Grating structure and method for manufacturing the same

Abstract

The present disclosure provides a grating structure and a preparation method thereof, and belongs to the technical field of display. The grating structure of the present disclosure comprises a substrate and a first grating arranged on the substrate, wherein the first grating is a blazed grating, and the first grating comprises a plurality of first sub-structures arranged at intervals; wherein the first grating satisfies at least one of the following conditions: the refractive index of the material of the first grating is 1.1-2.0; the period of the first grating is 200-800 nm; the duty cycle of the first grating is 0.1-0.9; and the height of the first grating is 200-600 nm.

Description

TECHNICAL FIELD

[0001] The present disclosure belongs to the technical field of display, and particularly relates to a grating structure and a preparation method thereof. BACKGROUND

[0002] With the vigorous development of technologies such as Augmented Reality (AR) and Virtual Reality (VR) brought by the "Meta Universe craze", people have gradually paid extensive attention to these technologies, and these technologies are widely used in fields such as commodity advertising, mobile shopping, multi-screen interaction, location navigation and gaming. The Surface Relief Grating (SRG) diffractive optical waveguide scheme is considered to be the most potential mainstream AR optical waveguide lens preparation scheme in the future due to its easy mass production and excellent performance.

[0003] At present, the problems to be solved in the SRG diffractive optical waveguide technology mainly include improvement of Field of View (FOV) and grating diffraction efficiency. Common grating types include rectangular gratings, tilted gratings and blazed gratings, among which blazed gratings are widely concerned due to their excellent diffraction efficiency. Due to processing limitations, the research on blazed gratings still needs to be further deepened. SUMMARY

[0004] The present disclosure aims to at least solve one of the technical problems existing in the prior art, and provide a grating structure and a preparation method thereof.

[0005] In a first aspect, the present disclosure provides a grating structure, which comprises a substrate and a first grating disposed on the substrate, the first grating being a blazed grating, the first grating comprising a plurality of first sub-structures arranged at intervals; wherein the first grating satisfies at least one of the following conditions:

[0006] The refractive index of the material of the first grating is 1.1-2.0;

[0007] The period of the first grating is 200-800 nm;

[0008] The duty cycle of the first grating is 0.1-0.9;

[0009] The height of the first grating is 200-600 nm.

[0010] In some embodiments, the grating structure further comprises a second grating disposed on the side of the first grating close to the substrate; the second grating comprises a plurality of second sub-structures arranged at intervals, and the second sub-structures are arranged one by one corresponding to the first sub-structures.

[0011] In some embodiments, the second substructure includes a rectangular block.

[0012] In some embodiments, the material of the first grating and the material of the second grating are the same.

[0013] In some embodiments, the grating structure further includes a first film layer disposed on the side of the first grating away from the substrate; the refractive index of the material of the first film layer is not less than the refractive index of the material of the first grating.

[0014] In some embodiments, the refractive index of the material of the first film layer is 2.0 to 4.0.

[0015] In some embodiments, the material of the first film layer is titanium dioxide.

[0016] Secondly, this disclosure also provides a method for fabricating a grating structure, which is used to fabricate a grating structure as described in any of the above embodiments, the method for fabricating the grating structure comprising:

[0017] Provide a substrate;

[0018] A first grating is formed on the substrate; wherein the first grating is a blazed grating, the first grating includes a plurality of first substructures spaced apart, and the first grating satisfies at least one of the following conditions:

[0019] The refractive index of the material of the first grating is 1.1 to 2.0;

[0020] The period of the first grating is 200–800 nm;

[0021] The duty cycle of the first grating is 0.1 to 0.9;

[0022] The height of the first grating is 200–600 nm.

[0023] In some embodiments, forming the first grating on the substrate includes:

[0024] The first grating is formed on the substrate using a master template and a nanoimprint process.

[0025] In some embodiments, preparing the master template includes:

[0026] Provide an auxiliary substrate;

[0027] A second film layer is formed on the auxiliary substrate, and the second film layer is exposed, etched, and developed to prepare a main template having the shape of the first grating;

[0028] The shape of the main template is transferred to the soft template by nanoimprinting to form the mother template with a first hollow pattern, the first hollow pattern being complementary to the shape of the first grating;

[0029] In some embodiments, forming the first grating on the substrate includes:

[0030] A third film layer is formed on the substrate, and the first grating is prepared by exposure etching and development of the third film layer.

