Optical waveguide device and preparation method therefor, and near-eye display device

Abstract

An optical waveguide device and a preparation method therefor, and a near-eye display device. The optical waveguide device (1) comprises at least one optical waveguide (10). The optical waveguide (10) comprises: a waveguide sheet (11), which is used for making light beams transmit in the waveguide sheet (11) in a total reflection manner, wherein the waveguide sheet (11) has a coupling-in region (B) and at least two coupling-out regions (A); a coupling-in grating (12), which is arranged in the coupling-in region (B) and is used for coupling the light beams into the waveguide sheet (11); and at least two coupling-out gratings (13), which are correspondingly arranged in the at least two coupling-out regions (A) on a one-to-one basis, and are used for coupling out the light beams, which are transmitted in the waveguide sheet (11) in a total reflection manner, wherein the light intensities of the light beams coupled out by the at least two coupling-out gratings (13) are identical. The present application can improve the exit pupil uniformity of the optical waveguide device (1), thereby improving the visual experience of users, and also reducing the research and development costs incurred by the use of masks and the impact caused by diffraction effects.

Description

Optical waveguide device, method of manufacturing the same, and near-eye display device

[0001] This application claims priority to the Chinese patent application No. 2024105275767, filed on April 28, 2024, and entitled "Optical waveguide device, method of manufacturing the same, and near-eye display device", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the field of optical technology, and in particular to an optical waveguide device, a method of manufacturing the same, and a near-eye display device. BACKGROUND

[0003] With the development of augmented reality (AR) near-eye display technology, near-eye display devices are gradually applied in fields such as life entertainment, medical treatment, navigation, and education.

[0004] Among them, the optical waveguide in the near-eye display device can realize a larger eyebox range without increasing the size of the device. The optical waveguide mainly includes a grating and a waveguide sheet. The light beam propagates forward in the waveguide sheet through multiple diffractions, and is coupled out to enter the human eye. However, with the increase of the number of diffractions, each time the diffraction light contacts the grating, part of the light beam will be coupled out, causing the light intensity to weaken in turn, resulting in the phenomenon of uneven energy of the out-pupil light rays, which leads to poor viewing effect of the human eye, thereby affecting the visual experience of the user.

[0005] In order to improve the out-pupil uniformity, in the current volume holographic grating related technology, a mask plate is usually used to adjust the exposure. However, the edge of the mask plate has a diffraction effect, which may affect the performance of the grating. In addition, new mask plates need to be developed for different waveguide output structures, thereby increasing the research and development cost. SUMMARY

[0006] The present application provides an optical waveguide device, a method of manufacturing the same, and a near-eye display device, which aims to solve the technical problem of uneven out-pupil light rays in the near-eye display device.

[0007] In a first aspect, to solve the above technical problem, the present application provides an optical waveguide device comprising: at least one optical waveguide, the optical waveguide comprising:

[0008] a waveguide sheet for total internal reflection transmission of a light beam in the waveguide sheet, the waveguide sheet having a coupling-in region and at least two coupling-out regions;

[0009] a coupling-in grating arranged in the coupling-in region, the coupling-in grating being configured to couple the light beam into the waveguide sheet;

[0010] At least two out-coupling gratings are arranged one by one in the at least two out-coupling regions, and the out-coupling gratings are used to couple out the light beams totally internally reflected and transmitted by the waveguide sheet.

[0011] The light beams coupled out by the at least two out-coupling gratings have consistent light intensity.

[0012] In an embodiment, the at least two out-coupling gratings include a first out-coupling grating and a last out-coupling grating, the first out-coupling grating is close to the in-coupling grating, and the last out-coupling grating is away from the in-coupling grating, and from the first out-coupling grating to the last out-coupling grating, the light beam coupling-out capability of the out-coupling gratings gradually increases.

[0013] In an embodiment, the in-coupling grating forms a one-dimensional region or a two-dimensional region in the in-coupling region, the one-dimensional region is used for light beams to be transmitted in one direction in the waveguide sheet, and the two-dimensional region is used for light beams to be transmitted in two mutually perpendicular directions in the waveguide sheet; and the at least two out-coupling gratings form a one-dimensional region or a two-dimensional region in the out-coupling region, the one-dimensional region is used for light beams to be coupled out in one direction in the waveguide sheet, and the two-dimensional region is used for light beams to be coupled out in two mutually perpendicular directions in the waveguide sheet.

[0014] In an embodiment, the optical waveguide device includes a plurality of optical waveguides arranged in layers, and different optical waveguides are used to transmit light beams of different incident angles.

[0015] In an embodiment, the optical waveguide device includes a plurality of optical waveguides arranged in layers, and different optical waveguides are used to transmit light beams of different wavelengths.

[0016] In an embodiment, the in-coupling grating includes a multiplex in-coupling grating used to couple in light beams of multiple incident angles; the out-coupling grating includes at least two sub-multiplex out-coupling gratings, each of which is used to couple out light beams of multiple exit angles; and the incident angles are equal to the exit angles.

[0017] In an embodiment, the in-coupling grating includes a multiplex in-coupling grating used to couple in light beams of multiple wavelengths; the out-coupling grating includes at least two sub-multiplex out-coupling gratings, each of which is used to couple out light beams of multiple wavelengths.

[0018] In a second aspect, the application further provides a preparation method of the optical waveguide device, comprising:

[0019] Obtaining materials with multiple different refractive indexes, and determining the shape of the region formed by each material with a different refractive index on the surface of the waveguide sheet;

[0020] According to the region shape, a printing technology is applied to print each material with different refractive index on the surface of the waveguide sheet to generate a material layer;

[0021] Based on a double-beam exposure technology, the material layer is exposed to obtain the in-coupling grating and the out-coupling grating with different refractive index modulation;

[0022] According to the waveguide sheet, the in-coupling grating and the out-coupling grating with different refractive index modulation, the optical waveguide device is prepared.

