Optical waveguide structure and processing method thereof

Abstract

The invention belongs to the technical field of diffraction optical waveguides, and relates to an optical waveguide structure and a processing method thereof. The optical waveguide structure comprises a substrate and a first diffraction grating, the substrate is provided with a plurality of functional areas, at least one functional area is provided with the first diffraction grating, and the first diffraction grating comprises a plurality of first grating units which are sequentially arranged at intervals. The heights of the multiple first grating units are gradually increased or decreased in the interval direction. According to the optical waveguide structure, the light emitting performance of the optical waveguide structure can be improved, and the average light emitting efficiency and the light emitting uniformity of the optical waveguide structure are improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of diffractive optical waveguide, and particularly relates to an optical waveguide structure and a processing method thereof. BACKGROUND

[0002] With the gradual maturity of augmented reality (AR) technology, people's requirements for its experience are also increasing. Diffractive optical waveguide technology is one of the mainstream solutions to realize AR technology. In the diffractive optical waveguide technology, the optical properties of the diffraction grating directly determine the final imaging quality of the diffractive optical waveguide system. The required diffraction properties are achieved by adjusting the height and duty cycle of the diffraction grating.

[0003] However, in the existing optical waveguide structure, as shown in FIG. 1, the diffraction grating 1a is generally composed of a plurality of grating units 11a with consistent height, and the light output performance is limited, the average light output efficiency is low, and the light output uniformity is poor. Figure 1 SUMMARY

[0004] The purpose of the embodiments of the present application is to provide an optical waveguide structure and a processing method thereof, aiming to solve the problem of limited light output performance of the existing optical waveguide structure.

[0005] To solve the above technical problems, on the one hand, the present application provides an optical waveguide structure, comprising a substrate and a first diffraction grating, the substrate is provided with a plurality of functional areas, at least one of the functional areas is provided with the first diffraction grating, the first diffraction grating comprises a plurality of first grating units arranged in sequence and at intervals, and the heights of the plurality of first grating units gradually increase or decrease along the interval direction.

[0006] According to the optical waveguide structure of the embodiments of the present application, the first diffraction grating is arranged on at least one of the functional areas on the substrate, and the heights of the plurality of first grating units of the same first diffraction grating gradually increase or decrease along the interval direction, so as to improve the light output performance of the optical waveguide structure, and improve the average light output efficiency and light output uniformity of the optical waveguide structure.

[0007] Optionally, the optical waveguide structure further comprises a second diffraction grating, the second diffraction grating comprises a plurality of second grating units arranged in sequence and at intervals, and the heights of the plurality of second grating units are consistent.

[0008] Among the plurality of functional areas, the functional area which is not provided with the first grating unit is provided with the second diffraction grating.

[0009] ​Optionally, the functional regions are provided with three, the three functional regions include a coupling-in region, a pupil expanding region and a coupling-out region according to their functions, the coupling-in region and the pupil expanding region are arranged along the first direction, and the pupil expanding region and the coupling-out region are arranged along the second direction;

[0010] The first diffraction grating is arranged on at least one of the coupling-in region, the pupil expanding region and the coupling-out region;

[0011] The second diffraction grating is arranged on the functional region without the first diffraction grating in the coupling-in region, the pupil expanding region and the coupling-out region.

[0012] In another aspect, the embodiment of the present application provides a processing method of an optical waveguide structure, which is used for processing the optical waveguide structure, and the processing method of the optical waveguide structure comprises the following steps:

[0013] Selecting a substrate;

[0014] Forming a plurality of functional regions on a first surface of the substrate;

[0015] Depositing grating materials in each of the functional regions to form initial gratings; wherein the initial grating deposited in at least one of the functional regions is a height-gradually-changing structure;

[0016] Etching each of the initial gratings to form an optical waveguide structure; wherein the initial grating with the height-gradually-changing structure forms a first diffraction grating after etching.

[0017] Optionally, the step of forming a plurality of functional regions on a first surface of the substrate comprises:

[0018] Placing a mask with hollow regions on the first surface of the substrate, and forming the functional regions on the substrate at positions corresponding to the hollow regions;

[0019] Before the step of etching each of the initial gratings, the method further comprises the step of removing the mask placed on the first surface of the substrate when forming a plurality of functional regions on the first surface of the substrate.

