WO2025054942A1 - Waveguide sheet and preparation method therefor, optical waveguide structure and preparation method therefor, and display apparatus - Google Patents

Abstract

A waveguide sheet (100) and a preparation method therefor, an optical waveguide structure (200) and a preparation method therefor, and a display apparatus (300). The waveguide sheet (100) comprises an optical waveguide body (101). The optical waveguide body (101) comprises a first main surface (101a) and a second main surface (101b) arranged opposite to each other. The first main surface (101a) is provided with an in-coupling grating (102) and an out-coupling grating (103), and a polarization structure (104) arranged between the in-coupling grating (102) and the out-coupling grating (103). The in-coupling grating (102) is configured to couple a light beam into the optical waveguide body (101). The polarization structure (104) is configured to reflect light having a first polarization state comprised in the light beam, and enable the light having the first polarization state to propagate in a total reflection mode in the optical waveguide body (101). The out-coupling grating (103) is configured to couple first color light transmitted to the out-coupling grating (103) out of the optical waveguide body (101), and the waveguide sheet (100) reflects the light having the first polarization state comprised in the light beam by means of the polarization structure (104), and enables the light having the first polarization state to propagate in the optical waveguide body (101) in the total reflection mode, so that the problem of color shift caused by the response of the optical waveguide to a whole band of visible light can be solved by stacking a plurality of layers of waveguide sheets (100).

Description

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

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

With the continuous advancement of science and technology, virtual reality (VR), augmented reality (AR) and mixed reality (MR) have gradually entered people's lives. For example, augmented reality (AR) technology is the integration of virtual information with the real world, represented by augmented reality glasses. In the fields of security and industry, augmented reality technology has shown great advantages and greatly improved the way of information interaction.

At present, augmented reality technology mainly includes prism technology, free-form surface technology, off-axis holographic lens technology and light waveguide technology. The devices used in prism technology and free-form surface technology are large in size, which limits their application in smart wearables, that is, augmented reality glasses. Off-axis holographic lens technology uses the unique optical properties of holographic films. It has the advantages of large field of view (FOV) and small volume. However, it is limited in large-scale mass production and large field of view due to its small eye movement range. Light waveguide technology is currently the best augmented reality glasses solution. Light waveguide technology includes geometric waveguide technology, embossed 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 film mirrors to achieve the purpose of displaying virtual information. Polarization array waveguide has the advantages of lightness, large eye movement range and uniform color. The embossed 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.

Summary of the invention

At least one embodiment of the present disclosure provides a waveguide plate and a method for preparing the same, an optical waveguide structure and a method for preparing the same, and a display device. The waveguide plate includes a polarization structure arranged between a coupling-in grating and a coupling-out grating. The polarization structure can reflect light with a first polarization state included in a light beam, and make the light of the first polarization state propagate in a total reflection manner within the optical waveguide body, so that 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.

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 the light beam with a first polarization state included in the light beam, and make the light beam of the first polarization state propagate in the optical waveguide body in a total reflection manner; the out-coupling grating is configured to couple the first color light beam transmitted to the out-coupling grating out of the optical waveguide body.

For example, the waveguide provided by 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.

For example, in the waveguide sheet 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.

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.

For example, the waveguide provided by at least one embodiment of the present disclosure further includes a half wave plate arranged on the first main surface or the second main surface of the optical waveguide body, wherein the orthographic projection of at least part 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 the light of the first polarization state, and the reflectivity of the light of the first polarization state is greater than 90%.

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.

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 inclined wire grating; the two-dimensional grating includes a two-dimensional metasurface array.

For example, in the waveguide provided in at least one embodiment of the present disclosure, the coupling-in grating comprises 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.

For example, in the waveguide provided in at least one embodiment of the present disclosure, the grating lines of the coupled grating The extension direction of the outcoupling grating intersects with the extension direction of the grating lines of the outcoupling grating.

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

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 multiple layers of the stacked waveguide sheets, wherein the cover plate is a glass cover plate or a transparent resin cover plate.

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.

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

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 comprises 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.

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 out-coupling 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.

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%.

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.

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 layers of the waveguide sheets using a sealing adhesive so that the plurality of waveguide sheets are integrated.

BRIEF DESCRIPTION OF THE DRAWINGS

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.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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;

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

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;

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

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

FIG22 is a schematic diagram of a cross-sectional structure of a display device provided by at least one embodiment of the present disclosure;

FIG23 is a flow chart of a method for preparing a waveguide sheet provided by at least one embodiment of the present disclosure;

FIG. 24 is a flow chart of a method for preparing a waveguide sheet according to at least one embodiment of the present disclosure;

FIG. 25 is a flow chart of a method for preparing a waveguide sheet according to at least one embodiment of the present disclosure;

FIG. 26 is a process diagram of a method for preparing a waveguide sheet provided by at least one embodiment of the present disclosure; and

FIG. 27 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

In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the 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.

Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. "First", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can 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 described object changes, the relative positional relationship may also change accordingly.

