Diffractive waveguide and smart glasses

Abstract

The application relates to the technical field of near-eye display, and discloses a diffractive waveguide and smart glasses, the diffractive waveguide comprising: a waveguide substrate; a coupling-out grating comprising a two-dimensional grating, the coupling-out grating being arranged on one side of the waveguide substrate, at least a part of the two-dimensional grating comprising two or more grating regions, wherein a first gap exists in the grating region, and the first gap width varies between different grating regions; and a deposition layer, the deposition layer being arranged on the side of the two-dimensional grating away from the waveguide substrate, and part of the structure of the deposition layer being filled in the first gap. According to the application, the first gap on the two-dimensional grating can be filled by part of the structure of the deposition layer, so that the loss of light energy can be reduced, and the optical efficiency is improved.

Description

Technical Field

[0001] This application relates to the field of near-eye display technology, and more particularly to a diffractive waveguide and smart glasses. Background Technology

[0002] In existing augmented reality (AR) optical solutions, diffractive waveguide-based designs are developing towards higher efficiency and higher uniformity. AR glasses receive light through the coupling grating of the diffractive waveguide and transmit it within the waveguide substrate. Then, the imaged light is guided to the eyes through the coupling grating, allowing the user to see the displayed content.

[0003] Two-dimensional diffraction gratings are a key technology due to their ability to extend the eyebox in two directions, providing a wider field of view. In fabricating such gratings, micro- and nano-fabrication devices are typically used to define periodic nanoscale structures on a waveguide substrate. However, these micro- and nano-fabrication devices have inherent physical precision limits (which can be understood as the minimum width of the cutting tool). Therefore, existing gratings may have gaps of at least 60 nanometers on both sides during etching. When light propagates within the waveguide to the areas with these gaps, it results in energy loss, thus reducing the efficiency of the entire optical system. Utility Model Content

[0004] The main objective of this application is to provide a diffractive waveguide and smart glasses, which aims to solve the technical problem that when light propagates in a region with a gap in the existing diffractive waveguide, light energy is lost, thereby reducing the efficiency of the entire optical system.

[0005] To achieve the above objectives, this application provides a diffraction waveguide, the diffraction waveguide comprising: Waveguide substrate; The coupling grating includes a two-dimensional grating disposed on one side of the waveguide substrate. At least a portion of the two-dimensional grating includes two or more grating regions, wherein a first gap exists within the grating regions, and the width of the first gap varies between different grating regions. A deposition layer covers the side of the two-dimensional grating away from the waveguide substrate, and a portion of the structure of the deposition layer fills the first gap.

[0006] In one embodiment, the coupled grating further includes: A one-dimensional grating is disposed on the waveguide substrate and adjacent to the two-dimensional grating, wherein the width of the first gap changes most steeply along the grating direction of the one-dimensional grating.

[0007] In one embodiment, the width of the first gap within the grating region is constant.

[0008] In one embodiment, a second gap exists between two or more of the grating regions, the second gap having a constant width and a direction inconsistent with that of the first gap.

[0009] In one embodiment, the diffraction waveguide further includes: The coupling grating is disposed on the side of the waveguide substrate on which the output grating is disposed, and the coupling grating is an asymmetric grating.

[0010] In one embodiment, the diffraction waveguide further includes: A buffer layer is disposed between the deposition layer and the two-dimensional grating.

[0011] In one embodiment, the deposition thickness of the buffer layer is not higher than the deposition thickness of the deposition layer.

[0012] In one embodiment, the buffer layer includes at least two buffer sub-layers, which are stacked together, and the at least two buffer sub-layers gradually decrease in size or increase in size along the direction from the waveguide substrate to the deposition layer.

[0013] In one embodiment, the deposition thickness of the buffer layer varies between different grating regions.

[0014] In addition, to achieve the above objectives, this application also provides smart glasses, which include the diffractive waveguide as described above.

[0015] This application provides a diffractive waveguide and smart glasses. The diffractive waveguide includes: a waveguide substrate; a coupling grating, including a two-dimensional grating, the coupling grating being disposed on one side of the waveguide substrate, at least a portion of the two-dimensional grating including two or more grating regions, wherein a first gap exists within the grating regions, the width of the first gap varying between different grating regions; and a deposition layer, the deposition layer covering the side of the two-dimensional grating away from the waveguide substrate, and a portion of the structure of the deposition layer filling the first gap.

