Display structure
By using input coupling structures with diffraction grating and sub-wavelength grating features in the display structure, the beams of different polarization are coupled to different waveguides respectively, which solves the problem of wavelength range coupling in optical applications and improves the image quality of the display device.
Patent Information
- Application Number
- CN202380089895.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-01-05
- Filing Date
- 2023-12-14
- Publication Date
- 2025-08-05
AI Technical Summary
In optical applications, especially in augmented reality (AR) applications, it is difficult to effectively couple light from different wavelength ranges into different waveguides, resulting in complexity in waveguide and optical component design.
The first waveguide and the second waveguide are adopted, and the first polarized and second polarized beams are coupled by the first input coupling structure and the second input coupling structure respectively through the first input coupling structure and the second input coupling structure, respectively, so as to achieve separate transmission of light in different wavelength ranges in different waveguides.
By separating light from different wavelength ranges, the design of waveguides and optical components is simplified, the targeted design of optical characteristics is improved, and the image quality of the display device is improved.
Smart Images
Figure CN120435677A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to the field of diffraction optics, and in particular to a display structure and a display device. Background Art
[0002] In various optical applications, such as augmented reality (AR), it may be desirable to couple light of different compositions (e.g., different wavelength ranges) into different waveguides. This can make the design of waveguides and the optical elements used to control light in the waveguides easier. Summary of the Invention
[0003] This summary is intended to introduce a selection of concepts in a simplified form that are further described in the detailed description below. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
[0004] The object of the present invention is to provide a display structure and a display device. The above and other objects are achieved by the features of the independent claims. Further embodiments are apparent from the dependent claims, the description and the drawings.
[0005] According to a first aspect, a display structure comprises: a first waveguide; a second waveguide; a first input coupling structure in / on the first waveguide, comprising a first diffraction grating feature and a first sub-wavelength grating feature, and configured to receive a set of input light beams comprising a first polarization and a second polarization, wherein the first diffraction grating feature is configured to couple at least a portion of the first polarization to the first waveguide, and wherein the first sub-wavelength grating feature is configured to render the first diffraction grating feature at least partially transparent to the second polarization; and a second input coupling structure in / on the second waveguide, configured to receive at least a portion of the second polarization passing through the first input coupling structure, and to couple at least some of the portion of the second polarization passing through the first input coupling structure to the second waveguide.
[0006] According to a second aspect, a display device includes the display structure according to the first aspect.
[0007] According to a third aspect, a diffraction grating includes a first diffraction grating feature and a first sub-wavelength grating feature, wherein the first diffraction grating feature includes a first plurality of grating lines and the first sub-wavelength grating feature includes a second plurality of grating lines, the second plurality of grating lines being located between the first plurality of grating lines.
[0008] Many of the additional features will become better understood by reference to the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The embodiments will be described in more detail below with reference to the accompanying drawings and figures, in which:
[0010] Figure 1 shows a schematic diagram of a display structure according to an embodiment;
[0011] Figure 2 shows a schematic diagram of an input coupling structure according to an embodiment;
[0012] Figure 3 shows a schematic diagram of an input coupling structure according to another embodiment;
[0013] Figure 4 shows a schematic diagram of an input coupling structure and polarization according to an embodiment;
[0014] Figure 5 shows a schematic diagram of a waveguide according to an embodiment; and
[0015] Figure 6 A schematic diagram showing a display device according to an embodiment is shown.
[0016] In the following, identical reference numerals denote similar or at least functionally equivalent features. DETAILED DESCRIPTION
[0017] In the following description, reference will be made to the accompanying drawings, which form a part of this disclosure and in which specific aspects of the disclosure are shown by way of illustration. It should be understood that other aspects may be utilized and structural or logical changes may be made without departing from the scope of this disclosure. Therefore, the detailed description below should not be considered restrictive, as the scope of the disclosure is defined by the appended claims.
[0018] For example, it should be understood that the disclosure related to the method also applies to a device or system configured to perform the method, and vice versa. For example, if specific method steps are described, the corresponding device may include a unit for performing the method steps, even if such a unit is not explicitly described or shown in the drawings. On the other hand, for example, if a specific device is described based on a functional unit, the corresponding method may include steps for performing the function, even if such steps are not explicitly described or shown in the drawings. In addition, it should be understood that unless otherwise specifically noted, aspects of the various examples described herein may be combined with each other.