[0023] In an embodiment, the materials with different refractive index are printed on the surface of the waveguide sheet by an inkjet printing technology, so that at least two out-coupling gratings are formed by one-time double-beam exposure.

[0024] In an embodiment, the double-beam includes a first recording beam and a second recording beam, and the first recording beam and the second recording beam are used to expose the waveguide sheet with the materials with different refractive index according to a preset recording beam included angle.

[0025] In a third aspect, the application further provides a near-eye display device, which includes an optical machine and the optical waveguide device according to any one of the embodiments of the first aspect, and the in-coupling grating is used to couple the light beam emitted by the optical machine into the waveguide sheet, and the out-coupling grating is used to couple the light beam transmitted by the waveguide sheet through total internal reflection out of the human eye.

[0026] The application provides an optical waveguide device, a preparation method thereof and a near-eye display device. By arranging a waveguide sheet, an in-coupling grating and at least two out-coupling gratings in the optical waveguide of the optical waveguide device, the out-coupling grating is used to couple out the light beam transmitted by the waveguide sheet through total internal reflection, so that the light intensity of the coupled-out light beam is consistent, the exit pupil uniformity of the optical waveguide device is improved, the visual experience of the user is improved when the optical waveguide device is used in the near-eye display device, and the research and development cost of using a mask plate and the influence of the diffraction effect are reduced. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed in the embodiment description. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can also be obtained by those skilled in the art without any creative labor.

[0028] FIG. 1 is a structural schematic diagram of an optical waveguide device according to an embodiment of the application;

[0029] FIG. 2 is a schematic diagram of the light propagation path of the optical waveguide device according to an embodiment of the application;

[0030] FIG. 3 is a schematic diagram of a light waveguide device structure according to another embodiment of the present application;

[0031] FIG. 4 is a schematic diagram of a light propagation path of a light waveguide device according to another embodiment of the present application;

[0032] FIG. 5 is a schematic diagram of a light propagation path according to an embodiment of the present application;

[0033] FIG. 6 is a schematic diagram of a light waveguide device structure according to yet another embodiment of the present application;

[0034] FIG. 7 is a schematic diagram of a light propagation path according to another embodiment of the present application;

[0035] FIG. 8 is a schematic diagram of a light propagation path of a multi-layer light waveguide device according to an embodiment of the present application;

[0036] FIG. 9 is a schematic diagram of a light propagation path of a multiplexed set of gratings according to an embodiment of the present application;

[0037] FIG. 10 is a schematic diagram of a light propagation path of a light waveguide device according to yet another embodiment of the present application;

[0038] FIG. 11 is a schematic diagram of a process for fabricating an out-coupling grating according to an embodiment of the present application;

[0039] FIG. 12 is a schematic diagram of a structure of an out-coupling grating according to an embodiment of the present application;

[0040] FIG. 13 is a schematic diagram of a near-eye display device according to an embodiment of the present application. DETAILED DESCRIPTION

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. For example, the terms "length", "width", "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, merely describe the orientation in the drawings on which the application is illustrated and are not intended to be limiting of the application.

[0042] The terms "comprise", "comprising", "include", "including", "have" and "having" and any variations thereof in the specification and claims herein are intended to cover both the singular and the plural unless otherwise indicated; the terms "first", "second", "third", and the like in the specification and claims herein are used for distinguishing between similar objects having different specific names and are not used logically to describe a particular sequence. The term "plurality" means two or more, unless otherwise indicated.

[0043] The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. It should also be noted that like reference numerals are used to designate corresponding parts throughout the figures.

[0044] Furthermore, references herein to "exemplary" mean that the particular feature, structure, or characteristic being referred to can be included in at least one embodiment of the application. The appearances of the phrase "in an exemplary embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily all referring to a common or all possible embodiments. It is expressly understood that any of the features, structures, or characteristics as described in connection with an embodiment can be included in at least one implementation of the application. Moreover, it is to be understood that the features, structures, or characteristics can be combined in any suitable manner in the application.

[0045] As shown in FIG. 1, in an embodiment, the application provides an optical waveguide device 1, which comprises at least one optical waveguide 10, the optical waveguide 10 comprising a waveguide sheet 11, an in-coupling grating 12 and at least two out-coupling gratings 13, the at least two out-coupling gratings 13 corresponding to at least two out-coupling areas A of the waveguide sheet 11, the in-coupling grating 12 being arranged at an in-coupling area B of the waveguide sheet 11, the in-coupling grating 12 being configured to in-couple a light beam into the waveguide sheet 11, the waveguide sheet 11 being configured to totally internally reflect and transmit the in-coupled light beam, and the out-coupling gratings 13 being configured to out-couple the totally internally reflected and transmitted light beam; wherein the light beams out-coupled by the at least two out-coupling gratings 13 have consistent light intensity.

[0046] It should be noted that the light beam propagates in a split manner when passing through the out-coupling gratings 13, a part of which is out-coupled as an exit light beam to the human eye, and another part of which continues to be totally internally reflected and transmitted in the waveguide sheet 11 to the next out-coupling grating 13 as a diffracted light beam. The light intensity of the diffracted light beam gradually attenuates in the waveguide sheet 11 each time the light beam is out-coupled as an exit light beam from the out-coupling grating 13. For a volume holographic grating, by arranging the out-coupling gratings 13 with different refractive index modulation, the diffraction efficiency of the out-coupling gratings can be changed, and the energy of the light beam out-coupled to the human eye can be adjusted to ensure that the light beams out-coupled by the out-coupling gratings 13 have consistent light intensity, thereby achieving the effect of uniform exit pupil.