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 a certain error. For example, the above-mentioned "approximately" may mean that the difference of the compared objects is within 10% or 5% of the average value of the compared objects. When the number of a component or element is not particularly specified in the following text of 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" means one or more, and "plurality" means 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 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.

Since the concept of "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. At present, the most popular augmented reality field is augmented reality glasses. Augmented reality glasses are predicted to become the "third screen" for humans. They can be used in military, education, medical and industrial fields, and have very broad development prospects. The implementation methods of augmented reality include geometric optics and diffraction optics. The surface relief grating (SRG) diffraction waveguide in the diffraction optics solution has attracted much attention because it is more suitable for mass production.

Due to the characteristics of the diffraction optics of the surface relief grating (SRG), the grating responds to the entire visible light band (380nm~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 avoiding the propagation of light of different wavelengths on non-corresponding waveguides.

The inventors of the present disclosure noticed 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, so as to solve 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.

At least one embodiment of the present disclosure provides a waveguide sheet and a method for preparing the same, an optical waveguide structure and a method for preparing the same, and a display device. The waveguide sheet 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 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 the light beam with a first polarization state included in the light beam, and make the light beam of the first polarization state propagate in a total reflection manner in the optical waveguide body; the out-coupling grating is configured to couple the first color light beam transmitted to the out-coupling grating out of the optical waveguide body, and the waveguide sheet includes a polarization structure arranged between the in-coupling grating and the out-coupling grating, and the polarization structure can reflect the light beam The invention includes light with a first polarization state, and makes the light with the first polarization state propagate in a total reflection manner in the optical waveguide body, so that the multi-layered arrangement of the waveguide sheets can solve the problem of color deviation caused by the response of the optical waveguide structure to the full band of visible light.

For example, FIG. 1 is a schematic diagram of a planar structure of a waveguide sheet provided in at least one embodiment of the present disclosure, and FIG. 2 is a schematic diagram of a cross-sectional structure of a waveguide sheet provided in at least one embodiment of the present disclosure. In combination with FIG. 1 and FIG. 2, 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 beam included in the first polarization state, and make the light of the first polarization state propagate in the optical waveguide body 101 in a total reflection manner, 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 the color deviation phenomenon.

For example, as shown in FIG1 , the waveguide plate 100 further includes a folding grating 105 disposed on the first main surface 101a, wherein the folding grating 105 is located between the coupling-in grating 102 and the coupling-out 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.

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.

2 , the polarization structure 104 and the coupling-in grating 102 are arranged on the same side of the optical waveguide body 101, and are both arranged on the first main 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 coupling-in grating 102 may also be arranged on different sides of the optical waveguide body 101.

For example, the embodiments of the present disclosure optimize the layout of the waveguide sheet, and use a high-refractive-index embossing glue 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 glue with a high refractive index have the same refractive index. For example, the waveguide sheet is composed of a variety of different waveguide gratings according to certain rules, and the waveguide gratings have different heights, different periods, or different duty cycles, etc. According to the function, the waveguide gratings mainly include the above-mentioned coupling gratings, folding gratings and coupling-out gratings. In addition to the coupling gratings usually included in the optical waveguide, The input grating, the folding grating and the output grating, the embodiment of the present disclosure also introduces a polarization structure, which 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 can be adjusted according to the polarization direction of the light emitted from the optical machine.

For example, the embodiment of the present disclosure simulates and optimizes the coupling grating of each waveguide plate. For the coupling grating of the waveguide plate that transmits blue light, its diffraction efficiency for the red light band is lowered. For the coupling grating of the waveguide plate that transmits red light, its diffraction efficiency for the blue light band is lowered. For the waveguide plate that transmits blue light, the waveguide plate that transmits red light, and the waveguide plate that transmits green light, the waveguide plate gratings of the corresponding wavelengths are designed respectively. For example, the wavelength corresponding to the waveguide plate grating that transmits blue light is 450nm, the wavelength corresponding to the waveguide plate grating that transmits green light is 532nm, and the wavelength corresponding to the waveguide plate grating that transmits red light is 630nm.

For example, the dimensions of the coupling-in grating, the folding grating, and the coupling-out grating can be designed according to the following design scheme: the height of the coupling-in grating is in the range of 150nm to 350nm, the height of the folding grating and the coupling-out grating are in the range of 40nm to 140nm, respectively, and the period of the coupling-in grating, the folding grating, and the coupling-out grating is in the range of 280nm to 500nm. The shapes of the coupling-in grating, the folding grating, and the coupling-out grating can be any one of a one-dimensional rectangular wire grating, a one-dimensional blazed grating, a one-dimensional tilted grating, and a two-dimensional metasurface array, and the embodiments of the present disclosure do not specifically limit this.

For example, in one example, in conjunction with 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 .