[0019] Figure 1 A schematic diagram showing a display structure according to an embodiment is shown.
[0020] According to an embodiment, the display structure 100 includes a first waveguide 101 and a second waveguide 102 .
[0021] The first waveguide 101 and / or the second waveguide 102 may include, for example, a substantially planar waveguide. Alternatively or additionally, the first waveguide 101 and / or the second waveguide 102 may also include a curved portion. For example, the first waveguide 101 and / or the second waveguide 102 may correspond to a lens of augmented reality (AR) glasses. For example, each of the first waveguide 101 and the second waveguide 102 may correspond to a layer of such AR glasses.
[0022] The display structure 100 may further include a first input coupling structure 103 in / on the first waveguide 101, the first input coupling structure comprising a first diffraction grating feature and a first sub-wavelength grating feature, and configured to receive an input light beam group 110 comprising a first polarization and a second polarization, wherein the first diffraction grating feature is configured to couple at least a portion of the first polarization to the first waveguide 101, wherein the first sub-wavelength grating feature is configured to make the first diffraction grating feature at least partially transparent to the second polarization.
[0023] The first polarization may also be referred to as a first linear polarization, and the second polarization may also be referred to as a second linear polarization.
[0024] As used herein, diffraction grating features may refer to grating features having a spatial periodicity on the same order of magnitude as or greater than the minimum wavelength of the input light beam group 110. Alternatively or additionally, sub-wavelength grating features may refer to grating features having a spatial periodicity on the same order of magnitude as or less than the minimum wavelength of visible light (e.g., less than 380 nanometers).
[0025] Alternatively or additionally, diffraction grating features may refer to grating features having a spatial periodicity which, in the incident mounting used, allows propagating diffraction orders to appear in the reflected or transmitted light.
[0026] Alternatively or additionally, sub-wavelength grating features may refer to grating features having a spatial periodicity that does not allow diffraction orders to appear in the incident setup used.
[0027] Subwavelength grating features can also be called zero-order grating features.
[0028] In this document, sub-wavelength grating features may refer to grating features having a spatial periodicity smaller than the minimum wavelength of the input light beam group 110. Alternatively or additionally, sub-wavelength grating features may refer to grating features having a spatial periodicity smaller than the minimum wavelength of visible light (e.g., less than 380 nm).
[0029] Since the first diffraction grating feature is configured to couple at least a portion of the first polarization to the first waveguide 101 , a portion of the first polarization may also pass through the first input coupling structure 103 and / or the first waveguide 101 .
[0030] Since the first sub-wavelength grating feature may make the first diffraction grating feature at least partially transparent to the second polarization, at least a portion of the second polarization may pass through the first waveguide 101 to the second waveguide 102 .
[0031] For example, Figure 1 As shown in the embodiment, some light 121 may pass through the first incoupling structure 103 and the first waveguide 101 .
[0032] The display structure 100 may further include a second input coupling structure 104 in / on the second waveguide 102, the second input coupling structure 104 being configured to receive at least a portion of the second polarization passing through the first input coupling structure and to couple at least some of the portion of the second polarization passing through the first input coupling structure to the second waveguide.
[0033] like Figure 1 As shown in the embodiment shown in FIG. 1 , some light 122 may pass through the second incoupling structure 104 and the second waveguide 102 .
[0034] exist Figure 1 The positioning of the first / second input coupling structures 103, 104 shown in the embodiment is merely exemplary, and the first / second input coupling structures 103, 104 can be positioned in various other ways. In some embodiments, the first / second input coupling structures 103, 104 can be positioned on any surface of the first / second waveguide 101, 102. In other embodiments, the first / second input coupling structures 103, 104 can be positioned inside the first / second waveguide 101, 102.
[0035] According to an embodiment, the second input-coupling structure comprises a second diffraction grating feature and a second sub-wavelength grating feature, wherein the second diffraction grating feature is configured to couple at least some of a portion of the second polarization passing through the first input-coupling structure to the second waveguide, and wherein the second sub-wavelength grating feature is configured to make the second diffraction grating feature at least partially transparent to the first polarization.
