display, so that one color or two colors correspond to one waveguide, but this requires preventing light of different wavelengths from propagating on non-corresponding waveguides.

[0057] The inventors of the present disclosure noted that by optimizing and improving the external optical machine, adjusting the position of the grating, or introducing a polarization grating, the characteristic of the surface relief grating (SRG) that responds to both transmitted polarized light and reflected polarized light can be utilized to avoid the propagation of light of different colors on their non-corresponding waveguides, thereby solving the problem of color deviation caused by the response of the optical waveguide structure to the full band of visible light in the architecture of the color augmented reality optical waveguide.

[0058] At least one embodiment of the present disclosure provides a waveguide plate and a method for manufacturing the same, an optical waveguide structure and a method for manufacturing the same, and a display device. The waveguide plate includes an optical waveguide body, wherein the optical waveguide body includes a first main surface and a second main surface arranged opposite to each other, and an in-coupling grating and an out-coupling grating are arranged on the first main surface, as well as a polarization structure arranged between the in-coupling grating and the out-coupling grating; the in-coupling grating is configured to couple a light beam into the optical waveguide body; the polarization structure is configured to reflect light with a first polarization state included in the light beam and cause the light with the first polarization state to propagate in the optical waveguide body by total reflection; the out-coupling grating is configured to couple the first color light transmitted to the out-coupling grating out of the optical waveguide body, and the waveguide plate includes a polarization structure arranged between the in-coupling grating and the out-coupling grating, wherein the polarization structure can reflect light with a first polarization state included in the light beam and cause the light with the first polarization state to propagate in the optical waveguide body by total reflection. Thus, stacking multiple layers of the above waveguide plates can solve the problem of color deviation caused by the optical waveguide structure's response to the full band of visible light.

[0059] For example, FIG1 is a schematic diagram of a planar structure of a waveguide sheet provided by at least one embodiment of the present disclosure, and FIG2 is a schematic diagram of a cross-sectional structure of a waveguide sheet provided by at least one embodiment of the present disclosure. In combination with FIG1 and FIG2, the waveguide sheet 100 includes an optical waveguide body 101, wherein the optical waveguide body 101 includes a first main surface 101a and a second main surface 101b arranged opposite to each other, and an in-coupling grating 102 and an out-coupling grating 103 are arranged on the first main surface 101a, and a coupling grating 102 and an out-coupling grating 103 are arranged on the coupling grating 102 and the out-coupling grating 103. The polarization structure 104 between the gratings 103, the coupling-in grating 102 is configured to couple the light beam into the optical waveguide body 101, the polarization structure 104 is configured to reflect the light with a first polarization state included in the light beam, and make the light of the first polarization state propagate in the optical waveguide body 101 by total reflection, and the coupling-out grating 103 is configured to couple the first color light transmitted to the coupling-out grating 103 out of the optical waveguide body 101, so that the light emitted from the waveguide plate 100 does not have color deviation.

[0060] For example, as shown in FIG1 , the waveguide plate 100 further includes a folding grating 105 disposed on the first major surface 101 a. The folding grating 105 is located between the coupling-in grating 102 and the outcoupling grating 103 in the propagation direction of the light beam, and the folding grating 105 is configured to receive light of the first polarization state transmitted from the coupling-in grating 102 and perform pupil expansion transmission.

[0061] For example, as shown in Figure 1, the out-coupling grating 103 and the polarization structure 104 both extend in the vertical direction, the in-coupling grating 102 extends in the horizontal direction, the extension direction of the grating lines of the in-coupling grating 102 intersects with the extension direction of the grating lines of the out-coupling grating 103, the folding grating 105 extends in the oblique direction, and the in-coupling grating 102, the polarization structure 104 and the folding grating 105 are arranged on the same vertical line.

[0062] 2 , the polarization structure 104 and the in-coupling grating 102 are disposed on the same side of the optical waveguide body 101 and are both disposed on the first major surface 101a of the optical waveguide body 101. Of course, the embodiments of the present disclosure are not limited thereto, and the polarization structure 104 and the in-coupling grating 102 may also be disposed on different sides of the optical waveguide body 101.

[0063] For example, the embodiments of the present disclosure optimize the layout of the waveguide sheet and use a high-refractive-index embossing adhesive to emboss a nanoscale structure on a glass with a high refractive index (as the optical waveguide body), and the glass with a high refractive index and the embossing adhesive have the same refractive index. For example, the waveguide sheet is composed of a variety of different waveguide gratings according to certain rules. The waveguide gratings have different heights, different periods, or different duty cycles, etc. According to their functions, the waveguide gratings mainly include the above-mentioned coupling-in gratings, folding gratings, and coupling-out gratings. In addition to the coupling-in gratings, folding gratings, and coupling-out gratings commonly included in optical waveguides, the embodiments of the present disclosure also introduce a polarization structure. The polarization structure can be a prepared polarization grating or a laminated film material with polarization function. The polarization structure can reflect light of a certain polarization state and absorb light of another polarization state, and the selection of the polarization structure is adjusted according to the polarization direction of the light emitted from the optical machine.

[0064] For example, the embodiments of the present disclosure simulate and optimize the coupling gratings of each waveguide. For the coupling grating of the waveguide that transmits blue light, its diffraction efficiency for the red light band is reduced. For the coupling grating of the waveguide that transmits red light, its diffraction efficiency for the blue light band is reduced. For the waveguide that transmits blue light, the waveguide that transmits red light, and the waveguide that transmits green light, the waveguide gratings are designed for their corresponding wavelengths. For example, the wavelength corresponding to the grating of the waveguide that transmits blue light is 450 nm, the wavelength corresponding to the grating of the waveguide that transmits green light is 532 nm, and the wavelength corresponding to the grating of the waveguide that transmits red light is 630 nm.

[0065] For example, the dimensions of the in-coupling grating, the folding grating, and the out-coupling grating can be designed as follows: the height of the in-coupling grating ranges from 150 nm to 350 nm, the heights of the folding grating and the out-coupling grating range from 40 nm to 140 nm, and the periods of the in-coupling grating, the folding grating, and the out-coupling grating range from 280 nm to 500 nm. The in-coupling grating, the folding grating, and the out-coupling grating can all take the form of a one-dimensional rectangular wire grating, a one-dimensional blazed grating, a one-dimensional tilted grating, or a two-dimensional metasurface array, and the embodiments of the present disclosure do not specifically limit this.

[0066] For example, in one example, referring to FIG. 1 , the refractive index of the polarization structure 104 is smaller than the refractive index of the optical waveguide body 101 , so that light can be totally reflected in the optical waveguide body 101 after passing through the polarization structure 104 .