[0047] The refractive index modulation of the grating is related to the refractive index of the material, and the refractive index of the material is different, so the refractive index modulation of the out-coupling grating 13 formed is also different. The refractive index modulation of the out-coupling grating 13 can be modulated by changing the composition of the coating material. The coating material can produce different refractive index modulations under the same wavelength and the same dose of exposure conditions, so that the out-coupling grating 13 with different refractive index modulations is obtained. The light intensity of the light beam coupled out by the out-coupling grating 13 is the same, the pupil uniformity of the optical waveguide device 1 is improved, and the influence of the non-uniform pupil on the user is avoided.

[0048] For example, the in-coupling grating is a surface relief grating or a volume holographic grating; and the out-coupling grating is a surface relief grating or a volume holographic grating. The in-coupling grating and the out-coupling grating can be selected as a surface relief grating or a volume holographic grating as needed.

[0049] For example, as shown in FIG. 2, the in-coupling grating 12 couples the incident light beam 20 into the waveguide sheet 11 to obtain a first diffracted light beam 301. The first diffracted light beam 301 is totally reflected and transmitted in the waveguide sheet 11. When the first diffracted light beam 301 is totally reflected to an out-coupling grating 13, the out-coupling grating 13 couples out the first diffracted light beam 301 to obtain a first exit light beam 401 and a second diffracted light beam 302, respectively. The first exit light beam 401 is incident on the human eye, and the second diffracted light beam 302 continues to be totally reflected and transmitted in the waveguide sheet 11. When the first diffracted light beam 301 is totally reflected to another out-coupling grating 13, the out-coupling grating 13 couples out the second diffracted light beam 302 to obtain a second exit light beam 402 and a third diffracted light beam 303, respectively. The second exit light beam 402 is incident on the human eye, and the third diffracted light beam 303 continues to be totally reflected and transmitted in the waveguide sheet 11. The process is repeated until the light beam transmission is completed. At this time, the light intensity of the first exit light beam 401 and the second exit light beam 402 is consistent, the pupil uniformity of the optical waveguide device 1 is achieved, and the user's visual experience is improved.

[0050] As shown in FIG. 3, in an embodiment, the at least two out-coupling gratings 13 include a first out-coupling grating 131 and a last out-coupling grating 133. The first out-coupling grating 131 is close to the in-coupling grating 12, and the last out-coupling grating 133 is far away from the in-coupling grating 12. From the first out-coupling grating 131 to the last out-coupling grating 133, the light beam coupling-out capability of the out-coupling gratings 13 gradually increases.

[0051] It should be noted that the light beam coupling-out capability of the out-coupling grating 13 can be represented by the diffraction efficiency. The calculation formula of the diffraction efficiency of the transmission type holographic volume grating is as follows:

[0052] In the formula, υ is an additional phase, and ζ is a phase mismatch parameter, which are respectively represented as:

[0053] where Δn is the refractive index modulation; d is the grating medium thickness; λ is the wavelength of the incident light beam in vacuum; θ r , θ s are the angles between the incident light beam and the diffracted light beam and the x-axis, respectively; δ is the phase mismatch factor, which can be expressed as:

[0054] where θ is the tilt angle of the grating; K is the grating vector; n0 is the refractive index of the medium; and from the above equation, it can be seen that the factors affecting the performance of the holographic volume grating are the incident angles θ r and θ s , the preparation wavelength λ, the thickness d of the holographic volume grating, and the refractive index modulation Δn.

[0055] In an embodiment, in order to make the light intensity of the light beams coupled out by the at least two out-coupling gratings consistent, the diffraction efficiency of the nth out-coupling grating is set to x n , and the energy of the light intensity of the light beam after the nth reflection of the incident light beam is set to η n , and there is x

[0056] For example, there are a first out-coupling grating and a last out-coupling grating, the diffraction efficiency of the first out-coupling grating is set to 20%, and the diffraction efficiency of the last out-coupling grating is set to 25% so as to make the light intensity of the light beams coupled out consistent. It can be understood that the diffraction efficiency of the reflection-type holographic volume grating can also be set accordingly so as to make the light intensity of the light beams coupled out consistent, which is not limited herein.

[0057] The refractive index modulation of the out-coupling gratings 13 is set to modulate the diffraction efficiency, so that the light beams coupled out by the first out-coupling grating 131 to the last out-coupling grating 133 have the same light intensity, thereby improving the exit pupil uniformity of the optical waveguide device 1.

[0058] In another embodiment, the in-coupling grating 12 and the out-coupling grating 13 are located on the same side of the waveguide sheet 11. It should be noted that the light beams are emitted from the same side of the in-coupling grating 12 and the out-coupling grating 13, the light beams contact the in-coupling grating 12 to be coupled into the waveguide sheet 11 for total reflection transmission, the total reflection transmitted light beams contact the out-coupling grating 13 to be coupled out to the exit light beams 40 entering the human eye, thereby being able to present the image formed by the light beams to the user through the optical waveguide device 1. In addition, the in-coupling grating 12 and the out-coupling grating 13 can also be located on opposite sides of the waveguide sheet 11, respectively.

