Optical waveguide device and preparation method thereof, AR near-eye display device and application thereof

Abstract

The present invention relates to an optical waveguide device and a preparation method thereof, an AR near-eye display device and applications thereof, wherein a super-surface structure layer is stacked on the outer surface of the coupling end of the optical waveguide device, and the light emitted by the light source device is directly or indirectly coupled into the optical waveguide through the super-surface structure layer for propagation. The super-surface structure layer is configured to phase-modulate the first light beam emitted to the super-surface structure layer, so that the second light beam emitted from the super-surface structure layer has collimation and directionality. The light entering the optical waveguide has collimation and directionality to improve the coupling efficiency of light, thereby improving the utilization rate of light energy and display brightness. The optical waveguide device plus the light source device of the present application constitute an AR near-eye display device, which can be applied to naked-eye 3D light field display. The super-surface structure layer not only realizes the collimation and directionality of the light emitted by the display panel, improves the light efficiency and brightness, but also facilitates the realization of the light-weight and thin display optical machine.

Description

Technical Field

[0001] The present invention relates to the field of display technology, and in particular to an optical waveguide device and a preparation method thereof, an AR near-eye display device and applications thereof. Background Art

[0002] AR is the abbreviation of Augmented Reality. In AR display devices, virtual images are superimposed on real images to achieve a display effect that combines virtual and real. Diffraction waveguides have the advantages of ultra-light and ultra-thin, large pupil expansion range, high transparency and low mass production cost, and are one of the mainstream solutions for realizing AR display. However, the existing diffraction waveguides use gratings to couple visible light into the waveguides, but due to the low diffraction efficiency of the gratings, the light energy utilization rate is poor. At present, the coupling efficiency of the mass-produced diffraction waveguide gratings is usually not higher than 10%. In addition, considering the mass production in the actual process, it is necessary to impose certain restrictions on the structural morphology of the coupling grating, so the final coupling efficiency of the coupling grating may be lower. The existing diffraction waveguide includes a light source device, a collimation system, a diffraction grating and a waveguide, wherein the light source device and the collimation system constitute the optical-mechanical part. A grating is used to couple visible light into the waveguide, but due to the low diffraction efficiency of the gratings, the light energy utilization rate is poor. Summary of the invention

[0003] The present invention provides an optical waveguide device and a preparation method thereof, an AR near-eye display device and applications thereof, so as to solve the technical problems of low coupling efficiency and poor light energy utilization.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] In a first aspect, the present application provides an optical waveguide device, comprising:

[0006] The optical waveguide has an in-coupling end and an out-coupling end arranged at intervals, and the signal light is coupled into the optical waveguide through the in-coupling end and propagates to the out-coupling end to couple out of the optical waveguide;

[0007] A metasurface structure layer, stacked on the outer surface of the optical waveguide at the coupling-in end, wherein the metasurface structure layer is configured to phase-modulate the first light beam emitted to the metasurface structure layer so that the second light beam emitted from the metasurface structure layer has collimation and directionality;

[0008] The metasurface structure layer includes a plurality of metasurface units arranged in an interval array and having three different phase structures. The metasurface unit corresponding to one phase structure can phase modulate light of one color. The metasurface unit phase modulates light of the corresponding color, satisfying the following formulas (1) to (3):

[0009]

[0010] In formula (1), is the phase delay, is the collimation delay phase; is the phase deflected to different angles;

[0011] In formula (2), f is the focal length, n is i is the refractive index of the medium through which the light incident on the metasurface structure layer passes, λ represents the wavelength of signal light of different colors, and x / y / z represents the spatial position coordinates of the metasurface structure;

[0012] In formula (3), represents the angle between the Z axis and the projection of the deflected beam in the XZ plane; represents the angle between the Z axis and the projection of the deflected beam in the YZ plane; n o represents the refractive index of the optical waveguide.

[0013] In one embodiment, the optical waveguide device further includes a protective adhesive layer, which is filled between the metasurface units; and / or the optical waveguide further includes encapsulation glass, which is arranged on a side of the metasurface structure layer away from the optical waveguide.