[0067] For example, as shown in FIG1 , the polarization structure 104 includes at least one of a metal wire grid polarizer, a chemical reflective polarizer, and a metasurface structure. For example, when the polarization structure 104 is a metal wire grid polarizer, it can be formed directly on the waveguide. The material of the metal wire grid polarizer can be a single metal such as aluminum (Al), gold (Au), molybdenum (Mo), or silver (Ag). The metal wire grid polarizer has a height ranging from 100 nm to 300 nm, a width ranging from 50 nm to 100 nm, a period ranging from 100 nm to 300 nm, and a duty cycle ranging from 0.4 to 0.6. When the polarization structure 104 is a chemical reflective polarizer, it can be integrated by laminating the chemical reflective polarizer. The specific polarization direction in each waveguide depends on the specific solution. When the polarization structure 104 is a metasurface structure, the metasurface structure can be an array of cylinders with different heights and diameters, or a combination of gratings with different widths. The height ranges from 100 nm to 400 nm.

[0068] For example, in other examples, the polarization structure 104 may also be a laminated iodine-based polarizer, etc., which is not limited in the embodiments of the present disclosure.

[0069] For example, in one embodiment, the polarization structure 104 and the coupling grating 102 can be on the same side of the optical waveguide body 101, or on different sides of the optical waveguide body 101. When the polarization structure 104 is between the coupling grating 102 and the folding grating 105, the width of the polarization structure 104 must be greater than or equal to the width of the coupling grating 102 to ensure that all light passing through the coupling grating 102 can pass through the polarization structure 104.

[0070] For example, in one embodiment, the area of ​​the coupling-in grating 102 is 4 mm × 4 mm, and the width of the polarization structure 104 is greater than or equal to 4 mm. In the length direction, if the polarization structure 104 and the coupling-in grating 102 are on the same side of the optical waveguide body 101, the polarization structure 104 can be tangential to the coupling-in grating 102 and the deflection grating 105. When the polarization structure 104 and the coupling-in grating 102 are on different sides of the optical waveguide body 101, in order to avoid blocking the perpendicular light path entering the coupling-in grating 102, the polarization structure 104 can be at most tangential to the coupling-in grating 102. When the polarization structure 104 is between the deflection grating 105 and the outcoupling grating 103, the length of the polarization structure 104 is greater than or equal to the width of the deflection grating 105 or the outcoupling grating 103, ensuring that both the deflected light and the outcoupling light have passed through the polarization structure 104. The width of the polarization structure 104 can be calculated based on the minimum step length of light. Different waveguides can have different step lengths for different colors of light, so their polarization structure 104 widths can vary. However, this width must be greater than or equal to the step length to ensure that light of the target wavelength is received and not missed. For example, for a red waveguide with a thickness of 1 mm, the width of the polarization structure 104 must be greater than or equal to 8.4 mm.

[0071] For example, the outcoupling grating 103 can emit light of uniform intensity by designing the grating structure, such as the width, height, and duty cycle of the grating, so that the light emitted from the waveguide plate can be more uniform, thereby improving the quality of the display image.

[0072] For example, the optical waveguide body of the waveguide sheet is glass with a high refractive index, the material of the polarization structure is a glue with a high refractive index, and the refractive index of the optical waveguide body and the polarization structure of the waveguide sheet is the same. For example, the refractive index of the optical waveguide body and the polarization structure can both be 1.7, 1.8, 1.9 or 2.0, and the thickness of the optical waveguide body can be 0.5 mm, 0.7 mm or 1.0 mm. The embodiments of the present disclosure are not limited to this. The refractive index of the optical waveguide body and the polarization structure of the waveguide sheet can also be other values, and the thickness of the optical waveguide body can also be other values.

[0073] For example, Figure 3 is a schematic diagram of the planar structure of another waveguide plate provided by at least one embodiment of the present disclosure. As shown in Figure 3, the out-coupling grating 103 extends in the vertical direction, the in-coupling grating 102 and the polarization structure 104 both extend in the horizontal direction, the extension direction of the grating lines of the in-coupling grating 102 intersects with the extension direction of the grating lines of the out-coupling grating 103, the folding grating 105 extends in the oblique direction, and the in-coupling grating 102, the polarization structure 104 and the folding grating 105 are arranged on the same vertical line.

[0074] For example, Figure 4 is a schematic diagram of the planar structure of another waveguide plate provided by at least one embodiment of the present disclosure. As shown in Figure 4, the out-coupling grating 103 and the polarization structure 104 both extend in the vertical direction, the in-coupling grating 102 extends in the horizontal direction, the extension direction of the grating lines of the in-coupling grating 102 intersects with the extension direction of the grating lines of the out-coupling grating 103, the folding grating 105 extends in the oblique direction, and the out-coupling grating 103, the polarization structure 104 and the folding grating 105 are arranged on the same horizontal line.

[0075] For example, Figure 5 is a schematic diagram of the planar structure of another waveguide plate provided by at least one embodiment of the present disclosure. As shown in Figure 5, the out-coupling grating 103 extends in the vertical direction, the in-coupling grating 102 and the polarization structure 104 both extend in the horizontal direction, the extension direction of the grating lines of the in-coupling grating 102 intersects with the extension direction of the grating lines of the out-coupling grating 103, the folding grating 105 extends in the oblique direction, and the out-coupling grating 103, the polarization structure 104 and the folding grating 105 are arranged on the same horizontal line.

[0076] It should be noted that the cross-sectional structures corresponding to FIG. 3 , FIG. 4 and FIG. 5 can refer to the above description of FIG. 2 , which will not be repeated here.

[0077] For example, FIG6 is a schematic cross-sectional view of another waveguide plate according to at least one embodiment of the present disclosure. The waveguide plate 100 further includes a half-wave plate 106 disposed on the first principal surface 101a or the second principal surface 101b of the optical waveguide body 101. FIG6 illustrates an example of a case where the half-wave plate 106 is disposed on the second principal surface 101b of the optical waveguide body 101. As shown in FIG6 , a light beam first passes through the half-wave plate 106 and then through the polarization structure 104. The half-wave plate 106 is configured to deflect light of a first polarization state, and has a reflectivity greater than 90% for light of the first polarization state. In other words, the half-wave plate 106 can alter the polarization state of light of the first polarization state to allow light of a specific polarization state to pass through.

[0078] For example, when using the waveguide plate shown in FIG6 for light transmission, it is not necessary to ensure that the different colored lights generated by the display have different polarization directions; the red, green, and blue lights all have the same polarization characteristics. A half-wave plate 106 is disposed on the first principal surface 101a or the second principal surface 101b of the optical waveguide body 101. For example, the half-wave plate 106 is disposed on the second principal surface 101b of the optical waveguide body 101, and at least a portion of the orthographic projection of the half-wave plate 106 on the optical waveguide body 101 is located between the orthographic projection of the polarization structure 104 on the optical waveguide body 101 and the orthographic projection of the coupling grating 102 on the optical waveguide body 101. This wavelength-selective single-wavelength reflective half-wave plate 106 deflects the polarization direction of light of a specific wavelength while maintaining the polarization of light of other wavelengths.