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 directly formed on a waveguide plate. The material of the metal wire grid polarizer can be a metal single substance such as aluminum (Al), gold (Au), molybdenum (Mo) or silver (Ag). The height of the metal wire grid polarizer ranges from 100nm to 300nm, the width ranges from 50nm to 100nm, the period ranges from 100nm to 300nm, and the duty cycle is 0.4 to 0.6. When the polarization structure 104 is a chemical reflective polarizer, it can be integrated by bonding the chemical reflective polarizer. The specific polarization direction in each waveguide plate depends on the specific scheme. When the polarization structure 104 is a metasurface structure, the metasurface structure can be a cylindrical array with different heights and diameters, or a grating combination with different widths, and its height ranges from 100nm to 400nm.

For example, in other examples, the polarization structure 104 may also be a laminated iodine-based polarizer, etc. The embodiments of the present disclosure are not limited to this.

For example, in one example, 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, and when the polarization structure 104 is between the coupling grating 102 and the folding 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 passing through the coupling grating 102 can pass through the polarization structure 104.

For example, in one example, 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 tangent to the coupling-in grating 102 and the folding 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 not to block the vertical light path entering the coupling-in grating 102, the polarization structure 104 is at most tangent to the coupling-in grating 102. When the polarization structure 104 is between the folding grating 105 and the coupling-out grating 103, the length of the polarization structure 104 is greater than or equal to the width of the folding grating 105 or the coupling-out grating 103, so as to ensure that the turned light and the coupled-out light have passed through the polarization structure 104. The width of the polarization structure 104 can be calculated according to the minimum step length of the light. For different waveguides, since the step lengths of the corresponding lights of different colors are different, the polarization structure 104 can have different widths, but the width must be greater than or equal to a step length to ensure that the light of the target wavelength can be received and will not be missed. For example, for a red waveguide with a thickness of 1 mm, the width of the polarization structure 104 is required to be greater than or equal to 8.4 mm.

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 is more uniform, thereby improving the quality of the display image.

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 material with a high refractive index, the optical waveguide body and the polarization structure of the waveguide sheet have the same refractive index, for example, the refractive indexes of the optical waveguide body and the polarization structure may be 1.7, 1.8, 1.9 or 2.0, and the thickness of the optical waveguide body may be 0.5 mm, 0.7 mm or 1.0 mm. The embodiments of the present disclosure are not limited to this, the refractive indexes of the optical waveguide body and the polarization structure of the waveguide sheet may also be other values, and the thickness of the optical waveguide body may also be other values.

For example, FIG3 is a schematic diagram of a planar structure of another waveguide provided by at least one embodiment of the present disclosure. As shown in FIG3, 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, and the extension direction of the grating lines of the in-coupling grating 102 and the extension direction of the out-coupling grating 103 are the same as those of the polarization structure 104. The extension directions of the grating lines intersect, the folding grating 105 extends in an oblique direction, and the coupling-in grating 102, the polarization structure 104 and the folding grating 105 are arranged on the same vertical line.

For example, Figure 4 is a schematic diagram of the planar structure of another waveguide 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 an oblique direction, and the out-coupling grating 103, the polarization structure 104 and the folding grating 105 are arranged on the same horizontal line.

For example, Figure 5 is a schematic diagram of the planar structure of another waveguide 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.

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

For example, FIG6 is a schematic diagram of the cross-sectional structure of another waveguide plate provided by at least one embodiment of the present disclosure, wherein the waveguide plate 100 further includes a half-wave plate 106 disposed on the first main surface 101a or the second main surface 101b of the optical waveguide body 101. FIG6 is an example of the half-wave plate 106 disposed on the second main surface 101b of the optical waveguide body 101. As shown in FIG6, the light beam first passes through the half-wave plate 106 and then passes through the polarization structure 104. The half-wave plate 106 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%, that is, the half-wave plate 106 can change the polarization state of the light of the first polarization state so that the light of a specific polarization state can pass through.

For example, when the waveguide plate shown in FIG6 is used for light transmission, it is not necessary to make the light of different colors generated by the display have different polarization directions, and the red light, the green light and the blue light all have the same polarization characteristics. A half-wave plate 106 is arranged on the first main surface 101a or the second main surface 101b of the optical waveguide body 101. For example, the half-wave plate 106 is arranged on the second main surface 101b of the optical waveguide body 101, and at least part 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. The single-wavelength reflective half-wave plate 106 with wavelength selectivity deflects the polarization direction of the light of a specific wavelength, and the polarization of the light of other wavelengths does not change.

It should be noted that the half wave plate can be arranged before the polarization structure in the direction of light propagation, and can be arranged on the same side of the optical waveguide body as the polarization grating, or on different sides of the optical waveguide body. The size of the half wave plate is required to be the same or substantially the same as that of the polarization structure, and the length of the half wave plate in each waveguide plate is greater than the maximum total reflection step length of the light emitted by the display.