[0031] In some embodiments, the method for fabricating the grating structure further includes:

[0032] A second grating is formed on the substrate; wherein the second grating is located on the side of the first grating close to the substrate, and the second grating includes a plurality of second substructures spaced apart, the second substructures corresponding one-to-one with the first substructures.

[0033] In some embodiments, the second grating and the first grating are fabricated using a single process.

[0034] In some embodiments, the method for fabricating the grating structure further includes:

[0035] A first film layer is formed on the side of the first grating away from the substrate, wherein the refractive index of the material of the first film layer is not less than the refractive index of the material of the first grating. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of a grating structure provided in an embodiment of the present disclosure;

[0037] Figure 2 This is a schematic diagram of another grating structure provided in an embodiment of the present disclosure;

[0038] Figure 3 This is a schematic diagram of another grating structure provided in an embodiment of the present disclosure;

[0039] Figures 4a to 4e This is a schematic diagram illustrating the preparation of a master template for nanoimprinting in an embodiment of this disclosure;

[0040] Figures 4f to 4g for Figure 4d A schematic diagram illustrating the preparation of the soft template used;

[0041] Figures 5a to 5d This is a schematic diagram of the fabrication of a grating structure provided in an embodiment of the present disclosure;

[0042] Figure 5e for Figure 5c A schematic diagram of the mother template used;

[0043] Figures 6a to 6c This is a schematic diagram illustrating the fabrication of another grating structure provided in an embodiment of this disclosure;

[0044] Figures 7a to 7e This is a schematic diagram illustrating the fabrication of another grating structure provided in an embodiment of this disclosure;

[0045] Figure 7f for Figure 7c A schematic diagram of the mother template used;

[0046] Figures 8a to 8g This is a schematic diagram illustrating the preparation of another nanoimprint master template in an embodiment of this disclosure;

[0047] Figures 9a to 9c This is a schematic diagram illustrating the fabrication of another grating structure provided in an embodiment of this disclosure.

[0048] The reference numerals in the attached figures are as follows: substrate 01; first grating 10; first substructure 11; grating constant d; slit width a; opaque blocking width b; second grating 20; second substructure 21; first film layer 30; third film layer 40; master template 02; auxiliary substrate 03; second film layer 50; main template 04; soft template 05; first hollow pattern 06; fourth film layer 60. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. The components of the embodiments of this disclosure described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this disclosure provided in the accompanying drawings is not intended to limit the scope of the claimed disclosure, but merely represents selected embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without inventive effort are within the scope of protection of this disclosure.

[0050] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an,” “a,” or “the,” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “including,” “comprising,” or “containing,” and similar terms mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. The terms “connected,” “linked,” or similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms “upper,” “lower,” “left,” and “right,” etc., are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described objects changes.

[0051] In this disclosure, "multiple or several" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0052] Optical waveguide schemes use planar waveguides as the light transmission medium and gratings as waveguide coupling devices to achieve light propagation. Multi-slit gratings concentrate most of the light energy at the zero order and cannot separate various wavelengths, while practical applications of gratings require concentrating as much light energy as possible at a specific order. Therefore, it is necessary to design the slot shape of the diffraction grating so that most of the light energy is concentrated at the designed diffraction order. When probed from the designed direction, the spectral intensity is maximum; this phenomenon is called blaze, and such gratings are called blazed gratings. Blaze greatly improves the diffraction efficiency of the grating, and when used as a coupling device in a grating waveguide, it can improve the coupling efficiency of the grating waveguide. In existing technologies, the efficiency of gratings still needs improvement.

[0053] Therefore, this disclosure provides a grating structure and a method for fabricating the same.

[0054] It should be noted that grating diffraction has 0th order, ±1st order, etc., and different orders have different angles and different energies. By setting the parameters of the grating, most of the light energy can be concentrated at a certain angle, thus achieving control over the direction of the light. In this disclosure, the ±1st order will be described.

[0055] In a first aspect, embodiments of this disclosure provide a grating structure that, through the design of the grating structure, achieves higher diffraction efficiency while simplifying the manufacturing process and reducing production costs.

