Method for controlling refractive index of planar waveguide

Abstract

According to an embodiment, a method for controlling a refractive index of a planar waveguide comprises: providing a planar waveguide comprising a plurality of region segments; and controlling the refractive index of the plurality of regional segments of the planar waveguide by exposing the planar waveguide to a plurality of electromagnetic radiation exposures corresponding to the plurality of regional segments and / or exposing the planar waveguide to a plurality of thermal exposures corresponding to the plurality of regional segments.

Description

Technical Field

[0001] The present invention relates to the field of optics, and more particularly to a method for controlling the refractive index of a planar waveguide, a display structure, and a display device. Background Art

[0002] Many optical properties of a waveguide are controlled by the refractive index of the waveguide. Thus, it is desirable to be able to control and / or modify the refractive index of the waveguide in terms of the geometry of the waveguide. Summary of the Invention

[0003] This summary is provided to introduce a series of concepts in a simplified form that will be 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] An object of the present invention is to provide a method for controlling the refractive index of a planar waveguide, 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 method for controlling the refractive index of a planar waveguide includes: providing a planar waveguide including a plurality of region segments; and controlling the refractive indices of the plurality of region segments of the planar waveguide by exposing the planar waveguide to a plurality of electromagnetic radiation exposures corresponding to the plurality of region segments and / or by exposing the planar waveguide to a plurality of thermal exposures corresponding to the plurality of region segments.

[0006] According to a second aspect, a display structure includes a planar waveguide obtained by the method according to the first aspect.

[0007] According to a third aspect, a display device includes the display structure according to the second aspect.

[0008] Many additional features will be better understood by reference to the following detailed description considered in conjunction with the accompanying drawings. Brief Description of the Drawings

[0009] Hereinafter, example embodiments will be described in more detail with reference to the drawings, in which:

[0010] Figure 1 A flowchart of a method according to an embodiment is shown;

[0011] Figure 2 A cross-sectional view of a planar waveguide according to an embodiment is shown;

[0012] Figure 3 A schematic diagram of a planar waveguide including at least one diffraction grating according to an embodiment is shown;

[0013] Figure 4 A cross-sectional view of a planar waveguide including a diffraction grating according to an embodiment is shown;

[0014] Figure 5 A schematic view of a display structure according to an embodiment is shown; and

[0015] Figure 6 A schematic view of a display device according to an embodiment is shown.

[0016] Hereinafter, the same reference numerals refer to similar or at least functionally equivalent features. Detailed Description

[0017] In the following description, reference is made to the accompanying drawings, which form a part of the present disclosure and in which specific aspects in which the present disclosure may be placed are shown in the manner shown. It should be understood that other aspects may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. Therefore, the following detailed description should not be taken in a limiting sense, as the scope of the present disclosure is defined by the appended claims.

[0018] For example, it should be understood that the disclosure related to the described method may also be applicable to the corresponding device or system configured to perform the method, and vice versa. For example, if specific method steps are described, the corresponding device may include units for performing the described method steps, even if such units are not explicitly described or shown in the drawings. On the other hand, for example, if a specific device is described based on functional units, the corresponding method may include steps for performing the described functions, even if such steps are not explicitly described or shown in the drawings. In addition, it should be understood that the features of the various example aspects described herein may be combined with each other unless specifically stated otherwise.

[0019] Figure 1 A flowchart of a method according to an embodiment is shown.

[0020] According to one embodiment, a method 100 for controlling the refractive index of a planar waveguide includes providing 101 a planar waveguide including a plurality of regional segments.

[0021] Controlling the refractive index of a planar waveguide may also be referred to as modifying the refractive index of the planar waveguide, adjusting the refractive index of the planar waveguide, adapting the refractive index of the planar waveguide, or similar terms.

[0022] Method 100 may further include controlling 102 the refractive index of multiple regional segments of the planar waveguide by exposing the planar waveguide to multiple electromagnetic radiation exposures corresponding to the multiple regional segments and / or by exposing the planar waveguide to multiple heat exposures corresponding to the multiple regional segments.