[0036] Since a portion of the first polarization can also propagate through the first input coupling structure 103 and the first waveguide 101, some of the first polarization can reach the second waveguide 102 and / or the second input coupling structure 104. Therefore, since the second sub-wavelength grating feature can make the second diffraction grating feature at least partially transparent to the first polarization, at least some of the first polarization can pass through the second waveguide 102 and / or the second input coupling structure 104. Therefore, the input coupling of the first polarization into the second waveguide 102 can be reduced.
[0037] The input light beam set 110 can be generated by, for example, a scanner-based optical engine. The input light beam set 110 can represent an image generated by, for example, such an optical engine. Therefore, the input light beam set 110 can also be referred to as, for example, image-bearing light rays / beams, image-carrying light rays / beams, etc.
[0038] According to an embodiment, the first polarization corresponds to a first wavelength range and the second polarization corresponds to a second wavelength range.
[0039] The second wavelength range may be different from the first wavelength range. For example, the first wavelength range and the second wavelength range may not overlap at least partially or completely.
[0040] For example, the first wavelength range may correspond to green and / or blue, and the second wavelength range may correspond to red, or vice versa. Alternatively, the first wavelength range may correspond to red and / or green, and the second wavelength range may correspond to blue, or vice versa.
[0041] Separating different wavelength ranges into different waveguides is advantageous because many optical phenomena are wavelength-dependent. Therefore, the optical properties of each waveguide can be tailored to a narrower wavelength range than would be possible using a single waveguide.
[0042] The first and / or second input coupling structures 103, 104 may comprise, for example, diffraction gratings on the surface of the first / second waveguides 101, 102. The first / second input coupling structures 103, 104 may couple the input beam group 110 to the first / second waveguides 101, 102 by diffraction.
[0043] Light coupled to the first / second waveguides 101 , 102 may be guided inside the first / second waveguides 101 , 102 by total internal reflection (TIR).
[0044] In this document, a beam may also be referred to as a ray, a light beam, or a ray.
[0045] According to an embodiment, the first in-coupling structure 103 and / or the second in-coupling structure 104 are configured to diffract light by zeroth and first order diffraction.
[0046] In any embodiments disclosed herein, the first input-coupling structure 103 and / or the second input-coupling structure 104 may comprise a reflective or transmissive diffraction grating.
[0047] It should be understood that Figure 1The geometric shape of the display structure 100 shown in the embodiment of FIG is merely exemplary, and the display structure 100 can be implemented in various other ways. For example, the distance between the first waveguide 101 and the second waveguide 102, the dimensions of the first waveguide 101 and the second waveguide 102, and the dimensions of the first input coupling structure 103 and the second input coupling structure 104 are selected for illustrative purposes.
[0048] Figure 2 FIG. 1 is a schematic diagram showing an input coupling structure according to an embodiment.
[0049] Figure 2 The embodiments of can correspond to the first input coupling structure 103 and / or the second input coupling structure 104 .
[0050] According to an embodiment, the first diffraction grating features 201 include a first plurality of grating lines, and the first sub-wavelength grating features 202 include a second plurality of grating lines.
[0051] According to an embodiment, the second diffraction grating features include a third plurality of grating lines and the first sub-wavelength grating features include a fourth plurality of grating lines.
[0052] According to one embodiment, the grating period of the first diffraction grating features 201 is greater than 250 nanometers (nm), and the grating period of the first sub-wavelength grating features 202 is less than 250 nm.
[0053] Alternatively or additionally, the grating period of the first diffraction grating features 201 is greater than 260 nm, 270 nm, 280 nm, 290 nm or 300 nm.
[0054] Alternatively or additionally, the grating period of the first sub-wavelength grating features 202 is less than 240 nm, 230 nm, or 220 nm.
[0055] According to an embodiment, the grating period of the second diffraction grating features is greater than 250 nm, and the grating period of the second sub-wavelength grating features is less than 250 nm.
[0056] Alternatively or additionally, the grating period of the second diffraction grating features 201 is greater than 260 nm, 270 nm, 280 nm, 290 nm or 300 nm.
[0057] Alternatively or additionally, the grating period of the second sub-wavelength grating features 202 is less than 240 nm, 230 nm, or 220 nm.
