Optical waveguide substrate, method for manufacturing optical waveguide substrate, and wearable display device

Abstract

Embodiments of the present disclosure provide an optical waveguide substrate, a method for manufacturing an optical waveguide substrate, and a wearable display device. The optical waveguide substrate comprises: a substrate configured to guide light propagating therein; and at least one grating element group located on the substrate, each grating element group comprising at least one grating element configured to change the propagation path of the light.

Description

Optical waveguide substrate, method of manufacturing optical waveguide substrate, and wearable display device TECHNICAL FIELD

[0001] The present disclosure relates to the field of display technology, and in particular, to an optical waveguide substrate, a method of manufacturing an optical waveguide substrate, and a wearable display device. BACKGROUND

[0002] Imaging systems can be used to present visual information to a user. For example, an imaging system can include optical components that project an image onto an imaging surface so that one or more users can view the image. In some cases, an imaging system can be incorporated into a wearable display system so that visual information is presented in a more immersive manner. For example, a wearable display system can be used to present visual information for a virtual reality (VR) or augmented reality (AR) system.

[0003] SUMMARY

[0004] Embodiments of the present disclosure provide an optical waveguide substrate, a method of manufacturing an optical waveguide substrate, and a wearable display device.

[0005] In an aspect of the present disclosure, an optical waveguide substrate includes a substrate configured to guide light propagating therein, and at least one grating element group on the substrate, each grating element group including at least one grating element configured to change a propagation path of the light.

[0006] In one or more embodiments of the present disclosure relating to an optical waveguide substrate, the substrate can include a plurality of optical waveguide regions, a portion of the optical waveguide substrate in each optical waveguide region serving as a single optical waveguide that guides light. In some embodiments, the at least one grating element group includes a plurality of grating element groups, a footprint of each of the plurality of grating element groups on the substrate being located in the plurality of optical waveguide regions, respectively.

[0007] In one or more embodiments of the present disclosure relating to an optical waveguide substrate, the plurality of optical waveguide regions can be arranged in a rectangular array.

[0008] In one or more embodiments of the present disclosure relating to an optical waveguide substrate, each of the at least one grating element group can include a first grating element configured to couple the light into the substrate so that the light propagates in the substrate with total internal reflection, and a second grating element configured to redirect the light guided within the substrate out of the substrate.

[0009] In one or more embodiments of the present disclosure relating to an optical waveguide substrate, a thickness of the first grating element can be greater than a thickness of the second grating element.

[0010] In one or more embodiments of the present disclosure related to an optical waveguide substrate, each of the at least one grating element group can further include a third grating element configured to deflect light coupled into the substrate toward the second grating element and distribute light on a side of the second grating element.

[0011] In one or more embodiments of the present disclosure related to an optical waveguide substrate, a thickness of the third grating element can be less than a thickness of the first grating element.

[0012] In one or more embodiments of the present disclosure related to an optical waveguide substrate, the optical waveguide substrate can further include an etch stop layer between the substrate and the grating element group.

[0013] In one or more embodiments of the present disclosure related to an optical waveguide substrate, the substrate can include a rectangular glass.

[0014] In one or more embodiments of the present disclosure related to an optical waveguide substrate, the at least one grating element can include an inorganic material.

[0015] In one or more embodiments of the present disclosure related to an optical waveguide substrate, the inorganic material can include any one of silicon oxide, silicon nitride, titanium oxide, or niobium oxide.

[0016] In another aspect of the present disclosure, a method of manufacturing an optical waveguide substrate is provided, including: providing a substrate configured to guide light propagating therein; and forming at least one grating element group on the substrate, each grating element group including at least one grating element configured to change a propagation path of the light.

[0017] In one or more embodiments related to a method of manufacturing an optical waveguide substrate, the substrate can include a plurality of optical waveguide regions, a portion of the optical waveguide substrate in each optical waveguide region serving as a single optical waveguide guiding light. In some embodiments, forming at least one grating element group on the substrate can include: depositing a layer of optical material on the substrate; and patterning the layer of optical material to form a plurality of grating element groups on the substrate respectively for the plurality of optical waveguide regions.

[0018] In one or more embodiments related to a method of manufacturing an optical waveguide substrate, the layer of optical material can include a plurality of portions of optical material. In some embodiments, depositing a layer of optical material on the substrate can include depositing the plurality of portions of optical material on the substrate respectively for the plurality of optical waveguide regions.

[0019] In one or more embodiments related to a method of fabricating an optical waveguide substrate, patterning the layer of optical material can include: depositing a mask layer on a surface of the substrate and the layer of optical material; patterning the mask layer; patterning the layer of optical material through the patterned mask layer; and removing the mask layer.

[0020] In one or more embodiments related to a method of fabricating an optical waveguide substrate, the mask layer can be patterned through a nanoimprint process and the layer of optical material can be patterned through an etching process.

[0021] In one or more embodiments related to a method of fabricating an optical waveguide substrate, the plurality of optical waveguide regions can be arranged in a rectangular array.

[0022] In one or more embodiments related to a method of fabricating an optical waveguide substrate, each of the at least one set of grating elements can include a first grating element configured to cause the light to couple into the substrate such that the light propagates in the substrate with total internal reflection and a second grating element configured to redirect light guided within the substrate out of the substrate.

[0023] In one or more embodiments related to a method of fabricating an optical waveguide substrate, a first thickness of the first grating element can be greater than a second thickness of the second grating element. In some embodiments, depositing the plurality of portions of optical material in the plurality of optical waveguide regions of the substrate respectively can include: depositing a first portion of optical material having the first thickness in each of the plurality of optical waveguide regions; and depositing a second portion of optical material having the second thickness in each of the plurality of optical waveguide regions, the second portion of optical material being non-overlapping with the first portion of optical material.

[0024] In one or more embodiments related to a method of fabricating an optical waveguide substrate, each of the at least one set of grating elements can further include a third grating element configured to deflect light coupled into the substrate toward the second grating element and to distribute light on a side of the second grating element.

[0025] In one or more embodiments related to a method of fabricating an optical waveguide substrate, a third thickness of the third grating element can be less than the first thickness of the first grating element. In some embodiments, depositing the plurality of portions of optical material in the plurality of optical waveguide regions of the substrate respectively includes further including: depositing a third portion of optical material having the third thickness in each of the plurality of optical waveguide regions, the third portion of optical material being non-overlapping with the first portion of optical material and the second portion of optical material.

