Optical waveguide device, preparation method, electronic device and electronic equipment
By coating a dielectric layer on the coupling grating of the optical waveguide device, the problem of light leakage caused by the inconsistent light output direction of different diffraction orders in the optical waveguide device was solved, thereby improving the optical efficiency and imaging quality.
Patent Information
- Application Number
- CN202410971352.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-18
- Publication Date
- 2026-01-20
AI Technical Summary
The different exit directions of light rays of different diffraction orders in an optical waveguide device lead to light leakage, resulting in the leakage of optical waveguide imaging information.
A dielectric layer is coated on the coupling grating. The material of the dielectric layer fills the grooves between the diffractive optical structures and forms a planar surface on the side away from the waveguide. The refractive index of the dielectric layer is less than that of the coupling grating. The coating process ensures that the dielectric layer is tightly bonded to the diffractive optical structures without any pores.
It effectively suppresses light leakage from the front of the optical waveguide device, improves imaging quality, reduces stray light, and enhances light efficiency and uniformity.
Smart Images
Figure CN121364523A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of display, in particular to a light waveguide device, a preparation method, an electronic device and an electronic equipment. BACKGROUND
[0002] In the light waveguide-based display, the light rays of different diffraction orders have different light-out directions, and the light rays with light-out directions different from the direction of the user will cause light leakage of the light waveguide, resulting in leakage of the imaging information of the light waveguide. SUMMARY
[0003] Therefore, the present application provides a light waveguide device, a preparation method, an electronic device and an electronic equipment to solve the light leakage problem of the light waveguide in the prior art.
[0004] In a first aspect, the present application provides a light waveguide device, which comprises a waveguide, a coupling-out grating and a dielectric layer. The coupling-out grating is used for emitting light rays, and the coupling-out grating comprises a plurality of diffractive optical structures. The plurality of diffractive optical structures are obliquely arranged on the waveguide, and a groove is formed between each two adjacent diffractive optical structures and the waveguide. At least part of the material of the dielectric layer fills the groove, at least part of the material of the dielectric layer coats the surface of the diffractive optical structure away from the waveguide, and the surface of the dielectric layer away from the waveguide is a plane. The refractive index of the dielectric layer is less than the refractive index of the coupling-out grating.
[0005] In the present application, the dielectric layer formed on the coupling-out grating by the coating process can fully fill the grooves between the plurality of diffractive optical structures, and a film layer with a certain thickness can be formed on the side of the coupling-out grating away from the waveguide. The surface of the film layer away from the waveguide is formed as a plane, and no recess is present on the plane, so that the effect of the recess on light leakage can be avoided, and undesirable stray light can be avoided, which is beneficial to improving the light efficiency and uniformity and ensuring the final imaging quality.
[0006] In a possible implementation, the dielectric layer comprises a first layer and a second layer, the first layer is connected to the second layer, the first layer is arranged in all or at least part of the grooves, and the first layer is attached to the inner wall of the groove. The second layer is arranged on the side of the diffractive optical structure and the first layer away from the waveguide, and covers all or at least part of the diffractive optical structure and the first layer. The first layer can fully fill the grooves, and no pores are present between the first layer and the diffractive optical structure. The side of the second layer away from the waveguide can form a flat surface, and a better light leakage elimination effect can be achieved.
[0007] In a possible implementation, the second layer has a preset thickness H0 and an actual thickness H1, a difference between the actual thickness H1 of the second layer and the preset thickness H0 of the second layer is ΔH, and a ratio of the difference ΔH to the preset thickness H0 is between -3% and 3%. In this way, the actual thickness H1 of the second layer is close to the preset thickness H0 by using the coating method, the thickness of the second layer is relatively uniform, the surface of the second layer away from the waveguide is relatively flat, the consistency of the refractive index of the second layer can be ensured, the consistency of the suppression effect of the front light leakage of the optical waveguide device can be improved, and meanwhile, the front light leakage can be reduced without introducing stray light and causing effective light loss.
[0008] In a possible implementation, a ratio of a difference between actual thicknesses of different positions on the second layer to a preset thickness of the second layer is between -3% and 3%. In this way, the difference between the thicknesses of any two positions on the second layer is small by using the coating process, that is, the thickness of the second layer is close to uniform, the surface of the second layer away from the waveguide is relatively flat, the consistency of the refractive index of the second layer can be ensured, the consistency of the suppression effect of the front light leakage of the optical waveguide device can be improved, and meanwhile, the front light leakage can be reduced without introducing stray light and causing effective light loss.
[0009] In a possible implementation, a distance between the surface of the medium layer away from the waveguide and the surface of the diffractive optical structure away from the waveguide is less than 1 μm. In this way, the front light leakage of the optical waveguide device can be reduced and the suppression effect of the light leakage can be improved by limiting the thickness of the second layer to be within 1 μm.
[0010] In a possible implementation, at least part of the diffractive optical structures have different heights in the thickness direction of the waveguide, and a distance between the surface of the diffractive optical structure with the largest height away from the waveguide and the surface of the medium layer away from the waveguide is less than 1 μm. In this way, the medium layer can be set based on the diffractive optical structure with the largest height, so that the medium layer can cover all the diffractive optical structures, and meanwhile, the diffractive optical structure can avoid having an excessively large thickness.
[0011] In a possible implementation, the flatness of the surface of the medium layer away from the waveguide is less than 15 nm. In this way, the surface of the medium layer away from the waveguide is close to a plane, has high thickness and flatness accuracy, and does not have a large concave, so that the consistency of the suppression effect of the front light leakage of the optical waveguide device can be improved. Figure 3
[0012] In a possible implementation, the difference between the refractive index of the out-coupling grating and the refractive index of the medium layer is between 0.15 and 0.25, so that the medium layer has a refractive index modulation with respect to the grating, which is beneficial to reflect and diffract most of the light propagating to the out-coupling grating in the waveguide to the user's eyes, and reduce the light transmitted and diffracted from the front of the light waveguide device.
