Display structure

Abstract

According to one embodiment, a display structure (100) includes: a waveguide (101) configured to guide coupled light (102) into the waveguide (101) via successive reflections from a first side (121) and a second side (122) of the waveguide (101), wherein the coupled light (102) includes a first polarization state (131) and a second polarization state (132); and an output coupling structure (111) located on the first side (121) of the waveguide (101) and configured to, when the coupled light (102) When incident on the first side (121) of the waveguide (101), a portion of the first polarization state (131) of the incident coupled light (102) is decoupled from the waveguide (101); and a polarization control structure (112) is located on the second side (122) of the waveguide (101) and configured to rotate at least a portion of the second polarization state (132) of the incident coupled light (102) to the first polarization state (131) when the incident coupled light (102) is incident on the second side (122) of the waveguide (101).

Description

Technical Field

[0001] This disclosure relates to the field of diffractive optics, and more specifically, to a display structure and a display device. Background Technology

[0002] In various optical applications, such as augmented reality (AR) applications, it is generally desirable to improve the quality of the images presented to the user. One aspect of image quality is image uniformity, such as brightness and color uniformity. When presenting an image to a user, it is typically expected that the entire image will have uniform brightness and color. Summary of the Invention

[0003] This section introduces some concepts in a simplified form, which will be further described in the detailed embodiments below. This section is not intended to identify key or essential features of the claimed subject matter, nor is it intended to limit the scope of the claimed subject matter.

[0004] The purpose of this application is to provide a display structure and a display device. The above and other objectives are achieved through the features of the independent claims. Further embodiments will become apparent from the dependent claims, this specification, and the accompanying drawings.

[0005] According to a first aspect, a display structure includes: a waveguide configured to guide coupled light into the waveguide via continuous reflections from a first side surface and a second side surface of the waveguide, wherein the coupled light includes a first polarization state and a second polarization state; an out-coupling structure located on the first side surface of the waveguide and configured to out-couple a portion of the first polarization state of the coupled light from the waveguide when the coupled light is incident on the first side surface of the waveguide; and a polarization modulation structure located on the second side surface of the waveguide and configured to rotate at least a portion of the second polarization state of the coupled light to the first polarization state when the coupled light is incident on the second side surface of the waveguide.

[0006] According to a second aspect, a display device includes the display structure described in the first aspect.

[0007] The many accompanying technical features of the present invention will be more readily understood by reading the following detailed description in conjunction with the accompanying drawings. Attached Figure Description

[0008] In the following description, various embodiments will be described in more detail with reference to the accompanying drawings, in which: Figure 1 A schematic diagram of a display structure according to one embodiment is shown; Figure 2 A schematic diagram of a display structure according to another embodiment is shown; Figure 3 A schematic diagram of an out-coupling structure according to one embodiment is shown; Figure 4 A schematic diagram of the out-coupling structure according to another embodiment is shown; Figure 5 A schematic diagram of the out-coupling structure according to yet another embodiment is shown; Figure 6 A schematic diagram of a polarization modulation structure according to one embodiment is shown; and Figure 7 A schematic diagram of a display device according to one embodiment is shown.

[0009] In the following text, the same reference numerals refer to the same or at least functionally equivalent structures. Detailed Implementation

[0010] The following description will be taken with reference to the accompanying drawings, which form part of this disclosure and illustrate specific embodiments of this disclosure by way of example. It should be understood that other implementations may be employed and structural or logical changes may be made without departing from the scope of this disclosure. Therefore, the following detailed description should not be considered limiting, and the scope of this disclosure is defined by the appended claims.

[0011] For example, it should be understood that the disclosure made in conjunction with the described method also applies to the corresponding device or system capable of performing the method, and vice versa. For example, if specific method steps are described, the corresponding device may include units that perform the described method steps, even if such units are not explicitly described or shown in the accompanying drawings. On the other hand, for example, if a specific device is described based on functional units, the corresponding method may include steps that perform the described functions, even if such steps are not explicitly described or shown in the accompanying drawings. Furthermore, unless otherwise explicitly stated, the features of the various example solutions described herein can be combined with each other.

[0012] Figure 1 A schematic diagram of a display structure according to one embodiment is shown.

[0013] According to one embodiment, the display structure 100 includes a waveguide 101 configured to guide a coupled light 102 into the waveguide 101 by successive reflections from a first side 121 and a second side 122 of the waveguide 101, wherein the coupled light 102 includes a first polarization state 131 and a second polarization state 132.