[0026] In one or more embodiments directed to a method of making an optical waveguide substrate, the method can further include forming an etch stop layer on the substrate. In such embodiments, forming at least one grating element group on the substrate can include forming the at least one grating element group on the etch stop layer.

[0027] In yet another aspect of the disclosure, a method of making an optical waveguide is also provided, comprising:

[0028] An optical waveguide substrate is made in accordance with any of the embodiments of the disclosure directed to a method of making an optical waveguide substrate, the substrate comprising a plurality of optical waveguide regions; and singulating the optical waveguide substrate in units of individual optical waveguide regions to form a plurality of individual optical waveguides.

[0029] In yet another aspect of the disclosure, a wearable display device is also provided, comprising an eyepiece comprising an optical waveguide formed in accordance with any of the embodiments of the disclosure directed to an optical waveguide substrate.

[0030] Further aspects and scope of applicability will become apparent from the description provided herein. It should be understood that various aspects of the application can be practiced alone or in combination with one or more other aspects. It should also be understood that the description and specific examples herein are intended for illustrative purposes only and are not intended to limit the scope of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0031] The drawings described herein are for purposes of illustration only and are not exhaustive list of all possible implementations. In the drawings:

[0032] FIG. 1 schematically illustrates an example of a wearable display system;

[0033] FIG. 2A schematically illustrates a plan view of an optical waveguide substrate in one or more embodiments of the disclosure;

[0034] FIG. 2B schematically illustrates a partial cross-sectional view of the optical waveguide substrate along line AA’ in FIG. 2A;

[0035] FIG. 2C schematically illustrates a partial cross-sectional view of the optical waveguide substrate along line BB’ in FIG. 2A;

[0036] FIG. 3 illustrates a picture of an optical waveguide substrate in one or more embodiments of the disclosure;

[0037] FIG. 4 illustrates a picture of an individual optical waveguide in one or more embodiments of the disclosure;

[0038] FIG. 5 schematically illustrates an optical waveguide substrate formed in a wafer process;

[0039] FIG. 6A schematically illustrates a simplified cross-sectional view of an optical waveguide including a first grating element and a third grating element in one or more embodiments of the present disclosure;

[0040] FIG. 6B schematically illustrates a perspective view of the optical waveguide of FIG. 6A;

[0041] FIG. 7 schematically illustrates a stack of optical waveguides;

[0042] FIG. 8A illustrates an optical waveguide based on a tilted grating element;

[0043] FIG. 8B illustrates an optical waveguide based on a blazed grating element;

[0044] FIG. 8C illustrates an optical waveguide based on a metasurface grating element;

[0045] FIG. 9 schematically illustrates a flowchart of a method of fabricating an optical waveguide substrate in one or more embodiments of the present disclosure;

[0046] FIG. 10 schematically illustrates a cross-sectional view of a single optical waveguide formed based on a wafer process;

[0047] FIG. 11 schematically illustrates a detailed flowchart of a method of fabricating an optical waveguide substrate in one or more embodiments of the present disclosure;

[0048] FIGS. 12A-12F schematically illustrate cross-sectional views of various intermediate structures formed during a process of fabricating an optical waveguide substrate;

[0049] FIG. 13 schematically illustrates a flowchart of a method of fabricating an optical waveguide in one or more embodiments of the present disclosure; and

[0050] FIGS. 14A-14D schematically illustrate wearable display devices in some embodiments of the present disclosure.

[0051] Throughout the drawings, like reference numerals indicate like parts throughout the several views of the drawings. DETAILED DESCRIPTION

[0052] Various embodiments will now be described in detail with reference to the drawings, which are provided as illustrative examples so as to enable those skilled in the art to implement the present disclosure. The embodiments described below are not intended to be exhaustive or to be limited to the precise form disclosed.

[0053] It is noted that the following drawings and examples are not meant to limit the scope of the present disclosure. Where certain elements of the present disclosure can be partially or fully implemented using known components, only those portions of such known components that are necessary for an understanding of the present disclosure will be described, and detailed descriptions of other portions of such known components will be omitted so as not to obscure the disclosure. Further, various embodiments encompass present and future known equivalents to the components referred to herein by way of illustration.

[0054] As used herein, the terms "have," "comprise," and "contain" and grammatical variations thereof are used in a non-exclusive sense, such that a process, method, article, or apparatus that "comprises," "has," or "contains" one or more elements or a combination of elements is not necessarily limited to those elements unless the text expressly states otherwise. The terms "a" and "an" are used in the sense that they mean one or more than one (i.e., "at least one"), and the terms "another" and "one or more" are used in the sense that they mean any one or more of the preceding claims.

[0055] However, as used herein, the term "on" does not refer to a specific geometric orientation of the optical waveguide substrate or the final stack of optical waveguides relative to the direction of gravity, but rather indicates the way the stack is manufactured, which after manufacturing can be placed in any geometric orientation, such as upside down. The terms "first," "second," "third," etc. are used for descriptive purposes only and should not be construed as indicating or implying relative importance and forming an order.

[0056] For the purposes of the surface description below, the terms "upper," "lower," "left," "right," "vertical," "horizontal," "top," "bottom," and derivatives thereof shall relate to the application as oriented in the drawings. The terms "overlying," "atop," "positioned on" or "positioned atop" mean that a first element is present on a second element, wherein intervening elements (e.g., an interface structure) can be present between the first element and the second element. The term "direct contact" means that a first element is connected to a second element without any intervening element present between the first element and the second element.

[0057] Figure 1 schematically illustrates an example of a wearable display system. As shown in Figure 1, display system 60 includes an eyepiece 70, as well as various mechanical and electronic modules and systems that support the functioning of this eyepiece 70. Eyepiece 70 can be coupled to a frame 80 that is wearable by a display system user or observer 90, and that is configured to position eyepiece 70 in front of the eyes of user 90. In some embodiments, eyepiece 70 can be considered an eyeglass lens. In some embodiments, a speaker 100 is coupled to frame 80 and is configured to be positioned near an ear canal of user 90 (in some embodiments, another speaker, not shown, is positioned near the other ear canal of the user to provide stereo / shapeable sound control). In some embodiments, the display system can also include one or more microphones 110 or other devices that detect sound. In some embodiments, the microphones are configured to allow the user to provide input or commands to system 60 (e.g., selection of voice menu commands, natural language questions, etc.), and / or can allow audio communication with other people (e.g., with other users of similar display systems). In some embodiments, the display system can also include a peripheral sensor 120a that can be separate from frame 80 and that is attached to the body of user 90 (e.g., on the head, torso, limb, etc. of user 90). In some embodiments, peripheral sensor 120a can be configured to gather data that characterizes a physiological state of user 90. For example, sensor 120a can be an electrode.