[0013] In a possible implementation, the material of the medium layer is photoresist or a mixture of photoresist and silicon dioxide. The material of the medium layer can be coated on the out-coupling grating by coating, so as to ensure reliable combination of the medium layer and the diffractive optical structure by coating, and ensure the flatness of the surface of the medium layer, thereby achieving the effect of light leakage elimination.
[0014] In a possible implementation, the medium layer is integrally formed by a coating process, so as to facilitate process processing and ensure the uniformity of the material of the medium layer.
[0015] In a possible implementation, the arrangement period of the plurality of diffractive optical structures is between 250 nm and 500 nm, the height of the diffractive optical structure is between 270 nm and 410 nm, the duty cycle of the diffractive optical structure is between 0.2 and 0.8, the included angle between the diffractive optical structure and the waveguide is between 20° and 45°, and the ratio of the width to the height of the diffractive optical structure is between 1:2 and 1:10. When the parameters of the out-coupling grating are within the above corresponding parameter ranges, the out-coupling grating can have better optical characteristics, which is beneficial to cooperate with the medium layer to suppress the problem of light leakage from the front of the light waveguide device.
[0016] In a second aspect, the application further provides a preparation method for preparing the light waveguide device provided in the first aspect of the application, which comprises the following steps:
[0017] A plurality of diffractive optical structures are arranged on the waveguide to form an out-coupling grating;
[0018] A medium material is coated on the out-coupling grating, so that at least part of the medium material fills the grooves between the plurality of diffractive optical structures, and at least part of the medium material is coated on the side of the diffractive optical structure away from the waveguide, and a medium film layer with a preset thickness is formed on the side of the diffractive optical structure away from the waveguide;
[0019] The medium material is cured to form a medium layer.
[0020] The medium material coating process provided in the embodiment can be used to fill the grooves between the diffractive optical structures with the medium material such as photoresist by the flowability of the medium material, and a film layer with a certain thickness can be formed on the side of the out-coupling grating away from the waveguide, and the surface on the side of the film layer away from the waveguide is formed as a plane, and no recess is formed on the plane, so that the effect of the recess on the light leakage can be avoided, and the stray light generated in the recess can be avoided, and the light efficiency and uniformity can be improved, and the final imaging quality can be ensured.
[0021] In a third aspect, the application further provides a preparation method for preparing the optical waveguide device provided in the first aspect of the application, and the preparation method comprises the following steps:
[0022] a plurality of diffractive optical structures are arranged on the waveguide, and at least part of the diffractive optical structures constitute an in-coupling grating, and at least part of the diffractive optical structures constitute an out-coupling grating;
[0023] a medium material is coated on the in-coupling grating and the out-coupling grating;
[0024] the medium material in the in-coupling grating or the out-coupling grating is exposed;
[0025] the medium material in the in-coupling grating is dissolved by using a developing solution.
[0026] Therefore, the medium material coating process provided in the embodiment can be used to fill the grooves between the diffractive optical structures with the medium material such as photoresist by the flowability of the medium material, and a film layer with a certain thickness can be formed on the side of the out-coupling grating away from the waveguide, and the surface on the side of the film layer away from the waveguide is formed as a plane, and no recess is formed on the plane, so that the effect of the recess on the light leakage can be avoided, and the stray light generated in the recess can be avoided, and the light efficiency and uniformity can be improved, and the final imaging quality can be ensured.
[0027] In a possible implementation manner, the medium material is a positive photoresist.
[0028] The exposure of the medium material in the in-coupling grating or the out-coupling grating specifically comprises the following steps:
[0029] a light shielding material or a mask plate is arranged on the light source at a position corresponding to the out-coupling grating;
[0030] the medium material in the in-coupling grating is irradiated by using the light source.
[0031] Wherein, when the medium material above the waveguide is irradiated by the light source, the light at the position on the light source corresponding to the light shielding material or the mask plate will not irradiate the medium material at the coupling-in grating, and the position on the light source not being shielded can be opposite to the coupling-out grating, so that the medium material at the coupling-out grating can be exposed by the light source.
[0032] In a possible implementation, the medium material is a negative photoresist.
[0033] The exposure of the medium material in the coupling-in grating or the coupling-out grating specifically includes:
[0034] The light shielding material or the mask plate is arranged at the position on the light source corresponding to the coupling-in grating.
[0035] The medium material in the coupling-out grating is irradiated by the light source.
[0036] Wherein, when the medium material above the waveguide is irradiated by the light source, the light at the position on the light source corresponding to the light shielding material or the mask plate will not irradiate the medium material at the coupling-in grating, and the position on the light source not being shielded can be opposite to the coupling-out grating, so that the medium material at the coupling-out grating can be exposed by the light source.
[0037] In a fourth aspect, the present application further provides an electronic device, which comprises the optical waveguide device provided in the first aspect of the present application.
[0038] In a fifth aspect, the present application further provides an electronic device, which comprises the electronic device provided in the fourth aspect of the present application.
[0039] It should be understood that the foregoing general description and the following detailed description are only exemplary, and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS
[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.
[0041] Figure 1 It is a structural schematic diagram of an optical waveguide device in a related art;
[0042] Figure 2 It is a structural schematic diagram of an optical waveguide device provided in an embodiment of the present application;
[0043] Figure 3 A schematic diagram of an optical waveguide device according to an embodiment of the application;
[0044] Figure 4 A schematic diagram of an electronic device according to an embodiment of the application;
[0045] Figure 5 A schematic diagram of an optical waveguide device according to another embodiment of the application;
[0046] Figure 6 A schematic diagram of a display device in an electronic device according to an embodiment of the application;
[0047] Figure 7 A schematic diagram of an optical waveguide device according to another embodiment of the application;
[0048] Figure 8 A schematic diagram of an optical waveguide device according to another embodiment of the application (without a dielectric layer);
[0049] Figure 9 A partial schematic diagram of an out-coupling grating according to an embodiment of the application;
[0050] Figure 10 A schematic diagram of an optical waveguide device according to another embodiment of the application;
[0051] Figure 11 A schematic diagram of an optical waveguide device according to another embodiment of the application;
[0052] Figure 12 A schematic diagram of an optical waveguide device according to another embodiment of the application;
[0053] Figure 13 A partial schematic diagram of an optical waveguide device according to an embodiment of the application;
[0054] Figure 14 A flow diagram of a method of manufacture according to an embodiment of the application;
[0055] Figure 15 A schematic diagram of an optical waveguide device during coating of a dielectric material according to an embodiment of the application;
[0056] Figure 16 A flow diagram of a method of manufacture according to another embodiment of the application;
[0057] Figure 17 A schematic diagram of a waveguide having a plurality of diffractive optical structures formed thereon according to an embodiment of the application;
[0058] Figure 18A schematic diagram showing the dielectric material coated on the coupling-in grating and coupling-out grating provided in the embodiments of this application;
[0059] Figure 19 This is a schematic diagram of the dielectric material on the waveguide during exposure, provided in an embodiment of this application.