[0056] Specifically, Figure 1 This is a schematic diagram of a grating structure provided in an embodiment of the present disclosure, such as... Figure 1 As shown, the grating structure includes a substrate 01 and a first grating 10 disposed on the substrate 01. The first grating 10 is a blazed grating and includes a plurality of first substructures 11 spaced apart. The first grating 10 satisfies at least one of the following conditions: the refractive index of the material of the first grating 10 is 1.1 to 2.0; the period of the first grating 10 is 200 to 800 nm; the duty cycle of the first grating 10 is 0.1 to 0.9; and the height of the first grating 10 is 200 to 600 nm.

[0057] It should be noted that when the grating is etched with a sawtooth-shaped groove cross-section, the light energy of the grating is concentrated in a predetermined direction, i.e., a certain spectral order. When detected from this direction, the intensity of the spectrum is the greatest; this phenomenon is called blaze, and such a grating is called a blaze grating. In such a blaze grating, the groove surface that performs diffraction is a smooth plane, and it forms an angle with the surface of the grating, called the blaze angle. In the embodiments of this disclosure, the first grating 10 is a blaze grating and is designed to improve the +1st order diffraction efficiency. Therefore, the blaze angle of the first grating 10 is not specifically limited, as long as the grating energy can be concentrated in the +1st order.

[0058] In this embodiment, the refractive index of the material of the first grating 10 is 1.1–2.0; the period of the first grating 10 is 200–800 nm; the duty cycle of the first grating 10 is 0.1–0.9; and the height of the first grating 10 is 200–600 nm. This embodiment achieves higher diffraction efficiency by setting the refractive index, period, duty cycle, and height of the material of the first grating 10. The period, duty cycle, and height of the first grating 10 in this embodiment are described in detail below: The period of the first grating 10, i.e., the grating constant d, is the sum of the slit width a and the opaque blocking width b between the slits; the duty cycle of the first grating 10 is the ratio of the slit width a to the grating period; the height of the first grating 10 is the height of the first grating 10 along the thickness direction of the substrate 01; the material of the first grating 10 can be an organic material or an inorganic material, as long as the refractive index is 1.1–2.0. In this embodiment of the disclosure, by setting the refractive index, period, duty cycle and height of the material of the first grating 10 of the grating structure, the grating structure can have a higher diffraction efficiency. As long as the setting of the grating structure meets any of the above conditions, the diffraction efficiency of the grating structure can be improved.

[0059] like Figure 1 As shown, taking the first grating 10 as an example, it includes five first substructures 11 spaced apart; wherein, the first substructure 11 is triangular. It should be noted that, for ease of description and understanding, the first substructure 11 in this embodiment is a right-angled triangle, that is, one side of the first substructure 11 is perpendicular to the substrate 01. However, in actual production, the first substructure 11 can also be an acute-angled triangle, and the three sides of the first substructure 11 can also be arc-shaped; in addition, this disclosure does not limit the number of first substructures 11.

[0060] In some embodiments, the material of the first grating 10 can be an inorganic material or an organic material. For example, the material of the first grating 10 can be an optical resin, thereby improving the diffraction efficiency of the first grating 10 for light.

[0061] It should be noted that the material of the substrate 01 is not limited in the embodiments of this disclosure. For example, the substrate 01 is a glass substrate. For ease of description, the following description will use the example of the substrate 01 being a glass substrate.

[0062] In some embodiments, Figure 2 This is a schematic diagram of another grating structure provided in an embodiment of the present disclosure, as shown below. Figure 2 As shown, the grating structure includes not only the structure described above, but also a second grating 20 disposed on the side of the first grating 10 near the substrate 01; the second grating 20 includes a plurality of second substructures 21 disposed at intervals, and the second substructures 21 are disposed in a one-to-one correspondence with the first substructures 11.

[0063] For example: Figure 2 As shown, the second grating 20 includes five second substructures 21 spaced apart, and one second substructure 21 is correspondingly arranged with one first substructure 11, thereby effectively improving the diffraction efficiency of the grating structure; in addition, this disclosure does not limit the number and shape of the second substructures 21.

[0064] In some embodiments, such as Figure 2 As shown, the second substructure 21 includes a rectangular block. The second substructure 21 is set as a rectangular block, that is, the second grating 20 is a rectangular grating. This setting allows the grating structure to not only have the characteristics of a rectangular grating structure, such as simplicity, ease of processing, high degree of freedom and good uniformity, but also the characteristics of a blazed grating, such as high diffraction efficiency, thereby further improving the diffraction efficiency and integration of the grating structure.