[0016] The coupling grating of this application may include a two-dimensional grating disposed on one side of a waveguide substrate. At least a portion of the two-dimensional grating may include two or more grating regions, each with a first gap. The first gap varies between different grating regions, and a deposition layer may be disposed covering the side of the two-dimensional grating away from the waveguide substrate, with the deposition layer partially filling the first gap. Because this application can fill the first gap on the two-dimensional grating with a portion of the deposition layer structure, light energy loss can be reduced, and optical efficiency can be improved. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a top view of a traditional diffractive waveguide surface. Figure 2 This is a macroscopic side view of a traditional diffractive waveguide; Figure 3 This is a side view formed by a two-dimensional grating along a certain gap direction; Figure 4 This is a schematic diagram of a first embodiment of the diffractive waveguide of this application; Figure 5 This is another structural schematic diagram of the first embodiment of the diffractive waveguide of this application; Figure 6 This is a side view of a two-dimensional grating along a certain gap direction in the first embodiment of the diffraction waveguide of this application; Figure 7 This is a schematic diagram of the gap in the two-dimensional grating before filling in the first embodiment of the diffraction waveguide of this application; Figure 8 This is a schematic diagram of the gap in the two-dimensional grating after filling in the first embodiment of the diffraction waveguide of this application; Figure 9 This is a schematic diagram of another structure of the coupling grating in the first embodiment of the diffraction waveguide of this application; Figure 10 This is a side view of a two-dimensional grating along a certain gap direction in the second embodiment of the diffraction waveguide of this application.

[0020] Explanation of icon numbers:

[0021] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0022] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application.

[0023] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0024] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0025] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0026] Understandably, in existing Augmented Reality (AR) optical solutions, diffraction waveguide-based designs are developing towards higher efficiency and higher uniformity. AR glasses receive light through the coupling grating 2 of the diffraction waveguide and transmit it within the waveguide substrate 1. Then, the imaged light is guided to the eyes through the coupling grating 3, allowing the user to see the displayed content.

[0027] Two-dimensional diffraction gratings are a key technology due to their ability to extend the eyebox in two directions, providing a wider field of view. In fabricating such 2D gratings 32, micro- and nano-fabrication equipment is typically used to define periodic nanoscale structures on the waveguide substrate 1. However, these micro- and nano-fabrication equipment have inherent physical precision limits (which can be understood as the minimum width of the cutting tool). Therefore, during the etching process, a gap of at least 60 nanometers may exist on both sides of the 2D grating 32. When light propagates within the waveguide to the regions with these gaps, it results in energy loss, thus reducing the efficiency of the entire optical system.

[0028] For ease of understanding, please refer to Figure 1 as well as Figure 2 , Figure 1 This is a top view of a traditional diffractive waveguide surface. Figure 2This is a macroscopic side view of a traditional diffractive waveguide. (Example) Figure 1 and Figure 2 As shown, a conventional diffraction waveguide may include a waveguide substrate 1, a coupling grating 2, and a coupling grating 3. The coupling grating 2 and the coupling grating 3 may be disposed on the same side of the waveguide substrate 1. The coupling grating 2 can receive light and transmit it through the waveguide substrate 1 to the coupling grating 3 for coupling out, thereby completing the imaging.

[0029] And as Figure 1 As shown, a two-dimensional grating 32 can exist in a conventional coupling grating 3. The two-dimensional grating 32 can be a grating with two etch gaps 4 in different directions. For the two-dimensional grating 32, there can be two gaps 4 in different directions. Figure 1 The dashed lines a to f represent gap 4. Generally, the gap width in the middle region of a two-dimensional grating 32 is consistent and relatively wide (i.e., Figure 1 (The widths of the central gap c and gap d are the same). In one direction, the gap 4 in the two side regions has the same width as the central region's gap, while in the other direction, it needs to become smaller as it approaches the sides, thus ensuring optical efficiency. That is... Figure 1 The directions of gaps a, c, and e are consistent, as are the directions of gaps b, d, and f. The widths of gaps a and c are consistent, as are the widths of gaps d and f. The width of gap b gradually decreases from the middle region of the two-dimensional grating 32 to the left, and the width of gap e gradually decreases from the middle region of the two-dimensional grating 32 to the right.