[0014] In one embodiment, each of the metasurface units has a cylindrical geometry or a ring geometry.

[0015] In one of the embodiments, the metasurface structure layer directly couples the signal light into the optical waveguide for propagation.

[0016] In one of the embodiments, the optical waveguide is further provided with a geometric optical element at the coupling-in end, and the signal light passes through the metasurface structure layer and the geometric optical element in sequence and is coupled into the optical waveguide for propagation.

[0017] In a second aspect, the present application provides a method for preparing an optical waveguide device, comprising the following steps:

[0018] Selecting an optical waveguide having an incoupling end and an outcoupling end;

[0019] Selecting three-color signal light: selecting signal light having red light, green light, and blue light, and measuring the wavelength of the red light, the wavelength of the green light, and the wavelength of the blue light in the signal light;

[0020] Designing a metasurface structure layer, wherein the design of the metasurface structure layer is based on a coupled wave method and a finite-difference time-domain method, wherein the coupled wave method is used for unit structure design, and the finite-difference time-domain method is used for overall structure design and verification;

[0021] The super surface structure layer is formed on the outer surface of the coupling end of the optical waveguide, and the super surface structure layer is configured to phase modulate the first light beam emitted to the super surface structure layer, so that the second light beam emitted from the super surface structure layer has collimation and directionality;

[0022] The metasurface structure layer includes a plurality of metasurface units arranged in an interval array and having three different phase structures. The metasurface unit corresponding to one phase structure can phase modulate light of one color. The metasurface unit phase modulates light of the corresponding color, satisfying the following formulas (1) to (3):

[0023] In formula (1), is the phase delay, is the collimation delay phase; is the phase deflected to different angles;

[0024] In formula (2), f is the focal length, n is i is the refractive index of the medium through which the light incident on the metasurface structure layer passes, λ represents the wavelength of signal light of different colors, and x / y / z represents the spatial position coordinates of the metasurface structure;

[0025] In formula (3), represents the angle between the Z axis and the projection of the deflected beam in the XZ plane; represents the angle between the Z axis and the projection of the deflected beam in the YZ plane; n o represents the refractive index of the optical waveguide.

[0026] In one embodiment, the process of designing the metasurface structure layer includes the following steps:

[0027] Based on the parameters of the three-color signal light, constructing a metasurface structure layer matching the three-color signal light;

[0028] Extracting phase distribution information of the metasurface structure layer;

[0029] Discretize the phase distribution information according to the periodic size of the metasurface unit library to obtain a phase discretization result;

[0030] The metasurface unit array is arranged according to the phase discretization results to construct a metasurface structure layer.

[0031] In one embodiment, forming the super surface structure layer comprises the following steps:

[0032] Depositing a super surface film layer and a hard mask layer in sequence on the outer surface of the coupling end;

[0033] Performing patterning and etching on the hard mask layer in sequence to transfer the pattern on the hard mask layer to the super surface film layer;

[0034] Removing the hard mask layer to form the super surface structure layer;

[0035] Wherein, the metasurface structure layer includes a plurality of metasurface units matching the wavelengths of RGB three primary colors of light.

[0036] In a third aspect, the present application provides an AR near-eye display device, comprising:

[0037] A light source device, emitting three-color signal light, the light source device comprising a red light sub-pixel, a green light sub-pixel and a blue light sub-pixel;

[0038] In the optical waveguide device as described in any of the foregoing embodiments or the optical waveguide device obtained by any of the foregoing method embodiments, the light source device is arranged at the coupling-in end, and the three metasurface units are aligned one by one with the red photon sub-pixel, the green photon sub-pixel and the blue photon sub-pixel respectively;

[0039] A coupling element is provided at the coupling end and is used to couple out the signal light in the optical waveguide.

[0040] In a fourth aspect, the AR near-eye display device described in the previous embodiment is applied to naked-eye 3D light field display.