[0065] In some embodiments, the first grating 10 is made of the same material as the second grating 20. In the embodiments of this disclosure, the first grating 10 and the second grating 20 may be made of the same material or different materials; when the first grating 10 and the second grating 20 are made of the same material, the first grating 10 and the second grating 20 may be an integrally formed structure.

[0066] It should be noted that, in this embodiment, the grating period and duty cycle of the second grating 20 are consistent with those of the first grating 10, thereby ensuring good uniformity of the grating structure and further improving the diffraction efficiency and integration of the grating structure.

[0067] In some embodiments, Figure 3 This is a schematic diagram of another grating structure provided in an embodiment of the present disclosure, as shown below. Figure 3 As shown, the grating structure includes not only the structure described above, but also a first film layer 30 disposed on the side of the first grating 10 away from the substrate 01; the refractive index of the material of the first film layer 30 is not less than the refractive index of the material of the first grating 10. This arrangement can make the grating structure have higher diffraction efficiency due to the addition of the high refractive index film layer without affecting the refractive index of the original grating structure.

[0068] In some embodiments, the refractive index of the material of the first film layer 30 is 2.0 to 4.0. Since the refractive index of the material of the first grating 10 is 1.1 to 2.0, setting the refractive index of the material of the first film layer 30 to 2.0 to 4.0 can make the grating structure have higher diffraction efficiency without affecting the refractive index of the original grating structure.

[0069] In some embodiments, the material of the first film layer 30 is titanium dioxide. The material of the first film layer 30 includes, but is not limited to, titanium dioxide. For example, the material of the first film layer 30 can be titanium pentoxide, titanium trioxide, cerium oxide, titanium monoxide, or tantalum pentoxide, so that the high refractive index film layer has a reasonable refractive index.

[0070] Secondly, based on the same inventive concept, this disclosure also provides a method for fabricating the above-mentioned grating structure, specifically including steps S11 to S12:

[0071] S11, Provide a substrate 01.

[0072] S12. A first grating 10 is formed on the substrate 01.

[0073] The first grating 10 is a blazed grating, which includes a plurality of first substructures 11 spaced apart. The first grating 10 satisfies at least one of the following conditions: the refractive index of the material of the first grating 10 is 1.1 to 2.0; the period of the first grating 10 is 200 to 800 nm; the duty cycle of the first grating 10 is 0.1 to 0.9; and the height of the first grating 10 is 200 to 600 nm.

[0074] Specifically, the substrate 01 can be a glass substrate, and the material of the first grating 10 can be an organic material or an inorganic material, as long as the refractive index is between 1.1 and 2.0. The period of the first grating 10, i.e. the grating constant d, is the sum of the slit width a and the opaque blocking width b between the slits. The duty cycle of the first grating 10 is the ratio of the slit width a to the grating period.

[0075] In this embodiment of the disclosure, by setting the refractive index, period, duty cycle and height of the material of the first grating 10 of the grating structure, the grating structure can have higher diffraction efficiency.

[0076] In some embodiments, the method for forming the first grating 10 on the substrate 01 may employ a master template 02 and form the first grating 10 on the substrate 01 using a nanoimprint lithography process. Figures 5a to 5d This is a schematic diagram illustrating the fabrication of a grating structure according to an embodiment of this disclosure. Figure 5e for Figure 5c A schematic diagram of the mother template used; such as Figures 5a to 5e As shown, step S12 specifically includes S12-1-1 to S12-1-3:

[0077] S12-1-1, as follows Figure 5a As shown, a substrate 01 is provided;

[0078] The substrate 01 can be a glass substrate.

[0079] S12-1-2, as shown Figure 5b As shown, a third film layer 40 is formed on the substrate 01;

[0080] The third film layer 40 can be deposited on the substrate 01 by spin coating or other methods, wherein the material of the third film layer 40 can be an optical resin.

[0081] S12-1-3, as follows Figures 5c to 5e As shown, the third film layer 40 is nanoimprinted with the mother template 02, and finally demolded to form the first grating 10.