[0058] With continued reference to FIG. 1, the eyepiece 70 is operatively coupled to a local data processing module 140 by a communication link 130, such as by a wired lead or wireless connectivity. The local data processing module 140 can be mounted in various configurations, such as fixedly attached to the frame 80, fixedly attached to a helmet or hat worn by the user, embedded in headphones, or otherwise removably attached to the user 90 (e.g., in a backpack- type configuration, in a belt-coupling type configuration). Similarly, the sensor 120a can be operatively coupled to the local data processor and data module 140 by a communication link 120b (e.g., a wired lead or wireless connectivity). The local processing and data module 140 can include a hardware processor, and digital memory, such as nonvolatile memory (e.g., flash memory or hard disk drive) which can be used to assist with the processing, caching and storage of data. The local processing and data module 140 can be operatively coupled by communication links 170, 180, such as via wired or wireless communication links, to a remote processing module 150 and remote data repository 160, such that these remote modules 150, 160 are operatively coupled to each other and available as resources to the local processing and data module 140. In some embodiments, the local processing and data module 140 can include one or more of the following: an image capture device, a microphone, an inertial measurement unit, an accelerometer, a compass, a GPS unit, a radio device, and / or a gyroscope.

[0059] With continued reference to FIG. 1, in some embodiments, the remote processing module 150 can include one or more processors configured to analyze and process data and / or image information. In some embodiments, the remote data repository 160 can include a digital data storage facility, which can be available through the Internet or other network configuration in a "cloud" resource configuration. In some embodiments, the remote data repository 160 can include one or more remote servers that provide information to the local processing and data module 140 and / or the remote processing module 150, e.g., information for generating augmented reality content. In some embodiments, all data is stored and all computing is performed in the local processing and data module, which allows for fully autonomous use from the remote modules.

[0060] In virtual reality application scenarios, the eyepiece 70 of the wearable display system can act as an optical waveguide that directs light carrying virtual image information to the eyes of the user 90. In augmented reality application scenarios, in addition to acting as an optical waveguide that directs light carrying virtual image information to the eyes of the user, the eyepiece 70 can also act as a transmissive element to present the real environment to the user. Thus, the wearable display system generally presents image information to the user based on optical waveguide technology.

[0061] Therefore, it can be crucial for wearable display systems to provide an optical waveguide substrate with high optical performance and low cost and a method of manufacturing such an optical waveguide substrate.

[0062] As used herein, the term "optical waveguide" refers to an optical component that can be used to guide light carrying image information to a user's eye. The term "optical waveguide substrate" can refer to an intermediate product in the process of manufacturing an optical waveguide, which can include a plurality of optical waveguides and can form a plurality of optical waveguides by cutting the intermediate product; it can also refer to a final optical waveguide. In the latter case, "optical waveguide substrate" has the same meaning as "optical waveguide".

[0063] To avoid confusion, in the embodiments described below, "optical waveguide substrate" refers to an intermediate product. However, it should be understood that the case where the optical waveguide substrate includes only one optical waveguide is also within the scope of the present disclosure, i.e., the case where the optical waveguide substrate serves as a final optical waveguide is also within the scope of the present disclosure.

[0064] In some embodiments of the present disclosure, an optical waveguide substrate is disclosed. The optical waveguide substrate can include a substrate configured to guide light propagating therein, and at least one grating element group located on the substrate. The light can propagate within the substrate by total internal reflection. Each grating element group can include at least one grating element configured to change the propagation path of the light.

[0065] It should be noted that in the embodiments of the present disclosure relating to methods, "at least one grating element group on the substrate" can refer to the case where the grating element group is directly located on the substrate, and can also refer to the case where the grating element group is indirectly located on the substrate. In the latter case, there can be intermediate elements between the grating element group and the substrate, for example, etching stop layers.

[0066] Based on the optical waveguide substrate provided by the embodiments of the present disclosure, a larger number of grating element groups can be provided on a single substrate. For example, tens or even hundreds of grating element groups can be provided on a single substrate. A plurality of optical waveguides can be formed by a cutting process. Therefore, the manufacturing cost of such an optical waveguide substrate and the final optical waveguide is low.

[0067] FIG. 2A schematically shows a plan view of the optical waveguide substrate 2 in one or more embodiments of the present disclosure. As shown in FIG. 2A, the optical waveguide substrate 2 can include a substrate 21 and a plurality of grating element groups 22. The substrate 21 can be a light guiding optical element for guiding light, which can propagate within the substrate 21 by total internal reflection. The substrate 21 can include a plurality of optical waveguide regions 211 (areas indicated by dashed lines in FIG. 2A, only two dashed lines are identified in FIG. 2A). The portions of the optical waveguide substrate 2 corresponding to each of the optical waveguide regions 211 can serve as a single optical waveguide for guiding light. The orthogonal projections of the plurality of grating element groups 22 on the substrate 21 can be located in the plurality of optical waveguide regions 211, respectively.

[0068] FIG. 3 shows a picture of an optical waveguide substrate in one or more embodiments of the present disclosure. FIG. 4 shows a picture of a single optical waveguide in one or more embodiments of the present disclosure. As shown in FIG. 3, a single optical waveguide substrate can include a plurality of optical waveguides. The plurality of single optical waveguides as shown in FIG. 4 can be formed by cutting the optical waveguide substrate shown in FIG. 3.

[0069] Referring back to FIG. 2A, the plurality of optical waveguide regions 211 can be arranged in a rectangular array. Accordingly, the plurality of grating element groups 22 are also arranged in a rectangular array. The rectangular array arrangement can allow a larger number of grating element groups 22 to be provided on a single substrate 21. Therefore, a single optical waveguide substrate 2 can include a larger number of optical waveguides, which can reduce the cost of manufacturing the optical waveguides.

[0070] In the related art, the optical waveguide can be prepared by using an 8-inch wafer process combined with nano-imprinting technology. In such a preparation process, an imprinting glue is coated on a wafer substrate, and then imprinted by an imprinting mold to form the required grating elements on the wafer substrate. FIG. 5 schematically shows an optical waveguide substrate 5 formed by a wafer process. As shown in FIG. 5, the substrate 51 in the wafer process is circular and has a relatively small size, usually no more than 8 inches. Therefore, due to the size and shape of the wafer substrate 51 or the mold, only a small number of optical waveguides can be prepared on a single substrate 51, usually no more than 6. This results in a relatively high overall manufacturing cost.