[0020] Optionally, the step of forming a plurality of functional regions on a first surface of the substrate comprises:

[0021] Coating a resist on the first surface of the substrate, exposing and developing the resist coated on the first surface of the substrate, exposing part of the substrate to the resist, and forming the functional regions on the part of the substrate exposed to the resist;

[0022] Before the "etching each of the initial gratings", further comprising: removing the photoresist coated on the first surface of the substrate when the "forming a plurality of functional areas on the surface of the substrate" is performed.

[0023] Optionally, when the "depositing grating material in each of the functional areas to form an initial grating" is performed, the initial grating deposited in part of the functional areas is a height-graduated structure, and the initial grating deposited in the rest of the functional areas is an equal-height structure.

[0024] When the "etching each of the initial gratings" is performed, the initial grating in the equal-height structure forms a second diffraction grating after being etched, and the second diffraction grating comprises a plurality of second grating units arranged in sequence and spaced apart, and the heights of the plurality of second grating units are consistent.

[0025] Optionally, the "depositing grating material in each of the functional areas" comprises:

[0026] Placing a deposition source above the substrate, and making the discharge port of the deposition source face the first surface of the substrate;

[0027] The deposition source and the substrate undergo lateral relative motion, so as to deposit grating material in each of the functional areas on the substrate by the deposition source.

[0028] Optionally, when the deposition source deposits grating material in a certain functional area, if the deposition source and the certain functional area always undergo lateral relative motion during the deposition process, the initial grating in the height-graduated structure is formed on the certain functional area; if the deposition source and the certain functional area are relatively static during the deposition process, the initial grating in the equal-height structure is formed on the certain functional area.

[0029] Optionally, when the deposition source deposits grating material in a certain functional area, a baffle is placed above the substrate;

[0030] If the baffle is located between the certain functional area and the deposition source, and the certain functional area and the deposition source are relatively static during the deposition process, and the baffle and the certain functional area always undergo lateral relative motion, the initial grating in the height-graduated structure is formed on the certain functional area.

[0031] If the baffle is separated from between the certain functional area and the deposition source, the initial grating in the equal-height structure is formed on the certain functional area.

[0032] Optionally, the "etching each of the initial gratings to form a light waveguide structure" comprises:

[0033] Coating photoresist on the surface of the initial grating;

[0034] exposing and developing the resist coated on the surface of the initial grating to form a grating resist structure on the surface of the initial grating;

[0035] dry etching the initial grating corresponding to the gap of the grating resist structure to form a grating structure; wherein the grating structure formed by etching the initial grating with a height gradient structure is a first diffraction grating, and the grating structure formed by etching the initial grating with an equal height structure is a second diffraction grating;

[0036] After the dry etching is completed, the grating resist structure is removed to form a light waveguide structure.

[0037] Optionally, the "etching the initial grating to form a light waveguide structure" comprises:

[0038] coating an anti-reflection material on the surface of the initial grating;

[0039] coating a photoresist on the surface of the anti-reflection material;

[0040] exposing the photoresist to form a grating resist structure on the surface of the anti-reflection material;

[0041] dry etching the anti-reflection material and the initial grating corresponding to the gap of the grating resist structure to form a grating structure; wherein the grating structure formed by etching the initial grating with a height gradient structure is a first diffraction grating, and the grating structure formed by etching the initial grating with an equal height structure is a second diffraction grating;

[0042] After the dry etching is completed, the grating resist structure is removed to form a light waveguide structure. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 is a schematic diagram of an existing light waveguide structure;

[0044] Figure 2 is a field tracing effect diagram of the light waveguide structure of Figure 1

[0045] Figure 3 is a light ray tracing effect diagram of the light waveguide structure of Figure 1

[0046] Figure 4 is a schematic diagram of a light waveguide structure provided by an embodiment of the present application;

[0047] Figure 5 is a flowchart of a processing method for the light waveguide structure of the embodiment;

[0048] ​​Figure 6 This is a schematic diagram of the structure of the substrate after processing in step S2;

[0049] Figure 7 for Figure 5 A schematic diagram of the deposition principle in step S3;

[0050] Figure 8 for Figure 5 A detailed flowchart of step S4 is shown below;

[0051] Figure 9 for Figure 8 A schematic diagram of the coating principle in step S41;