[0059] For example, as shown in FIG. 4, there is a coupling-out area A, the first out-coupling grating 131, the second out-coupling grating 132, and the last out-coupling grating 133 are correspondingly provided in the coupling-out area A, and the refractive index modulations of the first out-coupling grating 131, the second out-coupling grating 132, and the last out-coupling grating 133 are respectively δ n1 , δn2 and δ n3 The diffraction efficiencies of the first diffraction beam 301, the second diffraction beam 302 and the third diffraction beam 303 are x1%, x2% and x3% respectively. If the energy of the light intensity of the first diffraction beam 301, the second diffraction beam 302 and the third diffraction beam 303 is η1, η2 and η3 respectively, and the energy loss is ignored, then η1*x1% = η2*x2% = η3*x3%, wherein η1*(1-x1) = η2, η2*(1-x2) = η3. At this time, the light intensity of the light beam coupled out by each out-coupling grating 13 is consistent, thereby realizing the exit pupil uniformity of the optical waveguide device 1 and improving the visual experience of the user.

[0060] In an embodiment, the in-coupling grating forms a one-dimensional region or a two-dimensional region in the in-coupling region, the one-dimensional region being used for the transmission of the light beam in the waveguide sheet in one direction, and the two-dimensional region being used for the transmission of the light beam in the waveguide sheet in two mutually perpendicular directions; and the at least two out-coupling gratings form a one-dimensional region or a two-dimensional region in the out-coupling region, the one-dimensional region being used for the out-coupling of the light beam transmitted in the waveguide sheet in one direction, and the two-dimensional region being used for the out-coupling of the light beam transmitted in the waveguide sheet in two mutually perpendicular directions.

[0061] For example, the in-coupling grating 12 forms a one-dimensional region in the in-coupling region, and the out-coupling grating 13 forms a one-dimensional region in the out-coupling region. The in-coupling grating 12 in the one-dimensional region transmits the first diffraction beam coupled into the waveguide sheet 11 in one direction, and then transmits to the out-coupling region through total reflection. It can be understood that the in-coupling grating 12 in the one-dimensional region couples the incident light beam into the waveguide sheet to generate the first diffraction beam, and the out-coupling grating 13 in the one-dimensional region one-dimensionally expands the pupil of the first diffraction beam and out-couples, so that the one-dimensionally expanded exit light beam 40 can be out-coupled to the human eye, thereby increasing the distance between the left and right eyes in the eye socket, and thus solving the problem of different interpupillary distances of different people and improving the applicability of the optical waveguide device.

[0062] In another embodiment, the in-coupling grating 12 forms a two-dimensional region in the in-coupling region, and the out-coupling grating 13 forms a two-dimensional region in the out-coupling region. The in-coupling grating 12 in the two-dimensional region transmits the first diffraction beam coupled into the waveguide sheet 11 in two mutually perpendicular directions, and then transmits to the out-coupling region through total reflection. It can be understood that the in-coupling grating 12 in the two-dimensional region couples the incident light beam into the waveguide sheet to generate the first diffraction beam, and the out-coupling grating 13 in the two-dimensional region two-dimensionally expands the pupil of the first diffraction beam and out-couples, and makes the two-dimensionally expanded exit light beam 40 be out-coupled to the human eye. In addition to increasing the distance between the left and right eyes in the eye socket, it can also increase the distance between the front and back eyes in the eye socket, thereby being applicable to more users with different face shapes and further improving the applicability of the optical waveguide device.

[0063] As shown in FIGS. 3-7, in an embodiment, the at least two out-coupling gratings 13 form a one-dimensional region a or a two-dimensional region aa in the out-coupling area A, the one-dimensional region a is used to out-couple the light beams transmitted in one direction in the waveguide sheet 11, and the two-dimensional region aa is used to out-couple the light beams transmitted in two mutually perpendicular directions in the waveguide sheet 11.

[0064] It should be noted that the grating of the one-dimensional region can realize pupil expansion of the light beams in one direction, so as to increase the distance between the left and right eyes of the user in the dynamic eye socket, thereby solving the problem of different pupil distances of different people, and improving the applicability of the optical waveguide device. In addition, the grating of the two-dimensional region can realize pupil expansion of the light beams in two orthogonal directions, which can not only increase the distance between the left and right eyes of the user in the dynamic eye socket, but also increase the distance between the longitudinal directions of the user in the dynamic eye socket, thereby being applicable to more face shapes of the user, and further improving the applicability of the optical waveguide device.

[0065] For example, as shown in FIGS. 3-5, the in-coupling grating 12 forms a one-dimensional region b in the in-coupling area, and the at least two out-coupling gratings 13 form a one-dimensional region a in the out-coupling area A, the one-dimensional region a includes a region a1 and a region a2, the region a1 is arranged adjacent to the region a2, the first out-coupling grating 131 is arranged in the region a1, and the last out-coupling grating 133 is arranged in the region a2. The first diffracted light beam 301 coupled into the waveguide sheet 11 is transmitted to the region a1, and then transmitted to the region a2 through total reflection. It can be understood that the first out-coupling grating 131 in the region a1 completes one-dimensional pupil expansion of the first diffracted light beam 301, and the last out-coupling grating 133 in the region a2 further one-dimensionally expands the first diffracted light beam 301 after the one-dimensional pupil expansion, so as to finally realize one-dimensional pupil expansion of the light beams in the out-coupling area A, and make the out-coupled light beam 40 after the one-dimensional pupil expansion be able to be out-coupled to the human eye, so as to increase the distance between the left and right eyes of the user in the dynamic eye socket, thereby solving the problem of different pupil distances of different people, and improving the applicability of the optical waveguide device.