[0060] Figure 20 A schematic diagram of the dielectric material at the coupling grating provided in an embodiment of this application after exposure;
[0061] Figure 21 This is a schematic diagram showing the removal of the dielectric material at the coupling grating provided in an embodiment of this application.
[0062] Figure label:
[0063] 1-Waveguide;
[0064] 10-Electronic devices;
[0065] 10a - Display device; 101 - Coupling-in region; 102 - Coupling-out region; 103 - Turning-out region;
[0066] 100-waveguide;
[0067] 2-Output grating;
[0068] 20 - Spraying device; 21 - Diffractive optical structure; 22 - Groove;
[0069] 200 - Coupling grating; 210 - Diffraction microstructure; 220 - Groove region;
[0070] 3-Coupled grating;
[0071] 30 - Light source;
[0072] 300-coupled grating;
[0073] 4-Dielectric layer;
[0074] 40 - Mask; 41 - First layer; 42 - Second layer; 43 - Dielectric material;
[0075] 400 - Eye area;
[0076] 5-fold grating;
[0077] 500 - Low refractive index material; 510 - Depression. Detailed Implementation
[0078] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.
[0079] It should be noted that the embodiments described are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.
[0080] The terms used in the embodiments of the present application are merely for the purpose of describing the specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.
[0081] It should be understood that the term "and / or" used herein is only to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are in an "or" relationship.
[0082] In the description of the present application, unless otherwise expressly specified and limited, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance; unless otherwise specified or explained, the term "multiple" means two or more; the terms "connection", "fixation" and the like should be understood in a broad sense, for example, "connection" can be fixed connection, or detachable connection, or integrally connected, or electrically connected; it can be directly connected, or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.
[0083] In the light waveguide-based display, different diffraction order light rays have different light out directions, and the light waveguide diffracts light in directions both towards the user and different from the user's direction. Among them, for the light rays with light out direction different from the user's direction, it will cause the light leakage problem of the light waveguide, resulting in the leakage of the imaging information of the light waveguide. Exemplarily, Figure 1 A structure diagram of a light waveguide device in a related art is shown in FIG. 1. Figure 1 As shown in the figure, the light waveguide device includes a waveguide 100, a coupling-out grating 200 and a coupling-in grating 300, the coupling-out grating 200 and the coupling-in grating 300 each include a plurality of diffraction microstructures, the coupling-out grating 200 and the coupling-in grating 300 are located on the back of the waveguide 100, light rays are incident on the waveguide 100 through the coupling-in grating 300, transmitted through the waveguide 100 to the coupling-out grating 200, and the light rays are emitted through the coupling-out grating 200, the eye 400 of the user is located on the back of the light waveguide device, and the emitted light rays can be received by the eye 400. Among them, the light rays emitted from the back of the light waveguide device (for example Figure 1The light ray a) shown can be normally received by the user's eye 400, but due to different light ray directions of different diffraction orders, the light ray can be emitted from the front of the light waveguide device. The part of the light ray emitted from the front (for example Figure 1 The light ray b) shown causes light leakage of the light waveguide and also causes leakage of imaging information.
[0084] Figure 2 A structural schematic diagram of a light waveguide device provided for an embodiment of the present application is shown in FIG. 1. Figure 2 As shown, in order to make the light waveguide device have lower front light leakage, eliminate the diffraction order light rays of the light waveguide device that cause front light leakage, and protect the privacy and safety of the user, the out-coupling grating 200 can be arranged obliquely relative to the waveguide 100, and a low refractive index material 500 can be filled in the gap between the out-coupling gratings 200, so as to change the propagation direction of the diffraction light rays on the front of the light waveguide device, and thus eliminate the diffraction order light rays b on the front of the light waveguide device shown in FIG. 1. Figure 1 The diffraction order light rays b on the front of the light waveguide device shown in FIG. 1.
[0085] In this case, the inorganic low refractive index material can be deposited by using a semiconductor process. For example, a chemical vapor deposition (CVD) process, a physical vapor deposition (PVD) process, an atomic layer deposition (ALD) process, or the like can be used. However, these processes also bring many problems.
[0086] Figure 3 A schematic diagram of a light waveguide device provided for an embodiment of the present application is shown in FIG. 2. Figure 3 As shown, when the low refractive index material is deposited by using a CVD / PVD process, since the out-coupling grating includes a plurality of diffraction microstructures 210 distributed at intervals, a groove region 220 is formed between two adjacent diffraction microstructures 210. The low refractive index material needs to cover each diffraction microstructure 210 and also needs to be filled in the groove region 220. This will cause a depression 510 to appear on the surface of the low refractive index material at a position opposite to the groove region 220 after the material deposition is completed. This depression 510 will affect the light leakage elimination effect, cause undesirable stray light at the depression, and cause loss of effective light, which will reduce the light efficiency and uniformity and affect the final imaging quality. In addition, the low refractive index material is not completely filled in the groove region 220, and there is a gap between the low refractive index material and the diffraction microstructure 210. This gap will also cause loss of light efficiency and uniformity.