[0071] In some embodiments of the present disclosure, the substrate 21 can be a rectangular glass. Since the rectangular glass can have a relatively high refractive index, for example, 1.5-2.4, using the rectangular glass as the substrate 21 can improve the overall optical performance of the generated optical waveguide. In addition, the rectangular glass can have a relatively large size, so a larger number of grating element groups arranged in a rectangular array can be prepared on a single glass substrate, and thus a larger number of optical waveguides can be divided out. For example, the rectangular glass substrate can have a size of 370 mm*470 mm, and the rectangular glass substrate of such a size can be processed to form at least 30 optical waveguides. Therefore, the preparation efficiency of the optical waveguides is greatly improved, and the preparation cost is reduced.

[0072] Figure 2B schematically illustrates a partial cross-sectional view of the optical waveguide substrate along line AA’ in Figure 2A. Figure 2C schematically illustrates a partial cross-sectional view of the optical waveguide substrate along line BB’ in Figure 2A. Referring to Figures 2B and 2C, the optical waveguide substrate can further comprise an etch stop layer 23 between the substrate 21 and the plurality of grating element groups 22. In this case, the grating element groups 22 are on the etch stop layer 23, but the orthographic projection of the grating element groups 22 on the substrate 21 is still in the corresponding optical waveguide region 211. This etch stop layer 23 can prevent over-etching of the material during the process of fabricating the optical waveguide substrate 2.

[0073] Referring to Figures 2A to 2C, in some embodiments of the present disclosure, each grating element group can comprise a first grating element 221 and a second grating element 222. The first grating element 221 can be an in-coupling grating, which can be configured to couple light from an image source into the substrate 21 to propagate in the substrate 21 in total internal reflection. In some embodiments of the present disclosure, the first grating element 221 can be wavelength selective, such that it selectively redirects light of one or more wavelengths while transmitting light of other wavelengths. The second grating element 222 can be an out-coupling grating, which is configured to redirect light guided within the substrate 21 out of the optical waveguide. In an example embodiment, the second grating element 222 can be configured to deflect and redirect light guided within the waveguide at an angle relative to the normal of the surface of the substrate 21 to reduce the effect of total internal reflection, such that the light is not guided within the substrate but exits therefrom.

[0074] In some embodiments of the present disclosure, the first grating element 221 can have a different thickness from the second grating element 222. In an example embodiment, the thickness of the first grating element 221 can be greater than the thickness of the second grating element 222. For example, the thickness of the first grating element 221 can be about 100 nm to 500 nm, and the thickness of the second grating element 222 can be about 20 nm to 200 nm.

[0075] The thicker thickness of the first grating element 221 can improve the in-coupling efficiency of the first grating element 221 to couple more light into the optical waveguide. And the thinner thickness of the second grating element 222 can allow the second grating element 222 to distribute light over the length or width of the optical waveguide and exit across the entire length or width of the optical waveguide with a lower out-coupling efficiency. That is, when light guided within the substrate 21 first hits the second grating element 222, only a small portion of the light is coupled out of the substrate, and the remaining majority of the light is still guided within the substrate 21; when the remaining light second hits the second grating element 222, a small portion of the remaining light is coupled out of the substrate 21, and the other light is still guided within the substrate 21, and so on until substantially all the light is coupled out of the substrate 21.

[0076] Referring to FIGS. 2A and 2B, to distribute the light over a two-dimensional surface of the optical waveguide, each grating element group 22 can further include a third grating element 223. The third grating element 223 can be configured to deflect the light coupled into the substrate 21 toward the second grating element 222 and to distribute the light over the side of the second grating element 222.

[0077] In one or more embodiments of the present disclosure, the thickness of the third grating element 223 can be less than the thickness of the first grating element 221. For example, the thickness of the first grating element 221 can be about 100 nm to 500 nm, and the thickness of the third grating element 223 can be about 20 nm to 200 nm.

[0078] The smaller thickness of the third grating element 223 can cause the third grating element 223 to deflect the light toward the second grating element 222 with a smaller deflection efficiency. That is, when the light guided within the substrate 21 first impinges on the third grating element 223, only a small portion of the light is deflected by the third grating element 223 toward the second grating element 222, and the remaining majority of the light is still guided within the substrate 21; when the remaining light second impinges on the third grating element 223, a small portion of the remaining light is deflected by the third grating element 223 toward the second grating element 222, and the other light is still guided within the substrate 21, and so on, until substantially all of the light is deflected to the second grating element 222.

[0079] FIG. 6A schematically illustrates a simplified cross-sectional view of an optical waveguide including the first grating element 221 and the third grating element 223, and FIG. 6B schematically illustrates a perspective view of the optical waveguide of FIG. 6A. As shown in FIG. 6A, the light from the image source is coupled into the substrate 21 by the first grating element 221 and then propagates by TIR and is guided within the substrate 21. The guided light rays then impinge on the third grating element 223. As shown in FIG. 6B, the third grating element 223 deflects the light in a manner to distribute the light in a longitudinal direction of the optical waveguide and still guide the light within the substrate 21, such that the light propagates toward the second grating element 222, respectively. The second grating element 222 directs the light guided within the substrate 21 out of the substrate 21 and toward the user’s eye.

[0080] To realize three-dimensional display, a stack of multiple optical waveguides can be employed to project image information to multiple different depth planes. FIG. 7 schematically illustrates a stack of multiple optical waveguides. As shown in FIG. 7, each optical waveguide in the stack of multiple optical waveguides can have substantially the same configuration as that of FIGS. 6A and 6B. The stacked waveguides can be spaced apart by, for example, layers of gaseous, liquid or solid material having a smaller refractive index. To avoid interference between light corresponding to different depth planes, the first grating elements 221 of the individual optical waveguides can be arranged to be misaligned non-perpendicularly, but offset from each other in the horizontal direction as shown in the figure. This non-overlapping spatial arrangement facilitates injection of light from different sources (such as different light sources and / or displays) into different optical waveguides on a one-to-one basis, allowing a particular light source to be uniquely coupled to a particular optical waveguide.