[0014] The input coupling beam 102 can also be referred to as multiple coupled input beams, multiple coupled input rays, multiple coupled input beams, multiple coupled input light rays, or similar expressions.

[0015] The coupled light 102 can be guided inside the waveguide 101 by total internal reflection (TIR).

[0016] The first polarization state 131 can also be referred to as the first linear polarization state. The second polarization state 132 can also be referred to as the second linear polarization state.

[0017] The display structure 100 may further include an out-coupling structure 111 located on a first side 121 of the waveguide 101, the out-coupling structure 111 being configured to out-couple a portion of the first polarization state 131 of the input coupled light 102 from the waveguide 101 when the input coupled light 102 is incident on the first side 121 of the waveguide 101.

[0018] In some embodiments, the out-coupling structure 111 may also be configured such that when the incident light 102 is incident on the first side surface 121 of the waveguide 101, the second polarization state 132 of the incident light 102 is not out-coupled from the waveguide 101. In other embodiments, the out-coupling structure 111 may also be configured such that when the incident light 102 is incident on the first side surface 121 of the waveguide 101, the second polarization state 132 of the incident light 102 is substantially not out-coupled from the waveguide 101.

[0019] For example, in Figure 1 In this embodiment, the coupled light 103 includes only the first polarization state 131. In actual implementation, some of the second polarization state 132 may also be coupled out. However, this is usually not the desired effect.

[0020] In some embodiments, the out-coupling structure 111 may also be configured to substantially not couple out the second polarization state 132 compared to the first polarization state 131. For example, the out-coupling structure 111 may be configured to achieve a first out-coupling efficiency. The first polarization state 131 is coupled out, and the second coupling efficiency is achieved. The second polarization state 132 is coupled out, where ,For example , , , , and / or .

[0021] Therefore, the out-coupled structure 111 can diffract only light with a specific polarization direction, while light with another polarization direction can continue to propagate in the waveguide 101 through TIR.

[0022] The display structure 100 may further include a polarization control structure 112 located on the second side surface 122 of the waveguide 101. The polarization control structure 112 is configured to rotate at least a portion of the second polarization state 132 of the input coupled light 102 to a first polarization state 131 when the input coupled light 102 is incident on the second side surface 122 of the waveguide 101.

[0023] The polarization modulation structure 112 may include, for example, a film or a subwavelength grating.

[0024] When the incident coupled light 102 is incident on the polarization control structure 112, the reflected light undergoes polarization rotation. This polarization rotation affects the coupling process of the light when it is incident on the output coupling structure 111 again. By adapting and adjusting the polarization rotation intensity of the polarization control structure 112, for example, the amount of coupled light 103 when the light is incident multiple times consecutively can be balanced, thereby improving the brightness uniformity of the overall coupling region.

[0025] In some embodiments, the polarization control structure 112 may further be configured to rotate at least a portion of the first polarization state 131 of the incident coupled light 102 to a second polarization state 132 when the incident coupled light 102 is incident on the second side surface 122 of the waveguide 101. Therefore, in some embodiments, at least a portion of the first polarization state 131 of the incident coupled light 102 can be rotated to the second polarization state 132, and at least a portion of the second polarization state 132 of the incident coupled light 102 can be rotated to the first polarization state 131.

[0026] Despite Figure 1 Various optical paths (e.g., for the input coupling light 102) are illustrated using a single ray in other embodiments disclosed herein, but this is for illustrative purposes only. Any light in this disclosure may include, for example, multiple beams that can propagate in various directions.

[0027] The waveguide 101 may be, for example, a generally planar waveguide. Alternatively or additionally, the waveguide 101 may also include curved segments. For example, the waveguide 101 may correspond to a lens of augmented reality (AR) glasses. For example, the waveguide 101 may correspond to a layer in such AR glasses lenses.

[0028] The second polarization state 132 may not be parallel to the first polarization state 131.

[0029] According to one embodiment, the first polarization state 131 and the second polarization state 132 are substantially orthogonal.

[0030] For example, when the angle between the first polarization state 131 and the second polarization state 132 is 80° to 100°, 85° to 95°, 87.5° to 92.5°, 89° to 91°, and / or 89.5° to 90.5°, the first polarization state 131 and the second polarization state 132 can be substantially orthogonal.

[0031] In some embodiments, the first polarization state 131 and the second polarization state 132 may be orthogonal.