[0052] Figure 10 For the Figure 8 A schematic diagram of the grid-like corrosion-resistant structure after processing in step S42;

[0053] Figure 11 This is a schematic diagram of the optical waveguide structure provided in Embodiment 2 of the present invention;

[0054] Figure 12 This is a schematic flowchart of the fabrication method for the optical waveguide structure used in Embodiment 2;

[0055] Figure 13 for Figure 12 A schematic diagram of the deposition principle in step S7;

[0056] Figure 14 for Figure 12 A detailed flowchart of step S8 is shown below;

[0057] Figure 15 yes Figure 11 Field tracing effect diagram of optical waveguide structure;

[0058] Figure 16 yes Figure 11 A diagram illustrating the ray tracing effect of an optical waveguide structure.

[0059] The reference numerals in the accompanying drawings are as follows:

[0060] 1. Base; 10. Functional area; 10a. Coupling area; 10b. Pupil dilation area; 10c. Coupling out area;

[0061] 2. First diffraction grating; 21. First grating unit;

[0062] 3. Second diffraction grating; 31. Second grating unit;

[0063] 4. Sediment source;

[0064] 5. Barrier layer;

[0065] 6. Initial grating;

[0066] 7. Baffle;

[0067] 8. Spraying equipment;

[0068] 9. Grid-like corrosion-resistant structure. Detailed Implementation

[0069] The technical solutions of the embodiments of the present invention 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 the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0070] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0071] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are 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 with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0072] Example 1

[0073] like Figure 4 As shown, the optical waveguide structure provided in Embodiment 1 of the present invention includes a substrate 1 and a first diffraction grating 2. The substrate 1 has a plurality of functional regions 10, and each functional region 10 is provided with the first diffraction grating 2. The first diffraction grating 2 includes a plurality of first grating units 21 arranged at intervals. The height of the plurality of first grating units 21 gradually increases or decreases along the interval direction. It should be noted that the "interval direction" refers to the direction in which the plurality of first grating units 21 are arranged at intervals, that is, the arrangement direction of the plurality of first grating units 21.

[0074] The optical waveguide structure provided in Embodiment 1 of the present invention has a first diffraction grating 2 disposed on the functional region 10 of the substrate 1, and the height of a plurality of first grating units 21 of the same first diffraction grating 2 gradually increases or decreases along the spacing direction to improve the light output performance of the optical waveguide structure and improve the average light output efficiency and light output uniformity of the optical waveguide structure.

[0075] In Example 1, as Figure 4 As shown, the functional area 10 is provided in three parts, which include, according to their functions, an insertion area 10a, a pupil dilation area 10b, and an exit area 10c (see reference). Figure 6 As shown, the coupling region 10a and the pupil-expanding region 10b are arranged along the first direction, and the pupil-expanding region 10b and the coupling region 10c are arranged along the second direction. The first direction and the second direction intersect.

[0076] The first diffraction grating 2 is provided on the coupling region 10a, the pupil expansion region 10b and the coupling out region 10c.

[0077] The first diffraction grating 2 in the coupling region 10a is used to receive light signals and transmit the light to the first diffraction grating 2 in the pupil-expanding region 10b. The first diffraction grating 2 in the pupil-expanding region 10b is used to horizontally dilate the received light and transmit the dilated light to the first diffraction grating 2 in the coupling region 10c. The first diffraction grating 2 in the coupling region 10c is used to vertically dilate the received light and project the light into the human eye.

[0078] In Example 1, as Figure 4 As shown, the thickness of the substrate 1 is 0.3 mm to 1 mm, the area is 4 inches to 12 inches, and the material of the substrate 1 is silicon (Si) or silicon dioxide (SiO2).

[0079] In Embodiment 1, the coupling-in region 10a is rectangular, the pupil-expanding region 10b is trapezoidal, and the coupling-out region 10c is rectangular (e.g., ...). Figure 6 (As shown in the figure). In embodiments not shown in the figure, the shapes of the coupling region, the pupil expansion region, and the coupling out region can be set as needed, and can be regular shapes such as circles, rectangles, or trapezoids, or irregular shapes.

[0080] In Embodiment 1, the gradient direction of the first diffraction grating 2 in each of the functional regions 10 is not specifically defined. The first diffraction gratings 2 in the three functional regions 10 achieve uniform light output by combining different gradient directions.