[0082] Nanoimprint lithography offers advantages such as ultra-high resolution, easy mass production, low cost, and high consistency. In this embodiment, a first grating 10 is formed on a substrate 01 using nanoimprint lithography, thereby achieving very high resolution. Furthermore, the master template 02 prepared by nanoimprint lithography can be reused repeatedly, significantly reducing processing costs and effectively shortening processing time.

[0083] In some embodiments, Figures 4a to 4e This is a schematic diagram illustrating the preparation of a master template for nanoimprinting according to an embodiment of this disclosure. Figures 4f to 4g for Figure 4d A schematic diagram of the soft template preparation used; as shown. Figures 4a to 4g As shown, the specific steps for preparing the master template 02 include S12-1-3-1 to S12-1-3-3:

[0084] S12-1-3-1, as follows Figure 4a As shown, an auxiliary substrate 03 is provided;

[0085] Among them, the auxiliary substrate 03 can be a glass substrate.

[0086] S12-1-3-2, as shown Figure 4b As shown, a second film layer 50 is formed on the auxiliary substrate 03, such as... Figure 4c As shown, the second film layer 50 is exposed, etched, and developed to prepare a main template 04 having the shape of the first grating 10.

[0087] In some examples, step S12-1-3-2 may include: depositing a second film layer 50 on an auxiliary substrate 03 by spin coating or other methods, wherein the second film layer 50 may be a photoresist layer; when exposing, etching and developing the second film layer 50, electron beam lithography (EBL) etching and development methods may be used, so that the main template 04 pattern with the shape of the first grating 10 prepared in this way has high resolution and low production cost, which can save a lot of money in terms of cost.

[0088] S12-1-3-3, as follows Figures 4d to 4e , Figure 4g As shown, the shape of the main template 04 is transferred to the soft template 05 by nanoimprinting. After demolding, a mother template 02 with a first hollow pattern 06 is formed. The shape of the first hollow pattern 06 is complementary to that of the first grating 10.

[0089] Among them, such as Figure 4f and Figure 4gAs shown, the soft template 05 is formed by depositing a fourth film layer 60 on another auxiliary substrate 03. The auxiliary substrate 03 can also be a glass substrate, and the fourth film layer 60 can be a photoresist layer, for example, the material of the fourth film layer 60 is polydimethylsiloxane (PDMS) or its derivatives. The soft template 05 prepared in this way is not only suitable for fabricating high-precision, high-resolution patterns, but also has a simple process, greatly saving manufacturing costs. By performing nanoimprinting, the shape of the main template 04 is transferred to the soft template 05 to form a master template 02 with a first hollow pattern 06. The first hollow pattern 06 is complementary to the shape of the first grating 10. The complementarity of the first hollow pattern 06 and the first grating 10 means that they match each other geometrically and form a complete planar structure when spliced ​​together. The first grating 10 can be fabricated using the final master template 02 with the first hollow pattern 06 through nanoimprinting, resulting in a first grating 10 with high precision and high diffraction efficiency.

[0090] In some embodiments, the method for forming the first grating 10 on the substrate 01 described above can employ an etching process to form the first grating 10 on the substrate 01. Figures 6a to 6c This is a schematic diagram illustrating the fabrication of another grating structure provided in an embodiment of this disclosure, as shown below. Figures 6a to 6c As shown, step S12 specifically includes S12-2-1 to S12-2-3:

[0091] S12-2-1, as follows Figure 6a As shown, a substrate 01 is provided.

[0092] The substrate 01 can be a glass substrate.

[0093] S12-2-2, as follows Figure 6b As shown, a third film layer 40 is formed on the substrate 01;

[0094] In some examples, step S12-2-2 may include: depositing a third film layer 40 on the substrate 01 by means of spin coating or the like, wherein the material of the third film layer 40 includes, but is not limited to, optical resin.

[0095] S12-2-3, as follows Figure 6c As shown, the third film layer 40 is exposed, etched, and developed to prepare the first grating 10.

[0096] In this embodiment of the present disclosure, a third film layer 40 is formed on a substrate 01, and then the third film layer 40 is exposed, etched, and developed to prepare a first grating 10. This preparation method is simple, easy to operate, and can improve the diffraction efficiency of the grating structure.

[0097] In some embodiments, the grating structure includes not only the structure described above, but also a second grating 20; the method for fabricating such a grating structure includes not only the step of forming the first grating 10, but also the step of forming the second grating 20.