[0032] For example, in Figure 1 In the embodiment shown, the first polarization state 131 is perpendicular to Figure 1 The plane in which the second polarization state 132 is parallel Figure 1 The plane.

[0033] Figure 1 In the illustrated embodiment, the positioning of the outgoing coupling structure 111 is merely exemplary, and the outgoing coupling structure 111 can be positioned in various other ways. In some embodiments, the outgoing coupling structure 111 can be located inside the waveguide 101.

[0034] According to one embodiment, the out-coupling structure 111 is configured to out-couple a portion of the first polarization state 131 of the incident coupled light 102 from the waveguide 101 via zero-order and / or first-order diffraction.

[0035] In any of the embodiments disclosed herein, the out-coupling structure 111 may include a reflective or transmissive diffraction grating. For example, in Figure 1 In one embodiment, the outgoing coupling structure 111 may include a reflective diffraction grating, so the outgoing coupled light 103 exits the waveguide 101 from the second side 122. In an embodiment where the outgoing coupling structure 111 includes a transmissive diffraction grating, the outgoing coupled light 103 may exit the waveguide 101 from the first side 121.

[0036] It should be understood that Figure 1 The geometry of the display structure 100 shown in the illustrated embodiment is merely exemplary, and the display structure 100 can be implemented in various other ways. For example, the dimensions of the waveguide 101 and the outgoing coupling structure 111 in this embodiment are for illustrative purposes only.

[0037] According to one embodiment, the out-coupling efficiency of the out-coupling structure varies along at least one direction on the first side of the waveguide.

[0038] The out-coupling efficiency can be quantified as the proportion of the input coupling light 102 that is out-coupled each time the input coupling light 102 is incident on the first side surface 121 and interacts with the out-coupling structure 111.

[0039] According to one embodiment, the out-coupling efficiency of the out-coupling structure increases along the main propagation direction of the input coupled light.

[0040] The main propagation direction of the incident coupled light can refer to the propagation direction of the incident coupled light guided by the TIR. For example, in... Figure 1 In one embodiment, the main propagation direction can be in the positive x-direction.

[0041] The incident coupled light 102 can have various polarization forms. For example, the incident coupled light 102 can be in an elliptically polarized state. This polarization state can include a linear combination of a first polarization state 131 and a second polarization state 132. In this case, the out-coupling efficiency of the incident coupled light 102 each time it interacts with the out-coupling structure 111 depends on the amount of the first polarization state 131 in the light.

[0042] The polarization selectivity of the coupling structure 111 can be achieved through various structures, such as those disclosed in the embodiments herein. Different structures can produce polarization selectivity of varying strengths, and their overall optical response characteristics and fabrication adaptability also differ.

[0043] It should be understood that Figure 1 The polarization directions shown in the illustrated embodiment are merely exemplary. In other embodiments, the directions of the first polarization state 131 and the second polarization state 132 may be the same as those shown in the original embodiment. Figure 1 The differences are shown in the illustrated embodiments.

[0044] The out-coupling structure 111 can only diffract the first polarization state 131, thereby achieving coupling. Therefore, the out-coupling efficiency can be adjusted by appropriately configuring the out-coupling structure 111 and the polarization control structure 112. Since the out-coupling efficiency can depend on the amount of polarization rotation and the out-coupling efficiency of the out-coupling structure 111, the display structure 100 allows for better control over the out-coupling of the image. Therefore, the display structure 100 can provide additional design freedom for optimizing brightness and color uniformity.

[0045] Figure 2 A schematic diagram of a display structure according to another embodiment is shown.

[0046] According to one embodiment, the display structure 100 further includes an exit pupil expansion (EPE) structure 203, which includes a polarization-sensitive grating located on one of the first side 121 and the second side 122 of the waveguide 101, and a second polarization state modulation structure located on the side of the waveguide 101 opposite to the polarization-sensitive grating. The exit pupil expansion structure 203 is configured to reduce the second polarization state in the input coupled light 102 and guide the input coupled light 102 toward the exit coupled structure 111.

[0047] The exit pupil expansion structure 203 can be similar to Figure 1 The manner in which the output coupling structure 111 and polarization modulation structure 112 of the embodiment reduce the second polarization state in the input coupling light 102. For example, the polarization-sensitive grating of the exit pupil extension structure can diffract a portion of the first polarization state of the input coupling light 102 when the input coupling light 102 is incident on the polarization-sensitive grating. Due to diffraction, a portion of the first polarization state can be directed toward the output coupling structure 111. The second polarization state modulation structure can rotate at least a portion of the second polarization state of the input coupling light 102 back to the first polarization state when the input coupling light 102 is incident on the second polarization state modulation structure.