[0058] exist Figure 2 and Figure 3 In the embodiment of the present invention, the grating period of the first / second diffraction grating feature is represented by d x .
[0059] exist Figure 2 and Figure 3 In the embodiment of the present invention, the grating period of the first / second sub-wavelength grating feature is represented by d y .
[0060] According to an embodiment, the grating period of the first diffraction grating feature is 300-500.
[0061] According to one embodiment, the grating period of the second diffraction grating feature is 300-500.
[0062] According to an embodiment, each grating line of the first plurality of grating lines comprises an air gap 203 .
[0063] According to an embodiment, each grating line of the third plurality of grating lines comprises an air gap.
[0064] According to an embodiment, the width of each air gap in the first plurality of grating lines and / or the third plurality of grating lines is 30-100 nm.
[0065] The width of the air gap is Figure 2 In the embodiment, it is represented as a x .
[0066] According to an embodiment, the second plurality of grating lines are located between the first plurality of grating lines.
[0067] According to an embodiment, a distance between grating lines in each pair of consecutive grating lines in the second plurality of grating lines is 60-150 nm.
[0068] exist Figure 2 and Figure 3 In an embodiment of the present invention, the distance between the grating lines in each pair of consecutive grating lines in the second plurality of grating lines is represented by a y .
[0069] According to an embodiment, each grating line of the second plurality of grating lines has a width of 50-160 nm.
[0070] exist Figure 2 In the embodiment of FIG. 1 , cross-sections of the input coupling structure along the dashed line 210 and along the dotted line 211 are also shown. For the first input coupling structure 101, the first polarization may be along the dashed line 210, and the second polarization may be along the dotted line 211. For the second input coupling structure 102, the first polarization may be along the dotted line 211, and the second polarization may be along the dashed line 210.
[0071] As can be seen from the cross section along the dashed line 210, the polarization along the dashed line experiences the diffraction grating feature 201 as a diffraction grating. Therefore, the polarization along the dashed line 210 can be coupled to the corresponding waveguide using diffraction.
[0072] Because the sub-wavelength grating features 202 are sub-wavelength, polarization along the dotted line 211 experiences a spatially averaged refractive index caused by the sub-wavelength grating features 202 and the material (e.g., air) between the sub-wavelength grating features 202. This average refractive index can be adjusted to substantially match the refractive index of the material of the diffraction grating features 201. Thus, the diffraction grating features 201 can be made at least partially transparent to the second polarization in the first in-coupling structure 101 and the first polarization in the second in-coupling structure 102.
[0073] For example, in Figure 2 In the embodiment, by adjusting a x d x 、a y d y , the refractive index of the material of the diffraction grating features 201, and / or the refractive index of the material of the sub-wavelength grating features 202 such that the diffraction grating features 201 are at least partially transparent to the second polarization of the first in-coupling structure 101 and to the first polarization of the second in-coupling structure 102. Suitable values for at least some of these parameters can be found using, for example, optical simulations. In some cases, some of these parameters can have preset values, and the values of the remaining parameters can be found using optical simulations. For example, the refractive index of the material of the diffraction grating features 201 and / or the refractive index of the material of the sub-wavelength grating features 202 can be preset by the materials used, and a x d x 、a y , and / or d y This can be found through optical simulation.
[0074] According to an embodiment, the first sub-wavelength grating features are configured to render the first diffraction grating features at least partially transparent to the second polarization by having a substantially constant spatial average of the refractive index along the direction of the second polarization.
[0075] According to an embodiment, the refractive index of the material of the diffraction grating features is in the range of 1.9-2.4, and the refractive index of the material of the sub-wavelength grating features is in the range of 1.9-2.4.
[0076] According to one embodiment, d y In the range of 200-220nm, d x In the range of 300-500nm, a y In the range of 60-150nm, a x In the range of 30-100 nm, the refractive index of the material of the diffraction grating features is substantially 2.4, and the refractive index of the material of the sub-wavelength grating features is substantially 2.4.
[0077] Figure 3FIG. 1 is a schematic diagram showing an input coupling structure according to another embodiment.
[0078] Figure 3 The embodiments of can correspond to the first input coupling structure 103 and / or the second input coupling structure 104 .