[0098] It should be noted that when fabricating grating structures using nanoimprint lithography, in grating structures including a first grating 10 and a second grating 20, where the first grating 10 and the second grating 20 are integrally formed, the main difference between this type of grating structure and the fabrication method of a grating structure excluding the second grating 20 lies in the different master template 02. When fabricating grating structures using etching, the main difference between the two fabrication methods lies in the different etching patterns. These two cases will be explained in detail below.

[0099] Figure 7d This is a schematic diagram of another grating structure provided in an embodiment of the present disclosure, as shown below. Figure 7d As shown, the grating structure includes a first grating 10 and a second grating 20, and the second grating 20 and the first grating 10 are sequentially stacked on the substrate 01. The specific steps for fabricating the above grating structure include S11' to S12':

[0100] S11', Provide a substrate 01;

[0101] S12', A first grating 10 and a second grating 20 are formed on the substrate 01.

[0102] The first grating 10 is a blazed grating, and includes a plurality of first substructures 11 spaced apart. The first grating 10 satisfies at least one of the following conditions: the refractive index of the material of the first grating 10 is 1.1 to 2.0; the period of the first grating 10 is 200 to 800 nm; the duty cycle of the first grating 10 is 0.1 to 0.9; and the height of the first grating 10 is 200 to 600 nm. The second grating 20 is located on the side of the first grating 10 closest to the substrate 01, and includes a plurality of second substructures 21 spaced apart, with each second substructure 21 corresponding to one of the first substructures 11.

[0103] like Figure 7dAs shown, the second grating 20 includes five second substructures 21 spaced apart, with one second substructure 21 corresponding to one first substructure 11, thereby effectively improving the diffraction efficiency of the grating structure. The second substructure 21 can be a rectangular block, that is, the second grating 20 is a rectangular grating. This arrangement allows the grating structure to not only have the characteristics of a rectangular grating structure—simple, easy to process, high degree of freedom, and good uniformity—but also the characteristics of a blazed grating—high diffraction efficiency, thereby further improving the diffraction efficiency and integration of the grating structure. In this embodiment, the first grating 10 and the second grating 20 can be made of the same material or different materials. In addition, this disclosure does not limit the number and shape of the second substructures 21.

[0104] It should be noted that, in this embodiment, the grating period and duty cycle of the second grating 20 are consistent with those of the first grating 10, thereby ensuring good uniformity of the grating structure and further improving the diffraction efficiency and integration of the grating structure.

[0105] In some embodiments, the method for forming the first grating 10 and the second grating 20 on the substrate 01 can employ a master template 02 and form the first grating 10 and the second grating 20 on the substrate 01 using a nanoimprint lithography process. Figures 7a to 7e This is a schematic diagram illustrating the fabrication of another grating structure provided in an embodiment of this disclosure. Figure 7f for Figure 7c A schematic diagram of the mother template used; such as Figures 7a to 7d , Figure 7f As shown, step S12' specifically includes S12'-1-1 to S12'-1-3:

[0106] S12'-1-1, as shown Figure 7a As shown, a substrate 01 is provided;

[0107] The substrate 01 can be a glass substrate.

[0108] S12'-1-2, as shown Figure 7b As shown, a third film layer 40 is formed on the substrate 01;

[0109] The third film layer 40 can be deposited on the substrate 01 by spin coating or other methods, wherein the material of the third film layer 40 can be an optical resin.

[0110] S12'-1-3, as shown Figure 7f , 7c and Figure 7d As shown, the third film layer 40 is nanoimprinted with the mother template 02, and after demolding, the first grating 10 and the second grating 20 are formed.

[0111] Nanoimprint lithography offers advantages such as ultra-high resolution, easy mass production, low cost, and high consistency. In this embodiment, a first grating 10 and a second grating 20 are formed on a substrate 01 using nanoimprint lithography, thereby achieving very high resolution. Furthermore, the master template 02 prepared by nanoimprint lithography can be reused repeatedly, significantly reducing processing costs and effectively shortening processing time.

[0112] In some embodiments, Figures 8a to 8g This is a schematic diagram illustrating the preparation of another nanoimprint master template in an embodiment of this disclosure, as shown below. Figures 8a to 8g As shown, the specific steps for preparing the master template 02 include S12'-1-3-1 to S12'-1-3-3:

[0113] S12'-1-3-1、as Figure 8a As shown, an auxiliary substrate 03 is provided;

[0114] Among them, the auxiliary substrate 03 can be a glass substrate.