[0048] In some embodiments, the polarization-sensitive grating may be on the first side 121 of the waveguide 101, and the second polarization state modulation structure may be on the second side 122 of the waveguide 101. In other embodiments, the polarization-sensitive grating may be on the second side 122 of the waveguide 101, and the second polarization state modulation structure may be on the first side 121 of the waveguide 101.

[0049] According to one embodiment, the display structure 100 further includes an input coupling structure 201 configured to couple an input beam 202 as an input coupling beam 102 into a waveguide 101.

[0050] For example, in Figure 2 In one embodiment, the display structure 100 further includes an input coupling structure 201 configured to couple the input beam 202 as an input coupling light 102 into the waveguide 101 and guide the input coupling light 102 toward the exit pupil extension structure 203. The exit pupil extension structure 203 then reduces the second polarization state in the input coupling light 102 and guides the input coupling light 102 toward the exit coupling structure 111.

[0051] The exit pupil extension structure 203 can also be configured to extend the image corresponding to the incident coupled light 102 through diffraction.

[0052] It should be understood that Figure 2 The incident coupled light 102 extended by the exit pupil extension structure 203 shown in the illustrated embodiment is merely illustrative. In a real embodiment, the exit pupil extension structure 203 may diffract the incident coupled light 102 in multiple directions in a more complex manner, and the incident coupled light 102 may interact with the exit pupil extension structure 203 multiple times.

[0053] The output coupled light 103 is, for example, an extended version of the image formed by the input light beam 202.

[0054] The input beam 202 may also be referred to as incident light, multiple input beams, multiple input beams, multiple input light, multiple input rays, or similar expressions.

[0055] The input beam 202 can be generated by, for example, a scanner-based optical engine. The input beam 202 can represent, for example, an image generated by such an optical engine. Therefore, the input beam 202 can also be referred to as, for example, an image-carrying beam, an image-carrying ray / beam, an image-carrying ray / beam, etc. Alternatively or additionally, the input beam 202 can be provided by some other optical components (such as those disclosed in the embodiments herein).

[0056] The second polarization state modulation structure may include, for example, a quarter-wave plate. In this paper, a quarter-wave plate may also be referred to as... Wave plates, etc.

[0057] Since the exit pupil extension structure 203 can reduce the second polarization state in the incident coupled light 102, it can reduce or even eliminate the outgoing coupling between the outgoing coupling structure 111 and the incident coupled light 102 every other interaction. This is because the outgoing coupling (OC) structure 111 has polarization sensitive characteristics, and each time the incident coupled light 102 is incident on the polarization control structure 112, the polarization control structure 112 can rotate the first polarization state 131 to the second polarization state 132, and vice versa. Figure 2 This is illustrated in the embodiments, where, as indicated by the dashed arrows, the outgoing coupling between the outgoing coupling structure 111 and the incoming coupling light 102 is reduced or eliminated for every other interaction.

[0058] Figure 3 A schematic diagram of an out-coupling structure according to one embodiment is shown.

[0059] According to one embodiment, the out-coupling structure 111 includes a diffraction grating feature and a subwavelength grating feature, wherein the diffraction grating feature is configured to out-couple a portion of the first polarization state 131 of the incident coupled light 102 from the waveguide 101 when the incident coupled light 102 is incident on the first side surface 121 of the waveguide 101, and the subwavelength grating feature is configured to make the diffraction grating feature at least partially transparent to the second polarization state 132.

[0060] In this embodiment, the diffraction grating feature may refer to a grating structure having a spatial periodicity of the same order of magnitude or greater than the minimum wavelength of the incident coupled light 102. Alternatively or additionally, the subwavelength grating feature may refer to a grating structure having a spatial periodicity of the same order of magnitude or smaller than the minimum wavelength of visible light (e.g., less than 380 nanometers (nm)).

[0061] Alternatively or additionally, a diffraction grating feature may refer to a grating structure having such spatial periodicity that, in the incident mounting used, this spatial periodicity allows diffraction orders (whether in reflected or transmitted light) to appear.

[0062] Alternatively or additionally, a subwavelength grating feature may refer to a grating structure having such spatial periodicity that, in the incident mounting used, diffraction orders are not permitted to occur.

[0063] This subwavelength grating feature can also be referred to as a zero-order grating structure.