[0041] It can be seen from the above technical solutions that the embodiments of the present invention have at least the following advantages and positive effects:

[0042] The embodiment of the present invention provides an optical waveguide device and a preparation method thereof, an AR near-eye display device and its application. A super-surface structure layer is stacked on the outer surface of the coupling end of the optical waveguide device, and the light emitted by the light source device is directly or indirectly coupled into the optical waveguide through the super-surface structure layer for propagation. The super-surface structure layer is configured to phase modulate the first light beam emitted to the super-surface structure layer so that the second light beam emitted from the super-surface structure layer has collimation and directionality. The light entering the optical waveguide has collimation and directionality to improve the coupling efficiency of the light, thereby improving the utilization rate of light energy and display brightness. The optical waveguide device plus the light source device of the present application constitute an AR near-eye display device, which can be applied to naked-eye 3D light field display. The super-surface structure layer not only realizes the collimation and directionality of the light output, improves the light efficiency and brightness, but also facilitates the realization of the light-weight and thin display optical machine. On the other hand, the super-surface structure layer includes three super-surface units, each of which phase modulates light of one color, which can also reduce the optical crosstalk phenomenon. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0044] Figure 1 This is a schematic diagram of the optical path and overall structure of an optical waveguide device according to an embodiment of the present application;

[0045] Figure 2 for Figure 1 A schematic diagram of a local enlarged structure of the coupling end of the optical waveguide device shown;

[0046] Figure 3 It is a schematic diagram of the optical path and overall structure of an optical waveguide device in accordance with an embodiment of the present invention for coupling signal light through a metasurface structure layer;

[0047] Figure 4 The optical path and overall structure diagram of an optical waveguide device coupled into the signal light through a reflector according to an embodiment;

[0048] Figure 5 The optical path and overall structure diagram of an optical waveguide device in accordance with an embodiment of the present invention for coupling signal light through a prism;

[0049] Figure 6 for Figure 1 A flow chart of a method for preparing the optical waveguide device shown;

[0050] Figure 7 for Figure 6 The steps of designing the super surface structure layer in the preparation process shown;

[0051] Figure 8 for Figure 6 The steps of forming the super surface structure in the preparation process shown;

[0052] Fig. 9 This is a schematic diagram of the optical path and structure of an AR near-eye display device according to an embodiment of the present application;

[0053] Fig.10 for Fig. 9 An enlarged schematic diagram of the coupling part in the AR near-eye display device is shown.

[0054] The following are the descriptions of the reference numerals:

[0055] 1. AR near-eye display device;

[0056] 10. Optical waveguide device; 100. Optical waveguide; 110. Incoupling end; 111. Reflector; 112. Prism; 120. Outcoupling end; 200. Metasurface structure layer; 201. Red light metasurface unit; 202. Green light metasurface unit; 203. Blue light metasurface unit; 300. Protective adhesive layer; 400. Encapsulation glass;

[0057] 20. Light source device; 21. Red photon pixel; 22. Green photon pixel; 23. Blue photon pixel;

[0058] 30. Coupling element. DETAILED DESCRIPTION

[0059] Typical embodiments that embody the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have various changes in different embodiments without departing from the scope of the present invention, and the descriptions and illustrations therein are essentially used for illustration purposes rather than for limiting the present invention.

[0060] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0061] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "setting", and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0062] Traditional diffraction waveguides generally collimate the signal light before coupling into a parallel beam through a collimation system, and then deflect it into the waveguide by a diffraction coupler. However, due to the low diffraction efficiency of the diffraction grating, the coupling efficiency is low and the light energy utilization rate is poor. Figure 1 The present application provides an optical waveguide device 10, which can make the light beam collimated and directional to improve the utilization rate of light energy, and at the same time can save the collimation system to achieve the demand for lightweight display optical machine.