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 layer can include a film layer formed by inorganic materials such as Si, SiO, and Al, and the thickness of the film layer formed by the inorganic material is less than 6um. The film layer can be a super surface structure prepared by metal single substances such as Al, Au, Ag, or Si, SiO non-metallic materials. The super surface structure can be a cylindrical array with different heights and diameters, or a grating combination with different widths, and the height of the grating is between 100nm and 400nm. The super surface structure can also be prepared by embossing with a high refractive index glue. For example, the refractive index of the high refractive index glue is greater than 1.5. The super surface structure can be a cylindrical array with different heights and diameters, or a grating combination with different widths, and the height is between 100nm and 400nm. The half wave plate 106 may also be directly bonded to the first main surface 101a or the second main surface 101b of the optical waveguide body 101, and the refractive index of the half wave plate 106 is required to be the same as the refractive index of the optical waveguide body 101, and the total thickness of the half wave plate 106 and the optical waveguide body 101 is less than 6 um. It is sufficient that the half wave plate 106 can deflect polarized light and has a reflectivity greater than 90%.

For example, FIG7 is a schematic diagram of the optical path of various colors of light provided by at least one embodiment of the present disclosure through a half-wave plate and a polarization structure. As shown in FIG7 , the first color light, the second color light, and the third color light are respectively blue light (B), green light (G), and red light (R), and the waveguide plate is a blue waveguide plate. For example, the collimated light R, G, and B emitted from the display passes through the coupling grating 102. When passing through the blue waveguide plate, only the blue light is polarized and converted, and the propagation direction changes from the first direction to the second direction. The propagation directions of the red light and the green light remain unchanged, so the blue light continues to propagate after being reflected by the polarization structure, and the red light and the green light are absorbed by the polarization structure. Finally, only the blue light is coupled out by the coupling grating. The principle of the green waveguide plate and the red waveguide plate is the same as that of the blue waveguide plate. Finally, the three-color light is combined into a color pattern at the retina of the human eye.

For example, in addition to the polarization structure formed by the wire grid polarizer shown in FIG. 2, the polarization structure may also be in other forms. For example, FIG. 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 FIG. 8, a polarization structure 104 having a certain thickness may be formed by coating. The material of the polarization structure 104 may include a metal material or a multi-material. layer of organic optical film.

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 an adhesive having the same refractive index as that of the glass substrate and a transmittance greater than 90%. The thickness of the adhesive is as thin as possible, for example, less than 100 nm.

For example, FIG10 is a schematic diagram of a cross-sectional structure of another waveguide sheet provided by at least one embodiment of the present disclosure. As shown in FIG10 , the polarization structure 104 is formed by integrating by bonding a chemical reflective polarizer. The polarization direction of the polarization structure 104 in each waveguide sheet is determined according to a specific solution. The chemical reflective polarizer can be a laminated structure of a reflective polarizing film and a viscosity layer with a high refractive index.

For example, FIG11 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 FIG11 , for example, a super surface structure and a polarization grating are integrally printed using a high refractive index adhesive. For example, the super surface structure can be a cylindrical array with different heights and diameters, or a combination of gratings with different widths, and its height is between 100 nm and 400 nm. In FIG11 , the polarization structure 104 and the coupling-in grating 102 and the coupling-out grating 103 are on the same side.

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.

For example, FIG13 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 FIG13 , the polarization structure 104, the coupling grating 102, and the turning grating 105 are on different sides, and the polarization structure 104 is 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 area occupied by the coupling grating 102 is 4 mm×4 mm, and the width of the polarization structure 104 is greater than or equal to 4 mm. In order not to block 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, and the turning grating 105 is not limited because the light propagates in the waveguide.

For example, FIG14 is a schematic diagram of a 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 coupling grating 102, and the folding grating 105 are on the same side, and the polarization structure 104 is between the coupling grating 102 and the folding grating 105. The polarization structure 104, the coupling grating 102, and the folding grating 105 are all tangent to each other, and the length of the polarization structure 104 is greater than or equal to the length of the folding grating. The width of the grating 105 or the coupling grating 103 ensures that the light emitted from the folding grating 105 has passed through the polarization structure 104. The width of the polarization structure can be calculated according to the minimum step length of the emitted light. For different waveguides, because the step lengths of the corresponding lights of different colors are different, the width of the polarization structure can be different, but its width must be greater than or equal to a step length to ensure that the light of the target wavelength can be received and will not be missed. For example, for a red waveguide with a waveguide thickness of 1 mm, the width of its polarization structure must be greater than or equal to 8.4 mm.

For example, as shown in FIGS. 1 to 14 , the coupling-in grating 102, the folding grating 105, and the coupling-out grating 103 are all surface gratings or volume gratings. The surface grating is a grating formed directly on the surface of the optical waveguide body 101, and may include, for example, a diffractive optical element (DOE) such as a binary phase grating, a blazed grating, etc. 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 angle range, causing extinction and constructive interference, so that the propagation direction of the incident light can be changed. The volume grating may be formed separately from the optical waveguide body 101, and may include, for example, a holographic optical element (HOE), a geometric phase grating, a Bragg polarization grating, a holographically formed polymer dispersed liquid crystal (H-PDLC), etc. The volume grating may include a periodic fine pattern of materials with different refractive indices.