[0087] In addition, when the low refractive index material is deposited by using an ALD process, a depression 510 will also appear on the surface of the low refractive index material at a position opposite to the groove region 220. Moreover, the ALD deposition efficiency is low, and it is difficult to mass-produce in actual production.
[0088] Based on this, the embodiment of the present application provides an optical waveguide device, which can be applied in an electronic device, which can be a chip, a wafer containing a plurality of chips, a device after packaging of a chip and a circuit board, etc. Wherein, the electronic device can be applied in an electronic equipment, which can be a virtual reality (VR) equipment, an augmented reality (AR) equipment, etc. The type of the electronic device and the electronic equipment is not limited in the embodiment. Figure 4 The structural schematic diagram of the electronic equipment provided by the embodiment of the present application is shown in Figure 4 The embodiment of the present application takes the AR glasses shown in Figure 4 The display device 10a of the electronic equipment 10 can include a coupling-in area 101 and a coupling-out area 102. The coupling-in area 101 is used for coupling external light into the optical waveguide device, and the coupling-out area 102 is used for coupling the light propagating in the optical waveguide device out to the outside.
[0089] Figure 5 The structural schematic diagram of the optical waveguide device provided by another embodiment of the present application is shown in Figure 5 The optical waveguide device provided by the embodiment of the present application includes a waveguide 1, a coupling-out grating 2, a coupling-in grating 3 and a dielectric layer 4. Wherein, the waveguide 1 can be glass material, which has good light transmission characteristics. The coupling-in grating 3 and the coupling-out grating 2 can each include a plurality of diffractive optical structures 21. The external optical fiber can be incident into the waveguide 1 through the coupling-in grating 3, and transmitted to the coupling-out grating 2 through the waveguide 1, and the light can be emitted through the coupling-out grating 2. After the optical waveguide device is arranged in the electronic equipment, the coupling-in grating 3 is located in the coupling-in area 101 (as shown in Figure 4 ), and the coupling-out grating 2 is located in the coupling-out area 102 (as shown in Figure 4 ).
[0090] Figure 6 The structural schematic diagram of the display device in the electronic equipment provided by the embodiment of the present application is shown in Figure 6 The display device 10a of the electronic equipment 10 can further include a turning area 103, which is located between the coupling-in area 101 and the coupling-out area 102. Figure 7 The structural schematic diagram of the optical waveguide device provided by another embodiment of the present application is shown in Figure 7 The optical waveguide device can further include a turning grating 5, which is located between the coupling-out grating 2 and the coupling-in grating 3, and the turning grating 5 is located in the turning area 103 of the electronic equipment. Wherein, the turning grating 5 can direct part of the light of different diffraction orders to the coupling-out grating 2, which is conducive to improving the diffraction efficiency of the coupling-in grating 3.
[0091] Figure 8 A structural schematic diagram of the light waveguide device provided by another embodiment of the present application (without the medium layer 4) is shown in FIG. 3. As shown in FIG. 3, the plurality of diffractive optical structures 21 in the out-coupling grating 2 are obliquely arranged in the waveguide 1, which can achieve high diffraction efficiency of light coupling and improve uniformity of light diffraction. The plurality of diffractive optical structures 21 in the out-coupling grating 2 can be periodically and spacedly arranged, so that a groove 22 can be formed between any two adjacent diffractive optical structures 21 and the waveguide 1. Figure 8
[0092] Figure 9 A partial structural schematic diagram of the out-coupling grating 2 provided by an embodiment of the present application is shown in FIG. 4. As shown in FIG. 4, the arrangement period P of the plurality of diffractive optical structures 21 in the out-coupling grating 2 can be between 250 nm and 500 nm. The height H2 of the diffractive optical structure 21 in the thickness direction of the waveguide 1 can be between 270 nm and 410 nm. The duty cycle of the diffractive optical structure 21 can be between 0.2 and 0.8, and the duty cycle is the ratio of the B of the diffractive optical structure 21 to the period P. The included angle a between the diffractive optical structure 21 and the waveguide 1 can be between 20° and 45°. The ratio range of the width and the height of the diffractive optical structure 21 can be between 1:2 and 1:10. Wherein, when the parameters of the out-coupling grating 2 are within the above corresponding parameter ranges, the out-coupling grating 2 can have good optical characteristics, which is conducive to cooperating with the medium layer 4 to suppress the problem of front light leakage of the light waveguide device. Figure 9
[0093] Figure 10 A structural schematic diagram of the light waveguide device provided by another embodiment of the present application is shown in FIG. 5. As shown in FIG. 5, at least part of the material of the medium layer 4 is filled in the groove 22, at least part of the material of the medium layer 4 is coated on the surface of the diffractive optical structure 21 away from the waveguide 1, and the surface of the medium layer 4 away from the waveguide 1 is a plane. Wherein, the refractive index of the medium layer 4 is less than the refractive index of the out-coupling grating 2. Figure 10
[0094] Wherein, the material of the medium layer 4 can be selected from a material having a refractive index less than the refractive index of the out-coupling grating 2, so that the light waveguide device has a refractive index modulation with a certain refractive index difference, and the refractive index difference can be between 0.15 and 0.25. For example, the refractive index of the out-coupling grating 2 can be 2, the refractive index of the medium layer 4 can be 1.8, and the refractive index difference is 0.2, so that most of the light propagating from the waveguide 1 to the out-coupling grating 2 can be reflected and diffracted to the user's eyes, and the light diffracted and transmitted from the front of the light waveguide device can be reduced. Wherein, the refractive index of the medium layer 4 can be between 1.4 and 2.0, and according to the refractive index modulation requirements of the medium layer 4 and the out-coupling grating 2, a corresponding medium material for preparing the medium layer 4 can be selected.
[0095] The material of the medium layer 4 can be a high-molecular organic material such as a photoresist, which can be coated on the out-coupling grating 2 by coating. The material of the medium layer 4 can also be a photoresist doped with silica particles. By adjusting the size and amount of the doped silica particles, the photoresist can be adjusted to have a specific refractive index to meet the requirements of cooperation with different gratings.