[0023] As used herein, exposure may refer to, for example, the total amount of radiant energy and / or thermal energy per unit area to which the planar waveguide is exposed. The exposure can be controlled, for example, by controlling the intensity / power / brightness / luminance / wavelength / frequency of the electromagnetic radiation and / or the length of time each regional segment is exposed to the radiation.

[0024] Exposure may also refer to dose, electromagnetic radiation dose, electromagnetic radiation exposure, or similar terms.

[0025] In some embodiments, each of the multiple regional segments may be exposed to different electromagnetic radiation exposures and / or heat exposures. In some other embodiments, some of the multiple regional segments may be exposed to the same electromagnetic radiation exposures and / or heat exposures.

[0026] The planar waveguide may be composed of, for example, high refractive index glass. Additionally, other materials such as those disclosed herein may be incorporated into the planar waveguide.

[0027] The refractive index of the planar waveguide and / or the change in the refractive index of the planar waveguide may be wavelength-dependent. For example, the change in refractive index may be least significant for wavelengths corresponding to red and most significant for wavelengths corresponding to blue.

[0028] Controlling 102 the refractive index of multiple regional segments of the planar waveguide may include controlling the refractive index at least for visible wavelengths of light. As used herein, visible wavelengths of light may refer to the wavelength range of 380 - 750 nanometers (nm).

[0029] According to one embodiment, the electromagnetic radiation includes ultraviolet (UV) radiation and / or infrared (IR) radiation.

[0030] Method 100 is capable of controlling the refractive index of the regional segments of the planar waveguide. The possibility of controlling / regulating the refractive index of the planar waveguide can enable new waveguide design options and / or solve current waveguide design problems.

[0031] Figure 2 A cross-sectional view of a planar waveguide according to an embodiment is shown.

[0032] According to one embodiment, exposing the planar waveguide to a plurality of electromagnetic radiation exposures corresponding to a plurality of region segments and / or exposing the planar waveguide to a plurality of thermal exposures corresponding to a plurality of region segments includes at least one of the following: shielding at least one of the plurality of region segments; changing the intensity of electromagnetic radiation between the plurality of region segments; changing the intensity of heat between the plurality of region segments; and / or changing the wavelength of electromagnetic radiation between the plurality of region segments.

[0033] The planar waveguide 201 may refer to a waveguide whose dimensions in two directions are significantly larger than its dimension in a third direction. These two directions may be referred to as the width direction or a similar direction. This third direction may be referred to as the thickness direction or a similar direction. For example, the dimensions of the planar waveguide 201 may be several centimeters or dozens of centimeters in the width direction and less than one centimeter in the thickness direction.

[0034] In some embodiments, the planar waveguide 201 may have a curved shape. For example, the planar waveguide 201 may correspond to the lens of smart glasses, a windshield, goggles (such as helmet goggles), or the like.

[0035] Herein, a region segment of the planar waveguide 201 may refer to a segment / section / portion of the waveguide when viewed along the thickness direction. Thus, each region segment may form a boundary in the width direction and may surround the entire planar waveguide in the thickness direction. For example, in Figure 2 's embodiment, each region segment 210 - 213 is bounded by one of the two width directions and surrounds the entire planar waveguide 201 in the thickness direction. In the other of the two width directions (not shown in Figure 2 's embodiment), since from the Figure 2 's perspective, this direction corresponds to the depth direction, each region segment 210 - 213 may be bounded by the corresponding dimension of the planar waveguide 201 along this direction. Thus, Figure 2 each region segment 210 - 213 in's embodiment may correspond to a "slice" of the planar waveguide 201.

[0036] For example, in Figure 2 's embodiment, the plurality of region segments includes four region segments 210 to 213. The first region segment 210 and the third region segment 212 are shielded. Thus, the first region segment 210 and the third region segment 212 may not be exposed to electromagnetic radiation. In addition, the second region segment 211 is exposed to electromagnetic radiation 202 of a first intensity, and the fourth region segment 213 is exposed to electromagnetic radiation 203 of a second intensity.

[0037] In Figure 2The regional segments 210 - 213 shown in the embodiments are merely simplified examples and multiple regional segments can be arranged in various other ways.

[0038] According to one embodiment, the planar waveguide 201 includes a substance sensitive to electromagnetic radiation and / or heat, and / or a coating sensitive to electromagnetic radiation and / or heat.