[0081] In addition to coupling light out of the optical waveguide, the first grating elements 221 can also collimate or diverge light as if the light originated from an object at a distance or a closer distance, depth or depth plane, thereby positioning light coupled out of different optical waveguides at different depth planes.

[0082] As an alternative or supplement to the embodiment shown in FIG. 7, switching between multiple depth planes can be realized by a variable focus optical waveguide. As an example, the second grating elements on the optical waveguide can be arranged as variable focus grating elements with variable refractive power to project a virtual image on multiple depth planes, thereby realizing three-dimensional display.

[0083] As a further alternative or supplement to the embodiment shown in FIG. 7, the stack of optical waveguides shown in FIG. 7 can be arranged to project light of different colors respectively, to realize color display. As an example, red, green and blue light can be made to propagate through and couple out of three stacked optical waveguides respectively. In this embodiment, to realize three-dimensional display, each optical waveguide can be arranged to be variable focus. As an alternative, a stack of optical waveguides comprising multiple groups of optical waveguides can be arranged. Each group of optical waveguides comprises three optical waveguides to guide light of different colors respectively. Different groups of optical waveguides are configured to project image light to different depth planes.

[0084] As yet another alternative, red, green and blue light can be guided by two optical waveguides, where one optical waveguide can be configured to guide two colors of light alternately, for example, red and green light, while the other optical waveguide can be configured to guide light of the third color, for example, blue light.

[0085] In some embodiments of the present disclosure, at least one grating element can comprise an inorganic material, for example, silicon oxide, silicon nitride, titanium oxide or niobium oxide. Generally, inorganic materials can have a higher refractive index, which can be higher than that of the imprinted glue material. Using inorganic materials with high refractive index to fabricate grating elements can improve the optical performance of the grating elements.

[0086] It should be noted that the above embodiments describe the case where each grating element group includes three grating elements, but embodiments of the present disclosure are not limited thereto. Depending on the specific use of the optical waveguide, each grating element group can also include less than or more than three grating elements.

[0087] It should also be noted that the grating elements in the embodiments of the present disclosure are also not limited to the rectangular grating elements shown in FIGS. 2B and 2C, but can also include inclined grating elements, blazed grating elements and metasurface grating elements as shown in FIGS. 8A to 8C, respectively. FIG. 8A shows an optical waveguide based on inclined grating elements. The inclined gratings shown in FIG. 8A can be prepared using an IBE or RIBE process. The grating period of the inclined gratings can be 200-500 nm, the grating height can be 50-500 nm, the grating duty cycle can be 0.2-0.8, and the grating tilt angle can be 30°-80°. FIG. 8B shows an optical waveguide based on blazed grating elements. The blazed gratings shown in FIG. 8B can be prepared using gray-scale exposure or an IBE process. The grating period of the blazed gratings can be 200-500 nm, the grating height can be 50-500 nm, the grating duty cycle can be 0.2-0.8, and the grating tilt angle can be 30°-80°. FIG. 8C shows an optical waveguide based on metasurface grating elements. The metasurface gratings shown in FIG. 8C can improve uniformity, improve optical efficiency, etc. The grating period of the metasurface gratings can vary between 200-500 nm, the grating height can be 50-500 nm, and the grating duty cycle can gradually change between 0.2-0.8. The metasurface gratings can be transmission type structures, geometric type structures, or composite structures of both.

[0088] In other embodiments of the present disclosure, a method of manufacturing an optical waveguide substrate is disclosed. Preferably, the method can manufacture at least one optical waveguide substrate according to the present disclosure, such as at least one optical waveguide substrate according to one or more embodiments disclosed above and / or below in more detail. Thus, for optional embodiments of the method, reference can be made to the embodiments of the optical waveguide substrate.

[0089] The steps included in the method can be performed in the given order or in a different order. Furthermore, additional method steps not listed can be provided. Furthermore, two or more or even all of the method steps can be performed at least partially simultaneously. Furthermore, a method step can be repeated twice or even more than twice.

[0090] The method of manufacturing an optical waveguide substrate can comprise providing a substrate configured to guide light propagating therein; and forming at least one grating element group on the substrate, each grating element group can comprise at least one grating element configured to change a propagation path of the light.

[0091] The optical waveguide substrate prepared based on the embodiments of the present disclosure can form more grating element groups on a single substrate. For example, tens or even hundreds of grating element groups can be disposed on a single substrate. The plurality of optical waveguides can be formed by a cutting process. Therefore, the optical waveguide substrate prepared by the method of the present disclosure has a low cost and high efficiency.

[0092] It should be noted that in the embodiments of the present disclosure related to the method, “forming at least one grating element group on the substrate” can refer to the case where the grating element group is directly formed on the substrate, and can also refer to the case where the grating element group is indirectly formed on the substrate. In the latter case, the grating element group and the substrate can have an intermediate element therebetween, for example, an etching stop layer.

[0093] FIG. 9 schematically shows a flowchart of a method of preparing an optical waveguide substrate in one or more embodiments of the present disclosure. As shown in FIG. 9, the method of preparing an optical waveguide substrate can include the following steps:

[0094] S91: providing a substrate configured to guide light propagating therein;

[0095] S92: forming at least one grating element group on the substrate, each grating element group can include at least one grating element configured to change the propagation path of light.

[0096] In step S91, the substrate can guide light propagating therein in a total internal reflection manner. In order to make light more easily satisfy the total internal reflection condition, a substrate with a higher refractive index can be used. As an example, the substrate can be a rectangular glass with a higher refractive index, for example, the refractive index of the glass substrate can be about 1.5-2.4. In addition, the rectangular glass can have a larger size, so a larger number of grating element groups can be prepared on a single glass substrate, so that a larger number of optical waveguides can be divided out.

[0097] In some embodiments of the present disclosure, the substrate can include a plurality of optical waveguide regions, and the portion of the optical waveguide substrate in each optical waveguide region can serve as a single optical waveguide for guiding light.

[0098] In step S92, a plurality of grating element groups can be formed in a plurality of optical waveguide regions, respectively. In this step, an optical material layer can be deposited on the substrate, and then the optical material layer can be patterned to form a plurality of grating element groups in a plurality of optical waveguide regions of the substrate, respectively.

[0099] In some embodiments, the optical material layer can be a continuous layer. In other embodiments, the optical material layer can include a plurality of discontinuous optical material portions. In the latter case, a plurality of optical material portions can be deposited in a plurality of optical waveguide regions of the substrate, respectively, to form a plurality of grating element groups by patterning the plurality of optical material portions.