[0030] Reference Figure 3 , Figure 3 This is a side view of the two-dimensional grating 32 along a certain gap 4, which can then form a shape like this in the middle of the two-dimensional grating 32. Figure 3 The gap 4 shown can be set according to the actual situation, and this embodiment does not limit it.

[0031] Continue as Figure 1 As shown, the gap 4 of the two-dimensional grating 32 is obtained by etching the coupled grating 3 along two different directions using a micro-nano fabrication device. However, since the minimum width of the tool of the micro-nano fabrication device is at least 60 nanometers, even if it is smaller, there will still be a gap 4 of at least 60 nanometers in the two sides, i.e. the above-mentioned gap, which leads to light energy loss and reduces the efficiency of the entire optical system.

[0032] Therefore, to address the aforementioned shortcomings, this embodiment provides a diffractive waveguide and smart glasses. The coupling grating 3 in this embodiment may include a two-dimensional grating 32 disposed on one side of the waveguide substrate 1. At least a portion of the two-dimensional grating 32 may include two or more grating regions, each with a first gap. The first gap varies between different grating regions. A deposition layer 6 may be disposed covering the side of the two-dimensional grating 32 facing away from the waveguide substrate 1, and the deposition layer 6 may partially fill the first gap. Since this embodiment can fill the first gap on the two-dimensional grating 32 with a portion of the structure of the deposition layer 6, light energy loss can be reduced, and optical efficiency can be improved.

[0033] For ease of understanding, the following is combined with Figures 4 to 10 The diffraction waveguide provided in the embodiments of this application will be described in detail.

[0034] Reference Figures 4 to 6 , Figure 4 This is a schematic diagram of a first embodiment of the diffractive waveguide of this application. Figure 5 This is another structural schematic diagram of the first embodiment of the diffractive waveguide of this application. Figure 6 This is a side view of the two-dimensional grating 32 along a certain gap 4 in the first embodiment of the diffraction waveguide of this application. The first embodiment of the diffraction waveguide of this application is presented as follows: Figures 4 to 6 As shown, in this embodiment, the diffraction waveguide includes: Waveguide substrate 1; The coupling grating 3 includes a two-dimensional grating 32, which is disposed on one side of the waveguide substrate 1. At least a portion of the two-dimensional grating 32 includes two or more grating regions, wherein a first gap exists within the grating regions, and the width of the first gap varies between different grating regions. A deposition layer 6 is formed, which covers the side of the two-dimensional grating 32 away from the waveguide substrate 1, and a portion of the structure of the deposition layer 6 fills the first gap.

[0035] It should be noted that the waveguide substrate 1 described above can be a transparent optical element, which can be used to guide light to propagate within it. In this embodiment, the waveguide substrate 1 may include a high refractive index material, thereby enabling effective propagation of light.

[0036] It should also be noted that the above-mentioned coupling grating 3 can be a grating that couples light out from the waveguide substrate 1 and guides it to the human eye. Its material can be a light-transmitting material, and the specific material can be set according to the actual situation. This embodiment does not limit this.

[0037] Understandably, continuing as Figure 4As shown, the coupling grating 3 in this embodiment may also include a two-dimensional grating 32. The specific definition and setting position of the two-dimensional grating 32 can be referred to the description of the traditional diffraction waveguide above. This embodiment will not elaborate on this.

[0038] It is also understood that the two-dimensional grating 32 in this embodiment may also have a gap 4 in the middle. The definition of the gap 4 can also refer to the description of the conventional waveguide substrate 1 above. This embodiment does not limit it.

[0039] The aforementioned grating region can be any region on the two-dimensional grating 32, such as... Figure 4 as well as Figure 5 As shown, in this embodiment, the two-dimensional grating 32 can be divided into arbitrary sizes to obtain at least two or more grating regions. It is only necessary to ensure that gaps 4 exist within the grating regions during the division. The aforementioned first gap can be gap 4 within the grating regions. For example... Figure 4 As shown, the left two-dimensional grating 32 can be divided to obtain at least two or more grating regions, denoted as the first grating region 321, and the gap b can belong to the first grating region 321; the middle two-dimensional grating 32 can be divided to obtain at least two or more grating regions, denoted as the second grating region 322, and the gap c or gap d can belong to the second grating region 322, which can be determined according to the division direction; the right two-dimensional grating 32 can be divided to obtain at least two or more grating regions, denoted as the third grating region 323, and the gap e can belong to the third grating region 323. The division direction of the second grating region 322 can be the same as that of the first grating region 321 or the third grating region 323; this embodiment does not impose any restrictions on this.