[0039] In this context, the substance can also be referred to as an alloy, dopant, or the like.

[0040] For example, a coating sensitive to electromagnetic radiation and / or heat can be located on at least one surface of the planar waveguide 201.

[0041] In this context, a substance sensitive to electromagnetic radiation and / or heat or a coating sensitive to electromagnetic radiation and / or heat can mean that when the substance / coating in / on the planar waveguide 201 is exposed to electromagnetic radiation and / or heat, the substance / coating can cause a change in the refractive index of the planar waveguide 201.

[0042] According to one embodiment, the electromagnetic radiation includes ultraviolet (UV) radiation, and the substance and / or coating includes at least one of the following: titanium dioxide (TiO 2 ), germanium dioxide (GeO 2 ), germanium (Ge), and / or boron (B).

[0043] In some embodiments, the planar waveguide includes 1 - 30 weight percent (w%) of TiO 2 , 5 - 25 w% of TiO 2 , or 10 - 20 w% of TiO 2 .

[0044] When exposed to UV radiation, at least some of the aforementioned substances and / or coatings can change the refractive index of the planar waveguide.

[0045] The change in refractive index may be due to, for example, electromagnetic radiation heating the substance / coating, and thermal-induced changes in the crystal structure or recrystallization of the substance / coating. Similar changes can be achieved using thermal exposure.

[0046] In some embodiments, the substance can include microparticles and / or nanoparticles. For example, the substance can include amorphous form, microparticles, and / or nanoparticles of TiO 2 , amorphous form, microparticles, and / or nanoparticles of GeO 2 , amorphous form, microparticles, and / or nanoparticles of Ge, and / or amorphous form, microparticles, and / or nanoparticles of B.

[0047] According to one embodiment, the size of the microparticles and / or nanoparticles is in the range of 1 - 30 nm.

[0048] Alternatively or additionally, the size of the microparticles and / or nanoparticles can be in the range of 5 - 30 nm, 10 - 30 nm, 5 - 20 nm, or 1 - 20 nm.

[0049] In some embodiments, the microparticles and / or nanoparticles can be microspheres and / or nanospheres. The diameter of the microspheres and / or nanospheres can be in the range of 1 - 30 nm. Alternatively or additionally, the diameter of the microspheres and / or nanospheres can be in the range of 5 - 30 nm, 10 - 30 nm, 5 - 20 nm, or 1 - 20 nm.

[0050] According to one embodiment, the microparticles and / or nanoparticles include at least one of the following: microspheres and / or nanospheres, microrods and / or nanorods, microcubes and / or nanocubes, core - shell particles, nanopowder particles, raspberry - like particles, and / or spike particles.

[0051] Raspberry - like particles can refer to particles having substantially spherical protrusions on the particle surface.

[0052] Nanopowder can be defined as a powder material in which individual particles are nanoscale or a material having nanoscale crystals.

[0053] In some embodiments, the particles can include clusters (e.g., columnar and / or spike - shaped) of various shapes.

[0054] In some embodiments, the microparticles and / or nanoparticles can have random shapes.

[0055] According to one embodiment, the control of the refractive indices of multiple regional segments of a planar waveguide defines at least one refractive index gradient on the planar waveguide.

[0056] Herein, the refractive index gradient can refer to the change of the refractive index along a spatial dimension. For example, when there is a change in the refractive index between two regional segments among multiple regional segments, there can be a refractive index gradient between the two regional segments. Alternatively or additionally, when the refractive index changes within one of the multiple regional segments, there can be a refractive index gradient within that regional segment.

[0057] In some embodiments, the control of the refractive indices of the plurality of regional segments of the planar waveguide can define a refractive index gradient across the entire planar waveguide. For example, the plurality of regional segments can include a large number of regional segments, and there can be a small gradient between every two adjacent regional segments. Thus, the refractive index can vary effectively continuously across the entire planar waveguide.

[0058] For example, in Figure 2 the embodiment of, the refractive index of the planar waveguide 201 can vary from the first segment 210 to the second segment 211, from the second segment 211 to the third segment 212, and / or from the third segment 212 to the fourth segment 213.