[0079] It should be noted that the half-wave plate only needs to be placed before the polarization structure in the direction of light propagation. It can be placed on the same side of the optical waveguide body as the polarization grating, or on different sides. The size of the half-wave plate must be the same or approximately the same as the size of the polarization structure. The length of the half-wave plate in each waveguide plate must be greater than the maximum total internal reflection step length of the light emitted by the display.

[0080] For example, the half-wave plate can be prepared by depositing thin films, that is, a plurality of film layers with different refractive indices are continuously deposited, and the film layers can include film layers formed by inorganic materials such as Si, SiO, and Al, and the thickness of the film layers formed by the inorganic materials is less than 6um. The film layer can be a metasurface structure prepared by metal elements such as Al, Au, Ag, or non-metallic materials such as Si and SiO. The metasurface structure can be an array of cylinders with different heights and diameters, or a combination of gratings with different widths, and the height of the grating is between 100nm and 400nm. The metasurface structure can also be prepared by embossing using a high-refractive-index glue. For example, the refractive index of the high-refractive-index glue is greater than 1.5. The metasurface structure can be an array of cylinders with different heights and diameters, or a combination of gratings with different widths, and the height is between 100nm and 400nm. Alternatively, the half-wave plate 106 may be directly bonded to the first principal surface 101a or the second principal surface 101b of the optical waveguide body 101. The half-wave plate 106 must have the same refractive index as the optical waveguide body 101, and the combined thickness of the half-wave plate 106 and the optical waveguide body 101 must be less than 6 μm. This is sufficient as long as the half-wave plate 106 can deflect polarized light and has a reflectivity greater than 90%.

[0081] For example, FIG7 is a schematic diagram of the optical paths of various colored light rays passing through a half-wave plate and a polarization structure according to at least one embodiment of the present disclosure. As shown in FIG7 , the first, second, and third colored light rays are blue (B), green (G), and red (R), respectively, and the waveguide plate is a blue waveguide plate. For illustration, the collimated light rays R, G, and B emitted from the display pass through the coupling-in grating 102. Upon passing through the blue waveguide plate, only the blue light undergoes polarization conversion, changing its propagation direction from the first direction to the second direction. The propagation directions of the red and green light rays remain unchanged. Therefore, the blue light rays continue to propagate after being reflected by the polarization structure. The red and green light rays are absorbed by the polarization structure, and ultimately, only the blue light rays are coupled out by the coupling-out grating. The principles of the green and red waveguide plates are the same as those of the blue waveguide plate. Finally, the three colors of light combine to form a color pattern at the retina of the human eye.

[0082] For example, in addition to the polarization structure formed by the wire grid polarizer shown in Figure 2, the polarization structure can also take other forms. For example, Figure 8 is a schematic diagram of the cross-sectional structure of another waveguide provided in at least one embodiment of the present disclosure. As shown in Figure 8, a polarization structure 104 with a certain thickness can be formed by coating. The material of the polarization structure 104 can include a metal material or a multi-layer organic optical film layer.

[0083] For example, Figure 9 is a schematic diagram of the cross-sectional structure of another waveguide provided by at least one embodiment of the present disclosure. As shown in Figure 9, the wire grid polarizer can also be directly prepared on the glass substrate and then thinned. In order to ensure the lightness and thinness of the final device, the thickness of the wire grid polarizer can be thinned to 0.1 mm, and then the polarization grating and the waveguide are bonded using a glue material with the same refractive index as that of the glass substrate and a transmittance greater than 90%. The thickness of the glue material is as thin as possible, for example, less than 100 nm.

[0084] For example, FIG10 is a schematic diagram of the cross-sectional structure of another waveguide provided in at least one embodiment of the present disclosure. As shown in FIG10 , a polarization structure 104 is formed by laminating a chemically reflective polarizer. The polarization direction of the polarization structure 104 in each waveguide depends on the specific solution. The chemically reflective polarizer can be a laminated structure of a reflective polarizing film and a high-refractive-index viscosity layer.

[0085] For example, Figure 11 is a schematic diagram of the cross-sectional structure of another waveguide provided in at least one embodiment of the present disclosure. As shown in Figure 11, for example, a metasurface structure and polarization grating are integrally imprinted using a high-refractive-index adhesive. For example, the metasurface structure can be an array of cylinders of varying heights and diameters, or a combination of gratings of varying widths, with a height ranging from 100 nm to 400 nm. In Figure 11, the polarization structure 104 is on the same side as the in-coupling grating 102 and the out-coupling grating 103.

[0086] For example, Figure 12 is a schematic diagram of the cross-sectional structure of another waveguide provided in at least one embodiment of the present disclosure. As shown in Figure 12, the polarization structure 104 and the coupling-in grating 102 and the coupling-out grating 103 are on different sides, and the polarization structure 104 can also be a metasurface structure.

[0087] For example, FIG13 is a schematic diagram of the cross-sectional structure of another waveguide provided in at least one embodiment of the present disclosure. As shown in FIG13 , the polarization structure 104, the coupling grating 102, and the turning grating 105 are located on different sides, and the polarization structure 104 is located between the coupling grating 102 and the turning grating 105. The width of the polarization structure 104 is greater than or equal to the width of the coupling grating 102 to ensure that all light emitted from the coupling grating 102 can pass through the polarization structure 104. The coupling grating 102 occupies an area of ​​4 mm × 4 mm, and the width of the polarization structure 104 is greater than or equal to 4 mm. To avoid blocking the vertical optical path of the light emitted from the coupling grating 102, the polarization structure 104 is at most tangent to the coupling grating 102. Since light propagates within the waveguide, there is no restriction on the turning grating 105.

[0088] For example, FIG14 is a schematic diagram of the cross-sectional structure of another waveguide provided in at least one embodiment of the present disclosure. As shown in FIG14 , the polarization structure 104, the in-coupling grating 102, and the folding grating 105 are on the same side, and the polarization structure 104 is located between the in-coupling grating 102 and the folding grating 105. The polarization structure 104 is tangent to the in-coupling grating 102 and the folding grating 105. The length of the polarization structure 104 is greater than or equal to the width of the folding grating 105 or the out-coupling grating 103, ensuring that light emitted from the folding grating 105 has passed through the polarization structure 104. The width of the polarization structure can be calculated based on the minimum step size of the emitted light. For different waveguides, the width of the polarization structure can be different because the step sizes of the corresponding colors of light are different. However, the width must be greater than or equal to one step size to ensure that light of the target wavelength is received and not missed. For example, for a red waveguide with a waveguide thickness of 1 mm, the width of the polarization structure must be greater than or equal to 8.4 mm.

[0089] For example, as shown in Figures 1 to 14, the coupling-in grating 102, the deflection grating 105, and the coupling-out grating 103 are all surface gratings or volume gratings. Surface gratings are gratings formed directly on the surface of the optical waveguide body 101 and can include, for example, diffractive optical elements (DOEs) such as binary phase gratings and blazed gratings. The multiple grating patterns of the diffractive optical element act as diffraction gratings to diffract incident light. For example, based on the size, height, period, duty cycle, shape, etc. of the grating pattern, the incident light is diffracted within a specific angular range, causing extinction and constructive interference, thereby changing the propagation direction of the incident light. Volume gratings can be formed separately from the optical waveguide body 101 and can include, for example, holographic optical elements (HOEs), geometric phase gratings, Bragg polarization gratings, holographically formed polymer dispersed liquid crystals (H-PDLCs), etc. Volume gratings can include periodic fine patterns of materials with different refractive indices.