[0081] like Figure 5As shown, the fabrication method of the optical waveguide structure provided in Embodiment 1 of the present invention includes the following steps:

[0082] S1. Select substrate 1. The substrate 1 has a thickness of 0.5 mm and an area of ​​8 inches. The material of the substrate 1 is silicon (Si).

[0083] S2. Several functional regions 10 are formed on the first surface of the substrate 1.

[0084] In Example 1, as Figure 6 As shown, the first surface of the substrate 1 has three functional regions 10, including an insertion region 10a, a pupil-expanding region 10b, and an exit region 10c. The three functional regions 10 can be formed simultaneously or separately (i.e., one is formed first, and then the next is formed, with no restriction on the order).

[0085] In Embodiment 1, the functional region 10 can be formed using a mask. Specifically, a mask with a cutout area is placed on the first surface of the substrate 1 (see reference). Figure 7 The middle barrier layer 5) forms the functional area 10 on the substrate 1 at the position corresponding to the hollowed-out area. The mask can be a stainless steel mask.

[0086] Alternatively, the functional area 10 can be formed by coating a photoresist. Specifically, a photoresist is first coated on the first surface of the substrate 1, and then the photoresist coated on the first surface of the substrate 1 is exposed and developed, so that a portion of the substrate 1 is exposed to the photoresist, and the portion of the substrate 1 exposed to the photoresist forms the functional area 10.

[0087] Furthermore, when applying the photoresist, the photoresist can be coated onto the first surface of the substrate 1 by spin coating. That is, the photoresist is placed on the first surface of the substrate 1, and then the substrate 1 is rotated by a rotating mechanism, so that the photoresist is coated onto the first surface of the substrate 1 under the action of centrifugal force. Alternatively, the photoresist can also be coated onto the first surface of the substrate 1 by spraying, that is, by using a spraying device (see reference). Figure 9 The spraying device 8) shown sprays the resist directly onto the first surface of the substrate 1.

[0088] S3. Deposit grating material in each of the functional regions 10 to form an initial grating 6. In Embodiment 1, the initial grating 6 deposited in each of the functional regions 10 is a height-gradient structure.

[0089] During the deposition of grating material, a deposition source 4 can be placed above the substrate 1, with the outlet of the deposition source 4 facing the first surface of the substrate 1. Then, a lateral relative movement occurs between the deposition source 4 and the substrate 1, causing the deposition source 4 to move sequentially above each of the functional regions 10, and deposit grating material sequentially in each of the functional regions 10 on the substrate 1.

[0090] When the deposition source 4 deposits grating material on a certain functional region 10, the deposition source 4 always undergoes lateral relative movement with the functional region 10 during the deposition process (see reference). Figure 7 As shown), an initial grating 6 with a highly gradient structure is formed on the functional region 10. Understandably, since a mask or resist is applied to the substrate 1 during the formation of the functional region 10, the mask or residual resist on the substrate 1 will form a barrier layer 5 after the functional region 10 is formed. This barrier layer 5 remains on the first surface of the substrate 1 throughout the processing in step 3, ensuring that the deposited grating material adheres only to the functional region 10 on the substrate 1.

[0091] Specifically, such as Figure 7 As shown, during the deposition process, "the deposition source 4 always moves laterally relative to the functional region 10." The deposition source 4 remains stationary, while the substrate 1 and the barrier layer 5 move laterally to the left in the diagram, thereby forming an initial grating 6 with a height gradient structure on the functional region 10. The movement speed of the substrate 1 is adjustable, thereby indirectly controlling the height and gradient of the deposited grating material.

[0092] In other embodiments not shown in the figure, the deposition source may be kept stationary, and the substrate and barrier layer may move synchronously. Figure 7 The right side can be moved laterally as shown; or the substrate and barrier layer can be kept stationary while the deposition source moves, thereby forming an initial grating with a highly gradient structure on the functional area.

[0093] In other embodiments not shown in the figure, if an initial grating with an equal height structure is required for a certain functional area (the initial grating with an equal height structure will correspond to the second diffraction grating 3 in Embodiment 2), it is only necessary to keep the deposition source stationary relative to the functional area.