[0059] According to one embodiment, the control of the refractive indices of the plurality of regional segments of the planar waveguide defines at least one gradient in a direction perpendicular to the surface of the planar waveguide.

[0060] The direction perpendicular to the surface of the planar waveguide 201 can refer to the thickness direction. The direction perpendicular to the surface of the planar waveguide 201 can also be referred to as the direction parallel to the normal direction of the surface of the planar waveguide 201.

[0061] The at least one gradient in the direction perpendicular to the surface of the planar waveguide can be due to, for example, a gradient in the concentration of a substance in the direction perpendicular to the surface of the planar waveguide 201, and / or an attenuation of electromagnetic radiation and / or heat in the direction perpendicular to the surface of the planar waveguide 201.

[0062] In some other embodiments, the refractive index in the direction perpendicular to the surface of the planar waveguide 201 can be constant or substantially constant.

[0063] According to one embodiment, the method 100 further includes, after controlling 102 the refractive indices of the plurality of regional segments of the planar waveguide, coating a reflective coating on the planar waveguide, wherein the reflective coating reflects at least the electromagnetic radiation used to control the refractive indices of the plurality of regional segments of the planar waveguide.

[0064] The reflective coating can, for example, protect the planar waveguide 201 from electromagnetic radiation such that the refractive index of the planar waveguide 201 does not change due to, for example, exposure to UV and / or IR radiation from the sun or from other sources when the planar waveguide 201 is in use.

[0065] Figure 3 A schematic diagram of a planar waveguide including at least one diffraction grating according to one embodiment is shown.

[0066] According to one embodiment, at least one of the plurality of regional segments includes at least one diffraction grating.

[0067] For example, in Figure 3In an embodiment, the plurality of regional segments includes a first regional segment 310, the first regional segment 310 includes a first diffraction grating 320, and the second regional segment 311 includes a second diffraction grating 321. The first regional segment 310 and the second regional segment 311 form a boundary in the width direction. The remaining portion of the planar waveguide 201 that does not belong to the first regional segment 310 or the second regional segment 311 can be considered as a third regional segment.

[0068] Method 100 can be used, for example, to control / change the refractive index of the planar waveguide 201 on the first regional segment 310 and / or the second regional segment 311, while not changing the refractive index of the planar waveguide 201 on other regions. For example, other regions of the planar waveguide 201 can be masked, and / or electromagnetic radiation exposure and / or thermal exposure can be concentrated only on the first regional segment 310 and / or the second regional segment 311. Or, if it is only necessary to change the refractive index of the planar waveguide 201 outside the first regional segment 310 and / or the second regional segment 311, the opposite operation can be performed.

[0069] In this document, a diffraction grating can refer to an optical element whose working principle is based on the diffraction of light. Generally speaking, a diffraction grating can include structural features on the order of visible light wavelengths in at least one dimension, for example, at least one dimension less than one micron. A diffraction grating can include, for example, one-dimensional and two-dimensional diffraction gratings, which can be implemented as single-region diffraction gratings or multi-region diffraction gratings. A diffraction grating can be implemented as, for example, surface relief gratings or volume holographic gratings, and they can be configured to be used as transmissive and / or reflective diffraction gratings.

[0070] For example, in Figure 3 the embodiment, the first diffraction grating 320 and the second diffraction grating 321 include one-dimensional diffraction gratings, and the one-dimensional diffraction gratings include grooves / ridges that define the diffraction gratings. These are only exemplary, and at least one diffraction grating can also be implemented in various other ways.

[0071] In this document, a diffractive grating can also be referred to as a diffraction grating, an optical diffractive grating, an optical diffraction grating, a surface relief structure, a surface relief grating, or similar names.

[0072] At least one diffraction grating may include, for example, an in-coupling structure for coupling light into the planar waveguide 201 and / or an out-coupling structure for coupling light out of the planar waveguide 201. Alternatively or additionally, at least one diffraction grating may be configured to control the light propagating inside the planar waveguide 201 in various ways.

[0073] Figure 4 A cross-sectional view of a planar waveguide including a diffraction grating according to an embodiment is shown.