[0090] For example, the coupling-in grating 102, the folding grating 105, and the coupling-out grating 103 are all one-dimensional gratings, or are all two-dimensional gratings. The one-dimensional grating includes at least one of a one-dimensional rectangular wire grating, a one-dimensional blazed wire grating, and a one-dimensional tilted wire grating. The two-dimensional grating includes a two-dimensional metasurface array.

[0091] For example, the coupling grating 102 includes a transflective coupling grating, so that the coupling grating 102 couples the light beam into the waveguide 100 in both transmission and reflection modes.

[0092] For example, Figure 15 is a schematic diagram of the three-dimensional structure of an optical waveguide body and a coupling grating provided in at least one embodiment of the present disclosure. As shown in Figure 15, the coupling grating 102 includes a bottom block structure on which a plurality of grating lines and grooves are formed.

[0093] At least one embodiment of the present disclosure further provides an optical waveguide structure. For example, FIG16 is a schematic cross-sectional view of an optical waveguide structure according to at least one embodiment of the present disclosure. As shown in FIG16 , the optical waveguide structure 200 includes multiple layers of waveguide sheets 100 as described in any of the above embodiments. The multiple layers of waveguide sheets 100 are stacked, and adjacent layers of waveguide sheets 100 are connected by a sealant 201 to form a single integrated layer. The optical waveguide structure 200 can improve the uniformity of the emitted light and reduce pattern color deviation.

[0094] For example, as shown in FIG16 , two adjacent waveguide sheets 100 may be stacked in the height direction (i.e., the Z direction). The optical waveguide body included in each waveguide sheet 100 may include a resin layer or glass that transmits light in the wavelength range of approximately 400 nm to approximately 2000 nm. Each waveguide sheet 100 may have a refractive index in the range of approximately 1.2 to approximately 2.0. For example, the optical waveguide structure 200 includes a first waveguide sheet 110, a second waveguide sheet 120, and a third waveguide sheet 130 that are stacked. The first waveguide sheet 110, the second waveguide sheet 120, and the third waveguide sheet 130 may have substantially the same refractive index.

[0095] For example, as shown in FIG16 , the optical waveguide structure 200 further includes a cover plate 202 disposed on the outermost side of the stacked structure formed by the first waveguide plate 110, the second waveguide plate 120, and the third waveguide plate 130. This cover plate protects the first waveguide plate 110, the second waveguide plate 120, and the third waveguide plate 130. The cover plate 202 is a glass cover plate or a transparent resin cover plate. The cover plate 202 is transparent and has a visible light transmittance greater than 90%. The thickness of the cover plate is less than or equal to 0.5 mm, which ensures that light can pass smoothly through the cover plate 202. To increase the contrast of the AR glasses and prevent interference from external light, the cover plate can also take the form of sunglasses or be made of UV-resistant materials.

[0096] For example, in this optical waveguide structure, the arrangement order of the above-mentioned waveguide plates can be that the first waveguide plate 110, the second waveguide plate 120 and the third waveguide plate 130 are sequentially away from the external projection structure, that is, the light emitted from the projection structure first reaches the first waveguide plate 110, the light emitted from the first waveguide plate 110 then reaches the second waveguide plate 120, and the light emitted from the second waveguide plate 120 then reaches the third waveguide plate 130.

[0097] For example, in one embodiment, the light emitted from the projection structure can be a mixture of three primary colors: red, green, and blue. The first waveguide plate 110, the second waveguide plate 120, and the third waveguide plate 130 can be a blue waveguide plate, a green waveguide plate, and a red waveguide plate, respectively. The polarization structure on the first waveguide plate 110 allows blue light to be transmitted only in the blue waveguide plate, causing the blue light to propagate through the blue waveguide plate by total internal reflection and be emitted from the outcoupling grating. The polarization structure on the second waveguide plate 120 allows green light to be transmitted only in the green waveguide plate, causing the green light to propagate through the green waveguide plate by total internal reflection and be emitted from the outcoupling grating. The polarization structure on the third waveguide plate 130 allows red light to be transmitted only in the red waveguide plate, causing the red light to propagate through the red waveguide plate by total internal reflection and be emitted from the outcoupling grating.

[0098] For example, in another embodiment, the light emitted from the projection structure can be a mixture of three primary colors: red, green, and blue. The first waveguide plate 110, the second waveguide plate 120, and the third waveguide plate 130 can be a red waveguide plate, a green waveguide plate, and a blue waveguide plate, respectively. The polarization structure on the first waveguide plate 110 allows red light to be transmitted only in the red waveguide plate, and the red light is propagated in the red waveguide plate by total internal reflection and is emitted from the outcoupling grating. The polarization structure on the second waveguide plate 120 allows green light to be transmitted only in the green waveguide plate, and the green light is propagated in the green waveguide plate by total internal reflection and is emitted from the outcoupling grating. The polarization structure on the third waveguide plate 130 allows blue light to be transmitted only in the blue waveguide plate, and the blue light is propagated in the blue waveguide plate by total internal reflection and is emitted from the outcoupling grating.

[0099] For example, in one embodiment, the light emitted from the projection structure can be a mixture of three primary colors: red, green, and blue. The first waveguide plate 110, the second waveguide plate 120, and the third waveguide plate 130 can be a green waveguide plate, a red waveguide plate, and a blue waveguide plate, respectively. The polarization structure on the first waveguide plate 110 allows green light to be transmitted only in the green waveguide plate, causing the green light to propagate in the green waveguide plate by total internal reflection and be emitted from the outcoupling grating. The polarization structure on the second waveguide plate 120 allows red light to be transmitted only in the red waveguide plate, causing the red light to propagate in the red waveguide plate by total internal reflection and be emitted from the outcoupling grating. The polarization structure on the third waveguide plate 130 allows blue light to be transmitted only in the blue waveguide plate, causing the blue light to propagate in the blue waveguide plate by total internal reflection and be emitted from the outcoupling grating.

[0100] For example, in one example, in order to ensure that there is air with a refractive index of 1.0 between the first waveguide plate 110, the second waveguide plate 120 and the third waveguide plate 130, the first waveguide plate 110, the second waveguide plate 120 and the third waveguide plate 130 cannot contact each other, and frame sealing glue is used to seal between two adjacent waveguide plates. The width of the frame sealing glue in the extension direction of each waveguide plate is 0.5mm~1.0mm, and the height in the arrangement direction of the three waveguide plates is 3μm~8μm. The frame sealing glue can make the edges of two adjacent waveguide plates completely bonded, and can also bond partial areas of the edges of two adjacent waveguide plates.