[0094] It should be noted that the actual deposition area of ​​the deposition source 4 is larger than the area of ​​the functional area 10. The non-functional area (the location on the substrate 1 other than the functional area 10) will also be covered by the deposition material. However, because there is a mask or resist on the non-functional area, the deposition material in the non-functional area will cover the surface of the mask or resist and will not be in direct contact with the substrate 1.Figure 7 Only the deposition in the functional area 10 is shown.

[0095] In Embodiment One, the grating material can be SiNx or SiOx, where x is a positive integer, such as SiO2.

[0096] S4, etching each of the initial gratings 6 to form a light waveguide structure. The initial grating 6 in the height gradient structure forms a first diffraction grating 2 after etching.

[0097] Specifically, as shown in the figure, this step S4 includes the steps of: Figure 8

[0098] S41, coating a resist on the surface of the initial grating 6.

[0099] In step S41, when coating the resist, the resist can be covered on the surface of the initial grating 6 by spin coating, that is, the resist is placed on the surface of the initial grating 6, and then the substrate 1 is rotated by a rotating disc, so that the resist is coated on the surface of the initial grating 6 under the action of centrifugal force. Alternatively, the resist can be covered on the surface of the initial grating 6 by spraying, that is, the resist is directly sprayed on the surface of the initial grating 6 by a spraying device 8 (as shown in the figure). Figure 9

[0100] S42, exposing and developing the resist coated on the surface of the initial grating 6 to form a grating-shaped resist structure 9 (as shown in the figure) on the surface of the initial grating 6. Figure 10

[0101] In step S42, if electron beam exposure is used, proximity effect correction (PEC) needs to be performed according to the material of the substrate 1 to compensate for the layout of the electron beam exposure, so that the structure size after exposure reaches the design value.

[0102] S43, dry etching the part of the initial grating 6 corresponding to the gap of the grating-shaped resist structure 9, so that the initial grating 6 forms a grating-shaped structure. The grating-shaped structure formed by etching the initial grating 6 in the height gradient structure is a first diffraction grating 2.

[0103] S44, after dry etching, removing the grating-shaped resist structure 9 to form a light waveguide structure as shown in the figure. Figure 4

[0104] ​​​​During dry etching, it is necessary to ensure that the substrate 1 and the initial grating 6 do not react with the same etching gas. That is, the substrate 1 acts as an etching stop layer when etching the initial grating 6, so that the etching stops at the substrate 1, and only the initial grating 6 is etched.

[0105] In Embodiment 1, prior to step S4, the method further includes the step of removing the mask placed on the first surface of the substrate 1 during step S2. Alternatively, it includes removing the resist applied to the first surface of the substrate 1 during step S2.

[0106] Example 2

[0107] like Figure 11 As shown, the optical waveguide structure provided in Embodiment 2 of the present invention differs from that in Embodiment 1 in that, in Embodiment 2, the first diffraction grating 2 is provided on a portion of the functional regions 10, and the second diffraction grating 3 is provided on the remaining functional regions 10. The second diffraction grating 3 includes a plurality of second grating units 31 arranged at intervals in sequence, and the height of the plurality of second grating units 31 is the same.

[0108] Specifically, in Example 2, as Figure 11 As shown, the functional area 10 is provided in three parts. The three functional areas 10 include, according to their functions, an insertion area 10a, a pupil dilation area 10b, and an exit area 10c. The insertion area 10a and the pupil dilation area 10b are arranged along the first direction, and the pupil dilation area 10b and the exit area 10c are arranged along the second direction. The first direction and the second direction intersect.

[0109] The first diffraction grating 2 is disposed on the coupling region 10a, and the second diffraction grating 3 is disposed on the pupil expansion region 10b and the coupling out region 10c.

[0110] The first diffraction grating 2 in the coupling region 10a is used to receive light signals and transmit the light to the second diffraction grating 3 in the pupil-expanding region 10b. The second diffraction grating 3 in the pupil-expanding region 10b is used to horizontally dilate the received light and transmit the dilated light to the second diffraction grating 3 in the coupling region 10c. The second diffraction grating 3 in the coupling region 10c is used to vertically dilate the received light and project the light into the human eye.