[0100] In some embodiments, each of the at least one grating element group can include a first grating element and a second grating element. The first grating element can be configured to couple light into the substrate such that the light propagates in the substrate with TIR. The second grating element can be configured to redirect the light guided within the substrate out of the substrate.

[0101] In some embodiments, a first thickness of the first grating element can be greater than a second thickness of the second grating element. In this case, the depositing of the plurality of optical material portions in the plurality of optical waveguide regions respectively can include the following steps:

[0102] Step A: depositing, in each of the plurality of optical waveguide regions, a first optical material sub-portion having a first thickness, which can be used to form the first grating element; and

[0103] Step B: depositing, in each of the plurality of optical waveguide regions, a second optical material sub-portion having a second thickness, which can be used to form the second grating element.

[0104] In alternative embodiments, each of the at least one grating element group can further include a third grating element and the second grating element. The third grating element is configured to deflect light coupled into the substrate towards the second grating element and distribute the light on a side surface of the second grating element.

[0105] In some embodiments, a third thickness of the third grating element is less than the first thickness of the first grating element. In this case, the depositing of the plurality of optical material portions in the plurality of optical waveguide regions respectively can further include Step C: depositing, in each of the plurality of optical waveguide regions, a third optical material sub-portion having a third thickness, which can be used to form the third grating element.

[0106] In one or more embodiments of the present disclosure, the optical material layer can include an inorganic material layer. The inorganic material layer can have a relatively high refractive index, for example, 1.5-2.4. The inorganic material can be any one of silicon oxide, silicon nitride, titanium oxide, or niobium oxide, for example.

[0107] It should be noted that the above-mentioned Step A, Step B and optional Step C can be performed simultaneously or in the above-mentioned different orders.

[0108] In Step S92, the optical material layer can be patterned by the following steps:

[0109] Step a. Depositing a mask layer on the surface of the substrate and the optical material layer. In the case that the optical material layer is a continuous layer, the mask layer can be deposited on the surface of the optical material layer. In the case that the optical material layer is a plurality of separated optical material portions, the mask layer can be deposited on the portions of the surface of the substrate exposed by the optical material layer and the surfaces of the plurality of optical material portions.

[0110] Step b. Patterning the mask layer. In this embodiment, the mask layer can comprise a layer of imprint glue. In this step, the mask layer can be patterned by a nano-imprint process or by a photolithography process.

[0111] Step c. Patterning the optical material layer with the patterned mask layer as a mask. In this step, the optical material layer can be patterned by an etching process. In an optional embodiment, in order to prevent over-patterning of the optical material layer, an etch stop layer can be deposited on the substrate before depositing the optical material layer.

[0112] Step d. Removing the mask layer. In this step, the mask layer can be removed by an etching process.

[0113] As mentioned above, embodiments of the present disclosure can deposit a plurality of optical material portions (e.g. inorganic material portions) in a plurality of optical waveguide regions of a substrate. Each of the plurality of optical material portions can comprise optical material sub-portions of different thicknesses, which can be patterned by a process such as etching, so that grating elements with different grating heights can be formed. Since the grating elements are formed by etching the optical material, this way can achieve no high-refractive material residue at the grating voids, so that the finally formed optical waveguide can have better optical effect. Meanwhile, since the same optical waveguide substrate can carry a larger number of optical waveguides, a plurality of optical waveguides can be divided by cutting the optical waveguide. Therefore, this method of forming optical waveguides based on large-area optical waveguide substrates has lower cost.

[0114] Figure 10 schematically shows a cross-sectional view of a single optical waveguide formed based on wafer processing. As shown in Figure 10, the optical waveguide formed by wafer processing combined with imprint technology has a certain thickness of imprint glue 52 residue at the voids of the gratings. Due to the limitations of the process, the thickness of the residual imprint glue 52 is difficult to guarantee completely the same, which will affect the optical performance of the optical waveguide.

[0115] Figure 11 schematically illustrates a detailed flow chart of a method of fabricating an optical waveguide substrate in one or more embodiments of the present disclosure. Figures 12A-12F schematically illustrate cross-sectional views of various intermediate structures formed in the process of fabricating an optical waveguide substrate. Preferably, the method can fabricate at least one optical waveguide substrate according to the present disclosure, such as at least one optical waveguide substrate according to one or more embodiments disclosed above and / or below in more detail. Thus, for optional embodiments of the method, reference can be made to the embodiments of the optical waveguide substrate.

[0116] As shown in Figure 11, the method of fabricating an optical waveguide substrate can comprise the following steps S110, S112, S114, S116, S118, S120 and S122.

[0117] At step S110, a substrate 21 is provided (Figure 12A). The substrate 21 can be a rectangular glass substrate. The substrate 21 can comprise a plurality of optical waveguide regions 211, a portion of the optical waveguide substrate in each optical waveguide region 211 acting as a single optical waveguide guiding light.

[0118] At step S112, an etch stop layer 23 is deposited on the substrate 21 (Figure 12B). The etch stop layer 23 can prevent etching into the substrate in an etching process.

[0119] At step S114, an optical material layer 24 is deposited on the etch stop layer 23 (Figure 12C). This step can be achieved by the following sub-steps S114(a), S114(b) and optionally S114(c).

[0120] At sub-step S114(a), a first optical material portion 241 of a first thickness is deposited on the etch stop layer 23 in a region corresponding to each optical waveguide region 211 (Figure 12C). The first optical material portion 241 can be used to fabricate a first grating element 221 having a first thickness. The first grating element 221 can act as an in-coupling grating to in-couple light into the substrate 21 such that the light propagates in the substrate 21 by total internal reflection.

[0121] At sub-step S114(b), a second optical material portion 242 of a second thickness is deposited on the etch stop layer 23 in a region corresponding to each optical waveguide region 211 (Figure 12C). The second optical material portion 242 does not overlap the first optical material portion 241 and can be used to fabricate a second grating element 222 having a second thickness. The second grating element 222 can act as an out-coupling grating to redirect light guided within the substrate 21 out of the substrate 21.

[0122] In optional sub-step S114(c), a third portion of optical material (not shown) of a third thickness is deposited in the region of the etch stop layer 23 corresponding to each optical waveguide region. The third portion of optical material does not overlap the first and second portions of optical material and can be used to fabricate a third grating element 223 having a third thickness. The third grating element 223 can act as a light distribution element to deflect light coupled into the substrate 21 towards the second grating element 222 and to distribute the light on the side of the second grating element 222.