[0066] In another embodiment, as shown in FIGS. 6-7, the in-coupling grating 12 forms a two-dimensional region bb in the in-coupling region, and the out-coupling grating 13 forms a two-dimensional region aa in the out-coupling region A, the two-dimensional region aa includes a region aa1 and a region aa2, the region aa1 is arranged adjacent to the region aa2, the first out-coupling grating 131 is arranged in the region aa1, and the last out-coupling grating 133 is arranged in the region aa2. The first diffracted light beam 301 coupled into the waveguide sheet 11 is transmitted to the region aa1 and then transmitted to the region aa2 through total reflection. It can be understood that the first out-coupling grating 131 in the region aa1 completes two-dimensional pupil expansion of the first diffracted light beam 301, and the last out-coupling grating 133 in the region aa2 further expands the pupil of the first diffracted light beam 301, so as to finally realize two-dimensional pupil expansion of the light beam in the out-coupling region A and enable the two-dimensionally expanded light beam 40 to be coupled out to the human eye. In addition to increasing the horizontal distance between the left and right eyes of the user in the eyebox, the vertical distance between the eyes of the user in the eyebox can also be increased, so as to be applicable to more users with different face shapes, and further improve the applicability of the optical waveguide device 1. The regions aa1 and aa2 can be regions with different shapes and / or different sizes.

[0067] It should be noted that the in-coupling grating can be configured to fold the light beam through another grating (such as a folding grating), so as to realize pupil expansion of the light beam in two orthogonal directions. In addition, the in-coupling grating 12 and the out-coupling grating 13 can be further provided with other functional grating modules to expand the pupil of the light beam, and the pupil expansion is not limited to the horizontal direction or the vertical direction.

[0068] For example, when the in-coupling grating forms a one-dimensional region in the in-coupling region and the out-coupling grating forms a two-dimensional region in the out-coupling region, a folding grating can be arranged to fold the light beam transmitted in one direction of the one-dimensional region to the direction capable of being coupled out by the two-dimensional region.

[0069] In another embodiment, when the in-coupling grating forms a two-dimensional region in the in-coupling region and the out-coupling grating forms a one-dimensional region in the out-coupling region, a folding grating can be arranged to fold the light beam in the other direction of the two directions perpendicular to each other to the direction capable of being coupled out by the one-dimensional region.

[0070] As shown in FIG. 8, in an embodiment, the optical waveguide device 1 includes a plurality of optical waveguides 10 arranged in a stack, and different optical waveguides 10 are used to transmit light beams of different wavelengths. Among them, two adjacent optical waveguides 10 are bonded and fixed by the adhesive 50. It should be noted that by changing the exposure recording beam angle or the wavelength of the exposure beam, the in-coupling grating 12 of each layer can couple in an incident light beam 20 of a wavelength, and the out-coupling grating 13 of each layer can couple out an exit light beam 40 corresponding to the coupling-in wavelength of the in-coupling grating 12 of each layer, so that the optical waveguide device 1 including a plurality of optical waveguides 10 is suitable for light beams of multiple wavelengths, improves the application range of the optical waveguide device 1 for light beam wavelengths, realizes color display of the optical waveguide device 1, and also can realize pupil uniformity of the optical waveguide device 1.

[0071] For example, as shown in FIG. 8, a first optical waveguide 101, a second optical waveguide 102 and a third optical waveguide 103 are provided, each optical waveguide 10 can be incident to an incident light beam 20 of a wavelength, and three incident light beams 20 are respectively a first incident light beam 201, a second incident light beam 202 and a third incident light beam 203. The three incident light beams 20 are respectively coupled into the in-coupling grating 12 of the corresponding optical waveguide 10 at the same incident angle, each incident light beam 20 is transmitted by total reflection in the corresponding optical waveguide 10, the first optical waveguide 101 is provided with a first out-coupling grating 131, a second out-coupling grating 132 and a last out-coupling grating 133, which respectively couple out a first exit light beam 401, a second exit light beam 402 and a third exit light beam 403, and the first exit light beam 401, the second exit light beam 402 and the third exit light beam 403 have the same light intensity. It can be understood that the exit light beams 40 of the second optical waveguide 102 and the third optical waveguide 103 also have the same light intensity, so as to realize the pupil uniformity of the optical waveguide device 1 for light beams of different wavelengths, and further improve the visual experience of the user.

[0072] In another embodiment, the optical waveguide device includes a plurality of optical waveguides arranged in a stack, and different optical waveguides are used to transmit light beams of different incident angles. It should be noted that by changing the exposure conditions of the coating material on the waveguide sheet, for example, by changing the recording beam angle or the wavelength of the exposure beam, the in-coupling grating of each layer can couple in an incident light beam of an incident angle, and the out-coupling grating of each layer can couple out an exit light beam corresponding to the coupling-in incident angle of the in-coupling grating, so as to improve the application range of the optical waveguide device for light beam incident angles, and also can realize the pupil uniformity of the optical waveguide device.

[0073] As shown in FIG. 9, in an embodiment, the in-coupling grating 12 includes a multiplex in-coupling grating 14 for coupling in light beams of multiple incident angles; the out-coupling grating 13 includes at least two sub-multiplex out-coupling gratings 15, each of which is used for coupling out light beams of multiple exit angles; wherein the incident angle is equal to the exit angle.

[0074] It should be noted that the multiplex in-coupling grating and the multiplex out-coupling grating can form a multiplex set of gratings. Since the transmission directions of incident light beams of different incident angles are different, the multiplex in-coupling grating is needed to diffract incident light beams of different incident angles respectively, and then the multiplex out-coupling grating is used for coupling out. By changing the angle of the exposure beam in the same area of the in-coupling area or the out-coupling area, a plurality of sets of gratings can be recorded in the multiplex in-coupling grating or the multiplex out-coupling grating, and each set of grating equation can obtain a corresponding grating vector K. By designing the grating vector K, light beams of multiple wavelengths or multiple incident angles can be diffracted and coupled out.