[0040] Furthermore, since the width of the traditional gap b gradually decreases from the middle region of the two-dimensional grating 32 to the left, and the width of the gap e gradually decreases from the middle region of the two-dimensional grating 32 to the right, for the aforementioned first grating region 321 and third grating region 323, there can be a first gap with varying width between the grating regions, namely gap b and gap e respectively. The first gap can be larger or smaller between different grating regions, and this embodiment does not impose any restrictions on this.

[0041] It should be understood that the aforementioned deposition layer 6 can be a layer used to fill the gaps 4 in the two-dimensional grating 32. In this embodiment, the aforementioned deposition layer 6 can be covered on the side of the two-dimensional grating 32 facing away from the waveguide substrate 1, so that when covered, part of the structure in the deposition layer 6 can fill the gaps 4 in the two-dimensional grating 32, thereby reducing the width of the gaps. For ease of understanding, refer to... Figure 7 as well as Figure 8 , Figure 7 This is a schematic diagram of the gap 4 of the two-dimensional grating 32 before filling in the first embodiment of the diffraction waveguide of this application. Figure 8 This is a schematic diagram of the gap 4 of the two-dimensional grating 32 after filling in the first embodiment of the diffraction waveguide of this application.

[0042] like Figure 7 As shown, before filling, the width of the gap 4 in the two-dimensional grating 32 can be denoted as L, where L is generally greater than 60nm, which is the minimum precision of micro / nano fabrication equipment. Figure 7 The middle gap 4 is relatively wide. For example... Figure 8 As shown, after the gap 4 is filled by the aforementioned deposition layer 6, the width of the gap 4 in the two-dimensional grating 32 is significantly reduced. The specific thickness of the deposition layer 6 can be set according to the actual situation. Of course, the entire height of the gap 4 can be filled, thus forming a shape as shown in the figure. Figure 6 As shown in the figure. Furthermore, the duty cycle of the two-dimensional grating 32 (i.e., the width of a grating / (the width of a grating + the width of a gap 4)) can be significantly increased, specifically approaching 1 infinitely.

[0043] Furthermore, to achieve the above-mentioned filling operation through a filling layer, the filling layer in this embodiment can be implemented using atomic layer deposition (ALD) technology. Of course, other technologies can also be used. This embodiment uses ALD for explanation. In specific implementation, atomic deposition can be performed on the waveguide substrate 1 with the two-dimensional grating 32 using ALD on the area of ​​the two-dimensional grating 32 to fill the gap 4.

[0044] In order to reduce the influence of the deposition layer 6 on the coupling grating 3 after atomic deposition, in this embodiment, the material used for atomic deposition (i.e. the material of the deposition layer 6) can be a material with a refractive index similar to that of the coupling grating 3, preferably carbon monoxide, silicon oxide, etc., but this embodiment does not limit it.

[0045] In this embodiment, the gap 4 on the two-dimensional grating 32 can be filled by partially filling the structure of the deposition layer 6, thereby making its surface nearly flat, reducing light energy loss and improving optical efficiency.

[0046] Furthermore, considering that the one-dimensional grating 31 has higher diffraction efficiency in a specific direction, in order to improve the light energy utilization rate, the following... Figure 4 As shown, in this embodiment, the coupling grating 3 further includes: A one-dimensional grating 31 is disposed on the waveguide substrate 1 and adjacent to the two-dimensional grating 32. The width of the first gap changes most steeply along the grating direction of the one-dimensional grating 31.

[0047] It should be noted that the aforementioned one-dimensional grating 31 can be a grating with an etching gap 4 in a certain direction. For example... Figure 4As shown, in this embodiment, one-dimensional gratings 31 can be respectively set on the left and right adjacent sides of the two-dimensional grating 32. The one-dimensional grating 31 on the left side can contain a gap 4 in a certain direction, i.e. Figure 4 Within the central gap g, a gap 4 in another direction can exist within the one-dimensional grating 31 on the right side, i.e. Figure 4 The gap h is in the middle, and the direction and width of the gap g can be the same as those of the gap a. The direction and width of the gap h can be the same as those of the gap f, although the widths can be different. This embodiment uses the same width for explanation.