[0063] Specifically, Figure 1As shown, the optical waveguide device 10 includes an optical waveguide 100 and a super surface structure layer 200. In the direction of signal light propagation, the optical waveguide 100 has an in-coupling end 110 and an out-coupling end 120 arranged at intervals. The signal light is coupled into the optical waveguide 100 through the in-coupling end 110, propagates to the out-coupling end 120, and then exits the optical waveguide 100. The super surface structure layer 200 is stacked on the outer surface of the optical waveguide 100 at the in-coupling end 110. The super surface structure layer 200 is configured to phase modulate the first beam of light emitted to the super surface structure layer 200, so that the second beam of light emitted from the super surface structure layer 200 has extremely high collimation and directivity. It should be noted that the collimation of light means that the light beam is modulated from divergent light to a parallel light beam, and the directivity of light means that the light beam is modulated to be emitted at a preset angle. It should be noted that the metasurface structure layer 200 is composed of a group of metasurface unit structures whose scale is smaller than the wavelength of the incident light, arranged according to a certain arrangement rule. The metasurface structure layer 200 is usually a micro-nano structure (GaN, TiO, SiN, etc.) built on a substrate material (SiO2, Al2O3, etc.). The metasurface structure layer 200 can accurately modulate the phase of the incident light with its micro-nano structure optical modulation characteristics, thereby achieving precise control of the incident light. It has the characteristics of strong design, small structural size, and precise light control.

[0064] Specifically, Figure 2 It is shown that the signal light is RGB three-color light, and the metasurface structure layer 200 includes a plurality of metasurface units arranged in an interval array and having three different phase structures, namely, a red light metasurface unit 201, a green light metasurface unit 202, and a blue light metasurface unit 203. The red light metasurface unit 201 performs phase modulation on the red signal light; the green light metasurface unit 202 performs phase modulation on the green signal light; and the blue light metasurface unit 203 performs phase modulation on the blue signal light. That is, a metasurface unit corresponding to a phase structure performs phase modulation on a signal light of a color, and the metasurface unit performs phase modulation on the light emitted by the corresponding sub-pixel, satisfying the following formulas (1) to (3):

[0065]

[0066] In formula (1), is the phase delay, is the collimation delay phase; is the phase deflected to different angles;

[0067] In formula (2), f is the focal length, n is i is the refractive index of the medium through which the light incident on different metasurface units passes, λ represents the wavelength of the corresponding incident light, and x / y / z represents the spatial position coordinates of the metasurface structure;

[0068] In formula (3), represents the angle between the Z axis and the projection of the deflected beam in the XZ plane; represents the angle between the Z axis and the projection of the deflected beam in the YZ plane; n o represents the refractive index of the output medium, which refers to the refractive index of the optical waveguide 100 in this case.

[0069] Preferably, in one embodiment, continue to refer to Figure 1 , the super-surface structure layer 200, as a micro-nano structure, is very susceptible to damage if it is directly exposed to the air. Therefore, in order to protect the super-surface structure layer 200, on the one hand, the optical waveguide device 10 also includes a protective adhesive layer 300, and the protective adhesive layer 300 is filled between the super-surface units. On the other hand, the optical waveguide device 10 also includes an encapsulation glass 400, and the encapsulation glass 400 is stacked and arranged on the side of the super-surface structure layer 200 away from the optical waveguide 100, that is, covering the light incident surface of the super-surface structure layer 200. It should be understood that, without considering the need for the super-surface structure layer 200 to be protected, there is no limitation on whether the protective adhesive layer 300 or the encapsulation glass 400 is provided.

[0070] Preferably, in one embodiment, the minimum unit structure of each super surface unit is a regular structure such as a columnar geometry or annular geometry, which is conducive to the construction and processing of the super surface structure layer 200 (facilitating array arrangement). It should be noted that the columnar geometry includes but is not limited to a cylinder, a cuboid, and a cube, and the annular geometry includes but is not limited to concentric cylinders. It should be understood that, without considering the convenience of the construction and processing of the super surface structure layer 200, in this application, the morphology of the super surface unit is not limited.

[0071] refer to Figure 3 In one embodiment, the metasurface structure layer 200 can not only phase modulate the incident signal light, so that the signal light has collimation and directionality, but also deflect the incident signal light into the optical waveguide 100 for propagation. That is, the metasurface structure layer 200 can directly couple the signal light into the optical waveguide 100 for propagation. At this time, the metasurface structure layer 200, as the coupling structure of the optical waveguide device 10, has the functions of modulating the signal light and coupling the signal light at the same time, and does not need to set an additional coupling structure, thereby simplifying the structure of the optical waveguide device 10.