[0075] As shown in FIG. 10, k inc is the incident light beam wave vector, K is the grating vector, the output grating vector is obtained by vector addition of the incident light beam wave vector and the grating vector K, and the output grating vector is obtained according to the grating vector K obtained by the grating equation and the incident light beam wave vector, that is, the wave vector of the diffracted light beam is obtained, wherein the wave vector is the direction of light transmission, and the grating equation can be mλ=d(sinα+sinβ).

[0076] For example, the multiplex in-coupling grating can diffract light beams of multiple angles, the light beams of multiple angles are transmitted in the waveguide sheet by total reflection, when transmitted to at least two multiplex out-coupling gratings, the light beams of multiple angles are coupled out by the at least two multiplex out-coupling gratings, and the light intensity of the out-coupled light beams is uniform, which improves the field of view angle of the light waveguide device and ensures the out-pupil uniformity of the light waveguide device, wherein the field of view angle in the display system is the angle between the display edge and the observation point (human eye).

[0077] As shown in FIG. 9, the multiplexed in-coupling grating 14 couples in the incident light beams 20 with incident angles of 0° and ±30°, respectively. The incident light beam 20 with an incident angle of -30° is the first incident light beam 201, the incident light beam 20 with an incident angle of 0° is the second incident light beam 202, and the incident light beam 20 with an incident angle of +30° is the third incident light beam 203. The multiplexed out-coupling grating 15 includes a first multiplexed out-coupling grating 151, a second multiplexed out-coupling grating 152, and a last multiplexed out-coupling grating 153. The first incident light beam 201 is coupled in from the multiplexed in-coupling grating 14 to obtain a first-order first diffracted light beam 3011. The first-order first diffracted light beam 3011 is totally reflected in the waveguide sheet 11 and is coupled out by the first multiplexed out-coupling grating 151 when the first-order first diffracted light beam 3011 is totally reflected to the first multiplexed out-coupling grating 151. The first multiplexed out-coupling grating 151 couples out the first-order first diffracted light beam 3011 to obtain a first-order first out-coupled light beam 4011 and a first-order second diffracted light beam 3012. The first-order first out-coupled light beam 4011 is incident on the human eye, and the first-order second diffracted light beam 3012 continues to be totally reflected in the waveguide sheet 11. The first-order second diffracted light beam 3012 is coupled out by the second multiplexed out-coupling grating 152 when the first-order second diffracted light beam 3012 is totally reflected to the second multiplexed out-coupling grating 152. The second multiplexed out-coupling grating 152 couples out the first-order second diffracted light beam 3012 to obtain a first-order second out-coupled light beam 4012 and a first-order third diffracted light beam 3013. The first-order second out-coupled light beam 4012 is incident on the human eye, and the first-order third diffracted light beam 3013 continues to be totally reflected in the waveguide sheet 11. The first-order third diffracted light beam 3013 is coupled out from the last multiplexed out-coupling grating 153 to obtain a first-order third out-coupled light beam 4013. At this time, the light intensities of the first-order first out-coupled light beam 4011, the first-order second out-coupled light beam 4012, and the first-order third out-coupled light beam 4013 are consistent. It can be understood that the second incident light beam 202 and the third incident light beam 203 also have the same light intensity when they are coupled out from the first multiplexed out-coupling grating 151, the second multiplexed out-coupling grating 152, and the last multiplexed out-coupling grating 153. The light waveguide device 1 can expand the field of view while ensuring the out-pupil uniformity and improving the user's visual experience.

[0078] In an embodiment, the in-coupling grating includes a multiplexed in-coupling grating for coupling in light beams of multiple wavelengths, and the out-coupling grating includes at least two sub-multiplexed out-coupling gratings, each of which is used for coupling out light beams of multiple wavelengths.

[0079] It should be noted that the multiplexed in-coupling grating can diffract incident light beams of multiple wavelengths. The incident light beams of multiple wavelengths are totally reflected in the waveguide sheet and are coupled out by the at least two multiplexed out-coupling gratings when they are transmitted to the at least two multiplexed out-coupling gratings. The light intensities of the coupled-out light beams are consistent, which can improve the color display of the light waveguide device while ensuring the out-pupil uniformity of the light waveguide device.

[0080] For example, the multiplexed in-coupling grating respectively couples in red, green and blue incident light beams. The red incident light beam is the first incident light beam, the green incident light beam is the second incident light beam, and the blue incident light beam is the third incident light beam. The multiplexed out-coupling grating includes a first multiplexed out-coupling grating, a second multiplexed out-coupling grating and a last multiplexed out-coupling grating. The first incident light beam is coupled in from the multiplexed in-coupling grating to obtain a first-order first diffracted light beam. The first-order first diffracted light beam is totally reflected in the waveguide sheet. When the first-order first diffracted light beam is totally reflected to the first multiplexed out-coupling grating, the first multiplexed out-coupling grating couples out the first-order first diffracted light beam to obtain a first-order first out-coupled light beam and a first-order second diffracted light beam. The first-order first out-coupled light beam is incident on the human eye, and the first-order second diffracted light beam continues to be totally reflected in the waveguide sheet. When the first-order second diffracted light beam is totally reflected to the second multiplexed out-coupling grating, the second multiplexed out-coupling grating couples out the first-order second diffracted light beam to obtain a first-order second out-coupled light beam and a first-order third diffracted light beam. The first-order second out-coupled light beam is incident on the human eye, and the first-order third diffracted light beam continues to be totally reflected in the waveguide sheet. The first-order third diffracted light beam is coupled out from the last multiplexed out-coupling grating to obtain a first-order third out-coupled light beam. At this time, the light intensities of the first-order first out-coupled light beam, the first-order second out-coupled light beam and the first-order third out-coupled light beam are consistent. It can be understood that the out-coupled light beams of the second incident light beam and the third incident light beam respectively coupled out from the first multiplexed out-coupling grating, the second multiplexed out-coupling grating and the last multiplexed out-coupling grating also have the same light intensity. Therefore, not only the color display of the optical waveguide device can be realized, but also the pupil uniformity of the optical waveguide device can be realized, and the user's visual experience can be improved.