[0074] According to an embodiment, controlling the refractive index of a plurality of regional segments of a planar waveguide includes controlling the refractive index of at least one diffraction grating and / or controlling the refractive index of the planar waveguide in the regional segment corresponding to at least one diffraction grating.

[0075] Alternatively or additionally, controlling the refractive index of a plurality of regional segments of a planar waveguide includes controlling the refractive index of the planar waveguide in the regional segment not corresponding to at least one diffraction grating.

[0076] By controlling the refractive index of at least one diffraction grating 420 and / or the refractive index of the planar waveguide in the regional segment 401 corresponding to at least one diffraction grating 420, the diffraction characteristics of at least one diffraction grating 420 can be controlled.

[0077] The regional segment 401 corresponding to at least one diffraction grating 420 may refer to, for example, the regional segment of the planar waveguide 201 covered by at least one diffraction grating 420. Such a regional segment may also be referred to as the regional segment under at least one diffraction grating 420 or the like.

[0078] Any of the herein descriptions regarding controlling the refractive index of the planar waveguide 201 may also be applied to controlling the refractive index of at least one diffraction grating 420.

[0079] According to an embodiment, at least one diffraction grating includes a substance sensitive to electromagnetic radiation and / or to heat, and / or a coating sensitive to electromagnetic radiation and / or to heat.

[0080] Figure 5 A schematic diagram of a display structure according to an embodiment is shown.

[0081] According to an embodiment, the display structure 500 includes a planar waveguide 201 obtained by the method 100.

[0082] The display structure 500 may further include an in-coupling (IC) structure 502, which is configured to couple an input beam group 510 into the planar waveguide 201 as an in-coupled beam group 511.

[0083] The IC structure 502 may include, for example, a diffraction grating on the surface of the planar waveguide 201.

[0084] The display structure 500 may further include an exit pupil expansion (EPE) structure 503, which is configured to receive the inner-coupled beam group 511 and diffract the inner-coupled beam group 511 in multiple directions to generate a diffracted beam group 512.

[0085] It should be understood that Figure 5 the diffracted beam group 512 shown in the embodiments is only exemplary. In an actual embodiment, the EPE structure 503 may diffract the inner-coupled beam group 511 in multiple directions in a more complex manner, and the diffracted beam group 512 may interact with the EPE structure 503 multiple times.

[0086] The display structure 500 may further include an out-coupling (OC) structure 504, which is configured to receive at least the diffracted beam group 512 from the EPE structure 503 and couple at least the diffracted beam group 512 out of the planar waveguide 201 as an output beam group 513.

[0087] The output beam group 513 may represent, for example, an expanded version of an image formed by the input beam group 510.

[0088] The inner-coupled beam group 511 and the diffracted beam group 512 may be guided within the planar waveguide 201 by total internal reflection (TIR). Therefore, the guiding can be adjusted by controlling the refractive index of the planar waveguide 201 using method 100.

[0089] The IC structure 502, the EPE structure 503, and / or the OC structure 504 may include, for example, diffraction gratings on the surface of the planar waveguide 201. The IC structure 502 may couple the input beam group 510 into the planar waveguide 201 by diffraction. The EPE structure 503 may expand the image corresponding to the inner-coupled beam group 511 by diffraction. The OC structure 504 may couple the diffracted beam group 512 out of the planar waveguide 201 by diffraction. The diffraction characteristics of the IC structure 502, the EPE structure 503, and / or the OC structure 504 can be controlled using method 100.

[0090] Figure 6 A schematic diagram of a display device according to an embodiment is shown.

[0091] According to an embodiment, the display device 600 includes a display structure 500.

[0092] According to an embodiment, the display device 600 is implemented as a see-through display device.

[0093] According to one embodiment, the display device 600 is implemented as a head-mounted display device.

[0094] For example, in Figure 6 the embodiment of, the display device 600 is implemented as smart glasses. The planar waveguide 201 can correspond to the lens of such smart glasses. Such smart glasses can be used, for example, to implement augmented reality (AR) and / or virtual reality (VR) functions.

[0095] In Figure 6 the embodiment of, the input beam group 510 can be generated, for example, by an optical engine 601 (such as a scan-based optical engine). The input beam group 510 can represent an image generated by such an optical engine, for example. The display structure 500 of the display device 600 can direct the output beam group 513 representing the image generated by the optical engine 601 to the user's eyes.