[0072] refer to Figure 4 In one embodiment, the optical waveguide 100 is provided with a reflector 111 inside the coupling end 110. The signal light is modulated by the metasurface structure layer 200 and emitted to the reflector 111. Then, the signal light is reflected from the reflector 111 and coupled into the optical waveguide 100 for propagation.

[0073] refer to Figure 5In one embodiment, the optical waveguide 100 is provided with a prism 112 at the coupling end, and the super-surface structure layer 200 is attached to the mirror surface of the prism 112. The signal light is phase-modulated by the super-surface structure layer 200 and then emitted to the prism 112. The signal light is then refracted by the prism 112 and coupled into the optical waveguide 100 for propagation.

[0074] It should be noted that the reflector 111 and the prism 112 are both non-diffractive geometric optical elements. The signal light is phase modulated by the metasurface structure layer 200 and then coupled into the optical waveguide 100 through the geometric optical element for propagation. Here, by adjusting the incident angle or shape of the signal light, the signal light can meet the total reflection condition in the optical waveguide 100, and the signal light is totally reflected in the optical waveguide 100 to the coupling-out end 120, thereby improving the utilization rate of light energy. Part of the signal light is coupled out of the optical waveguide 100 and enters the human eye, and the remaining light continues to propagate in the optical waveguide 100.

[0075] It should be understood that in the present application, whether an additional coupling structure (such as a geometric optical element) is provided at the coupling end 210 is not limited, and the signal light can be directly coupled into the optical waveguide 100 through the super-surface structure layer 200 for propagation; or an additional coupling structure can be provided at the coupling end 110, and the signal light can be phase-modulated by the super-surface structure layer 200 and then coupled into the optical waveguide 100 through the coupling structure for propagation. Here, the specific structure of the coupling structure is not limited.

[0076] Second, refer to Figure 6 The present invention provides a method for preparing an optical waveguide device 10, comprising the following steps:

[0077] S10, selecting an optical waveguide 100 having an incoupling end 110 and an outcoupling end 120;

[0078] S20, selecting three-color signal light: selecting signal light having red light, green light, and blue light, and measuring the wavelength of the red light, the wavelength of the green light, and the wavelength of the blue light in the signal light;

[0079] S30, designing the metasurface structure layer 200. The design of the metasurface structure layer 200 is based on the rigorous coupled wave method (RCWA) and the finite difference time domain method (FDTD), wherein RCWA is used for unit structure design and FDTD is used for overall structure design and verification. The main parameters involved in the design process are: the height of the metasurface structure layer 200, the morphology of the minimum unit structure of a single metasurface unit, which can be a regular structure such as a column or a ring, or a free morphology structure;

[0080] S40, preparing the optical waveguide device 10, forming a metasurface structure layer 200 on the outer surface of the coupling end 110 of the optical waveguide 100, wherein the metasurface structure layer 200 is configured to phase modulate the first light beam emitted to the metasurface structure layer 200, so that the second light beam emitted from the metasurface structure layer 200 has collimation and directionality;

[0081] The metasurface structure layer 200 includes three metasurface units with different structures. Each metasurface unit performs phase modulation on light of one color. Each metasurface unit performs phase modulation on a light signal of one color, satisfying the following formulas (1) to (3):

[0082]

[0083] In formula (1), is the phase delay, is the collimation delay phase; is the phase deflected to different angles;

[0084] In formula (2), f is the focal length, n is i is the refractive index of the medium through which the light incident on different metasurface units passes, λ represents the wavelength of the corresponding incident light, and x / y / z represents the spatial position coordinates of the metasurface structure;

[0085] In formula (3), represents the angle between the Z axis and the projection of the deflected beam in the XZ plane; represents the angle between the Z axis and the projection of the deflected beam in the YZ plane; n o represents the refractive index of the output medium, which refers to the refractive index of the optical waveguide 100 in this case.