[0079] According to an embodiment, the first plurality of grating lines are made of a material having a first refractive index and the second plurality of grating lines are made of a material having a second refractive index different from the first refractive index.
[0080] The first refractive index may be represented by n1, and the second refractive index may be represented by n2.
[0081] According to an embodiment, the third plurality of grating lines are made of a material having a third refractive index and the fourth plurality of grating lines are made of a material having a fourth refractive index different from the third refractive index.
[0082] The refractive index of a material can refer to the refractive index experienced by light when interacting with a substantially uniform block of material. The refractive index of a material can be wavelength-dependent. It should be understood that because the subwavelength grating features 202 have subwavelength dimensions, the effective refractive index induced by, for example, the subwavelength grating features 202 can differ from the refractive index of the material from which the subwavelength grating features 202 are made. Because the subwavelength grating features 202 have subwavelength dimensions, light experiences a spatially averaged effective refractive index that depends on the relative orientation of the subwavelength grating features 202 and the polarization of the light. Therefore, the effective refractive index of the subwavelength grating features 202 is anisotropic and polarization-dependent.
[0083] exist Figure 3 In the embodiment of FIG. 1 , cross-sections of the input coupling structures along the dashed line 310 and along the dotted line 311 are also shown. For the first input coupling structure 101, the first polarization may be along the dashed line 310, and the second polarization may be along the dotted line 311. For the second input coupling structure 102, the first polarization may be along the dotted line 311, and the second polarization may be along the dashed line 310.
[0084] As can be seen from the cross section along the dashed line 310, the polarization along the dashed line 310 experiences the diffraction grating feature 201 as a diffraction grating. Therefore, the polarization along the dashed line 310 can be coupled to the corresponding waveguide using diffraction.
[0085] Because the sub-wavelength grating features 202 are sub-wavelength, polarization along the dotted line 311 experiences a spatially averaged refractive index caused by the sub-wavelength grating features 202 and the material (e.g., air) between the sub-wavelength grating features 202. This average refractive index can be adjusted to substantially match the refractive index of the material of the diffraction grating features 201. Thus, the diffraction grating features 201 can be made at least partially transparent to the second polarization in the first in-coupling structure 101 and to the first polarization in the second in-coupling structure 102.
[0086] For example, in Figure 3 In the embodiment, by adjusting d x 、a y d y , the refractive index of the material of the diffraction grating features 201, and / or the refractive index of the material of the sub-wavelength grating features 202, such that the diffraction grating features 201 are at least partially transparent to the second polarization in the first incoupling structure 101 and to the first polarization in the second incoupling structure 102. Suitable values for at least some of these parameters can be found using, for example, optical simulations. In some cases, some of these parameters can have preset values, and the values of the remaining parameters can be found using optical simulations. For example, the refractive index of the material of the diffraction grating features 201 and / or the refractive index of the material of the sub-wavelength grating features 202 can be preset by the materials used, and d x 、a y , and / or d y This can be found through optical simulation.
[0087] According to an embodiment, each grating line of the first plurality of grating lines comprises an air gap 203, the first plurality of grating lines are made of a material having a first refractive index, and the second plurality of grating lines are made of a material having a second refractive index different from the first refractive index. Figure 2 and Figure 3 The embodiments can be combined into another embodiment.
[0088] Figure 4 Schematic diagram showing input coupling structure and polarization according to an embodiment.
[0089] exist Figure 4 In the embodiment of FIG, for the purpose of clarity, two grating lines of the diffraction grating feature and some grating lines of the sub-wavelength grating feature between the grating lines of the diffraction grating feature are shown. In actual applications, the diffraction grating feature and the sub-wavelength grating feature may include a significantly larger number of grating lines.
[0090] According to an embodiment, the first sub-wavelength grating features and the second sub-wavelength grating features are substantially orthogonal.