[0064] For example, Figure 3 An embodiment illustrates an out-coupling structure 111, which includes a diffraction grating feature along the x-direction and a subwavelength grating feature along the y-direction.

[0065] According to one embodiment, the grating period of the diffraction grating feature (by...) (Indicated as 300 nanometers to 400 nanometers (nm)).

[0066] According to one embodiment, the grating period of the subwavelength grating feature (by...) (Indicated) 150nm to 200nm.

[0067] According to one embodiment, the grating height of the diffraction grating feature and / or the subwavelength grating feature is 20 nm to 100 nm.

[0068] According to one embodiment, the linewidth of the diffraction grating feature and / or the subwavelength grating feature is 60 nm to 200 nm.

[0069] According to one embodiment, the refractive index of the diffraction grating feature and / or the subwavelength grating feature is 1.9 to 2.5.

[0070] The diffraction grating feature and / or the subwavelength grating feature may be made of a dielectric material (e.g., titanium dioxide, TiO2). The refractive index of TiO2 is approximately 2.4.

[0071] According to one embodiment, the diffraction grating feature includes multiple diffraction grating lines 301, and the subwavelength grating feature includes multiple subwavelength grating lines 302.

[0072] According to one embodiment, the grating lines in the plurality of diffraction grating lines 301 are substantially parallel to the first polarization state 131.

[0073] According to one embodiment, each of the plurality of diffraction grating lines 301 includes an air gap 303.

[0074] According to one embodiment, the grating period of the diffraction grating feature is greater than 250 nm, and the grating period of the subwavelength grating feature is less than 250 nm.

[0075] According to one embodiment, the width of each air gap 303 in the plurality of diffraction grating lines 301 is 30 nm to 100 nm.

[0076] exist Figure 3 In the embodiment shown, the width of the air gap 303 is determined by... express.

[0077] For example, in Figure 3 , Figure 4 and Figure 5 In the illustrated embodiment, the multiple diffraction grating lines 301 and the multiple subwavelength grating lines 302 are not parallel to each other. For example, as shown... Figure 3 , Figure 4 and Figure 5 As shown in the embodiments, the multiple diffraction grating lines 301 and the multiple subwavelength grating lines 302 can be substantially orthogonal to each other. Alternatively, the multiple diffraction grating lines 301 and the multiple subwavelength grating lines 302 can be arranged in any other non-parallel orientation.

[0078] According to one embodiment, in the plurality of subwavelength grating lines 302, the spacing between each pair of adjacent grating lines is 60 nm to 150 nm.

[0079] exist Figure 3 and Figure 4 In the embodiment, the spacing between each pair of adjacent grating lines in the multiple subwavelength grating lines 302 is determined by... express.

[0080] According to one embodiment, the width of each of the multiple subwavelength grating lines is 50 nm to 160 nm.

[0081] According to one embodiment, the grating lines in the plurality of diffraction grating lines are substantially parallel to the first polarization state.

[0082] exist Figure 3 In one embodiment, cross-sections of the out-coupling structure 111 along the dashed line 310 and along the dotted line 311 are also shown. In this out-coupling structure 111, the first polarization state 13 can be along the dotted line 311, and the second polarization state 132 can be along the dashed line 310.

[0083] Light treats the subwavelength grating feature as a birefringent medium. Therefore, the polarization along the dashed line 310 and along the dotted line 311 has different effective refractive indices. By adjusting the size of the subwavelength feature, the refractive index can be adjusted so that the diffraction grating is at least partially transparent to polarization along the dashed line 310.

[0084] In this embodiment, transverse electric (TE) polarization can refer to polarization in which the electric field is substantially parallel to the diffraction grating lines of the diffraction grating feature section of the coupling structure 111. Therefore, in Figures 1 to 6 In this embodiment, the polarization of the electric field along the y-direction can be referred to as transverse electric polarization. Similarly, transverse magnetic (TM) polarization can refer to polarization in which the magnetic field is substantially parallel to the diffraction grating lines of the diffraction grating feature section of the coupling structure 111. Therefore, in Figures 1 to 6 In this embodiment, the polarization of the electric field in the xz plane can be referred to as transverse magnetic polarization.

[0085] For example, in Figure 3 In some embodiments, adjustments can be made. , , , The refractive index of the material of the diffraction grating feature portion, and / or the refractive index of the material of the subwavelength grating feature portion, makes the diffraction grating feature portion at least partially transparent to the second polarization state 132. Appropriate values ​​for at least some of these parameters can be found, for example, using optical simulation. In some cases, some of these parameters may have predetermined values, and the values ​​of the remaining parameters can be found using optical simulation. For example, the refractive index of the material of the diffraction grating feature portion, and / or the refractive index of the material of the subwavelength grating line 302, can be predetermined by the materials used and can be found using optical simulation. , , and / or .