[0111] In other embodiments not shown in the figures, the pupil expansion region can be provided with a first diffraction grating, the in-coupling region and the out-coupling region can be provided with a second diffraction grating; or the out-coupling region can be provided with a first diffraction grating, the in-coupling region and the pupil expansion region can be provided with a second diffraction grating; or the in-coupling region and the pupil expansion region can be provided with a first diffraction grating, the out-coupling region can be provided with a second diffraction grating; or the in-coupling region and the out-coupling region can be provided with a first diffraction grating, the pupil expansion region can be provided with a second diffraction grating; or the pupil expansion region and the out-coupling region can be provided with a first diffraction grating, the in-coupling region can be provided with a second diffraction grating. It is only required that at least one of the functional regions is provided with the first diffraction grating.

[0112] As shown in Figure 12 Embodiment two of the present application provides a method for processing a light waveguide structure, comprising the steps of:

[0113] S5, selecting a substrate 1. The thickness of the substrate 1 is 0.8 mm, and the area is 10 inches. The material of the substrate 1 is silicon dioxide (SiO2).

[0114] S6, forming a plurality of functional regions 10 on the first surface of the substrate 1.

[0115] The forming method of the functional regions 10 in this step S6 is consistent with the forming method of the functional regions 10 in step S2 of embodiment one, and will not be described here again.

[0116] S7, depositing grating material in each of the functional regions 10 to form an initial grating 6. Among them, the initial grating 6 deposited in part of the functional regions 10 (the in-coupling region 10a) is a height gradient structure, and the initial grating 6 deposited in the remaining functional regions 10 (the pupil expansion region 10b and the out-coupling region 10c) is an equal height structure.

[0117] When depositing grating material, a deposition source 4 can be placed above the substrate 1, and the discharge port of the deposition source 4 is directed towards the first surface of the substrate 1. Then, the deposition source 4 and the substrate 1 move laterally relative to each other, so that the deposition source 4 moves to above each of the functional regions 10 in turn, and deposits grating material in each of the functional regions 10 on the substrate 1 in turn.

[0118] When the deposition source 4 deposits grating material in a certain functional region 10, a baffle 7 (see Figure 13 ) can be placed above the substrate 1, so that the baffle 7 is located between the functional region 10 and the deposition source 4. During the deposition process, the functional region 10 and the deposition source 4 are relatively stationary.

[0119] Specifically, asFigure 13 As shown, when the initial grating 6 in the height gradient structure is deposited in the coupling-in region 10a, the shutter 7 always moves laterally relative to the coupling-in region 10a in the direction shown to the right, thereby forming the initial grating 6 in the height gradient structure with the left height higher than the right height on the coupling-in region 10a. In other embodiments not shown in the figure, the shutter can be made to move laterally to the left in the direction shown, thereby forming the initial grating 6 in the height gradient structure with the right height higher than the left height on the corresponding functional region 10. The moving speed of the shutter 7 is adjustable, controlling the rate of height variation of the grating material. Figure 12 As shown, when the initial grating 6 in the height gradient structure is deposited in the coupling-in region 10a, the shutter 7 always moves laterally relative to the coupling-in region 10a in the direction shown to the right, thereby forming the initial grating 6 in the height gradient structure with the left height higher than the right height on the coupling-in region 10a. In other embodiments not shown in the figure, the shutter can be made to move laterally to the left in the direction shown, thereby forming the initial grating 6 in the height gradient structure with the right height higher than the left height on the corresponding functional region 10. The moving speed of the shutter 7 is adjustable, controlling the rate of height variation of the grating material.

[0120] When the initial grating 6 in the height gradient structure is deposited in the pupil-expanding region 10b (or the coupling-out region 10c), the shutter 7 is then separated from the pupil-expanding region 10b (or the coupling-out region 10c) and the deposition source 4, thereby forming the initial grating 6 in the height gradient structure on the pupil-expanding region 10b (or the coupling-out region 10c).

[0121] S8, etching each of the initial gratings 6 to form a light waveguide structure. The initial grating 6 in the height gradient structure is etched to form the first diffraction grating 2, and the initial grating 6 in the height gradient structure is etched to form the second diffraction grating 3.

[0122] Specifically, as shown, this step S8 includes the steps of: Figure 14 As shown, this step S8 includes the steps of:

[0123] S81, coating an anti-reflection material on the surface of the initial grating 6.

[0124] The anti-reflection material can reduce the excessive exposure of the photoresist caused by the reflection of the substrate 1 in the subsequent steps, and can cause problems such as image blur and distortion. The anti-reflection material can be selected from organic silicon dioxide (SiO2) or silicon nitride (Si3N4).