[0115] S12'-1-3-2, as shown Figure 8b As shown, a second film layer 50 is formed on the auxiliary substrate 03, such as... Figure 8c As shown, the second film layer 50 is exposed, etched, and developed to prepare a main template 04 having the shape of the first grating 10 and the second grating 20.

[0116] In some examples, step S12'-1-3-2 may include: depositing a second film layer 50 on an auxiliary substrate 03 by spin coating or other methods, wherein the second film layer 50 may be a photoresist layer; when exposing, etching and developing the second film layer 50, an EBL etching and developing method may be used, so that the main template 04 pattern with the shape of the first grating 10 and the second grating 20 prepared in this way has high resolution and low production cost, which can save a lot of money in terms of cost.

[0117] S12'-1-3-3, as shown Figure 8d and Figure 8e As shown, the shape of the main template 04 is transferred to the soft template 05 by nanoimprinting. After demolding, a mother template 02 with a first hollow pattern 06 is formed. The first hollow pattern 06 is complementary to the shape of the first grating 10 and the second grating 20.

[0118] Among them, such as Figure 8f and Figure 8gAs shown, the soft template 05 is prepared by depositing a fourth film layer 60 on another auxiliary substrate 03; wherein, the auxiliary substrate 03 can also be a glass substrate, and the fourth film layer 60 can be a photoresist layer, for example, the material of the fourth film layer 60 is PDMS and its derivatives. The soft template 05 prepared in this way is not only suitable for making high-precision, high-resolution patterns, but also has a simple process, which greatly saves manufacturing costs. By performing a molding process using nanoimprinting, the shape of the main template 04 is transferred to the soft template 05 to form a master template 02 with a first hollow pattern 06. The first hollow pattern 06 is complementary to the shape of the first grating 10 and the second grating 20. When the first grating 10 and the second grating 20 are stacked, they form a trapezoidal grating shape. The complementarity between the first hollow pattern 06 and the first grating 10 and the second grating 20 means that the first hollow pattern 06 and the trapezoidal combined grating are geometrically matched and form a complete planar structure when spliced ​​together. The first grating 10 and the second grating 20 can be prepared by using a nanoimprint process through a master template 02 with a first hollow pattern 06. The first grating 10 and the second grating 20 prepared in this way have high precision and high diffraction efficiency.

[0119] In some embodiments, the method for forming the first grating 10 and the second grating 20 on the substrate 01 can employ an etching process to form the first grating 10 and the second grating 20 on the substrate 01. Figures 9a to 9c This is a schematic diagram illustrating the fabrication of another grating structure provided in an embodiment of this disclosure, as shown below. Figures 9a to 9c As shown, step S12' specifically includes S12'-2-1 to S12'-2-3:

[0120] S12'-2-1, as follows Figure 9a As shown, a substrate 01 is provided.

[0121] The substrate 01 can be a glass substrate.

[0122] S12'-2-2, as shown Figure 9b As shown, a third film layer 40 is formed on the substrate 01;

[0123] In some examples, step S12'-2-2 may include: depositing a third film layer 40 on the substrate 01 by means of spin coating or the like, wherein the material of the third film layer 40 includes, but is not limited to, optical resin.

[0124] S12'-2-3, as shown Figure 9c As shown, the third film layer 40 is exposed, etched, and developed to prepare the first grating 10 and the second grating 20.

[0125] In this embodiment of the disclosure, a third film layer 40 is formed on a substrate 01, and then the third film layer 40 is exposed, etched, and developed to prepare a first grating 10 and a second grating 20. This preparation method is simple, easy to operate, and can improve the diffraction efficiency of the grating structure.

[0126] In some embodiments, the second grating 20 and the first grating 10 are fabricated in a single process. When the second grating 20 and the first grating 10 are fabricated in a single process, for example, both the second grating 20 and the first grating 10 are fabricated using a nanoimprinting process; that is, when fabricating the master template 02 for nanoimprinting, a master template 04 with the shapes of the first grating 10 and the second grating 20 is simultaneously fabricated, thereby subsequently fabricating a first perforated pattern 06 complementary to the shapes of the first grating 10 and the second grating 20 for use in the subsequent fabrication of the grating structure. Similarly, when both the second grating 20 and the first grating 10 are formed on the substrate 01 using an etching process, the third film layer 40 is exposed, etched, and developed to fabricate the first grating 10 and the second grating 20, which will not be elaborated further here.