[0101] For example, Figure 17 is a schematic diagram of an optical path propagating in an optical waveguide structure provided by at least one embodiment of the present disclosure. As shown in Figure 17, the first waveguide plate 110, the second waveguide plate 120 and the third waveguide plate 130 are respectively a blue waveguide plate, a green waveguide plate and a red waveguide plate. Correspondingly, the monochromatic light transmitted by total reflection in the first waveguide plate 110, the second waveguide plate 120 and the third waveguide plate 130 are blue light, green light and red light, respectively.

[0102] For example, a display can be improved to generate blue polarized light and red polarized light transmitted in a first polarization direction, and green light transmitted in a second polarization direction. For example, to generate blue light, green light, and red light with the aforementioned polarization directions, a Micro LED light engine capable of generating polarized light can be directly used.

[0103] For example, as shown in FIG17 , the display generates three-color light consisting of red, green, and blue light. The three-color light first passes through the coupling-in grating 102 of the first waveguide plate 110 (blue waveguide plate). Since its diffraction efficiency for red light is very low, the +1st-order diffraction light or -1st-order diffraction light of the red light can be basically ignored. The 0th-order transmitted light continues to propagate downward, and the +1st-order diffraction light or -1st-order diffraction light of the blue and green light enters the first waveguide plate 110. The blue and green light propagate in the blue waveguide plate by total internal reflection. When passing through the polarization structure 104 on the first waveguide plate 110, due to the different polarization directions of the blue and green light, the green light is absorbed, leaving only the blue light to continue to propagate in the blue waveguide plate. Finally, the blue light is coupled out from the coupling-out grating 103 of the blue waveguide plate and enters the human eye. For the second waveguide plate 120 (green waveguide plate), the three-color light formed by the red, green, and blue light all generate +1st-order diffraction light or -1st-order diffraction light. The +1st and -1st diffraction lights of the blue light are basically negligible. The +1st and -1st diffraction lights of the red light and the green light enter the red waveguide plate. The red and green light propagate in the red waveguide plate by total internal reflection. When passing through the polarization structure 104 on the third waveguide plate 130, the green light is absorbed by the polarization structure 104 on the third waveguide plate due to the different polarization directions of the red light and the green light, leaving only the red light to continue propagating. The green light is finally coupled out from the coupling grating 103 on the red waveguide plate and enters the human eye. The three colors of light formed by red light, green light and blue light are mixed in the human eye and finally present a color image on the retina of the human eye.

[0104] For example, in the structure shown in FIG17 , the first waveguide plate 110, the second waveguide plate 120, and the third waveguide plate 130 can be used as an example to illustrate that the display generates blue polarized light and red polarized light transmitted in the first polarization direction, and green light transmitted in the second polarization direction. Correspondingly, the monochromatic light transmitted in the first waveguide plate 110, the second waveguide plate 120, and the third waveguide plate 130 by total internal reflection is red light, green light, and blue light, respectively. The three-color light first passes through the first waveguide plate 110 (red waveguide plate 120) and the third waveguide plate 130. The coupling grating 102 of the first waveguide plate has a very low diffraction efficiency for blue light, so the +1st order diffraction light or -1st order diffraction light of the blue light can be basically ignored. The 0th order transmitted light continues to propagate downward. The +1st order diffraction light or -1st order diffraction light of the red light and the green light enters the first waveguide plate 110. The red light and the green light propagate in the red waveguide plate by total internal reflection. When passing through the polarization structure 104 on the first waveguide plate 110, the green light is absorbed due to the different polarization directions of the red light and the green light, leaving only the red light to continue to propagate in the red waveguide plate. Finally, the red light is reflected by the polarization structure 104 on the first waveguide plate 110. The red light is coupled out from the outcoupling grating 103 of the red waveguide plate and enters the human eye; for the second waveguide plate 120 (green waveguide plate), the three-color light formed by the red light, the green light and the blue light all generate +1-order diffraction light or -1-order diffraction light, and the three-color light is totally reflected and propagated in the green waveguide plate. Since the polarization directions of the green light and the red light and the blue light are different, the red light and the blue light are absorbed by the polarization structure 104 on the second waveguide plate 120, leaving only the green light to continue to propagate in the green waveguide plate. Finally, the green light is coupled out from the outcoupling grating 103 of the green waveguide plate The third waveguide plate 130 (blue waveguide plate) is similar to the red waveguide plate. The +1st-order diffracted light and -1st-order diffracted light of the red light can be basically ignored. The +1st-order diffracted light and -1st-order diffracted light of the blue and green light rays enter the blue waveguide plate. The blue and green light rays propagate through the blue waveguide plate by total internal reflection. When passing through the polarization structure 104 on the third waveguide plate 130, the green light is absorbed due to the different polarization directions of the blue and green light rays, leaving only the blue light to continue propagating. Finally, it is coupled out of the coupling grating 103 of the blue waveguide plate and enters the human eye. The three-color light formed by the red, green, and blue light rays mixes in the human eye, and finally presents a color image on the human retina.

[0105] For example, in the structure shown in FIG17 , the first waveguide plate 110, the second waveguide plate 120, and the third waveguide plate 130 can be used as an example to illustrate that the display generates blue polarized light and red polarized light transmitted in the first polarization direction, and green light transmitted in the second polarization direction. Correspondingly, the monochromatic light transmitted in the first waveguide plate 110, the second waveguide plate 120, and the third waveguide plate 130 by total reflection is green light, red light, and blue light, respectively. The three-color light first passes through the first waveguide plate 110 (green polarized light) and then passes through the third waveguide plate 130. The three colors of light formed by the red, green, and blue light all generate +1-order diffraction light or -1-order diffraction light through the coupling grating 102 of the green waveguide. The three colors of light are all totally reflected and propagated in the green waveguide. Since the polarization directions of the green light and the red and blue light are different, the red and blue light are absorbed by the polarization structure 104 on the second waveguide 120, leaving only the green light to continue propagating in the green waveguide. Finally, the green light is coupled out from the coupling grating 103 of the green waveguide into the human eye. For the second waveguide 120 (red waveguide), since it has a high polarization resistance to blue light, the green light is absorbed by the polarization structure 104 on the second waveguide 120. The diffraction efficiency of the blue light is very low, so the +1st order diffraction light or -1st order diffraction light of the blue light can be basically ignored, and the 0th order transmitted light continues to propagate downward, and the +1st order diffraction light or -1st order diffraction light of the red light and the green light enters the first waveguide plate 110. The red light and the green light propagate in the red waveguide plate by total internal reflection. When passing through the polarization structure 104 on the first waveguide plate 110, due to the different polarization directions of the red light and the green light, the green light is absorbed, leaving only the red light to continue to propagate in the red waveguide plate. Finally, the red light is coupled out from the outcoupling grating 103 of the red waveguide plate. The third waveguide plate 130 (blue waveguide plate) is similar to the red waveguide plate. The +1st-order diffracted light and -1st-order diffracted light of the red light can be basically ignored. The +1st-order diffracted light and -1st-order diffracted light of the blue and green light rays enter the blue waveguide plate. The blue and green light rays propagate through the blue waveguide plate by total internal reflection. When passing through the polarization structure 104 on the third waveguide plate 130, the green light is absorbed due to the different polarization directions of the blue and green light rays, leaving only the blue light to continue propagating. Finally, it is coupled out of the blue waveguide plate through the coupling grating 103 and enters the human eye. The three-color light formed by the red, green, and blue light rays mixes in the human eye, and finally presents a color image on the human retina.