[0048] It should also be noted that, since one-dimensional gratings 31 are provided on both the left and right sides, in the actual manufacturing process, gaps 4 in a certain direction can be etched in the coupling grating 3 from left to right, with the width gradually decreasing starting from the third grating region 323. That is, according to the direction and width of gap g, gaps g, a, c, and e can be obtained sequentially, and the width gradually decreases from gap e until there is no width, thus ensuring that the one-dimensional grating 31 on the right side has no gap 4 in that direction. Similarly, gaps 4 in another direction can be etched in the coupling grating 3 from right to left, with the width gradually decreasing starting from the first grating region 321. That is, according to the direction and width of gap h, gaps h, f, d, and b can be obtained sequentially, and the width gradually decreases from gap b until there is no width, thus ensuring that the one-dimensional grating 31 on the left side has no gap 4 in that direction. This results in an output grating 3 with a two-dimensional grating 32 in the middle and one-dimensional gratings 31 on both sides. After the input grating 2 receives light, it can first transmit the light to the two-dimensional grating 32 through the one-dimensional grating 31, thereby improving the light energy utilization rate.

[0049] It should be understood that, since the width of gap e gradually decreases until it has no width, and the width of gap b also gradually decreases until it has no width, the first gap within the grating region can gradually change with the steepest change in the direction towards the one-dimensional grating 31, that is... Figure 4 The width of the first gap in the first grating region 321 can gradually change to its steepest point along direction 1 towards the left of the one-dimensional grating 31. Similarly, the width of the first gap in the third grating region 323 can gradually change to its steepest point along direction 2 towards the right of the one-dimensional grating 31. This steepest change can be either a gradual decrease or a gradual increase. Figure 4 The gap b can gradually decrease towards the left and gradually increase towards the right.

[0050] Furthermore, considering that excessive deposition may lead to overfilling of the gap 4 in the two-dimensional grating 32 in the middle region of the coupled grating 3, affecting subsequent display, in this embodiment, the width of the gap 4 gradually decreases from the central region of the two-dimensional grating 32 towards the side closer to the one-dimensional grating 31.

[0051] Understandably, during setup, the gap 4 width of the two-dimensional grating 32 in this embodiment can gradually decrease from the central region of the two-dimensional grating 32 towards the one-dimensional grating 31 on both sides. Specifically, a region in the middle area of ​​the two-dimensional grating 32 where the gap 4 remains unchanged can be reserved in advance (i.e., Figure 4 The middle portion of the two-dimensional grating 32 ensures efficient display. In the area of ​​the two-dimensional grating 32 near the left-hand one-dimensional grating 31, excluding this middle area, the closer to the left-hand one-dimensional grating 31, the larger the gap 4 (i.e., ... Figure 4 The gap in the middle gap (direction b) can be gradually reduced. Similarly, for the region outside this middle region that is close to the right one-dimensional grating 31, the closer to the right one-dimensional grating 31, the smaller the gap 4 (i.e., the gap in the middle gap b direction) becomes. Figure 4 The gap (in the e-direction) can also be gradually reduced. It can be reduced to the minimum precision of micro / nano fabrication equipment.

[0052] It needs to be emphasized that, such as Figure 5 As shown, when a hybrid grating of one-dimensional grating 31 and two-dimensional grating 32 is used, the grating structure of the coupling grating 3 is generally fabricated using micro-nano fabrication equipment. When the coupling grating 3 uses a hybrid grating of one-dimensional grating 31 and two-dimensional grating 32, it is necessary to use micro-nano fabrication equipment to etch two gaps 4 of different directions but the same width in the middle region of the coupling grating 3 to form the two-dimensional grating 32. However, due to the precision limit of micro-nano fabrication equipment (which can be understood as the minimum width of the tool), there will be a gap 4 of at least 60 nanometers between the one-dimensional grating 31 and the two-dimensional grating 32 during the existing etching process. This results in an upper limit to the duty cycle and a significant abrupt change between the one-dimensional grating 31 and the two-dimensional grating 32. Figure 1 The transition areas between the one-dimensional grating 31 and the two-dimensional grating 32 on the left and the one-dimensional grating 31 and the two-dimensional grating 32 on the right both have a clear vertical dividing line. These two dividing lines will affect the user's sensory experience.