[0091] In this context, when the first sub-wavelength grating feature and the second sub-wavelength grating feature are substantially orthogonal, the grating vector of the first sub-wavelength grating feature and the grating vector of the second sub-wavelength grating feature can be substantially orthogonal. For example, if the first sub-wavelength grating feature includes a first plurality of grating lines and the second sub-wavelength grating feature includes a third plurality of grating lines, the first plurality of grating lines and the third plurality of grating lines can be substantially orthogonal. Alternatively or additionally, if the first sub-wavelength grating feature and the second sub-wavelength grating feature include other types of gratings, such as two-dimensional gratings, the grating vectors of these gratings can be substantially orthogonal.
[0092] According to an embodiment, the first plurality of grating lines and the second plurality of grating lines are non-parallel.
[0093] According to an embodiment, the third plurality of grating lines and the fourth plurality of grating lines are non-parallel.
[0094] For example, in Figure 2 、 Figure 3 and Figure 4 In an embodiment of the present invention, the first plurality of grating lines and the second plurality of grating lines are not parallel. For example, the first plurality of grating lines and the second plurality of grating lines may be as follows: Figure 2 and Figure 3 Alternatively, the first plurality of grating lines and the second plurality of grating lines may be substantially orthogonal to each other as shown in the embodiment of FIG. Figure 4 Any other non-parallel orientations as shown in the embodiments.
[0095] According to an embodiment, the first polarization 401 and the second polarization 402 are substantially orthogonal.
[0096] like Figure 4 As shown in the embodiment, a portion of the first polarization 401 in the input light beam group 110 can be input coupled to the first waveguide 101 through the first input coupling structure 103, while a portion of the first polarization 411 can pass through the first waveguide 101 and the first input coupling structure 103.
[0097] Similarly, due to, for example, optical losses, only a portion of the second polarization 402 in the input light beam group 110 may pass through the first waveguide 101 and the first input-coupling structure 103. Furthermore, due to, for example, light scattering to other directions without reaching the second waveguide 102 and / or various other optical phenomena, the second input-coupling structure 104 may receive only a portion of the second polarization 412 that passed through the first input-coupling structure 103.
[0098] The second input coupling structure 104 may couple only a portion of the second polarization 412 passing through the first input coupling structure 103 to the second waveguide 102. For example, a portion of the second polarization 412 may pass through the second input coupling structure 104. Figure 4As shown in the embodiment of FIG. 4 , the light passing through the second incoupling structure 104 may include at least a portion of the first polarization 421 and a portion of the second polarization 422 .
[0099] In some embodiments, the first input coupling structure 103 and the second input coupling structure 104 can include similar diffraction grating features 201 and / or similar sub-wavelength grating features 202. For example, the first diffraction grating features and the second diffraction grating features can have similar or substantially identical dimensions. Alternatively, the characteristics (e.g., dimensions) of the first and second diffraction grating features can be optimized based on, for example, the wavelength ranges to be coupled to the corresponding waveguides. For example, the first input coupling structure 103 can be designed based on a first wavelength range, and the second input coupling structure 104 can be designed based on a second wavelength range.
[0100] In some embodiments, the first sub-wavelength grating features and the second sub-wavelength grating features can have similar or substantially identical dimensions, and the first sub-wavelength grating features and the second sub-wavelength grating features can be oriented relative to each other to achieve a desired polarization selectivity. For example, the first sub-wavelength grating features and the second sub-wavelength grating features can be substantially orthogonal.
[0101] Figure 5 A schematic diagram of a waveguide according to an embodiment is shown.
[0102] Figure 5 The waveguides shown in the embodiment of the present invention may correspond to the first waveguide 101 and / or the second waveguide 102. The first waveguide 101 may be configured to perform the functions described herein for light (e.g., a first polarization) coupled into the first waveguide 101. Figure 5 Similarly, the second waveguide 102 can be configured to perform the functions disclosed in this article on the light (e.g., the second polarization) coupled into the second waveguide 102. Figure 5 The functions disclosed in the embodiments.
[0103] The input coupling structures 103, 104 can couple a portion of the input beam group 110 to the corresponding waveguides 101, 102 as the input coupled beam group 511. For example, the first input coupling structure 103 can couple at least a portion of the first polarization to the first waveguide 101, and the second input coupling structure can couple at least a portion of the second polarization to the second waveguide 102.
[0104] The waveguides 101 , 102 may further include an exit pupil expansion (EPE) structure 503 configured to receive the in-coupled beam set 511 and diffract the in-coupled beam set 511 in multiple directions to generate a diffracted beam set 512 .