[0106] For example, FIG18 is a schematic diagram of another optical path propagating in an optical waveguide structure according to at least one embodiment of the present disclosure. As shown in FIG18 , the first waveguide plate 110, the second waveguide plate 120, and the third waveguide plate 130 are used as an example for illustration. Accordingly, the monochromatic light transmitted by total internal reflection in the first waveguide plate 110, the second waveguide plate 120, and the third waveguide plate 130 is blue light, green light, and red light, respectively. These blue, green, and red lights have the same polarization direction. For example, when collimated light R, G, and B emitted from a display passes through the incoupling grating 102 and the blue waveguide plate, only the blue light undergoes polarization conversion, changing its propagation direction from a first direction to a second direction. The propagation directions of the red and green lights remain unchanged. Therefore, the blue light continues to propagate after being reflected by the polarization structure, while the red and green lights are absorbed by the polarization structure. Ultimately, only the blue light is coupled out by the outcoupling grating. The red, green, and blue light rays emitted from the first waveguide plate 110 (blue waveguide plate) reach the second waveguide plate 120 (green waveguide plate) and pass through the coupling-in grating 102 of the second waveguide plate 120. When propagating through the green waveguide plate, only the green light undergoes polarization conversion, and its propagation direction changes from the first direction to the second direction. The propagation directions of the red and blue light rays remain unchanged, so the green light continues to propagate after being reflected by the polarization structure. The red and blue light rays are absorbed by the polarization structure, and finally only the green light is coupled out by the coupling-out grating. Finally, the three colors of light are combined into a colorful pattern at the cornea of ​​the human eye. When the first waveguide plate 110, the second waveguide plate 120 and the third waveguide plate 130 are respectively a green waveguide plate, a blue waveguide plate and a red waveguide plate, or when the first waveguide plate 110, the second waveguide plate 120 and the third waveguide plate 130 are respectively a green waveguide plate, a red waveguide plate and a blue waveguide plate, the principle can be referred to the relevant description above, and finally the three colors of light are combined into a color pattern at the retina of the human eye.

[0107] For example, FIG19 is a schematic diagram of another optical path propagating in an optical waveguide structure provided by at least one embodiment of the present disclosure. The optical waveguide structure 200 is formed by stacking two waveguide sheets 100. Since the wavelengths of green light, blue light, and red light are similar, and green light responds to both the red and blue waveguide sheets, FIG19 is equivalent to decomposing and fusing the green waveguide sheet into the blue and red waveguide sheets, forming a BG waveguide sheet (blue-green waveguide sheet) and an RG waveguide sheet (red-green waveguide sheet). For the blue-green waveguide sheet, a grating structure with low red light efficiency is selected. For the red-green waveguide sheet, a grating structure with low blue light efficiency is selected. The green light can be designed to be unpolarized, and the polarization directions of the blue and red light can be designed to be opposite.

[0108] For example, as shown in FIG19 , the first waveguide plate 110 is a blue-green waveguide plate, and the second waveguide plate 120 is a red-green waveguide plate. When light emitted from a display passes through the blue-green waveguide plate, the red light is blocked by the polarization structure, while the blue and green light continue to propagate and are coupled out to the human eye by the coupling grating 103 on the first waveguide plate 110. When light enters the red-green waveguide plate, the blue light is blocked by the polarization structure, while the red and green light continue to propagate and are coupled out to the human eye by the coupling grating 103 on the second waveguide plate 120. Finally, the three colors of light combine to form a color pattern at the human retina.

[0109] For example, in another embodiment, the first waveguide plate 110 may be a red-green waveguide plate, and the second waveguide plate 120 may be a blue-green waveguide plate. When light emitted from the display passes through the red-green waveguide plate, the blue light is blocked by the polarization structure, while the red and green light continue to propagate and are coupled out to the human eye by the coupling grating 103 on the first waveguide plate 110. When light enters the blue-green waveguide plate, the red light is blocked by the polarization structure, while the blue and green light continue to propagate and are coupled out to the human eye by the coupling grating 103 on the second waveguide plate 120. Finally, the three colors of light are combined to form a color pattern at the retina of the human eye.

[0110] For example, Figure 20 is a schematic diagram of another light path propagating in an optical waveguide structure provided by at least one embodiment of the present disclosure. The optical waveguide structure 200 is formed by stacking two waveguide plates 100. The blue light and red light emitted by the display have polarization directions of the same direction. The polarization directions of the monochromatic light are converted by the corresponding waveguide plates, so that the combined light (BG) of the blue light and the green light and the combined light (RG) of the red light and the green light propagate in the corresponding blue-green waveguide plate and red-green waveguide plate, respectively.

[0111] For example, as shown in FIG20 , the first waveguide plate 110 is a blue-green waveguide plate, and the second waveguide plate 120 is a red-green waveguide plate. When light emitted from a display passes through the blue-green waveguide plate, since the green light contains both horizontally polarized light and vertically polarized light, the green light can continue to propagate. The waveguide plate needs to convert the polarization direction of one of the blue or red light, so that the blue light can be reflected by the polarization structure and the red light can be absorbed by the polarization structure, ultimately coupling the blue and green light out of the coupling grating. When the light transmitted from the blue-green waveguide plate reaches the red-green waveguide plate, the red-green waveguide plate needs to convert the polarization direction of one of the blue and red light, so that the red light can be reflected by the polarization structure and the blue light can be absorbed by the polarization structure, ultimately coupling the red and green light out of the coupling grating. Finally, the three colors of light are combined to form a color pattern at the cornea of ​​the human eye.

[0112] For example, in another embodiment, the first waveguide plate 110 is a red-green waveguide plate, and the second waveguide plate 120 is a blue-green waveguide plate. When light emitted from a display passes through the red-green waveguide plate, since the green light contains both light polarized in the first polarization direction and light polarized in the second polarization direction, the green light can continue to propagate. The waveguide plate needs to convert the polarization direction of one of the red or blue light, so that the red light can be reflected by the polarization structure and the blue light can be absorbed by the polarization structure, ultimately allowing the red and green light to be coupled out of the coupling grating. When the light transmitted from the red-green waveguide plate reaches the blue-green waveguide plate, the blue-green waveguide plate needs to convert the polarization direction of one of the red and blue light, so that the blue light can be reflected by the polarization structure and the red light can be absorbed by the polarization structure, ultimately allowing the blue and green light to be coupled out of the coupling grating. Finally, the three-color light is combined into a color pattern at the cornea of ​​the human eye.