[0086] According to one embodiment, the subwavelength grating feature is configured to be at least partially transparent to the second polarization state 132 by keeping the average spatial refractive index in the direction of the second polarization state 132 substantially constant.

[0087] According to one embodiment, the refractive index of the material of the diffraction grating feature is in the range of 1.9 to 2.4, and the refractive index of the material of the subwavelength grating feature is in the range of 1.9 to 2.4.

[0088] According to one embodiment, Within the range of 200nm to 220nm, In the range of 300nm to 500nm, Within the range of 60nm to 150nm, In the range of 30 nm to 100 nm, the refractive index of the material of the diffraction grating feature is essentially 2.4, and the refractive index of the material of the subwavelength grating feature is also essentially 2.4.

[0089] Figure 4 A schematic diagram of the out-coupling structure according to another embodiment is shown.

[0090] According to one embodiment, a plurality of diffraction grating lines are made of a material having a first refractive index, and a plurality of subwavelength grating lines are made of a material having a second refractive index, which is different from the first refractive index.

[0091] The first refractive index can be determined by... This indicates that the second refractive index can be derived from... express.

[0092] In other embodiments, the multiple diffraction grating lines and the multiple subwavelength grating lines may be made of the same material.

[0093] The refractive index of a material refers to the equivalent refractive index when light interacts with a nearly uniform region of that material. The refractive index of a material can be wavelength-dependent. It is important to understand that because the subwavelength grating feature is of a subwavelength size, the effective refractive index generated by this structure can differ from the refractive index of the substrate on which the subwavelength grating feature is fabricated. Due to the influence of the subwavelength size, the light exhibits a spatially averaged effective refractive index, which is related to the relative orientation of the subwavelength grating feature and the polarization state of the incident light. Therefore, the effective refractive index of the subwavelength grating feature is anisotropic and polarization-dependent.

[0094] exist Figure 4 In the embodiment, cross-sections of the out-coupling structure 111 along the dashed line 410 and along the dotted line 411 are also shown. In this out-coupling structure 111, the first polarization state 131 can be along the dotted line 411, and the second polarization state 132 can be along the dashed line 410.

[0095] The light rays treat the subwavelength grating feature as a birefringent medium. Therefore, polarized light along the dashed line 410 and the dotted line 411 has different effective refractive indices. By adjusting the size of the subwavelength structure, the refractive index can be controlled so that the diffraction grating feature exhibits at least partial transmittance for polarized light along the dashed line 410.

[0096] For example, in Figure 4 In some embodiments, adjustments can be made. The refractive index of the material of the diffraction grating feature and / or the refractive index of the material of the subwavelength grating line 302 make the diffraction grating feature at least partially transparent to the second polarization state 132. Appropriate values ​​for at least some of these parameters can be found, for example, using optical simulation. In some cases, some of these parameters may have predetermined values, and the values ​​of the remaining parameters can be found using optical simulation. For example, the refractive index of the material of the diffraction grating line 301 and / or the refractive index of the material of the subwavelength grating line 302 can be predetermined by the materials used and can be found using optical simulation. and / or .

[0097] According to one embodiment, each of the plurality of diffraction grating lines includes an air gap 303, the plurality of diffraction grating lines are made of a material having a first refractive index, and the plurality of subwavelength grating lines 202 are made of a material having a second refractive index different from the first refractive index. Therefore, Figure 3 and Figure 4 One embodiment can be combined with another embodiment.

[0098] According to one embodiment, multiple subwavelength grating lines are located between multiple diffraction grating lines, and the multiple diffraction grating lines and the multiple subwavelength grating lines are not parallel to each other.

[0099] Figure 5 A schematic diagram of the out-coupling structure according to another embodiment is shown.

[0100] exist Figure 5 In this embodiment, the multiple diffraction grating lines 301 and the multiple subwavelength grating lines 302 are made of the same material. For example, the multiple diffraction grating lines 301 and the multiple subwavelength grating lines 302 can be made of titanium dioxide (TiO2). The refractive index of TiO2 is approximately 2.4. The space between the multiple diffraction grating lines 301 and the multiple subwavelength grating lines 302 can be, for example, air.