[0123] In some alternative embodiments, the above-mentioned sub-steps S114(a), S114(b), S114(c) can be performed simultaneously or in different orders. In other embodiments, one or two of the sub-steps S114(a), S114(b), S114(c) can be omitted or at least one step of depositing a portion of optical material can be added in the sub-steps S114(a), S114(b), S114(c) to form more grating elements, depending on the actual application.

[0124] At step S116, a layer of imprinting glue 25 is coated on the accessible surfaces of the etch stop layer 23 and the optical material layer 24 (Figure 12D). The thickness of the portion of the imprinting glue layer 25 on the optical material layer 24 can be less than the thickness of the portion on the etch stop layer 23, which can make the surface of the imprinting glue layer 25 away from the substrate 21 relatively flat.

[0125] At step S118, the imprinting glue layer 25 is patterned by a nano-imprinting process or a photolithography process to form a patterned imprinting glue layer (Figure 12E), which is used as a mask for patterning the optical material layer. The mask formed by the imprinting glue layer can have a pattern corresponding to the grating period of the desired grating element.

[0126] At step S120, the optical material layer 24 is patterned with the patterned imprinting glue layer 251 as a mask. In this step, the optical material layer 24 can be patterned by an etching process (e.g. a dry etching process), which can reduce or even eliminate the residue of unwanted optical material, thereby improving the optical performance of the resulting optical waveguide.

[0127] At step S122, the residual imprinting glue is removed to form the first grating element 221, the second grating element 222 and the third grating element (Figure 12F). After the patterning of the optical material layer 24, the imprinting glue that is part of the mask remains above the grating lines of the grating elements. In order to prevent the residual imprinting glue from affecting the performance of the final optical waveguide, the residual imprinting glue can be removed. This step can also be accomplished by an etching process.

[0128] The above steps S110, S112, S114, S116, S118, S120 and S122 can form an optical waveguide substrate including a plurality of optical waveguides. To form the final optical waveguides, the optical waveguide substrate can be cut in units of single optical waveguide regions to form a plurality of individual optical waveguides.

[0129] In yet some embodiments of the present disclosure, a method of manufacturing optical waveguides is provided. The method can include manufacturing an optical waveguide substrate using any of the embodiments of the method of manufacturing an optical waveguide substrate, and cutting the optical waveguide substrate in units of single optical waveguide regions to form a plurality of individual optical waveguides.

[0130] FIG. 13 schematically illustrates a flowchart of a method of manufacturing optical waveguides in one or more embodiments of the present disclosure. As shown in FIG. 13, the method of manufacturing optical waveguides can include steps S130, S132, optional S134 and optional S136.

[0131] In step S130, an optical waveguide substrate is manufactured, which can include a plurality of optical waveguide regions. The optical waveguide substrate can be manufactured using any of the embodiments of the method of manufacturing an optical waveguide substrate. Thus, for this step of manufacturing an optical waveguide substrate, reference can be made to the embodiments of the method of manufacturing an optical waveguide substrate.

[0132] In step S132, the optical waveguide substrate is cut in units of single optical waveguide regions to form a plurality of individual optical waveguides. In this step, the plurality of optical waveguides on the optical waveguide substrate can be separated by laser cutting.

[0133] In step S134, edge blackening is performed on each optical waveguide. In some embodiments, an edge blackening process can be performed on the individual optical waveguides to prevent light guided in the optical waveguides from leaking out of the side surfaces of the optical waveguides. In such embodiments, edge blackening of the optical waveguides can be achieved by disposing a reflective film or light-absorbing material on the side surfaces of the optical waveguides.

[0134] In step S136, an additional functional layer is attached to each optical waveguide. As an example, the additional functional layer can include a cover glass to protect the optical waveguides from adverse effects of the external environment.

[0135] The optical waveguides manufactured by the methods provided by the embodiments of the present disclosure can improve the efficiency of manufacturing optical waveguides and reduce the manufacturing cost.

[0136] The flowcharts depicted in the present disclosure are merely examples. There can be many variations to this flowchart or the steps described therein without departing from the spirit of the present disclosure. For example, the steps can be performed in a different order, or steps can be added, deleted, or modified. All these variations are considered a part of the claimed aspect.

[0137] In yet other embodiments of the present disclosure, a wearable display device is provided that can include eyepieces that include the optical waveguides provided in embodiments of the present disclosure. The optical waveguides can be fabricated from the optical waveguide substrates provided by any of the embodiments of the present disclosure relating to optical waveguide substrates. Thus, with respect to alternative embodiments of the wearable display device, reference can be made to the embodiments of the optical waveguide substrates and the embodiments of the methods of fabricating the optical waveguide substrates.

[0138] FIGS. 14A-14D schematically illustrate a wearable display device in some embodiments of the present disclosure. As shown in FIGS. 14A-14D, the wearable display device 14 can include an example left eyepiece 141 and an example right eyepiece 142. Each eyepiece can include an optical waveguide that can include surface diffractive optical elements for controlling the flow of image light, such as the first grating elements, second grating elements, and third grating elements mentioned above. For example, the left optical waveguide 143 can include a left first grating element 1431, a left second grating element 1432, and a left third grating element 1433. Similarly, the right optical waveguide 144 can include a right first grating element 1441, a right second grating element 1442, and a right third grating element 1443.

[0139] In some embodiments, the wearable display device can include a frame 145 that can include a left temple arm 2130 and a right temple arm 2132. A number of components can be disposed on the left and right temple arms 2130, 2132. As an example, the left temple arm 2130 can include a left speaker 2134 and the right temple arm 2132 includes a right speaker 2136. As another example, an inertial measurement unit (IMU) 2140 can be positioned in the right temple arm 2132, or in another suitable location in the wearable head device 2102.

[0140] In some embodiments, an image source can be disposed proximate to a first grating element such that the first grating element couples light from the image source out of the optical waveguide. In some examples, a left image source 146 can be vertically aligned with a left first grating element 1431 (as shown in FIGS. 14A-14C) such that light from the left image source 146 is normally incident on the left first grating element 1431. The left first grating element 1431 couples the light from the left image source 146 into the left optical waveguide 143 by redirecting the light. Similarly, a right image source 147 can be vertically aligned with a right first grating element 1441 (as shown in FIGS. 14A-14C) such that light from the right image source 147 is normally incident on the right first grating element 1441. The right first grating element 1441 couples the light from the right image source 147 into the right optical waveguide 144 by redirecting the light. In other examples, the left image source 147 can be located on a side of the left optical waveguide 143 proximate to the left strut 2130 (as shown in FIG. 14D) such that light from the left image source 146 is incident on the left first grating element 1431 from the side. The left first grating element 1431 couples the light from the left image source 146 into the left optical waveguide by redirecting the light. Similarly, the right image source 147 can be located on a side of the right optical waveguide 144 proximate to the right strut 2130 (as shown in FIG. 14D) such that light from the right image source 147 is incident on the right first grating element 1441 from the side. The right first grating element 1441 couples the light from the right image source 147 into the right optical waveguide 144 by redirecting the light.