[0081] The application further provides a preparation method of the optical waveguide device 1, which comprises the following steps:

[0082] Obtaining materials with different refractive indexes, and determining the shape of a region formed by each material with a different refractive index on the surface of the waveguide sheet;

[0083] According to the region shape, printing each material with a different refractive index on the surface of the waveguide sheet by using a printing technology to generate a material layer;

[0084] Based on a double-beam exposure technology, the material layer is subjected to exposure processing to obtain an in-coupling grating and an out-coupling grating with different refractive index modulation degrees;

[0085] The optical waveguide device is prepared according to the waveguide sheet, the in-coupling grating and the out-coupling grating with different refractive index modulation degrees.

[0086] It should be noted that the materials with different refractive indexes can form gratings with different refractive index modulation degrees after double-beam exposure. The exposure intensity and / or exposure time can be controlled during the exposure processing to obtain the out-coupling grating with different refractive index modulation degrees.

[0087] As shown in FIG. 11, in an embodiment, the materials with different refractive indexes are printed on the surface of the waveguide sheet 11 by inkjet printing technology, so that the at least two out-coupling gratings 13 are formed by one-time double-beam exposure.

[0088] It should be noted that the materials are coated on the surface of the waveguide sheet 11 by inkjet printing technology, and then one-time double-beam exposure is performed, so that the out-coupling gratings 13 with different refractive index modulation degrees are formed, thereby the exit beams 40 coupled out from the out-coupling gratings 13 have the same light intensity, and the exit pupil uniformity of the optical waveguide device 1 is improved. The printing parameters of the inkjet printing technology can be set according to the viscosity and / or surface tension of the sprayed liquid to set the spraying speed and / or spraying pressure, so as to control the uniformity of the printing layer thickness. The printing technology for coating the materials on the surface of the waveguide sheet 11 includes but is not limited to the inkjet printing technology, and can also be other printing technologies, which are not limited herein. The double-beam exposure can be one-time exposure with the same wavelength and the same exposure dose to obtain the out-coupling gratings with different refractive index modulation degrees, wherein the exposure dose is equal to the exposure intensity multiplied by the exposure time.

[0089] For example, as shown in FIGS. 11 and 12, the double beams include a first recording beam L1 and a second recording beam L2, the inkjet printing device P coats the materials M1 to M5 on the substrate in sequence, and the exposure device is opened by an electronic switch, so that the first recording beam L1 and the second recording beam L2 form interference fringes in the materials M1 to M5 in the printing area and are exposed. Due to the different refractive indexes of the materials, the refractive index modulation degrees of the formed out-coupling gratings 13 are also different, so that the out-coupling gratings 13 with different refractive index modulation degrees can be formed after one-time double-beam exposure, the exit beams 40 coupled out from the out-coupling gratings 13 have the same light intensity, and the exit pupil uniformity of the optical waveguide device 1 is improved. The printing technology for coating the materials on the surface of the waveguide sheet 11 includes but is not limited to the inkjet printing technology, and can also be other printing technologies, which are not limited herein.

[0090] As shown in FIG. 11, in an embodiment, the double beams include a first recording beam L1 and a second recording beam L2, and the waveguide sheet 11 printed with at least two materials is exposed according to a preset recording beam included angle α. It should be noted that the wavelength of the double beams or the recording beam included angle α is changed during exposure, so that the gratings can couple in or out beams with different wavelengths, thereby improving the color display of the optical waveguide device 1, and the out-coupling gratings 13 with different refractive index modulation degrees can also ensure the exit pupil uniformity of the optical waveguide device 1. The recording beam included angle α is the included angle between the first recording beam L1 and the second recording beam L2. For example, the recording beam included angle α between the first recording beam and the second recording beam can be 45° or 60°.

[0091] The embodiment of the present application further provides another preparation method of the optical waveguide device 1. The preparation method comprises the following steps: spin-coating photoresist on the waveguide sheet, exposing the photoresist by means of a mask, spin-coating at least two materials with different refractive indexes on the waveguide sheet, and then performing one-time double-beam exposure to form at least two out-coupling gratings.

[0092] It should be noted that the photoresist can be divided into two categories. One is a positive photoresist. The part of the positive photoresist exposed to light undergoes a degradation reaction and can be dissolved by a developer. The pattern of the remaining non-exposed part is consistent with the mask. The other is a negative photoresist. The part of the negative photoresist exposed to light undergoes a cross-linking reaction and becomes insoluble. The non-exposed part is dissolved by the developer. The obtained pattern is complementary to the mask pattern. In the embodiment, the photoresist can be a positive photoresist or a negative photoresist.

[0093] For example, after spin-coating the photoresist on the waveguide sheet, the photoresist is exposed by means of the mask, and the developer is applied to the exposed area, so that the photoresist forms the same pattern as the mask. Then, the material is spin-coated on the developed area. The mask is continuously moved, and the above operations are sequentially performed until the material coating is completed. Finally, one-time double-beam exposure is performed on the material coated on the substrate to form out-coupling gratings with different refractive index modulation. In this way, the uniform out-pupil effect can be achieved, and higher-precision grating partitioning can be realized, thereby further improving the diffraction efficiency at the grating partitioning.