[0113] At least one embodiment of the present disclosure further provides a display device. For example, FIG21 is a block diagram of a display device provided by at least one embodiment of the present disclosure. As shown in FIG21 , the display device 300 includes the optical waveguide structure 200 of any of the above embodiments, and the display device 300 also includes a projection structure 302. The projection structure 302 includes a display 303, and the display 303 is configured to emit a light beam containing image information. The features of the display device 300 can be found in the above description of the optical waveguide structure 200 and will not be repeated here. For example, the display device 300 can improve the uniformity of the emitted light to ensure the clarity of the image displayed by the display device 300.

[0114] For example, Figure 22 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 Figure 22, the display device 300 also includes a projection structure 302. The projection structure 302 includes a display 303. The display 303 is used to emit a light beam with image information. After the emitted light beam is transmitted in the optical waveguide structure 200, the uniformity of the image finally displayed on the display device is better.

[0115] For example, referring to Figures 21 and 22 , the display device 300 may include, in addition to a display 303 for providing light and an optical waveguide structure 200 for guiding the light from the display 303, a spatial light modulator for diffracting the light from the optical waveguide structure 200 to reproduce a holographic image. The display 303 may provide a coherent light beam, such as a beam emitted by a laser diode. However, if the light has a certain degree of spatial coherence or no spatial coherence, the light can be diffracted and modulated into coherent light by a spatial light modulator. Therefore, other light source structures may also be used, even if they emit light with a certain degree of spatial coherence or no spatial coherence. The light source structure may include multiple light sources emitting light of different wavelengths. For example, a first light source emitting light in a first wavelength band, a second light source emitting light in a second wavelength band different from the first wavelength band, and a third light source emitting light in a third wavelength band different from the first and second wavelength bands. The light in the first, second, and third wavelength bands may be red, green, and blue, respectively.

[0116] For example, the display device 300 may further include a controller that controls the driving of the light source structure. The controller may include multiple control units that sequentially control the radiation direction of the light beams to form display images in the left and right eyes of the viewer in a time sequence.

[0117] At least one embodiment of the present disclosure further provides a method for preparing a waveguide sheet, comprising: providing an optical waveguide body, wherein the optical waveguide body includes a first main surface and a second main surface arranged opposite to each other; forming an in-coupling grating, a polarization structure, and an out-coupling grating on the first main surface, wherein the polarization structure is between the in-coupling grating and the out-coupling grating. The process of forming the waveguide sheet using this preparation method includes forming a polarization structure between the in-coupling grating and the out-coupling grating. The polarization structure can reflect light with a first polarization state included in the light beam, and cause the light with the first polarization state to propagate in a total reflection manner within the optical waveguide body. Subsequently, stacking multiple layers of the above waveguide sheets to form an optical waveguide structure can solve the problem of color deviation caused by the response of conventional optical waveguide structures to the full band of visible light.

[0118] For example, FIG23 is a flow chart of a method for preparing a waveguide plate provided in at least one embodiment of the present disclosure, and the preparation method includes the following steps.

[0119] Step S101: providing an optical waveguide body, wherein the optical waveguide body comprises a first main surface and a second main surface arranged opposite to each other.

[0120] For example, the oppositely disposed first main surface and second main surface of the optical waveguide body are surfaces on which grating structures or other components are disposed.

[0121] Step S102: forming an in-coupling grating, a polarization structure and an out-coupling grating on the first main surface, wherein the polarization structure is between the in-coupling grating and the out-coupling grating.

[0122] For example, the polarization structure can cause light to propagate in a total reflection manner within the optical waveguide body, thereby improving the color deviation problem caused by the conventional optical waveguide structure's response to the full band of visible light.

[0123] For example, FIG24 is a flow chart of another method for preparing a waveguide plate provided by at least one embodiment of the present disclosure, and the preparation method includes the following steps.

[0124] Step S201: providing an optical waveguide body, wherein the optical waveguide body comprises a first main surface and a second main surface opposite to each other.

[0125] Step S202: forming an in-coupling grating, a polarization structure, a folding grating and an out-coupling grating on the first main surface, wherein the polarization structure is between the in-coupling grating and the out-coupling grating, and the folding grating is between the in-coupling grating and the out-coupling grating.

[0126] For example, the folding grating is configured to receive light of a first polarization state input from the coupling-in grating and perform pupil-expanding transmission.

[0127] For example, in the flowchart of the preparation method shown in FIG24 , a preparation process of a folding grating is added, and the folding grating has the effect of expanding the pupil of the light transmitted thereto.

[0128] For example, FIG25 is a flow chart of another method for preparing a waveguide plate provided by at least one embodiment of the present disclosure, and the preparation method includes the following steps.

[0129] Step S301: providing an optical waveguide body, wherein the optical waveguide body comprises a first main surface and a second main surface that are oppositely arranged.

[0130] Step S302: forming an in-coupling grating, a polarization structure, a folding grating and an out-coupling grating on the first main surface, wherein the polarization structure is between the in-coupling grating and the out-coupling grating, and the folding grating is between the in-coupling grating and the out-coupling grating.

[0131] For example, the folding grating is configured to receive light of a first polarization state input from the coupling-in grating and perform pupil-expanding transmission.

[0132] Step S303: forming a half-wave plate on the first main surface or the second main surface of the optical waveguide body, and the light beam first passes through the half-wave plate and then passes through the polarization structure.

[0133] For example, the half-wave plate is configured to deflect light of a first polarization state, and the reflectivity of the light of the first polarization state is greater than 90%.

[0134] For example, in one embodiment, the polarization structure is a metal wire grid polarizer, and a nanoimprinting method is used to form an in-coupling grating, a metal wire grid polarizer, a folding grating, and an out-coupling grating.

[0135] For example, Figure 26 is a process diagram of a method for fabricating a waveguide sheet according to at least one embodiment of the present disclosure. As shown in Figure 26 , an optical waveguide template can be fabricated using electron beam lithography or ultraviolet lithography. For example, nanoimprint lithography (NIL) manufacturing equipment can be used for mass production.

[0136] For example, in Figure 26, process (A) is a process for preparing an electron beam exposure master template, which includes providing a base substrate 501, which can be a silicon wafer, coating an electron beam exposure paste 502 on the silicon wafer, irradiating the electron beam exposure paste by electron beam direct writing, and then forming a pattern 503 of the electron beam exposure paste by development, and finally performing a composition process on the silicon wafer using the pattern 503 of the electron beam exposure paste as a mask to form an electron beam exposure master template 504.

[0137] For example, in Figure 26, process (B) is a process for preparing a nanoimprint lithography template, which includes providing an electron beam exposure master template 504 prepared by process (A), coating a template glue 505 on the electron beam exposure master template 504, and then placing a template 506 on the template glue 505, UV-curing or thermally curing the template glue 505, and finally performing a demolding process to separate the template glue 505 and the template 506 as a whole from the electron beam exposure master template 504 to form a nanoimprint lithography template 507.