[0053] Therefore, when filling at this point, since the width of gap 4 decreases towards the sides, after depositing the same material on the top of the 2D grating 32, the smaller gaps 4 will be filled first, while the larger gaps 4 may still remain. Thus, once the deposition of gaps 4 on both sides meets the requirements, deposition can be stopped. Continuing this process ensures that the middle region of the 2D grating 32 still contains two gaps 4 in different directions, preserving the structural characteristics of the 2D grating 32. It also allows for a smooth transition from the 1D grating 31 to the 2D grating 32, improving the sensory experience.

[0054] In this embodiment, the gaps 4 on the two-dimensional grating 32 can be filled by partially filling the structure of the deposition layer 6, thereby reducing the abrupt change between the one-dimensional grating 31 and the two-dimensional grating 32, reducing the obviousness of the appearance boundary between the one-dimensional grating 31 and the two-dimensional grating 32, and improving the user's sensory experience.

[0055] Furthermore, continue as Figure 4 As shown, in this embodiment, the width of the first gap within the grating region is constant.

[0056] In this embodiment, the width of the first gap within the first grating region 321 to the third grating region 323 is constant, that is... Figure 4 In the first grating region 321, there may be at least two gaps 4 in the same direction as the slit b, and the width of each gap is constant. In the second grating region 322, there may be at least two gaps 4 in the same direction as the slit d, and the width of each gap is constant. In the third grating region 323, there may be at least two gaps 4 in the same direction as the slit e, and the width of each gap is constant.

[0057] Furthermore, a second gap exists between two or more of the grating regions, the width of the second gap being constant, and the direction of the second gap being inconsistent with the direction of the first gap.

[0058] It should be noted that the aforementioned second gap can be gap 4 in the two-dimensional grating 32, which has a direction inconsistent with the first gap. Continuing as... Figure 4 As shown, for the first grating region 321, a second gap may exist between the first grating regions 321, that is... Figure 4 The gap is aligned with the direction of gap a. Multiple gaps may exist, and the gap remains constant in the left region of the two-dimensional grating 32. Similarly, for the second grating region 322, a second gap may exist between the second grating regions 322, that is... Figure 4 The gap is aligned with the direction of gap c. Multiple such second gaps may exist and remain constant in the middle region of the two-dimensional grating 32. For the third grating region 323, a second gap may exist between the third grating regions 323, that is... Figure 4 The gap is aligned with the direction of the gap f. There may be multiple such second gaps, and they remain constant in the right region of the two-dimensional grating 32.

[0059] Furthermore, in order to improve the optical efficiency of the coupling grating 2, refer to Figure 9 , Figure 9 This is another structural schematic diagram of the coupling grating 2 in the first embodiment of the diffraction waveguide of this application. (See attached diagram.) Figure 9 As shown, in this embodiment, the diffraction waveguide further includes: The coupling grating 2 is disposed on the side of the waveguide substrate 1 where the coupling grating 3 is disposed, and the coupling grating 2 is an asymmetric grating.

[0060] It should be noted that the number of coupled gratings 2 in this embodiment can be set to one or more; this embodiment uses one for illustration.

[0061] It should also be noted that the aforementioned asymmetric grating can be a grating in which the lines and gaps 4 are asymmetrically distributed along the center line, meaning the structures on both sides of the grating are different. Because an asymmetric grating can diffract light primarily in one direction, it improves the diffraction efficiency in that specific direction, reduces energy dispersion, and improves coupling efficiency. Preferably, as... Figure 9 As shown, in this embodiment, the asymmetric grating can be a tilted grating, and the specific tilt angle can be set according to the actual situation. This embodiment does not limit this.

[0062] Furthermore, in order to improve the transmittance of the diffractive waveguide, continue as follows Figure 5 As shown, in this embodiment, the waveguide substrate 1 is provided with a micro / nano structure region, and the micro / nano structure region has a periodic micro / nano structure 5.