[0101] According to one embodiment, the width of each of the plurality of diffraction grating lines 301 is 80 nm, and the width of each of the plurality of subwavelength grating lines 202 is 80 nm.

[0102] According to one embodiment, the grating period Within the range of 300nm to 400nm.

[0103] According to one embodiment, the grating period Within the range of 150nm to 200nm.

[0104] Figure 6 A schematic diagram of a polarization control structure according to one embodiment is shown.

[0105] According to one embodiment, the polarization control structure 112 includes multiple polarization control grating lines 601, which are not parallel to multiple diffraction grating lines 301.

[0106] According to one embodiment, the polarization modulation structure 112 includes a subwavelength polarization modulation grating.

[0107] According to one embodiment, the grating period of the polarization control grating is less than 250 nm.

[0108] For example, a subwavelength polarization modulation grating can be made of TiO2. The space between the grating lines in the subwavelength polarization modulation grating can be, for example, air.

[0109] Figure 5 An embodiment illustrates an example of a polarization modulation structure 112, which includes a subwavelength polarization modulation grating 601. The grating period of the polarization modulation structure 112 is determined by... The grating height of each grating line in the subwavelength polarization modulation grating 601 is represented by h. A cross-section along the dotted line 611 is also shown.

[0110] According to one embodiment, the width of each grating line in the subwavelength polarization modulation grating can be 70 nm.

[0111] According to one embodiment, the grating period of the subwavelength polarization modulation grating Within the range of 150nm to 200nm, the width of each grating line in a subwavelength polarization modulation grating can be from 75nm to 100nm.

[0112] According to one embodiment, the grating height h of the subwavelength polarization modulation grating is in the range of 50 nm to 250 nm.

[0113] According to one embodiment, the refractive index of the subwavelength polarization modulation grating is in the range of 1.9 to 2.5.

[0114] For example, in Figure 5 In the embodiments, h can be adjusted. The width of each grating line in the subwavelength polarization modulation grating 601, and / or the refractive index of each grating line in the subwavelength polarization modulation grating 601, configure the polarization modulation structure 112 to rotatably couple the polarization of the input light 102. Appropriate values ​​for at least some of these parameters can be found, for example, using optical simulation. In some cases, some of these parameters may have predetermined values, and the values ​​of the remaining parameters can be found using optical simulation. For example, the refractive index of the material of the subwavelength polarization modulation grating 601 can be predetermined by the material used.

[0115] According to one embodiment, the polarization control structure 112 includes a one-dimensional polarization control grating.

[0116] Figure 5 The embodiments described are merely examples of a polarization control structure 112, and the polarization control structure 112 can also be implemented in various other ways. For example, in some embodiments, the polarization control structure 112 may include a tilted grating.

[0117] Figure 7 A schematic diagram of a display device according to one embodiment is shown.

[0118] According to one embodiment, the display device 800 includes a display structure 100.

[0119] According to one embodiment, the display device 800 further includes an optical engine 801 for directing the input light beam 202 toward the waveguide 101.

[0120] According to one embodiment, the display device 800 is implemented as a perspective display device.

[0121] According to one embodiment, the display device 800 is implemented as a head-mounted display device.

[0122] For example, in Figure 7 In one embodiment, the display device 800 is implemented as smart glasses. Waveguide 101 may correspond to a layer in the lens of the smart glasses. The smart glasses can be used to, for example, implement augmented reality (AR), virtual reality (VR), and / or extended reality (XR) functions.

[0123] exist Figure 7 In one embodiment, the input light beam 202 may be generated, for example, by an optical engine 801 (e.g., a scanner-based optical engine). The input light beam 202 may represent, for example, an image generated by such an optical engine. The display structure 100 of the display device 800 may direct the coupled light 103 representing the image generated by the optical engine 801 to the user's eye.

[0124] Without departing from the intended technical effect, any numerical range or device parameter described in this specification can be expanded or adjusted. Furthermore, unless expressly prohibited, any embodiment can be combined with other embodiments.

[0125] Although this technical solution has been described in conjunction with structural and / or operational features, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are disclosed merely as examples of implementing the claims, and other equivalent features and actions fall within the scope of protection of these claims.

[0126] It should be understood that the various beneficial effects described above may correspond to a single embodiment or multiple embodiments. The embodiments of this application are not limited to solutions capable of solving all the problems or possessing all the beneficial effects. It should also be understood that the singular form "a / an" may refer to one or more objects of the same kind.