[0141] With respect to the action of the various grating elements on light, reference can be made to the embodiments of the optical waveguide substrate, which are not repeated here.

[0142] The foregoing description of the embodiments has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the application to the precise form disclosed. Various elements or features of a specific embodiment are generally not limited to that particular embodiment, but are interchangeable with other embodiments, and can be used in a selected embodiment, even if not specifically shown or described. Modifications can also be made to a variety of the above-described embodiments with the same purpose and scope. Such modifications do not depart from the spirit and scope of the application, and all such modifications are intended to be included within the scope of the following claims.

Claims

1. An optical waveguide substrate, comprising: a substrate configured to guide light propagating therein; as well as At least one grating element group is located on the substrate, and each grating element group includes at least one grating element configured to change a propagation path of the light.

2. The optical waveguide substrate according to claim 1, wherein The substrate includes a plurality of optical waveguide regions, a portion of the optical waveguide substrate in each optical waveguide region serving as a single optical waveguide for guiding light, The at least one grating element group includes a plurality of grating element groups, and the orthographic projections of the plurality of grating element groups on the substrate are respectively located in the plurality of optical waveguide regions.

3. The optical waveguide substrate according to claim 2, wherein The plurality of optical waveguide regions are arranged in a rectangular array.

4. The optical waveguide substrate according to claim 1, wherein Each of the at least one grating element group includes a first grating element configured to couple the light into the substrate so that the light propagates in the substrate by total internal reflection, and a second grating element configured to redirect the light guided within the substrate out of the substrate.

5. The optical waveguide substrate according to claim 4, wherein The thickness of the first grating element is greater than the thickness of the second grating element.

6. The optical waveguide substrate according to claim 4, wherein Each of the at least one grating element group further includes a third grating element configured to deflect light coupled into the substrate toward the second grating element and distribute the light on a side surface of the second grating element.

7. The optical waveguide substrate according to claim 6, wherein The thickness of the third grating element is smaller than the thickness of the first grating element. 8 . The optical waveguide substrate according to claim 1 , further comprising an etching stopper layer between the substrate and the grating element group.

9. The optical waveguide substrate according to any one of claims 1 to 7, wherein The substrate includes rectangular glass.

10. The optical waveguide substrate according to any one of claims 1 to 7, wherein The at least one grating element comprises an inorganic material. 11 . The optical waveguide substrate according to claim 10 , wherein the inorganic material comprises any one of silicon oxide, silicon nitride, titanium oxide, and niobium oxide.

12. A method for preparing an optical waveguide substrate, comprising: providing a substrate configured to guide light propagating therein; as well as At least one grating element group is formed on the substrate, and each grating element group includes at least one grating element configured to change a propagation path of the light.

13. The method according to claim 12, wherein: The substrate includes a plurality of optical waveguide regions, a portion of the optical waveguide substrate in each optical waveguide region serving as a single optical waveguide for guiding light, And wherein forming at least one grating element group on the substrate comprises: depositing a layer of optical material on the substrate; and The optical material layer is patterned to form a plurality of grating element groups in the plurality of optical waveguide regions of the substrate.

14. The method according to claim 13, wherein The optical material layer comprises a plurality of optical material portions, And wherein depositing an optical material layer on the substrate comprises: The plurality of optical material portions are respectively deposited on the plurality of optical waveguide regions of the substrate.

15. The method according to claim 13 or 14, wherein: Patterning the optical material layer includes: depositing a mask layer on the surfaces of the substrate and the optical material layer; patterning the mask layer; patterning the optical material layer by a patterned mask layer; and The mask layer is removed.

16. The method according to claim 14, wherein The mask layer is patterned by a nanoimprint process, and the optical material layer is patterned by an etching process.

17. The method according to claim 13, wherein: The plurality of optical waveguide regions are arranged in a rectangular array.

18. The method according to claim 14, wherein Each of the at least one grating element group includes a first grating element configured to couple the light into the substrate so that the light propagates in the substrate by total internal reflection, and a second grating element configured to redirect the light guided within the substrate out of the substrate.

19. The method according to claim 18, wherein a first thickness of the first grating element is greater than a second thickness of the second grating element, Wherein, depositing the plurality of optical material portions respectively on the plurality of optical waveguide regions of the substrate comprises: depositing a first sub-portion of optical material having a first thickness in each of the plurality of optical waveguide regions; and A second sub-portion of optical material having a second thickness is deposited in each of the plurality of optical waveguide regions, the second sub-portion of optical material not overlapping the first sub-portion of optical material.

20. The method according to claim 19, wherein Each of the at least one grating element group further includes a third grating element configured to deflect light coupled into the substrate toward the second grating element and distribute the light on a side surface of the second grating element.

21. The method according to claim 20, wherein The third thickness of the third grating element is smaller than the first thickness of the first grating element, Wherein, depositing the plurality of optical material portions on the plurality of optical waveguide regions of the substrate respectively includes: A third optical material sub-portion having a third thickness is deposited in each of the plurality of optical waveguide regions, the third optical material sub-portion not overlapping the first optical material sub-portion and the second optical material sub-portion.

22. The method according to any one of claims 12 to 14, 16 to 21, further comprising: forming an etching stopper layer on the substrate, Wherein, forming at least one grating element group on the substrate comprises: The at least one grating element group is formed on the etch stop layer.

23. A method for preparing an optical waveguide, comprising: An optical waveguide substrate is prepared according to the method of any one of claims 12 to 22, wherein the substrate comprises a plurality of optical waveguide regions; as well as The optical waveguide substrate is cut in units of individual optical waveguide regions to form a plurality of individual optical waveguides.

24. A wearable display device comprising an eyepiece, wherein the eyepiece comprises an optical waveguide formed based on the optical waveguide substrate according to any one of claims 1 to 12.

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