[0105] It should be understood that Figure 5The diffracted beam group 512 shown in the embodiment is only exemplary. In actual embodiments, the EPE structure 503 can diffract the input coupling beam group 511 in multiple directions in a more complex manner, and the diffracted beam group 512 can interact with the EPE structure 503 multiple times.
[0106] The display structure 500 may further include an output coupling structure 504 configured to receive at least the diffracted light beam group 512 from the EPE structure 503 and output couple at least the diffracted light beam group 512 from the planar waveguide 201 as an output light beam group 513 .
[0107] Output beam set 513 may represent, for example, an expanded version of the image formed by input beam set 110 .
[0108] The in-coupled beam set 511 and the diffracted beam set 512 may be guided inside the waveguides 101 , 102 by total internal reflection (TIR).
[0109] The input coupling structures 103, 104, the EPE structure 503, and / or the output coupling structure 504 may include, for example, a diffraction grating on the surface of the planar waveguide 201. The input coupling structure can couple the input light beam group 110 to the planar waveguide 201 by diffraction. The EPE structure 503 can expand the image corresponding to the input light beam group 511 by diffraction. The output coupling structure 504 can couple the diffracted light beam group 512 out of the planar waveguide 201 by diffraction.
[0110] Figure 6 A schematic diagram showing a display device according to an embodiment is shown.
[0111] According to one embodiment, the display device 600 includes a display structure 100 .
[0112] According to an embodiment, the display device 600 further comprises an optical engine 601 for guiding the input light beam group 110 to the first input coupling structure 103 .
[0113] According to an embodiment, the optical engine 601 is configured to generate the set of input light beams 110 in such a way that the first polarization includes a first wavelength range and the second polarization includes a second wavelength range.
[0114] When the first polarization includes a first wavelength range and the second polarization includes a second wavelength range, the first wavelength range and the second wavelength range can be separated into different waveguides. In this way, each waveguide can be designed for a corresponding wavelength range, and the image quality generated by the display device 600 can be improved compared to a solution using a single waveguide.
[0115] According to an embodiment, the display device 600 is implemented as a see-through display device.
[0116] According to an embodiment, the display device 600 is implemented as a head-mounted display device.
[0117] For example, in Figure 6 In an embodiment, the display device 600 is implemented as smart glasses. The first waveguide 101 and the second waveguide 102 may correspond to layers of lenses of such smart glasses. Such smart glasses may be used, for example, to implement augmented reality (AR) and / or virtual reality (VR) functions.
[0118] exist Figure 6 In an embodiment of the present invention, the input light beam set 110 can be generated by, for example, an optical engine 601 (e.g., a scanner-based optical engine). The input light beam set 110 can represent an image generated by, for example, such an optical engine. The display structure 100 of the display device 600 can direct the output light beam set 513 representing the image generated by the optical engine 601 to the user's eyes.
[0119] Any range or device value given herein may be expanded or changed without losing the effect sought. Unless expressly prohibited, any embodiment may be combined with another embodiment.
[0120] Although the subject matter has been described in language specific to structural features and / or acts, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as examples of the claims and other equivalent features and acts are intended to fall within the scope of the claims.
[0121] It should be understood that the description of the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. The embodiments are not limited to those that solve any or all of the problems described or those that have any or all of the benefits and advantages described. It should be further understood that reference to "an" item may refer to one or more of these items.
[0122] Any aspect of the above-described embodiments may be combined with any aspect of the other above-described embodiments to form further embodiments without losing the effects sought.
[0123] In this document, the term "comprising" is used to indicate that the identified method, block or element is included, but such blocks or elements do not include an exclusive list and the method or apparatus may include additional blocks or elements.
[0124] It should be understood that the above description is given by way of example only and that various modifications may be made by those skilled in the art. The above description, examples, and data provide a complete description of the structure and use of the exemplary embodiments. Although various embodiments have been described above with a certain degree of specificity or with reference to one or more individual embodiments, those skilled in the art may make various changes to the disclosed embodiments without departing from the spirit or scope of this specification.