[0063] It should be noted that the aforementioned micro / nano structure region can be the area remaining on the side surface of the waveguide substrate 1 where the coupling grating 2 is provided, excluding the area where the coupling grating 2 is located and the area where the coupling grating 3 is located. In this embodiment, the aforementioned periodic micro / nano structure 5 can be provided in this micro / nano structure region. Since the aforementioned periodic micro / nano structure 5 can serve as an anti-reflection structure, it reduces the reflection of light on the surface of the waveguide substrate 1, thereby improving the transmittance of the diffraction waveguide.

[0064] It should be emphasized that the micro-nano structure 5 in this embodiment can be set at any position in the micro-nano structure region. The specific setting can be made according to the actual situation, and this embodiment does not impose any restrictions on it.

[0065] Furthermore, the micro / nano structure 5 is at least one of a cylindrical structure, a triangular prism structure, or a rectangular prism structure.

[0066] It is understood that the micro / nano structure 5 in this embodiment can adopt at least one of the following structures: cylindrical structure, triangular prism structure, or rectangular prism structure. Specifically, the cylindrical structure can be a prism structure with a circular top view, the triangular prism structure can be a prism structure with a triangular top view, and the rectangular prism structure can be a prism structure with a rectangular top view.

[0067] This embodiment can employ at least one of the three structures described above, thereby improving the transmittance of the diffraction waveguide. The specific structure can be customized according to actual conditions; this embodiment does not impose any limitations on this.

[0068] In this embodiment, the coupling grating 3 may include a two-dimensional grating 32 disposed on one side of the waveguide substrate 1. At least a portion of the two-dimensional grating 32 may include two or more grating regions, each with a first gap. The first gap varies between different grating regions. A deposition layer 6 may be disposed on the side of the two-dimensional grating 32 facing away from the waveguide substrate 1, and the deposition layer 6 may partially fill the first gap. Since this embodiment can fill the first gap on the two-dimensional grating 32 with a portion of the structure of the deposition layer 6, light energy loss can be reduced and optical efficiency improved.

[0069] Reference Figure 10 , Figure 10 This is a side view of the two-dimensional grating 32 along a certain gap 4 in the second embodiment of the diffraction waveguide of this application. Considering that directly contacting the deposited layer 6 with the two-dimensional grating 32 might affect reflection and scattering, therefore... Figure 10 As shown, in this embodiment, the diffraction waveguide further includes: Buffer layer 7 is disposed between the deposition layer 6 and the two-dimensional grating 32.

[0070] It should be noted that the aforementioned buffer layer 7 can be a light-transmitting layer, and can be made of highly transparent materials such as silicon dioxide or silicon nitride. The specific material can be set according to the actual situation, and this embodiment does not impose any restrictions on it.

[0071] In actual fabrication, after obtaining the coupled grating 3, ALD can be used to deposit on the side of the two-dimensional grating 32 away from the waveguide substrate 1 to obtain the buffer layer 7. After obtaining the buffer layer 7, deposition can be performed to obtain the deposition layer 6.

[0072] Furthermore, considering that excessively thick buffer layer 7 may introduce additional optical discontinuities, leading to increased light scattering and reflection, in this embodiment, the deposition thickness of buffer layer 7 is not greater than the deposition thickness of deposition layer 6.

[0073] It is understood that the specific thickness of the buffer layer 7 can be set according to the actual situation, and this embodiment does not impose any restrictions on it.

[0074] Furthermore, in order to better achieve a smooth transition of refractive index, the buffer layer 7 includes at least two buffer sub-layers (not shown in the figure), the at least two buffer sub-layers are stacked, and the at least two buffer sub-layers gradually decrease or increase in size along the direction from the waveguide substrate 1 to the deposition layer 6.

[0075] It should be understood that in this embodiment, the buffer layer 7 may be provided with multiple buffer sub-layers stacked sequentially. The refractive index of each buffer sub-layer is different. Furthermore, the refractive index may increase or decrease layer by layer from the waveguide substrate 1 to the deposition layer 6.

[0076] Specifically, when the refractive index of the deposited layer 6 is higher than that of the waveguide substrate 1, the refractive index of each buffer sublayer can be higher than that of the waveguide substrate 1 but lower than that of the deposited layer 6, and thus can increase sequentially from bottom to top. Similarly, when the refractive index of the deposited layer 6 is lower than that of the waveguide substrate 1, the refractive index of each buffer sublayer can be higher than that of the deposited layer 6 but lower than that of the waveguide substrate 1, and thus can decrease sequentially from bottom to top. This achieves a smooth transition.