[0094] In another embodiment, the mask can be of any shape, so that the out-coupling gratings can meet various shape requirements. Meanwhile, multiple masks can be used for regional exposure, so that higher-precision grating partitioning can be realized, thereby further improving the diffraction efficiency at the grating partitioning.

[0095] As shown in FIG. 13, in an embodiment, the near-eye display device comprises an optical engine and an optical waveguide device as provided in any of the above embodiments. The in-coupling grating is used to couple the light beam emitted by the optical engine into the waveguide sheet, and the out-coupling grating arranged in the out-coupling domain of the waveguide sheet is used to diffract and couple out the light beam propagating by total internal reflection in the waveguide sheet to the human eye.

[0096] It can be understood that the optical waveguide device provided in any of the above embodiments can couple the light emitted by the optical engine into the waveguide sheet, and the out-coupling grating arranged in the out-coupling domain of the waveguide sheet can diffract and couple out the light propagating by total internal reflection in the waveguide sheet, so that the user can see the image displayed in the waveguide sheet. In addition, the out-coupling grating can couple out the light beams with the same light intensity, thereby improving the out-pupil uniformity of the optical waveguide device. Therefore, when the optical waveguide device is used in the near-eye display device, the visual effect is more comfortable, the user experience of the near-eye display device is improved, and the research and development cost of the mask and the influence of the diffraction effect are reduced.

[0097] By way of example, the near-eye display device includes an AR wearable device, such as AR glasses.

[0098] The above descriptions are merely specific embodiments of the present application, but not for restricting the present application. Various modifications and changes can be made on the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of claims of the present application.

Claims

1. A photonic waveguide device comprising at least one photonic waveguide, the photonic waveguide comprising: a waveguide slab for total internal reflection transmission of a light beam, the waveguide slab having an in-coupling region and at least two out-coupling regions; an in-coupling grating disposed at the in-coupling region, the in-coupling grating for in-coupling the light beam into the waveguide slab; and at least two out-coupling gratings, one corresponding to each of the at least two out-coupling regions, the out-coupling gratings for out-coupling the light beam that is totally internally reflected in the waveguide slab; wherein the light beams out-coupled by the at least two out-coupling gratings have consistent light intensity. The at least two out-coupling gratings comprise a first out-coupling grating and a last out-coupling grating, the first out-coupling grating being close to the in-coupling grating, the last out-coupling grating being away from the in-coupling grating, and the light beam out-coupling capability of the out-coupling gratings gradually increases from the first out-coupling grating to the last out-coupling grating. The in-coupling grating forms a one-dimensional region or a two-dimensional region at the in-coupling region, the one-dimensional region being used for transmission of the light beam in the waveguide slab in one direction, and the two-dimensional region being used for transmission of the light beam in the waveguide slab in two mutually perpendicular directions. The at least two out-coupling gratings form a one-dimensional region or a two-dimensional region at the out-coupling region, the one-dimensional region being used for out-coupling of the light beam in the waveguide slab in one direction, and the two-dimensional region being used for out-coupling of the light beam in the waveguide slab in two mutually perpendicular directions. The photonic waveguide device comprises a plurality of photonic waveguides arranged in layers, and different photonic waveguides are used for transmission of light beams with different incident angles.

2. The optical waveguide device of claim 1, wherein, The photonic waveguide device comprises a plurality of photonic waveguides arranged in layers, and different photonic waveguides are used for transmission of light beams with different wavelengths.

3. The optical waveguide device of claim 2, wherein, 6.The photonic waveguide device according to any one of claims 1-3, wherein: the in-coupling grating comprises a multiplexing in-coupling grating for in-coupling light beams with a plurality of incident angles; and the out-coupling gratings comprise at least two sub-multiplexing out-coupling gratings, each of the sub-multiplexing out-coupling gratings being used for out-coupling light beams with a plurality of exit angles; wherein the incident angles are equal to the exit angles. 7.The photonic waveguide device according to any one of claims 1-3, wherein: the in-coupling grating comprises a multiplexing in-coupling grating for in-coupling light beams with a plurality of wavelengths; and the out-coupling gratings comprise at least two sub-multiplexing out-coupling gratings, each of the sub-multiplexing out-coupling gratings being used for out-coupling light beams with a plurality of wavelengths.

4. The optical waveguide device according to any one of claims 1 to 3, wherein, 8.A method for manufacturing the photonic waveguide device according to any one of claims 1-7, comprising: obtaining a plurality of materials with different refractive indexes, and determining a region shape of each of the materials with different refractive indexes on a surface of a waveguide slab; printing each of the materials with different refractive indexes on the surface of the waveguide slab according to the region shape by using a printing technology to generate a material layer; exposing the material layer based on a two-beam exposure technology to obtain an in-coupling grating and out-coupling gratings with different refractive index modulation degrees; and manufacturing the photonic waveguide device according to the waveguide slab, the in-coupling grating, and the out-coupling gratings with different refractive index modulation degrees.

5. The optical waveguide device according to any one of claims 1 to 3, wherein, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 9. The production method according to claim 8, wherein The material with different refractive index is printed on the surface of the waveguide sheet by inkjet printing technology, so that at least two out-coupling gratings are formed by one-time double-beam exposure.

10. The production method according to claim 9, wherein The double-beam includes a first recording beam and a second recording beam, and the first recording beam and the second recording beam expose the waveguide sheet with the material with different refractive index according to a preset recording beam included angle.

11. A near-eye display device, comprising an optical engine and the optical waveguide device according to any one of claims 1-7, wherein the in-coupling grating is configured to in-couple a light beam emitted by the optical engine into the waveguide sheet, and the out-coupling grating is configured to out-couple a light beam totally internally reflected by the waveguide sheet to a human eye.

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