Claims
1. A display structure (100), comprising: a first waveguide (101); a second waveguide (102); a first input coupling structure (103) in / on the first waveguide (101), comprising a first diffraction grating feature (201) and a first sub-wavelength grating feature (202), wherein the first input coupling structure (103) is configured to receive an input light beam group (110) comprising a first polarization (401) and a second polarization (402), wherein the first diffraction grating feature (201) is configured to couple at least a portion of the first polarization (401) to the first waveguide (101), and wherein the first sub-wavelength grating feature (202) is configured to make the first diffraction grating feature (201) at least partially transparent to the second polarization (402); as well as A second input coupling structure (104) in / on the second waveguide (102) is configured to receive at least a portion of the second polarization passing through the first input coupling structure (103) and couple at least some of the portion of the second polarization passing through the first input coupling structure (103) to the second waveguide (102).
2. The display structure (100) according to claim 1, wherein: The second input-coupling structure includes a second diffraction grating feature and a second sub-wavelength grating feature, wherein the second diffraction grating feature is configured to couple at least some of a portion of the second polarization passing through the first input-coupling structure to the second waveguide, and wherein the second sub-wavelength grating feature is configured to render the second diffraction grating feature at least partially transparent to the first polarization.
3. The display structure (100) according to claim 2, wherein: The first sub-wavelength grating features and the second sub-wavelength grating features are substantially orthogonal.
4. The display structure (100) according to any one of the preceding claims, wherein The first sub-wavelength grating features are configured to render the first diffraction grating features at least partially transparent to the second polarization by having a substantially constant spatial average of the refractive index along the direction of the second polarization.
5. The display structure (100) according to any one of the preceding claims, wherein The first diffraction grating features include a first plurality of grating lines, and the first sub-wavelength grating features include a second plurality of grating lines.
6. The display structure (100) according to claim 5, wherein: The grating period of the first diffraction grating feature is greater than 250 nanometers, and the grating period of the first sub-wavelength grating feature is less than 250 nanometers.
7. The display structure (100) according to claim 5 or 6, wherein: Each grating line of the first plurality of grating lines includes an air gap.
8. The display structure (100) according to any one of claims 5 to 7, wherein: The first plurality of grating lines are made of a material having a first refractive index, and the second plurality of grating lines are made of a material having a second refractive index different from the first refractive index.
9. The display structure (100) according to any one of claims 5 to 8, wherein: The second plurality of grating lines are located between the first plurality of grating lines.
10. The display structure (100) according to any one of claims 5 to 9, wherein: The first plurality of grating lines and the second plurality of grating lines are non-parallel.
11. The display structure (100) according to any one of the preceding claims, wherein The first polarization and the second polarization are substantially orthogonal.
12. The display structure (100) according to any one of the preceding claims, wherein The first polarization corresponds to a first wavelength range, and the second polarization corresponds to a second wavelength range.
13. A display device (600) comprising the display structure (100) according to any one of the preceding claims.
14. The display device (600) according to claim 13, further comprising an optical engine (601) for directing the set of input light beams (110) to the first incoupling structure (103).
15. The display device (600) according to claim 14, wherein: The optical engine (601) is configured to generate an input light beam set (110) in such a way that the first polarization (401) includes a first wavelength range and the second polarization (402) includes a second wavelength range.
16. A diffraction grating (103, 104) comprising a first diffraction grating feature (201) and a first sub-wavelength grating feature (202), wherein: The first diffraction grating features include a first plurality of grating lines, the first sub-wavelength grating features include a second plurality of grating lines, and the second plurality of grating lines are located between the first plurality of grating lines.
17. The diffraction grating (103, 104) according to claim 16, wherein The grating period of the first diffraction grating features is greater than 250 nanometers, and the grating period of the first sub-wavelength grating features is less than 250 nanometers.
18. The diffraction grating (103, 104) according to claim 16 or 17, wherein: Each grating line of the first plurality of grating lines includes an air gap.
19. The diffraction grating (103, 104) according to any one of claims 16 to 18, wherein: The first plurality of grating lines are made of a material having a first refractive index, and the second plurality of grating lines are made of a material having a second refractive index different from the first refractive index.
20. The diffraction grating (103, 104) according to any one of claims 16 to 19, wherein: The first plurality of grating lines are non-parallel to the second plurality of grating lines.