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 inclined wire grating. The two-dimensional grating includes a two-dimensional metasurface array.

For example, the coupling grating 102 includes a transmissive-reflective coupling grating, so that the coupling grating 102 couples the light beam into the waveguide 100 in both transmission and reflection forms.

For example, FIG15 is a schematic diagram of a 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 FIG15 , the coupling grating 102 includes a bottom block structure on which a plurality of grating lines and grooves are formed.

At least one embodiment of the present disclosure further provides an optical waveguide structure. For example, FIG16 is a schematic diagram of a cross-sectional structure of an optical waveguide structure provided by 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 in any of the above embodiments, and the multiple layers of waveguide sheets 100 are stacked, and two adjacent layers of waveguide sheets 100 are connected by a sealing glue 201, so that the multiple layers of waveguide sheets 100 are integrated. The optical waveguide structure 200 can improve the uniformity of the emitted light and reduce the color deviation of the pattern.

For example, as shown in FIG. 16 , two adjacent waveguide plates 100 may be arranged in a height direction (ie, in the Z direction). The optical waveguide structure 200 may be stacked in the direction of the first waveguide sheet 110 and the second waveguide sheet 120. 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 about 400nm to about 2000nm. Each waveguide sheet 100 may have a refractive index in the range of about 1.2 to about 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, and the first waveguide sheet 110, the second waveguide sheet 120, and the third waveguide sheet 130 may have substantially the same refractive index.

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 sheet 110, the second waveguide sheet 120 and the third waveguide sheet 130, and the cover plate can protect the first waveguide sheet 110, the second waveguide sheet 120 and the third waveguide sheet 130. The cover plate 202 is a glass cover plate or a transparent resin cover plate, and the cover plate 202 is a transparent cover plate, and the transmittance of the cover plate 202 to visible light is greater than 90%, and the thickness of the cover plate is less than or equal to 0.5 mm, so that the light can smoothly pass through the cover plate 202. In order to increase the contrast of the AR glasses and prevent interference from external light, the cover plate can also be in the form of sunglasses, or can be formed of ultraviolet-proof materials.

For example, in the 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.

For example, in one example, the light emitted from the projection structure can be a mixed light of three primary colors of red light, green light and blue light, and 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 the blue light to be transmitted only in the blue waveguide plate, and the blue light is propagated in the blue waveguide plate in a total reflection manner and is emitted from the coupling grating. The polarization structure on the second waveguide plate 120 allows the green light to be transmitted only in the green waveguide plate, and the green light is propagated in the green waveguide plate in a total reflection manner and is emitted from the coupling grating. The polarization structure on the third waveguide plate 130 allows the red light to be transmitted only in the red waveguide plate, and the red light is propagated in the red waveguide plate in a total reflection manner and is emitted from the coupling grating.

For example, in another example, the light emitted from the projection structure can be a mixed light of three primary colors of red light, green light and blue light. 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 only the red light to be transmitted in the red waveguide plate, and the red light can be transmitted in the red waveguide plate. The colored light propagates in the red waveguide plate by total reflection and is emitted from the outcoupling grating. The polarization structure on the second waveguide plate 120 allows only the green light to be transmitted in the green waveguide plate, and allows the green light to propagate in the green waveguide plate by total reflection and be emitted from the outcoupling grating. The polarization structure on the third waveguide plate 130 allows only the blue light to be transmitted in the blue waveguide plate, and allows the blue light to propagate in the blue waveguide plate by total reflection and be emitted from the outcoupling grating.

For example, in one example, the light emitted from the projection structure may be a mixed light of three primary colors of red light, green light and blue light, and the first waveguide plate 110, the second waveguide plate 120 and the third waveguide plate 130 may 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, and allows the green light to propagate in the green waveguide plate in a total reflection manner 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, and allows the red light to propagate in the red waveguide plate in a total reflection manner 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, and allows the blue light to propagate in the blue waveguide plate in a total reflection manner and be emitted from the outcoupling grating.

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

For example, Figure 17 is a schematic diagram of a light 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 lights transmitted by total reflection in the first waveguide plate 110, the second waveguide plate 120 and the third waveguide plate 130 are respectively blue light, green light and red light.

For example, the display is 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 form blue light, green light, and red light with the above polarization directions, a Micro LED light machine that can generate polarized light can be directly used.