[0125] S82, coating a photoresist on the surface of the anti-reflection material.

[0126] The ratio between the minimum height a of the photoresist and the maximum height b of the corresponding initial grating 6 is preferably 1:5-5:1, ensuring the etching of the initial grating 6 in the subsequent steps.

[0127] S83, exposing the photoresist to form a grid-shaped gel structure on the surface of the anti-reflection material (for reference to the grid-shaped resist structure 9 in Figure 10 ).

[0128] S84, dry etching is performed on the anti-reflection material and the part of the initial grating 6 corresponding to the gap of the grating-like colloidal structure, so that the initial grating 6 forms a grating structure. The grating structure formed by etching the initial grating 6 in the height gradient structure is the first diffraction grating 2, and the grating structure formed by etching the initial grating 6 in the equal-height structure is the second diffraction grating 3.

[0129] S85, after the dry etching is completed, the grating-like colloidal structure is removed, and the optical waveguide structure as shown in Figure 11 is formed.

[0130] In order to more intuitively reflect the optical performance improvement effect of the height gradient first diffraction grating 2 on the optical waveguide structure, the existing optical waveguide structure and the optical waveguide structure provided in Embodiment Two are compared and simulated. As shown in Figure 1 , each diffraction grating 1a on the existing optical waveguide structure is composed of a plurality of grating units 11a with consistent height.

[0131] Through simulation calculation, the field tracing effect diagram (as shown in Figure 2 ) and the ray tracing effect diagram (as shown in Figure 3 ) of the existing optical waveguide structure are obtained, and the field tracing effect diagram (as shown in Figure 15 ) and the ray tracing effect diagram (as shown in Figure 16 ) of the optical waveguide structure provided in Embodiment Two are obtained.

[0132] According to each field tracing effect diagram, the average optical power of the existing optical waveguide structure is 4.43x10 -3 , the uniformity is 32.732%, the average optical power of the optical waveguide structure provided in Embodiment Two is 6.99x10 -3 , and the uniformity is 51.294%, so it can be explained that after the height gradient first diffraction grating 2 is introduced into the optical waveguide structure provided in Embodiment Two, the light output performance of the optical waveguide structure is significantly improved.

[0133] According to each ray tracing effect diagram, the ray tracing effect Figure 1 of the existing optical waveguide structure and the optical waveguide structure provided in Embodiment Two is consistent, which indicates that the light transmission trajectories of the existing optical waveguide structure and the optical waveguide structure provided in Embodiment Two are consistent.

[0134] According to each field tracing effect diagram and each ray tracing effect diagram, compared with the existing optical waveguide structure, the optical performance of the optical waveguide structure provided in Embodiment Two of the application is significantly improved.

[0135] The above merely describes preferred embodiments of the present application, and is not used to limit the present application, any modification, equivalent replacement and improvement within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. An optical waveguide structure, characterized in that, The device includes a substrate and a first diffraction grating. The substrate has several functional regions, and at least one of the functional regions has the first diffraction grating. The first diffraction grating includes a plurality of first grating units arranged at intervals in sequence, and the height of the plurality of first grating units gradually increases or decreases along the interval direction.

2. The optical waveguide structure according to claim 1, characterized in that, The optical waveguide structure further includes a second diffraction grating, which includes a plurality of second grating units arranged at intervals in sequence, and the plurality of second grating units have the same height; In several of the functional regions, the functional regions that do not have the first grating unit are provided with the second diffraction grating.

3. The optical waveguide structure according to claim 2, characterized in that, The functional area is provided in three parts, which include an insertion area, a pupil dilation area and an exit area according to their functions. The insertion area and the pupil dilation area are arranged along the first direction, and the pupil dilation area and the exit area are arranged along the second direction. The first diffraction grating is provided on at least one of the functional regions of the coupling-in region, the pupil expansion region and the coupling-out region; In the coupling-in region, the pupil expansion region, and the coupling-out region, a second diffraction grating is provided on the functional region where the first diffraction grating is not provided.

4. A method for fabricating an optical waveguide structure, characterized in that, The method for processing the optical waveguide structure according to claim 1 includes: Select a substrate; Several functional areas are formed on the first surface of the substrate; A grating material is deposited in each of the functional regions to form an initial grating; wherein, the initial grating deposited in at least one of the functional regions has a height gradient structure; The initial gratings are etched to form an optical waveguide structure; wherein the initial grating with a highly gradient structure is etched to form a first diffraction grating.