[0138] For example, in Figure 26, process (C) is a process for preparing a nanoimprint lithography substrate, which includes coating a glue material 508 on a base substrate, imprinting the glue material 508 using a nanoimprint lithography template 507, and performing ultraviolet curing on the glue material 508 during the imprinting process. After the glue material 508 is cured, the nanoimprint lithography template 507 is removed to form a nanoimprint lithography substrate 509.

[0139] At least one embodiment of the present disclosure further provides a method for preparing an optical waveguide structure. For example, FIG27 is a flow chart of a method for preparing an optical waveguide structure provided by at least one embodiment of the present disclosure. The method includes the following steps.

[0140] Step S401: providing a multi-layer waveguide sheet.

[0141] For example, the structure of the waveguide plate can refer to the relevant description above, which will not be repeated here.

[0142] Step S402: stacking multiple waveguide sheets.

[0143] Step S403: using a sealing adhesive to connect two adjacent layers of waveguide sheets, so that the multi-layer waveguide sheets are integrated.

[0144] For example, the width of the frame sealing glue in the extension direction of each waveguide plate is 0.5mm~1.0mm, and the height in the arrangement direction of the three waveguide plates is 3μm~8μm. The frame sealing glue can make the edges of two adjacent waveguide plates fully bonded, or it can bond half of the edges of two adjacent waveguide plates.

[0145] At least one embodiment of the present disclosure provides a waveguide plate and a method for manufacturing the same, an optical waveguide structure and a method for manufacturing the same, and a display device, which have at least the following beneficial technical effects: the waveguide plate includes a polarization structure arranged between an in-coupling grating and an out-coupling grating, and the polarization structure can reflect light with a first polarization state included in a light beam, and cause the light with the first polarization state to propagate by total reflection within the optical waveguide body, thereby stacking multiple layers of the above-mentioned waveguide plates to solve the problem of color deviation caused by the optical waveguide structure's response to the full band of visible light.

[0146] There are a few points to note:

[0147] (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.

[0148] (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.

[0149] (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.

[0150] 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. A waveguide sheet, comprising an optical waveguide body, wherein: The optical waveguide body comprises a first main surface and a second main surface which are arranged opposite to each other, an in-coupling grating and an out-coupling grating are arranged on the first main surface, and a polarization structure is arranged between the in-coupling grating and the out-coupling grating; The coupling-in grating is configured to couple a light beam into the optical waveguide body; The polarization structure is configured to reflect the light having a first polarization state included in the light beam, and to make the light having the first polarization state propagate in the optical waveguide body in a total reflection manner; The outcoupling grating is configured to couple the first color light transmitted to the outcoupling grating out of the optical waveguide body.

2. The waveguide sheet according to claim 1, further comprising a folding grating disposed on the first main surface, wherein: The folding grating is disposed between the coupling-in grating and the coupling-out grating, and the folding grating is configured to receive the light of the first polarization state transmitted from the coupling-in grating and perform pupil expansion transmission.

3. The waveguide sheet according to claim 1 or 2, wherein: The refractive index of the polarization structure is smaller than the refractive index of the optical waveguide body.

4. The waveguide sheet according to claim 3, wherein: The polarization structure includes at least one of a metal wire grid polarizer, a chemical reflective polarizer and a metasurface structure.

5. The waveguide plate according to claim 3, further comprising a half-wave plate disposed on the first main surface or the second main surface of the optical waveguide body, wherein: An orthographic projection of at least part of the half wave plate on the optical waveguide body is located between an orthographic projection of the polarization structure on the optical waveguide body and an orthographic projection of the coupling grating on the optical waveguide body. The light beam first passes through the half wave plate and then passes through the polarization structure. The half wave plate is configured to deflect the light of the first polarization state, and the reflectivity of the light of the first polarization state is greater than 90%.

6. The waveguide sheet according to claim 5, wherein: The coupling-in grating, the folding grating and the coupling-out grating are all one-dimensional gratings, or are all two-dimensional gratings.

7. The waveguide sheet according to claim 6, wherein: The one-dimensional grating includes at least one of a one-dimensional rectangular wire grating, a one-dimensional blazed wire grating and a one-dimensional inclined wire grating; the two-dimensional grating includes a two-dimensional metasurface array.

8. The waveguide sheet according to any one of claims 1 to 7, wherein: The coupling-in grating comprises a transmissive-reflective coupling-in grating, so that the coupling-in grating couples the light beam into the waveguide plate in both transmission and reflection forms.

9. The waveguide sheet according to any one of claims 1 to 7, wherein: An extension direction of the grating lines of the coupling-in grating intersects an extension direction of the grating lines of the coupling-out grating.

10. An optical waveguide structure, comprising a plurality of waveguide sheets as claimed in any one of claims 1 to 9, wherein the plurality of waveguide sheets are stacked, and two adjacent layers of the waveguide sheets are connected by a sealing adhesive so that the plurality of waveguide sheets are integrated.

11. The optical waveguide structure according to claim 10, further comprising a cover plate arranged at the outermost side of the plurality of layers of the waveguide sheets stacked, wherein: The cover plate is a glass cover plate or a transparent resin cover plate.

12. A display device comprising the optical waveguide structure according to claim 10 or 11. 13 . The display device according to claim 12 , further comprising a projection structure, wherein the projection structure comprises a display, and the display is used to emit a light beam having image information.

14. A method for preparing a waveguide sheet, comprising: Providing an optical waveguide body, wherein the optical waveguide body comprises a first main surface and a second main surface arranged opposite to each other; An in-coupling grating, a polarization structure and an out-coupling grating are formed on the first main surface, wherein the A polarization structure is between the in-coupling grating and the out-coupling grating.

15. The preparation method according to claim 14, further comprising: A folding grating is formed on the first main surface, wherein the folding grating is between the coupling-in grating and the coupling-out grating, and the folding grating is configured to receive the light of the first polarization state transmitted from the coupling-in grating and perform pupil expansion transmission.

16. The preparation method according to claim 15, further comprising: A half wave plate is formed on the first main surface or the second main surface of the optical waveguide body, wherein the light beam first passes through the half wave plate and then passes through the polarization structure, and the half wave plate is configured to deflect the light of the first polarization state, and the reflectivity of the light of the first polarization state is greater than 90%.

17. The preparation method according to claim 15, wherein: The polarization structure is a metal wire grid polarizer, and the coupling-in grating, the metal wire grid polarizer, the folding grating and the coupling-out grating are formed by a nano-imprinting method.

18. A method for preparing an optical waveguide structure, comprising: Providing a multilayer waveguide sheet according to any one of claims 1 to 9; Laying down a plurality of waveguide sheets; Two adjacent layers of the waveguide sheets are connected by using a sealing adhesive, so that the multiple layers of the waveguide sheets are integrated.

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