[0096] Exemplarily, the medium layer 4 can be coated on the out-coupling grating 2 by a spin coating process. The spin coating (or spin coating) is a coating process that relies on the centrifugal force and gravity generated when the workpiece rotates to fully coat the coating liquid droplets falling on the workpiece on the surface of the workpiece. In this embodiment, the photoresist can be fully coated on each position of the out-coupling grating 2 by the spin coating process, i.e., the photoresist can be sufficiently filled in the groove 22 between the adjacent two diffractive optical structures 21 by the fluidity of the photoresist, so that the photoresist can be fully combined with the diffractive optical structures 21. After the photoresist is solidified, there is no gap between the medium layer 4 formed by the solidified photoresist and the diffractive optical structures 21, so that the loss of light efficiency and uniformity caused by the gap can be avoided.
[0097] In addition, the spin coating process is different from the traditional deposition process. The photoresist has a certain fluidity during the spin coating process. The photoresist can not only achieve sufficient filling of the groove 22 by its fluidity, but also form a film layer with a certain thickness on the side of the out-coupling grating 2 away from the waveguide 1. The surface of the film layer on the side away from the waveguide 1 is formed as a plane, and the plane does not have the recess 510 shown in the prior art, so that the effect of the recess 510 on the light leakage can be avoided, and the ideal stray light can be generated at the recess 510, which is beneficial to improve the light efficiency and uniformity and can ensure the final imaging quality. Figure 3
[0098] In other embodiments, the medium material can also be sprayed on the out-coupling grating 2 by a spraying filling method. The medium material can also achieve sufficient filling of the groove 22, and no gap is generated between the medium layer 4 formed by the solidified medium material and the diffractive optical structures 21. At the same time, the surface of the medium layer 4 on the side away from the waveguide 1 can be formed as a plane.
[0099] In one embodiment, as shown in FIG. 6, the medium layer 4 can be coated on the out-coupling grating 2 by a spray coating process. The spray coating process is a coating process that relies on the centrifugal force and gravity generated when the workpiece rotates to fully coat the coating liquid droplets falling on the workpiece on the surface of the workpiece. In this embodiment, the photoresist can be fully coated on each position of the out-coupling grating 2 by the spray coating process, i.e., the photoresist can be sufficiently filled in the groove 22 between the adjacent two diffractive optical structures 21 by the fluidity of the photoresist, so that the photoresist can be fully combined with the diffractive optical structures 21. After the photoresist is solidified, there is no gap between the medium layer 4 formed by the solidified photoresist and the diffractive optical structures 21, so that the loss of light efficiency and uniformity caused by the gap can be avoided. Figure 10 As shown, the medium layer 4 includes a first layer 41 and a second layer 42, the first layer 41 is connected to the second layer 42, the first layer 41 is arranged in all or at least part of the groove 22, and the first layer 41 is attached to the inner wall of the groove 22, that is, the first layer 41 can be closely combined with the diffractive optical element and no pores are generated. The second layer 42 is arranged on the side of the diffractive optical structure 21 and the first layer 41 away from the waveguide 1, and covers all or at least part of the diffractive optical structure 21 and the first layer 41. Among them, the height of each diffractive optical structure 21 in the thickness direction of the waveguide 1 can be the same, or only part of the height can be the same, and part of the height can be different. Exemplarily, taking the different height of the partial diffractive optical structure 21 as an example, as shown in the figure, Figure 10 As shown, the first layer 41 and the second layer 42 can be gradually formed during the medium material coating process, that is, the first layer 41 and the second layer 42 are an integrated structure. During the continuous coating process of the medium material on the out-coupling grating 2, the medium material can gradually fill the groove 22, and when the medium material is on the waveguide 1, the surface of the medium layer 4 away from the waveguide 1 is almost planar, has high thickness and flatness accuracy, and will not appear Figure 3 As shown, the thickness of the upper coating reaches the height of the diffractive optical structure 21 with the highest height, which can be understood as that the first layer 41 is formed by the medium material on the waveguide 1. Then, with the continuous coating of the medium material, the second layer 42 with a certain thickness can be continuously formed above the diffractive optical structure 21 and the first layer 41, that is, the second layer 42 can cover the diffractive optical structure 21 and the first layer 41.
[0100] Exemplarily, Figure 11 The structure schematic diagram of the light waveguide device provided for another embodiment of the application is as shown in the figure, Figure 11 As shown, taking the example that the height of each diffractive optical structure 21 in the out-coupling grating 2 is the same, when the thickness of the medium material coated on the waveguide 1 reaches the height of each diffractive optical structure 21, it can be understood that the first layer 41 is formed by the medium material on the waveguide 1. Then, with the continuous coating of the medium material, the second layer 42 with a certain thickness can be continuously formed above the diffractive optical structure 21 and the first layer 41.
[0101] Therefore, by using the coating method, the medium layer 4 can be formed on the out-coupling grating 2 including diffractive optical structures 21 with various size specifications and distribution methods, and no pores can be ensured between the medium layer 4 and the diffractive optical structure 21, and a flat surface can be formed on the side of the medium layer 4 away from the waveguide 1, and a better light leakage suppression effect can be achieved.
[0102] Furthermore, by using a coating method, dielectric material can be coated at various locations of the coupling grating 2, or it can be coated at localized locations of the coupling grating 2. For example... Figure 11 As shown, a spin coating process can be used to coat a large area of dielectric material, which can form a dielectric layer 4 at various positions of the coupling grating 2, facilitating the processing.
[0103] Figure 12 This is a schematic diagram of the structure of an optical waveguide device provided in another embodiment of this application, as shown below. Figure 12 As shown, a dielectric layer 4 can be formed at a local location of the coupling grating 2. Specifically, the dielectric material can be sprayed onto a designated area using a spraying method, and the dielectric layer 4 is formed after the dielectric material cures. The area where the dielectric layer 4 is formed can be determined according to optical characteristics and structural design requirements, providing great flexibility and meeting the needs of different application scenarios.