[0127] Without departing from the intended technical effect, any of the above embodiments can be combined with any other embodiments to form more embodiments.

[0128] The term "comprising" as used in this specification means that it includes the defined method, unit and component, and such unit and component is not exhaustive; other components or units may be added to the method or apparatus.

[0129] It should be understood that the above description is given only as an example, and various modifications can be made by those skilled in the art. The above specification, embodiments, and data provide a complete description of the structure and use of exemplary embodiments. Although various embodiments have been described above with a degree of specificity or by reference to one or more individual embodiments, those skilled in the art can make various modifications and variations to the disclosed embodiments without departing from the spirit or scope of this specification.

Claims

1. A display structure (100), characterized in that, include: A waveguide (101) is configured to guide a coupling light (102) into the waveguide (101) by continuous reflection from a first side (121) and a second side (122) of the waveguide (101), wherein the coupled light (102) includes a first polarization state (131) and a second polarization state (132). An out-coupling structure (111) is located on a first side (121) of the waveguide (101) and configured to out-couple a portion of the first polarization state (131) of the input coupling light (102) from the waveguide (101) when the input coupling light (102) is incident on the first side (121) of the waveguide (101). The out-coupling structure (111) includes a diffraction grating feature and a subwavelength grating feature. The diffraction grating feature is configured to out-couple a portion of the first polarization state (131) of the input coupling light (102) from the waveguide (101) when the input coupling light (102) is incident on the first side (121) of the waveguide (101), and the subwavelength grating feature is configured to be at least partially transparent to the second polarization state (132). as well as A polarization control structure (112) is located on the second side (122) of the waveguide (101) and is configured to rotate at least a portion of the second polarization state (132) of the input coupling light (102) to the first polarization state (131) when the input coupling light (102) is incident on the second side (122) of the waveguide (101).

2. The display structure (100) according to any of the preceding claims, characterized in that, The out-coupling efficiency of the out-coupling structure (111) varies along at least one direction on the first side (121) of the waveguide (101).

3. The display structure (100) according to any of the preceding claims, characterized in that, The out-coupling efficiency of the out-coupling structure (111) increases along the main propagation direction of the input-coupling light (102).

4. The display structure (100) according to any of the preceding claims, characterized in that, Also includes: Exit pupil expansion (EPE) structure (203); The exit pupil extension structure (203) includes: a polarization-sensitive grating located on one of the first side (121) and the second side (122) of the waveguide (101), and a second polarization state control structure located on the side of the waveguide opposite to the polarization-sensitive grating, wherein the exit pupil extension structure (203) is configured to reduce the proportion of the second polarization state in the input coupling light (102) and guide the input coupling light (102) to the exit coupling structure (111).

5. The display structure (100) according to any of the preceding claims, characterized in that, The diffraction grating feature includes multiple diffraction grating lines (301), and the subwavelength grating feature includes multiple subwavelength grating lines (302).

6. The display structure (100) according to claim 5, characterized in that, The grating lines in the plurality of diffraction grating lines (301) are substantially parallel to the first polarization state.

7. The display structure (100) according to claim 5 or 6, characterized in that, Each of the multiple diffraction grating lines (301) includes an air gap.

8. The display structure (100) according to any one of claims 5 to 7, characterized in that, The plurality of diffraction grating lines (301) are made of a material having a first refractive index, and the plurality of subwavelength grating lines (302) are made of a material having a second refractive index, which is different from the first refractive index.

9. The display structure (100) according to any one of claims 5 to 8, characterized in that, The multiple subwavelength grating lines (302) are located between the multiple diffraction grating lines (301), and the multiple diffraction grating lines (301) and the multiple subwavelength grating lines (302) are not parallel to each other.

10. The display structure (100) according to any one of claims 1 to 9, characterized in that, The grating period of the diffraction grating feature is greater than 250 nanometers, and the grating period of the subwavelength grating feature is less than 250 nanometers.

11. The display structure (100) according to any of the preceding claims, characterized in that, The polarization control structure (112) includes a subwavelength polarization control grating (601).

12. The display structure (100) according to any of the preceding claims, characterized in that, The first polarization state (131) and the second polarization state (132) are substantially orthogonal.

13. The display structure (100) according to any of the preceding claims, characterized in that, It also includes an input coupling structure (201) configured to couple an input beam (202) into the waveguide (101) to form the input coupled beam (102).

14. A display device (800), characterized in that, Includes the display structure (100) described in any of the preceding claims.

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