[0086] refer to Figure 7 In the process of preparing the optical waveguide device 10, the specific steps of designing the super surface structure layer are as follows:

[0087] S31, collimation and deflection phase design, based on the parameters of the luminous pixel, constructing a metasurface structure layer matching the luminous pixel, and extracting phase distribution information of the metasurface structure;

[0088] S32, phase discretization, discretizing the phase distribution information according to the periodic size of the metasurface unit library to obtain a phase discretization result;

[0089] S33, constructing a metasurface unit structure library, the metasurface unit structure library corresponds to the luminous spectrum range of the luminous pixel and includes a plurality of metasurface unit structures, each metasurface unit structure corresponds to a phase value in the range of 0 to 2π, and each metasurface unit structure corresponds to a different phase value;

[0090] S34, constructing a metasurface structure layer, and arranging a metasurface unit array according to the phase discretization result to construct a metasurface structure layer.

[0091] In one embodiment, the phase distribution information is discretized according to the period size of the metasurface unit structure library, including: taking the period of the metasurface unit structure as the minimum division scale, dividing the phase distribution information, so that the phase distribution information is discretized into phase values ​​within the range of 0 to 2π

[0092] refer to Figure 8 In the process of preparing the optical waveguide device 10, the specific steps of forming the supersurface structure layer 200 are as follows:

[0093] S41, depositing two thin films, sequentially depositing a supersurface material film (may be SiNx, nanoimprint glue, etc.) and a hard mask film (aluminum Al, titanium Ti, chromium Cr, etc.) on the outer surface of the optical waveguide 100 where the coupling end 110 is located;

[0094] S42, imaging processing, patterning the hard mask film so that the hard mask film forms a pattern of a super surface structure to form a hard mask layer;

[0095] S43, etching, using the hard mask layer as a mask to etch the super surface material film to transfer the pattern of the hard mask layer to the super surface material film;

[0096] S44, cleaning, and then removing the hard mask layer to form a super surface structure layer;

[0097] The metasurface structure layer 200 includes a plurality of metasurface unit structures that match the wavelengths of the three primary colors of RGB light.

[0098] Thirdly, combined with reference Fig. 9 and Fig.10 The present invention provides an AR near-eye display device 1, comprising a light source device 20, an optical waveguide device 10 and a coupling-out element 30, wherein the light source device 20 is disposed at a coupling-in end 110 and is capable of emitting three-color signal light. Specifically, referring to Fig. 9, the light source device 20 includes a plurality of red sub-pixels 21, a plurality of green sub-pixels 22, and a plurality of blue sub-pixels 23. The red sub-pixels 21 in the light source device 20 are aligned one by one with the red light metasurface unit 201, the green sub-pixels 22 are aligned one by one with the green light metasurface unit 202, and the blue sub-pixels 23 are aligned one by one with the blue light metasurface unit 203, that is, the three metasurface units are aligned one by one with the sub-pixels of the three colors, respectively, so that one metasurface unit performs phase modulation on light of one color. The coupling-out element 30 is provided at the coupling-out end 120 and is used to couple out the signal light in the optical waveguide 100. Here, the light source device 20 includes but is not limited to LCOS, LED, OLED, quantum dots, etc.; the structure of the coupling-out element 30 includes but is not limited to gratings, metasurfaces, holographic or liquid crystal material structures, microprisms, and other optical elements with coupling-out functions.

[0099] Here, the metasurface unit and the sub-pixel can be aligned one by one using high-precision alignment and bonding technology to align the metasurface structure layer with the light-emitting pixel. When preparing the light-emitting unit, an alignment mark is made at the same time. When the metasurface structure is subsequently processed, the alignment mark is referred to to achieve pixel alignment.