5. The fabrication method of the optical waveguide structure according to claim 4, characterized in that, The phrase "forming a plurality of functional regions on the first surface of the substrate" includes: A mask with a cutout area is placed on the first surface of the substrate, and the functional area is formed on the substrate at the position corresponding to the cutout area. Before "etching each of the initial gratings", the process further includes: removing the mask placed on the first surface of the substrate when "forming a plurality of functional regions on the surface of the substrate".

6. The fabrication method of the optical waveguide structure according to claim 4, characterized in that, The phrase "forming a plurality of functional regions on the first surface of the substrate" includes: A photoresist is coated on the first surface of the substrate. The photoresist coated on the first surface of the substrate is exposed and developed, so that a portion of the substrate is exposed to the photoresist. The portion of the substrate exposed to the photoresist forms the functional area. Before "etching each of the initial gratings", the process further includes: removing the resist applied to the first surface of the substrate when "forming a plurality of functional regions on the surface of the substrate".

7. The fabrication method of the optical waveguide structure according to claim 4, characterized in that, When "depositing grating material in each of the functional regions to form an initial grating", the initial grating deposited in some of the functional regions is a height gradient structure, while the initial grating deposited in the remaining functional regions is a constant height structure; When "etching each of the initial gratings", the initial gratings with equal height structure are etched to form a second diffraction grating. The second diffraction grating includes a plurality of second grating units arranged at intervals in sequence, and the height of the plurality of second grating units is the same.

8. The fabrication method of the optical waveguide structure according to claim 7, characterized in that, The "depositing of grating material in each of the aforementioned functional regions" includes: A deposition source is placed above the substrate, with the outlet of the deposition source facing the first surface of the substrate; The deposition source and the substrate undergo lateral relative movement to deposit grating material in each of the functional regions on the substrate through the deposition source.

9. The fabrication method of the optical waveguide structure according to claim 8, characterized in that, When the deposition source deposits grating material on a certain functional region, if the deposition source always moves laterally relative to the functional region during the deposition process, an initial grating with a height gradient structure is formed on the functional region; if the deposition source is relatively stationary with respect to the functional region during the deposition process, an initial grating with a uniform height structure is formed on the functional region.

10. The fabrication method of the optical waveguide structure according to claim 8, characterized in that, When the deposition source deposits grating material on a certain functional area, a baffle is placed above the substrate; If the baffle is located between the functional area and the deposition source, and the functional area and the deposition source are relatively stationary during the deposition process, while the baffle always moves laterally relative to the functional area, then an initial grating with a highly gradient structure is formed on the functional area. If the baffle is removed from the functional area and the deposition source, an initial grating with an equal height structure is formed on the functional area.

11. The fabrication method of the optical waveguide structure according to claim 7, characterized in that, The phrase "etching each of the initial gratings to form an optical waveguide structure" includes: A resist is coated on the surface of the initial grating; The resist coated on the surface of the initial grating is exposed and developed to form a grating-shaped resist structure on the surface of the initial grating; Dry etching is performed on the portion of the initial grating corresponding to the gap of the grating-shaped anti-etching structure to form a grating structure from the initial grating; wherein, the grating structure formed by etching the initial grating with a height gradient structure is the first diffraction grating, and the grating structure formed by etching the initial grating with a uniform height structure is the second diffraction grating. After dry etching is completed, the grid-like resist structure is removed to form an optical waveguide structure.

12. The fabrication method of the optical waveguide structure according to claim 7, characterized in that, The phrase "etching each of the initial gratings to form an optical waveguide structure" includes: An anti-reflective material is coated onto the surface of the initial grating; Photoresist is coated onto the surface of the antireflective material; The photoresist is exposed to form a grid-like colloidal structure on the surface of the antireflective material; Dry etching is performed on the portion of the antireflective material and the initial grating corresponding to the gap of the grating colloidal structure to form a grating structure of the initial grating; wherein, the grating structure formed by etching the initial grating with a height gradient structure is the first diffraction grating, and the grating structure formed by etching the initial grating with a uniform height structure is the second diffraction grating. After dry etching is completed, the grid-like colloidal structure is removed to form an optical waveguide structure.

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