For example, as shown in FIG. 17 , the red light, green light, and blue light generated by the display are 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 +1-order diffraction light or -1-order diffraction light of the red light can be basically ignored, and the 0-order transmitted light continues to propagate downward, and the +1-order diffraction light or -1-order diffraction light of the blue light and the green light enters the first waveguide plate 110. The blue light and the green light propagate in the blue waveguide plate by total reflection. When passing through the polarization structure 104 on the first waveguide plate 110, due to the different polarization directions of the blue light and the 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 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 all in the green waveguide plate. The green light propagates in the waveguide plate by total reflection. Since the polarization directions of the green light, 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, and finally the green light is coupled out from the coupling grating 103 of the green waveguide plate and enters the human eye; for the third waveguide plate 130 (red waveguide plate), similar to the blue waveguide plate, the +1st order diffraction light or -1st order diffraction light of the blue light can be basically ignored, and the +1st order diffraction light or -1st order diffraction light of the red light and the green light enter the red waveguide plate, and the red light and the green light propagate in the red waveguide plate by total reflection. When passing through the polarization structure 104 on the third waveguide plate 130, since the polarization directions of the red light and the green light are different, the green light is absorbed and only the red light continues to propagate, and finally it is coupled out from the coupling grating 103 of the red waveguide plate and enters the human eye. The three colors of light formed by red, green and blue light are mixed in the human eye and finally present a color image on the retina of the human eye.

For example, in the structure shown in FIG. 17 , the first waveguide plate 110, the second waveguide plate 120 and the third waveguide plate 130 can be respectively used as a red waveguide plate, a green waveguide plate and a blue waveguide plate. 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 lights transmitted in the first waveguide plate 110, the second waveguide plate 120 and the third waveguide plate 130 by total reflection are red light, green light and blue light respectively. The three-color light first passes through the first waveguide plate 110, the second waveguide plate 120 and the third waveguide plate 130. The coupling grating 102 of the first waveguide plate 110 (red 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, and 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 reflection. When passing through the polarization structure 104 on the first waveguide plate 110, the green light is reflected due to the different polarization directions of the red light and the green light. After absorption, only the red light continues to propagate in the red waveguide plate, and finally the red light is coupled out from the coupling 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 produce +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, and only the green light continues to propagate in the green waveguide plate. Finally, the green light is transmitted from the green waveguide plate to the human eye. The out-coupling grating 103 of the waveguide plate is coupled out to enter the human eye; for the third waveguide plate 130 (blue waveguide plate), similar to the red waveguide plate, the +1st order diffraction light or -1st order diffraction light of the red light can be basically ignored, and the +1st order diffraction light or -1st order diffraction light of the blue light and the green light enters the blue waveguide plate, and the blue light and the green light propagate in the blue waveguide plate by total reflection. When passing through the polarization structure 104 on the third waveguide plate 130, due to the different polarization directions of the blue light and the green light, the green light is absorbed, and only the blue light continues to propagate, and finally coupled out from the out-coupling grating 103 of the blue waveguide plate to enter the human eye. The three-color light formed by the red light, the green light and the blue light is mixed at the human eye, and finally a color image is presented on the retina of the human eye.

For example, in the structure shown in FIG. 17 , the first waveguide plate 110, the second waveguide plate 120 and the third waveguide plate 130 can be taken as an example to illustrate that the blue polarized light and the red polarized light transmitted in the first polarization direction and the green light transmitted in the second polarization direction are generated by the display. 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 are green light, red light and blue light respectively. The three-color light first passes through the coupling grating 102 of the first waveguide plate 110 (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. The three-color light is all totally reflected and propagated in the green waveguide. Due to the polarization of the green light and the red light and the blue light The red and blue lights have different directions, and are absorbed by the polarization structure 104 on the second waveguide plate 120, leaving only the green light to continue propagating in the green waveguide plate, and finally the green light is coupled out from the coupling grating 103 of the green waveguide plate into the human eye; for the second waveguide plate 120 (red waveguide plate), since its diffraction efficiency for the blue light is very low, 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 and green lights enter the first waveguide plate 110, and the red and green lights propagate in the red waveguide plate by total reflection. When passing through the polarization structure 104 on the first waveguide plate 110, due to the different polarization directions of the red and green lights, the green light is absorbed, leaving only the red light to continue propagating in the red waveguide plate, and finally the red The color light is coupled out from the coupling grating 103 of the red waveguide plate and enters the human eye; for the third waveguide plate 130 (blue waveguide plate), similar to the red waveguide plate, the +1st order diffraction light or -1st order diffraction light of the red light can be basically ignored, and the +1st order diffraction light or -1st order diffraction light of the blue light and the green light enters the blue waveguide plate, and the blue light and the green light propagate in the blue waveguide plate by total reflection. When passing through the polarization structure 104 on the third waveguide plate 130, due to the different polarization directions of the blue light and the green light, the green light is absorbed and only the blue light continues to propagate, and finally coupled out from the coupling grating 103 of the blue waveguide plate and enters the human eye. The three-color light formed by the red light, the green light and the blue light is mixed at the human eye, and finally a color image is presented on the retina of the human eye.