[0104] Figure 13 This is a partial schematic diagram of an optical waveguide device provided in one embodiment of this application, as shown below. Figure 13 As shown. Before coating with the dielectric material, the thickness of the second layer 42 in the dielectric layer 4 can be set, and can be defined as the preset thickness of the second layer 42 as H0. Due to factors such as process and coating environment, there will be a certain thickness difference ΔH between the actual thickness H1 of the second layer 42 and the preset thickness H0. The ratio of this difference ΔH to the preset thickness H0 is between -3% and 3%. For example, the preset thickness H0 of the second layer 42 can be 500nm. Using the coating process, the actual thickness H1 of the second layer 42 can be between 485nm and 515nm. That is to say, by using the coating method, the actual thickness H1 of the second layer 42 can be close to the preset thickness H0, the thickness of the second layer 42 is more uniform, and the surface of the second layer 42 away from the waveguide 1 is more flat. This can ensure the consistency of the refractive index of the second layer 42, improve the consistency of the suppression effect on the front light leakage of the optical waveguide device, and at the same time, reduce the front light leakage while ensuring that stray light is not introduced and effective light loss is not caused.
[0105] In one embodiment, the ratio of the difference in actual thickness at different locations on the second layer 42 to the preset thickness of the second layer 42 can be between -3% and 3%. However, due to factors such as the process and coating environment, the thickness at different locations on the second layer 42 may vary. In this embodiment, by employing a coating process, the thickness difference between any two locations on the second layer 42 is small. For example, if the preset thickness of the second layer 42 is 400nm, and the average actual thickness of the second layer 42 matches the preset thickness, the difference in actual thickness between two different locations on the second layer 42 is within 12nm. That is, the thickness of the second layer 42 is nearly uniform, and the surface of the second layer 42 away from the waveguide 1 is relatively flat. This ensures the consistency of the refractive index of the second layer 42, improves the consistency of the suppression effect on front light leakage of the optical waveguide device, and simultaneously reduces front light leakage while ensuring no stray light is introduced and no effective light loss occurs.
[0106] In one embodiment, the distance between the surface of the dielectric layer 4 on the side away from the waveguide 1 and the surface of the diffractive optical structure 21 on the side away from the waveguide 1 is less than 1 μm. That is, as... Figure 13 As shown, the actual thickness H1 of the second layer 42 in the dielectric layer 4 is less than 1 μm. For example, the actual thickness of the second layer 42 can be between 20 nm and 200 nm. For example, the actual thickness of the second layer 42 can be 50 nm. In this embodiment, by limiting the thickness of the second layer 42 to within 1 μm, light leakage from the front of the optical waveguide device can be reduced, and the suppression effect on light leakage can be improved.
[0107] In one embodiment, as described above, the heights of the various diffractive optical structures 21 along the thickness direction of the waveguide 1 can be the same, or only partially the same, while partially different. Specifically, for the case where at least some of the diffractive optical structures 21 have different heights along the thickness direction of the waveguide 1, for example, multiple diffractive optical structures 21 can be arranged in a gradient of increasing or decreasing heights along a predetermined arrangement direction. The distance between the surface of the diffractive optical structure 21 with the largest height on the side away from the waveguide 1 and the surface of the dielectric layer 4 on the side away from the waveguide 1 is the thickness of the second layer 42, which is less than 1 μm. For the case where the heights of the various diffractive optical structures 21 are the same, the distance between the surface of the dielectric layer 4 on the side away from the waveguide 1 and the surfaces of each diffractive optical structure 21 on the side away from the waveguide 1 is the thickness of the second layer 42, which is also less than 1 μm. Therefore, regardless of the size and arrangement of the diffraction optical structure 21 in the coupling grating 2, a dielectric layer 4 can be formed on the coupling grating 2, and the dielectric layer 4 may include a second layer 42 located on the side of the coupling grating 2 away from the bottom, thereby reducing the impact of light leakage on the front of the optical waveguide device.
[0108] In an embodiment, the medium layer 4 formed on the out-coupling grating 2 by the coating process has a flatness of less than 15 nm on the surface away from the waveguide 1, and in an example, the flatness of the medium layer 4 on the surface away from the waveguide 1 is less than 5 nm, so that the surface of the medium layer 4 away from the waveguide 1 is almost planar, has a high thickness and flatness accuracy, and does not have the large concave shown in the prior art, so that the consistency of the suppression effect of the front light leakage of the optical waveguide device can be improved. Figure 3
[0109] Figure 14 A flowchart of a preparation method provided by an embodiment of the present application is shown in FIG. 6, and the present application also provides a preparation method, which can be used to prepare the optical waveguide device provided by any embodiment of the present application. The preparation method includes the following steps: Figure 14
[0110] In step S1, a plurality of diffractive optical structures 21 are arranged on the waveguide 1 to form the out-coupling grating 2. The diffractive optical structures 21 can be formed on the waveguide 1 by etching or nanoimprint technology. In some embodiments, the in-coupling grating 3 and the turning grating can also be formed on the waveguide 1.
[0111] In step S2, a medium material is coated on the out-coupling grating 2, so that at least part of the medium material fills the grooves 22 between the plurality of diffractive optical structures 21 in the out-coupling grating 2, and at least part of the medium material is coated on the side of the diffractive optical structures 21 in the out-coupling grating 2 away from the waveguide 1, and a medium film layer with a preset thickness is formed on the side of the diffractive optical structures 21 in the out-coupling grating 2 away from the waveguide 1.
[0112] Figure 15 A schematic diagram of the optical waveguide device provided by an embodiment of the present application in the process of coating the medium material is shown in FIG. 7. The medium material can be coated on the out-coupling grating 2 by a spraying process, for example, a spraying device 20 containing the medium material can be moved along a set direction, and the spraying device 20 can continuously spray the medium material on the out-coupling grating 2 during the movement. The spraying process can be used to coat the gratings in a specific area, for example, the medium material can be coated only on the out-coupling grating 2, and the in-coupling grating 3 and the turning grating 5 are not coated with the medium material. By using the spraying method, the gratings in any area on a wafer or other electronic device can be locally filled, which has great flexibility, is convenient to operate, and saves processing cost. Figure 15 In step S3, the medium material is solidified to form the medium layer 4. The medium material can be solidified by exposure or heating, so that the medium layer 4 formed by solidification has a certain structural strength.