[0100] Fourthly, 3D display is a technology that can display scenes and objects with a sense of depth, allowing observers to directly observe 3D images with physical depth. At present, 3D display technologies mainly include naked-eye and device-assisted display. Among them, naked-eye 3D display technology has attracted much attention due to its advantages of convenience and flexibility, without the need for glasses and other device assistance. Naked-eye 3D display technology is a light field display technology. The encoded light field information is projected to different positions in space through a light field modulation device to form a real 3D light field with continuous parallax at different positions in space, which can provide stereoscopic parallax in multiple directions such as horizontal and vertical directions at the same time. Since the focal depth of the diffraction light waveguide is at infinity, it is limited to displaying two-dimensional images at a fixed distance from the user. These limitations cause the convergence-adjustment conflict of the user's eyeballs, resulting in reduced sense of reality and visual discomfort.

[0101] Fig. 9It is illustrated that the AR near-eye display device 1 provided by the present invention can be applied to naked-eye 3D light field display. The light source device 20 emits three-color signal light, and the metasurface structure layer 200 is used to collimate and direct the outgoing light of each pixel. The emission direction not only meets the viewing angle rule of the diffraction light waveguide, but also meets the light field modulation rule of the light field display to restore the 3D light field visible to the naked eye. The modulated light will form multiple independent viewpoints at the user's eyeball. When more than two viewpoints enter the human eye at the same time, the human eye will be guided to focus, thereby generating depth perception. The optical waveguide 100 is used to propagate signal light. The coupling element 30 is used to couple the signal light in the optical waveguide 100 to the outside of the optical waveguide 100. The coupling element 30 includes but is not limited to gratings, metasurfaces, holographic or liquid crystal material structures, microprisms and other optical elements with coupling functions.

[0102] The present invention provides an optical waveguide device 10 and a preparation method thereof, an AR near-eye display device 1 and an application thereof, wherein a super-surface structure layer 200 is stacked on the outer surface of the coupling end 110 of the optical waveguide device 10, and the signal light emitted by the light source device 20 is directly or indirectly coupled into the optical waveguide 100 through the super-surface structure layer 200 for propagation. The super-surface structure layer 200 is configured to phase-modulate the first light beam emitted to the super-surface structure layer 200, so that the second light beam emitted from the super-surface structure layer has collimation and directionality. The light entering the optical waveguide 100 has collimation and directionality, so as to improve the coupling efficiency of light, thereby improving the utilization rate of light energy and display brightness. The optical waveguide device 10 plus the light source device 20 of the present application constitute an AR near-eye display device 1, which can be applied to naked-eye 3D light field display. The super-surface structure layer 200 not only realizes the collimation and directionality of the emitted light, improves the light efficiency and brightness, but also facilitates the realization of a lightweight display optical machine. On the other hand, the metasurface structure layer 200 includes three metasurface units, each of which performs phase modulation on light of one color, which can also reduce optical crosstalk.

[0103] Although the present invention has been described with reference to several typical embodiments, it should be understood that the terms used are illustrative and exemplary, rather than restrictive. Since the present invention can be embodied in a variety of forms without departing from the spirit or essence of the invention, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims, so all changes and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. An optical waveguide device, characterized in that: include: The optical waveguide has an in-coupling end and an out-coupling end arranged at intervals, and the signal light is coupled into the optical waveguide through the in-coupling end and propagates to the out-coupling end to couple out of the optical waveguide; A metasurface structure layer, stacked on the outer surface of the optical waveguide at the coupling-in end, wherein the metasurface structure layer is configured to phase-modulate the first light beam emitted to the metasurface structure layer so that the second light beam emitted from the metasurface structure layer has collimation and directionality; The metasurface structure layer includes a plurality of metasurface units arranged in an interval array and having three different phase structures. The metasurface unit corresponding to one phase structure can phase modulate light of one color. The metasurface unit phase modulates light of the corresponding color, satisfying the following formulas (1) to (3): In formula (1), is the phase delay, is the collimation delay phase; is the phase deflected to different angles; In formula (2), f is the focal length, n is i is the refractive index of the medium through which the light incident on the metasurface structure layer passes, λ represents the wavelength of signal light of different colors, and x / y / z represents the spatial position coordinates of the metasurface structure; In formula (3), represents the angle between the Z axis and the projection of the deflected beam in the XZ plane; represents the angle between the Z axis and the projection of the deflected beam in the YZ plane; n o represents the refractive index of the optical waveguide.