For example, FIG18 is a schematic diagram of another optical path propagating in an optical waveguide structure provided by 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 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 respectively a blue light, a green light and a red light, and the polarization directions of the blue light, the green light and the red light are the same. For example, the collimated light R, G, B emitted from the display passes through the coupling grating 102. When passing through the blue waveguide plate, only the blue light is polarized and converted, and the propagation direction changes from the first direction to the second direction, and the propagation directions of the red light and the green light remain unchanged, so the blue light continues to propagate after being reflected by the polarization structure, and the red light and the green light are absorbed by the polarization structure. Finally, only the blue light is coupled out by the coupling grating. The red light, green light and blue light emitted from the first waveguide plate 110 (blue waveguide plate) reach the second waveguide plate 120 (green waveguide plate), and pass through the coupling grating 102 of the second waveguide plate 120. When propagating through the green waveguide plate, only the green light is polarized and the propagation direction is changed from the first direction to the second direction. The propagation directions of the red light and the blue light remain unchanged, so the green light continues to propagate after being reflected by the polarization structure, and the red light and the blue light are absorbed by the polarization structure. Finally, only the green light is coupled out by the coupling grating, and finally the three-color light is combined into a color 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-color light will be combined into a color pattern at the retina of the human eye.

For example, FIG. 19 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 the green light is transmitted between the red waveguide sheet and the blue waveguide sheet, the green light is transmitted between the blue waveguide sheet and the red waveguide sheet. There are responses in the blue waveguide sheet. Figure 19 is equivalent to decomposing and fusing the green waveguide sheet into the blue waveguide sheet and the red waveguide sheet, forming the BG waveguide sheet (blue-green waveguide sheet) and the 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, and the green light can be designed as non-polarized light, and the polarization directions of the blue light and the red light are designed to be in opposite directions.

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 the light emitted by the display passes through the blue-green waveguide plate, the red light will be blocked by the polarization structure, and the blue light and the green light will continue to propagate and be coupled out to the human eye by the coupling grating 103 on the first waveguide plate 110. When the light is incident on the red-green waveguide plate, the blue light will be blocked by the polarization structure, and the red light and the green light will continue to propagate and be coupled out to the human eye by the coupling grating 103 on the second waveguide plate 120. Finally, the three-color light is combined into a color pattern at the retina of the human eye.

For example, in another example, the first waveguide plate 110 may also be a red-green waveguide plate, and the second waveguide plate 120 may also be a blue-green waveguide plate. When the light emitted by the display passes through the red-green waveguide plate, the blue light will be blocked by the polarization structure, and the red light and the green light will continue to propagate and be coupled out to the human eye by the coupling grating 103 on the first waveguide plate 110. When the light is incident on the blue-green waveguide plate, the red light will be blocked by the polarization structure, and the blue light and the green light will continue to propagate and be coupled out to the human eye by the coupling grating 103 on the second waveguide plate 120. Finally, the three-color light is combined into a color pattern at the retina of the human eye.

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 the red light emitted by the display have polarization directions of the same direction. The polarization directions of the monochromatic light are converted by 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 the red-green waveguide plate, respectively.

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 the light emitted by the display passes through the blue-green waveguide plate, since the green light has 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 light or the 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, and finally the blue light and the green light are coupled out from 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 light and the red light, so that the red light can be reflected by the polarization structure, and the blue light is absorbed by the polarization structure, and finally the red light and the green light are coupled out from the coupling grating, and finally the three-color light is combined at the cornea of the human eye. Into colorful patterns.

For example, in another example, the first waveguide plate 110 is a red-green waveguide plate, and the second waveguide plate 120 is a blue-green waveguide plate. When the light emitted by the display passes through the red-green waveguide plate, since the green light has both the light polarized in the first polarization direction and the 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 light or the 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, and finally the red light and the green light are coupled out from 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 light and the blue light, so that the blue light can be reflected by the polarization structure, and the red light is absorbed by the polarization structure, and finally the blue light and the green light are coupled out from the coupling grating, and finally the three-color light is combined into a color pattern at the cornea of the human eye.

At least one embodiment of the present disclosure further provides a display device. For example, FIG. 21 is a block diagram of a display device provided by at least one embodiment of the present disclosure. As shown in FIG. 21, the display device 300 includes the optical waveguide structure 200 in 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 used to emit a light beam with image information. The features of the display device 300 can refer to the above description of the optical waveguide structure 200, which 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.

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.

For example, in combination with Figures 21 and 22, the display device 300 may include a spatial light modulator for diffracting light from the light waveguide structure 200 to reproduce a holographic image, in addition to a display 303 for providing light and an optical waveguide structure 200 for guiding light from the display 303. The display 303 can provide a coherent light beam, for example, a light 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 can 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 that emit light of different wavelengths. For example, a first light source emitting light of a first wavelength band, A second light source emits light of a second wavelength band different from the first wavelength band, and a third light source emits light of a third wavelength band different from the first and second wavelength bands. The light of the first, second and third wavelength bands may be red, green and blue, respectively.

For example, the display device 300 may further include a controller that controls the driving of the light source structure. The controller may include a plurality of control units that sequentially control the radiation direction of the light beams, thereby forming a display image in the left eye and the right eye of the viewer in a time sequence.