[0113]
[0114] Therefore, by using the medium material coating process provided in the embodiment, the medium material such as photoresist can realize sufficient filling of the groove 22 between the diffractive optical structures 21 by the flowability of the medium material during coating, and a film layer with a certain thickness can be formed on the side of the out-coupling grating 2 away from the waveguide 1, and the surface on the side of the film layer away from the waveguide 1 is formed as a plane, and no recess will appear on the plane, so that the effect of the recess on the light leakage can be avoided, and the undesirable stray light can also be avoided, which is beneficial to improve the light efficiency and uniformity, and can ensure the final imaging quality.
[0115] Figure 16 The flowchart of the preparation method provided in another embodiment of the present application is shown in Figure 16 The present application also provides a preparation method, which can be used to prepare the optical waveguide device provided in any embodiment of the present application. The preparation method comprises the following steps:
[0116] Figure 17 The schematic diagram of the waveguide 1 on which a plurality of diffractive optical structures 21 are formed is shown in Figure 17 Step S10, a plurality of diffractive optical structures 21 are arranged on the waveguide 1, and at least part of the diffractive optical structures 21 constitute the in-coupling grating 3, and at least part of the diffractive optical structures 21 constitute the out-coupling grating 2. In some embodiments, a turning grating including a plurality of diffractive optical structures 21 can also be formed on the waveguide 1.
[0117] Figure 18 The schematic diagram of the in-coupling grating 3 and the out-coupling grating 2 on which the medium material 43 is coated is shown in Figure 18 Step S20, the medium material 43 is coated on the in-coupling grating 3 and the out-coupling grating 2.
[0118] The spin coating process can be used to coat the medium material 43 on a larger area of the waveguide 1, and the coated area can include the area where the in-coupling grating 3 and the out-coupling grating 2 are located, and the spin coating process can realize efficient coating of the medium material 43.
[0119] Step S30, the medium material in the in-coupling grating 3 or the out-coupling grating 2 is exposed.
[0120] The medium material in only one of the in-coupling grating 3 and the out-coupling grating 2 can be exposed, so that the exposed medium material can react chemically, and then the medium material in one of the in-coupling grating 3 and the out-coupling grating 2 can be dissolved by the developing solution.
[0121] It should be noted that the medium material can be photoresist, and the photoresist can include positive photoresist and negative photoresist, and the positive photoresist and the negative photoresist have different chemical reactions after being exposed.
[0122] In one embodiment, if the photoresist used for the dielectric layer 4 is a positive photoresist, it can be dissolved by the developer after exposure. Therefore, only the dielectric material at the coupling grating 3 can be exposed, while the dielectric material at the coupling grating 2 can remain unexposed. This allows the dielectric material at the coupling grating 3 to be removed by the developer, while the unexposed dielectric material at the coupling grating 2 will not be dissolved by the developer, thus forming a structurally stable dielectric layer 4. Furthermore, if the waveguide 1 has a folding grating, the dielectric material at the folding grating can also be exposed simultaneously with the dielectric material at the coupling grating 3, so that the dielectric material at both the coupling grating 3 and the folding grating can be removed simultaneously by the developer.
[0123] Figure 19 This is a schematic diagram of the dielectric material on waveguide 1 during exposure, as provided in the embodiments of this application. Figure 19 As shown, the light source 30 can be used to expose the dielectric material 43. If the photoresist used in the dielectric layer 4 is a positive photoresist, a light-shielding material or mask 40 can be placed on the light source 30 at a position corresponding to the output grating 2. The light-shielding material and mask 40 can prevent light transmission. When the light source 30 illuminates the dielectric material 43 at various locations above the waveguide 1, the light from the position on the light source 30 opposite to the light-shielding material or mask 40 will not illuminate the dielectric material at the output grating 2. The unshielded positions on the light source 30 can be opposite to the input grating 3, thus allowing the light source 30 to expose the dielectric material at the input grating 3.
[0124] Figure 20 This is a schematic diagram of the dielectric material at the coupling grating 3 provided in the embodiments of this application after exposure, as shown below. Figure 20 As shown, after exposure, the dielectric material 43 at the coupled grating 3 undergoes a chemical reaction, which allows the dielectric material 43 at the coupled grating 3 to dissolve in the developing solution, while the unexposed dielectric material at the coupled grating 2 can form a structurally stable dielectric layer 4.
[0125] In an embodiment, for the photoresist used for the medium layer 4 is a negative photoresist, after exposure, the negative photoresist can form a stable structure and cannot be dissolved by the developing solution; and the negative photoresist can be dissolved by the developing solution in the unexposed state. Therefore, only the medium material at the out-coupling grating 2 can be exposed, and the medium material at the in-coupling grating 3 is not exposed, so that the medium material at the in-coupling grating 3 which is not exposed can be removed by the developing solution, and the exposed medium material at the out-coupling grating 2 cannot be dissolved by the developing solution, and a stable medium layer 4 can be formed. In addition, if the waveguide 1 has a turning grating, the medium material at the turning grating can also not be exposed with the medium material at the in-coupling grating 3, so that the medium material at the in-coupling grating 3 and the turning grating can be removed by the developing solution at the same time.
[0126] In the embodiment, the medium material can be exposed by a light source. The light source can be provided with a light shielding material or a mask plate corresponding to the in-coupling grating 3. The light shielding material and the mask plate can prevent light from passing through. When the light source is used to irradiate the medium material at each position above the waveguide 1, the light at the position of the light source opposite to the light shielding material or the mask plate cannot irradiate the medium material at the in-coupling grating 3, and the position of the light source which is not shielded can be opposite to the out-coupling grating 2, so that the medium material at the out-coupling grating 2 can be exposed by the light source to solidify the medium material at the out-coupling grating 2 into a stable medium layer 4.