2. The optical waveguide device according to claim 1, characterized in that The optical waveguide device further includes a protective adhesive layer, which is filled between the metasurface units; and / or the optical waveguide further includes encapsulation glass, which is arranged on a side of the metasurface structure layer away from the optical waveguide.

3. The optical waveguide device according to claim 1, characterized in that Each of the super surface units has a cylindrical geometric shape or a ring geometric shape.

4. The optical waveguide device according to claim 1, wherein: The metasurface structure layer directly couples the signal light into the optical waveguide for propagation.

5. The optical waveguide device according to claim 1, wherein: The optical waveguide is also provided with a geometric optical element at the coupling-in end, and the signal light is coupled into the optical waveguide after passing through the metasurface structure layer and the geometric optical element in sequence for propagation.

6. A method for preparing an optical waveguide device, characterized in that: The steps include: Selecting an optical waveguide having an incoupling end and an outcoupling end; Selecting three-color signal light: selecting signal light having red light, green light, and blue light, and measuring the wavelength of the red light, the wavelength of the green light, and the wavelength of the blue light in the signal light; Designing a metasurface structure layer, wherein the design of the metasurface structure layer is based on a coupled wave method and a finite-difference time-domain method, wherein the coupled wave method is used for unit structure design, and the finite-difference time-domain method is used for overall structure design and verification; The super surface structure layer is formed on the outer surface of the coupling end of the optical waveguide, and the super surface structure layer is configured to phase modulate the first light beam emitted to the super surface structure layer, so that the second light beam emitted from the super surface structure layer has collimation and directionality; The metasurface structure layer includes a plurality of metasurface units arranged in an interval array and having three different phase structures. The metasurface unit corresponding to one phase structure can phase modulate light of one color. The metasurface unit phase modulates light of the corresponding color, satisfying the following formulas (1) to (3): In formula (1), is the phase delay, is the collimation delay phase; is the phase deflected to different angles; In formula (2), f is the focal length, n is i is the refractive index of the medium through which the light incident on the metasurface structure layer passes, λ represents the wavelength of signal light of different colors, and x / y / z represents the spatial position coordinates of the metasurface structure; In formula (3), represents the angle between the Z axis and the projection of the deflected beam in the XZ plane; represents the angle between the Z axis and the projection of the deflected beam in the YZ plane; n o represents the refractive index of the optical waveguide.

7. The method for preparing an optical waveguide device according to claim 6, characterized in that: The process of designing the metasurface structure layer includes the following steps: Based on the parameters of the three-color signal light, constructing a metasurface structure layer matching the three-color signal light; Extracting phase distribution information of the metasurface structure layer; Discretize the phase distribution information according to the periodic size of the metasurface unit library to obtain a phase discretization result; The metasurface unit array is arranged according to the phase discretization results to construct a metasurface structure layer.

8. The method for preparing an optical waveguide device according to claim 6, characterized in that: Forming the super surface structure layer comprises the following steps: Depositing a super surface film layer and a hard mask layer in sequence on the outer surface of the coupling end; Performing patterning and etching on the hard mask layer in sequence to transfer the pattern on the hard mask layer to the super surface film layer; Removing the hard mask layer to form the super surface structure layer; Wherein, the metasurface structure layer includes a plurality of metasurface units matching the wavelengths of RGB three primary colors of light.

9. An AR near-eye display device, characterized in that: include: A light source device, emitting three-color signal light, the light source device comprising a red light sub-pixel, a green light sub-pixel and a blue light sub-pixel; The optical waveguide device according to any one of claims 1 to 5 or the optical waveguide device prepared by the preparation method according to any one of claims 6 to 8, wherein the light source device is arranged at the coupling-in end, and the three types of metasurface units are aligned one by one with the red photon pixel, the green photon pixel and the blue photon pixel respectively; The coupling-out element is arranged at the coupling-out end and is used for coupling out the signal light in the optical waveguide.

10. An application of an AR near-eye display device, characterized in that: The AR near-eye display device described in claim 9 is applied to naked-eye 3D light field display.

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