At least one embodiment of the present disclosure further provides a method for preparing a waveguide sheet, the method for preparing the 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; 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, and the process of forming the waveguide sheet using the preparation method comprises forming a polarization structure between the in-coupling grating and the out-coupling grating, the polarization structure can reflect light having a first polarization state included in the light beam, and make the light of the first polarization state propagate in a total reflection manner in the optical waveguide body, and 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.

For example, FIG. 23 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.

Step S101: providing 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.

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.

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.

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

For example, FIG. 24 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.

Step S201: providing 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.

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.

For example, the folding grating is configured to receive light of a first polarization state transmitted from the coupling-in grating and perform pupil expansion transmission.

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 a pupil expansion effect on the light transmitted thereto.

For example, FIG. 25 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.

Step S301: providing 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.

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.

For example, the folding grating is configured to receive light of a first polarization state transmitted from the coupling-in grating and perform pupil expansion transmission.

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.

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%.

For example, in one example, the polarization structure is a metal wire grid polarizer, and a nano-imprinting method is used to form an in-coupling grating, a metal wire grid polarizer, a folding grating, and an out-coupling grating.

For example, FIG26 is a process diagram of a method for preparing a waveguide sheet provided by at least one embodiment of the present disclosure. As shown in FIG26 , an electron beam exposure technique or an ultraviolet exposure technique may be used to prepare a template of an optical waveguide. For example, a nanoimprint lithography (NIL) manufacturing device may be used for mass production.

For example, in Figure 26, process (A) is a process for preparing an electron beam exposure master template, which includes providing a substrate 501, which may 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 developing, 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.

For example, in FIG. 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 adhesive 505 on the electron beam exposure master template 504, and then placing a template 506 on the template adhesive 505, UV curing or thermal curing the template adhesive 505, and finally performing a demolding process to remove the template adhesive 505. The entirety of the template 506 is detached from the electron beam exposure master template 504 to form a nanoimprint lithography template 507 .

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, performing an imprint treatment on the glue material 508 using a nanoimprint lithography template 507, and performing an ultraviolet curing treatment on the glue material 508 during the imprint treatment, and removing the nanoimprint lithography template 507 after the glue material 508 is cured to form a nanoimprint lithography substrate 509.

At least one embodiment of the present disclosure further provides a method for preparing an optical waveguide structure. For example, FIG. 27 is a flow chart of a method for preparing an optical waveguide structure provided by at least one embodiment of the present disclosure. The preparation method includes the following steps.

Step S401: providing a multi-layer waveguide.

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

Step S402: stacking multiple waveguide sheets.

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

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 bond the edges of two adjacent waveguide plates in their entirety, or it can bond half of the edges of two adjacent waveguide plates.

The waveguide plate and its preparation method, the optical waveguide structure and its preparation method, and the display device provided by at least one embodiment of the present disclosure have at least the following beneficial technical effects: the waveguide plate includes a polarization structure arranged between the coupling-in grating and the coupling-out grating, and the polarization structure can reflect the light with a first polarization state included in the light beam, and make the light with the first polarization state propagate in the optical waveguide body in a total reflection manner, so that the stacking of multiple layers of the above-mentioned waveguide plates can solve the problem of color deviation caused by the response of the optical waveguide structure to the full band of visible light.

There are a few points to note:

(1) The drawings of the embodiments of the present disclosure only relate to the structures related to the embodiments of the present disclosure, and other structures may refer to the general design.

(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 enlarged or reduced, that is, these drawings are not drawn according to the actual scale.

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

The above description is only a specific implementation 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 (18)

A waveguide sheet comprises 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. The waveguide according to claim 1 further comprises a folding grating arranged on the first major 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. 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. The waveguide according to claim 3, wherein the polarization structure comprises at least one of a metal wire grid polarizer, a chemical reflective polarizer, and a metasurface structure. 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%. The waveguide plate 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. The waveguide sheet according to claim 6, wherein the one-dimensional grating comprises at least one of a one-dimensional rectangular wire grating, a one-dimensional blazed wire grating and a one-dimensional tilted wire grating; and the two-dimensional grating comprises a two-dimensional metasurface array. The waveguide plate 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. The waveguide plate according to any one of claims 1 to 7, wherein an extension direction of the grating lines of the in-coupling grating intersects with an extension direction of the grating lines of the out-coupling grating. An optical waveguide structure comprises multiple layers of waveguide sheets as described in any one of claims 1 to 9, wherein the multiple layers of waveguide sheets are stacked, and two adjacent layers of the waveguide sheets are connected by a sealing glue so that the multiple layers of the waveguide sheets are integrated. The optical waveguide structure according to claim 10 further comprises a cover plate arranged at the outermost side of the plurality of layers of the stacked waveguide sheets, wherein the cover plate is a glass cover plate or a transparent resin cover plate. A display device comprising the optical waveguide structure according to claim 10 or 11. The display device according to claim 12 further comprises a projection structure, wherein the projection structure comprises a display, and the display is used to emit a light beam having image information. 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. The preparation method according to claim 14 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. The preparation method according to claim 15, further comprising: 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%. According to the preparation method of 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 nanoimprinting method. 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.