[0077] It should be emphasized that the specific materials used for each buffer sublayer and the number of buffer sublayers can be set according to the actual situation, and this embodiment does not impose any restrictions on this.

[0078] Furthermore, considering that during setup, the gap 4 width of the two-dimensional grating 32 in this embodiment can gradually decrease from the central region of the two-dimensional grating 32 towards the one-dimensional grating 31 on both sides, the thickness of the buffer layer 7 can also be set to gradually change during deposition. Specifically, the deposition thickness of the buffer layer can vary between different grating regions. That is, the deposition thickness of the buffer layer can gradually increase or gradually decrease between different grating regions, depending on the width of the first gap. The smaller the width of the first gap, the smaller the deposition thickness; the wider the width of the first gap, the higher the deposition thickness.

[0079] In this embodiment, the middle region of the two-dimensional grating 32 can be configured to gradually decrease towards the side closer to the one-dimensional grating 31. Specifically, the deposition thickness of the buffer layer 7 can gradually decrease from the middle region of the two-dimensional grating 32 towards the side closer to the one-dimensional grating 31.

[0080] In practical use, the gap 4 of the two-dimensional grating 32 can be gradually reduced from the central region of the two-dimensional grating 32 to the one-dimensional grating 31 on both sides. Therefore, during deposition, the thickness of the buffer layer 7 of the same thickness will be higher after deposition if the gap 4 is smaller. Thus, the deposition thickness of the buffer layer 7 can be set to gradually decrease from the central region of the two-dimensional grating 32 to the one-dimensional grating 31 on both sides. In this way, when the deposition layer 6 is deposited later, the gap 4 closer to the one-dimensional grating 31 will not be over-deposited, thus forming a protrusion phenomenon, ensuring the consistency of deposition.

[0081] In addition, to achieve the above objectives, embodiments of this application also provide smart glasses, which include the diffractive waveguide as described above; It should be emphasized that the specific implementation of the smart glasses in this embodiment can refer to the specific implementation of the diffraction waveguide described above, and therefore also has all the beneficial effects of the diffraction waveguide embodiment described above. This embodiment will not elaborate on this further.

[0082] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A diffractive waveguide, characterized in that, The diffraction waveguide includes: Waveguide substrate; The coupling grating includes a two-dimensional grating disposed on one side of the waveguide substrate. At least a portion of the two-dimensional grating includes two or more grating regions, wherein a first gap exists within the grating regions, and the width of the first gap varies between different grating regions. A deposition layer covers the side of the two-dimensional grating away from the waveguide substrate, and a portion of the structure of the deposition layer fills the first gap.

2. The diffraction waveguide as described in claim 1, characterized in that, The coupling grating further includes: A one-dimensional grating is disposed on the waveguide substrate and adjacent to the two-dimensional grating, wherein the width of the first gap changes most steeply along the grating direction of the one-dimensional grating.

3. The diffraction waveguide as described in claim 2, characterized in that, The width of the first gap within the grating region is constant.

4. The diffraction waveguide as described in claim 2, characterized in that, A second gap exists between two or more of the grating regions, the width of the second gap is constant, and the direction of the second gap is not the same as the direction of the first gap.

5. The diffraction waveguide as described in claim 1, characterized in that, The diffraction waveguide also includes: The coupling grating is disposed on the side of the waveguide substrate on which the output grating is disposed, and the coupling grating is an asymmetric grating.

6. The diffraction waveguide as described in claim 1, characterized in that, The diffraction waveguide also includes: A buffer layer is disposed between the deposition layer and the two-dimensional grating.

7. The diffraction waveguide as described in claim 6, characterized in that, The deposition thickness of the buffer layer is not higher than the deposition thickness of the deposition layer.

8. The diffraction waveguide as described in claim 6, characterized in that, The buffer layer includes at least two buffer sub-layers, which are stacked together, and the at least two buffer sub-layers gradually decrease in size or increase in size along the direction from the waveguide substrate to the deposition layer.

9. The diffraction waveguide as described in claim 6, characterized in that, The deposition thickness of the buffer layer varies between different grating regions.

10. A type of smart glasses, characterized in that, The smart glasses include a diffractive waveguide as described in any one of claims 1 to 9.

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