[0127] In step S40, the medium material in the in-coupling grating 3 is dissolved by the developing solution. Figure 21 A schematic diagram of the medium material at the in-coupling grating 3 after removal is provided in the embodiment of the present application, as shown in FIG. 4, after the medium material at the in-coupling grating 3 is removed by the developing solution, a waveguide device having a medium layer 4 only at the out-coupling grating 2 can be formed. Figure 21
[0128] Therefore, by using the medium material coating process provided in the embodiment, the medium material such as photoresist can realize sufficient filling of the groove 22 between the diffractive optical structures 21 by the flowability of the medium material itself in the coating process, and a film layer with a certain thickness can be formed on the side of the out-coupling grating 2 away from the waveguide 1, and the surface on the side of the film layer away from the waveguide 1 is formed as a plane, and no recess will appear on the plane, so that the effect of the recess on the light leakage can be avoided, and the stray light at the recess can also be avoided, which is conducive to improving the light efficiency and uniformity and ensuring the final imaging quality.
[0129] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Various modifications and changes can be made by those skilled in the art based on the spirit and principles of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.
Claims
1. An optical waveguide device, characterized by, The application relates to a waveguide and a coupling-out grating. The coupling-out grating is used for emitting light rays, and comprises a plurality of diffractive optical structures which are arranged in a slanting manner on the waveguide, and a groove is formed between two adjacent diffractive optical structures and the waveguide. A medium layer, at least part of the material of the medium layer is filled in the groove, at least part of the material of the medium layer is coated on the surface of the diffractive optical structure away from the waveguide, and the surface of the medium layer away from the waveguide is a plane; the refractive index of the medium layer is smaller than the refractive index of the coupling-out grating. The medium layer comprises a first layer and a second layer, the first layer is connected to the second layer, the first layer is arranged in all or at least part of the groove, and the first layer is attached to the inner wall of the groove.
2. The optical waveguide device of claim 1, wherein, The second layer is arranged on the side of the diffractive optical structure and the first layer away from the waveguide, and covers all or at least part of the diffractive optical structure and the first layer. The preset thickness of the second layer is H0, the actual thickness of the second layer is H1, the difference between the actual thickness H1 of the second layer and the preset thickness H0 of the second layer is AH, and the ratio of the difference AH to the preset thickness H0 is between -3% and 3%.
3. The optical waveguide device of claim 2, wherein, The ratio of the difference of the actual thickness at different positions of the second layer to the preset thickness of the second layer is between -3% and 3%.
4. The optical waveguide device of claim 2, wherein, The distance between the surface of the medium layer away from the waveguide and the surface of the diffractive optical structure away from the waveguide is less than 1 mu m.
5. The optical waveguide device of any of claims 1-4, wherein, At least part of the diffractive optical structure has different heights along the thickness direction of the waveguide, wherein the distance between the surface of the diffractive optical structure with the largest height away from the waveguide and the surface of the medium layer away from the waveguide is less than 1 mu m.
6. The optical waveguide device of claim 5, wherein, The flatness of the surface of the medium layer away from the waveguide is less than 15 nm.
7. The optical waveguide device of any of claims 1-6, wherein, The difference between the refractive index of the coupling-out grating and the refractive index of the medium layer is between 0.15 and 0.
25.
8. The optical waveguide device of any of claims 1-7, wherein, The material of the medium layer is photoresist or a mixture of photoresist and silicon dioxide.
9. The optical waveguide device of any of claims 1-8, wherein, The medium layer is integrally formed through a coating process.
10. The optical waveguide device of any of claims 1-9, wherein, The arrangement period of the plurality of diffractive optical structures is between 250 nm and 500 nm, the height of the diffractive optical structure is between 270 nm and 410 nm, the duty cycle of the diffractive optical structure is between 0.2 and 0.8, the included angle between the diffractive optical structure and the waveguide is between 20 degrees and 45 degrees, and the ratio of the width to the height of the diffractive optical structure ranges from 1:2 to 1:
10.
11. The optical waveguide device of any of claims 1-10, wherein, The application relates to a waveguide and a coupling-out grating.
12. A method of manufacturing the optical waveguide device according to any one of claims 1 to 11, characterized by, A plurality of diffractive optical structures are arranged on the waveguide to form a coupling-out grating. A medium material is coated on the coupling-out grating, at least part of the medium material is filled in the groove between the plurality of diffractive optical structures, at least part of the medium material is coated on the side of the diffractive optical structure away from the waveguide, and a medium film layer with a preset thickness is formed on the side of the diffractive optical structure away from the waveguide. The medium material is solidified to form a medium layer. The application relates to a waveguide and a coupling-out grating.
13. A method of manufacturing the optical waveguide device according to any one of claims 1 to 11, characterized by, A plurality of diffractive optical structures are arranged on the waveguide, so that at least part of the diffractive optical structures constitute an in-coupling grating and at least part of the diffractive optical structures constitute an out-coupling grating; A medium material is coated on the in-coupling grating and the out-coupling grating; The medium material in the in-coupling grating or the out-coupling grating is exposed; The medium material in the in-coupling grating is dissolved by using a developing solution.
14. The method of claim 13, wherein the method further comprises: The medium material is a positive photoresist; The exposure of the medium material in the in-coupling grating or the out-coupling grating specifically includes: A light shielding material or a mask plate is arranged on a light source at a position corresponding to the out-coupling grating; The medium material in the in-coupling grating is irradiated by using the light source.
15. The method of claim 13, wherein the method further comprises: The medium material is a negative photoresist; The exposure of the medium material in the in-coupling grating or the out-coupling grating specifically includes: A light shielding material or a mask plate is arranged on a light source at a position corresponding to the in-coupling grating; The medium material in the out-coupling grating is irradiated by using the light source.
16. An electronic device, characterized in that The optical waveguide device of any one of claims 1-11.
17. An electronic device, comprising: The electronic device of claim 16.