[0096] Any range or device value given herein can be extended or changed without losing the desired effect. In addition, unless explicitly prohibited, any embodiment can be combined with another embodiment.

[0097] 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. On the contrary, the above specific features and acts are disclosed as examples of the claims and other equivalent features and acts and are intended to fall within the scope of the claims.

[0098] It should be understood that the above description of benefits and advantages may relate to one embodiment or may relate to several embodiments. Embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages. It should be further understood that a reference to "one" item can mean one or more of these items.

[0099] Any aspect of the above embodiments can be combined with any aspect of the other above embodiments to form a further embodiment without losing the desired effect.

[0100] In this document, the term "comprising" is used to mean including the identified method, block, or element, but such block or element does not include an exclusive list, and the method or device can include additional blocks or elements.

[0101] It should be understood that the above description is given by way of example only, and those skilled in the art can make various modifications. The above specification, examples and data provide a complete description of the structure and use of the exemplary embodiments. Although the various embodiments have been described above to a certain degree of particularity or with reference to one or more separate embodiments, those skilled in the art can make various changes to the disclosed embodiments without departing from the spirit or scope of this specification.

Claims

1. A method (100) for controlling the refractive index of a planar waveguide, comprising: providing (101) a planar waveguide including a plurality of regional segments; and controlling (102) the refractive index of the plurality of regional segments of the planar waveguide by exposing the planar waveguide to a plurality of electromagnetic radiation exposures corresponding to the plurality of regional segments and / or by exposing the planar waveguide to a plurality of thermal exposures corresponding to the plurality of regional segments; wherein the planar waveguide includes a substance sensitive to electromagnetic radiation and / or to heat.

2. The method (100) according to claim 1, wherein exposing the planar waveguide to a plurality of electromagnetic radiation exposures corresponding to the plurality of regional segments and / or exposing the planar waveguide to a plurality of thermal exposures corresponding to the plurality of regional segments includes at least one of the following: masking at least one of the plurality of regional segments; changing the intensity of the electromagnetic radiation between the plurality of regional segments; changing the intensity of the heat between the plurality of regional segments; and / or changing the wavelength of the electromagnetic radiation between the plurality of regional segments.

3. The method (100) according to claim 1 or 2, wherein the electromagnetic radiation includes ultraviolet radiation and / or infrared radiation.

4. The method (100) according to any one of the preceding claims, wherein the planar waveguide further includes a coating sensitive to electromagnetic radiation and / or to heat.

5. The method (100) according to claim 4, wherein the electromagnetic radiation includes ultraviolet radiation, and the substance and / or the coating includes at least one of the following: titanium dioxide, germanium dioxide, germanium, and / or boron.

6. The method (100) according to any one of the preceding claims, wherein at least one of the plurality of regional segments includes at least one diffraction grating.

7. The method (100) according to claim 6, wherein controlling the refractive index of the plurality of regional segments of the planar waveguide includes controlling the refractive index of at least one diffraction grating and / or controlling the refractive index of the planar waveguide in the regional segment corresponding to at least one diffraction grating.

8. The method (100) according to any one of the preceding claims, wherein the control of the refractive index of the plurality of regional segments of the planar waveguide defines at least one refractive index gradient on the planar waveguide.

9. The method (100) according to any one of the preceding claims, wherein the control of the refractive index of the plurality of regional segments of the planar waveguide defines at least one gradient in a direction perpendicular to the surface of the planar waveguide.

10. The method (100) according to any one of the preceding claims, the method further comprising, after controlling the refractive index of the plurality of regional segments of the planar waveguide, coating a reflective coating on the planar waveguide, wherein the reflective coating reflects at least the electromagnetic radiation used to control the refractive index of the plurality of regional segments of the planar waveguide.

11. A display structure comprising a planar waveguide obtained by the method according to any one of the preceding claims.

12. A display device comprising the display structure according to claim 11.

13. The display device according to claim 12, implemented as a see-through display device.

14. The display device according to claim 12 or 13, implemented as a head-mounted display device.

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