[0127] In some embodiments, the grating structure may include not only the structure described above, but also a third grating; the method for fabricating such a grating structure includes not only the steps of forming the first grating 10 and the second grating 20, but also the step of forming the third grating. In this embodiment, the number of layers in the grating structure is not limited, as long as any one of the above-described conditions for setting the refractive index, period, duty cycle, and height of the grating material is met, the effect of improving the diffraction efficiency of the grating structure can be achieved.

[0128] In some embodiments, such as Figure 7e As shown, the fabrication method of the grating structure includes not only the above steps, but also S13:

[0129] S13. A first film layer 30 is formed on the side of the first grating 10 away from the substrate 01, and the refractive index of the material of the first film layer 30 is not less than the refractive index of the material of the first grating 10.

[0130] The methods for forming the first film layer 30 on the side of the first grating 10 away from the substrate 01 include, but are not limited to, plasma-enhanced chemical vapor deposition (PECVD) and film deposition by using a mask to block the grating area.

[0131] The refractive index of the material of the first film layer 30 is not less than the refractive index of the material of the first grating 10. This arrangement allows the grating structure to have higher diffraction efficiency due to the addition of a high-refractive-index film layer without affecting the original refractive index of the grating structure. The material of the first film layer 30 includes, but is not limited to, titanium dioxide. For example, the material of the first film layer 30 can be titanium pentoxide, titanium trioxide, cerium oxide, titanium monoxide, or tantalum pentoxide, so that the high-refractive-index film layer has a reasonable refractive index.

[0132] It should be noted that the grating structure disclosed herein can be used not only as an input grating but also as an output grating. When used as an input grating, the grating structure disclosed herein has high input diffraction efficiency and is easy to fabricate and integrate. When used as an output grating, the grating structure disclosed herein has good FOV uniformity, can achieve brightness uniformity in the output region, and can be applied in the AR field.

[0133] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A grating structure, comprising a substrate substrate, and a first grating disposed on the substrate substrate, the first grating being a blazed grating, the first grating comprising a plurality of first sub-structures arranged at intervals; the first sub-structure being a right-angled triangle; wherein, The first grating satisfies at least one of the following conditions: The refractive index of the material of the first grating is 1.1-2.0; The period of the first grating is 200-800 nm; The duty cycle of the first grating is 0.1-0.9; The height of the first grating is 200-600 nm; The grating structure further comprises a second grating arranged on the side of the first grating close to the substrate substrate; the second grating and the first grating are sequentially stacked on the substrate substrate; The period and duty cycle of the second grating are consistent with those of the first grating; the second grating comprises a plurality of second substructures arranged at intervals, the second substructure comprises a rectangular block; the second substructure is arranged one by one corresponding to the first substructure; the slits of the second grating are arranged corresponding to the slits of the first grating, and for the corresponding arrangement of the slits of the second grating and the slits of the first grating, they communicate with each other; The material of the first grating and the material of the second grating are the same, and the first grating and the second grating are an integral structure.

2. The grating structure of claim 1, wherein, The grating structure further comprises a first film layer arranged on the side of the first grating away from the substrate substrate; the refractive index of the material of the first film layer is not less than the refractive index of the material of the first grating.

3. The grating structure of claim 2, wherein, The refractive index of the material of the first film layer is 2.0-4.

0.

4. The grating structure of claim 3, wherein, The material of the first film layer is titanium dioxide.

5. A method of fabricating a grating structure, wherein, The grating structure is the grating structure of any one of claims 1-4, and the preparation method comprises: providing a substrate substrate; forming a first grating on the substrate substrate; wherein the first grating is a blazed grating, the first grating comprises a plurality of first substructures arranged at intervals, and the first grating satisfies at least one of the following conditions: The refractive index of the material of the first grating is 1.1-2.0; The period of the first grating is 200-800 nm; The duty cycle of the first grating is 0.1-0.9; The height of the first grating is 200-600 nm.

6. The method of fabricating a grating structure according to claim 5, wherein, The first grating is formed on the substrate substrate, comprising: using a master template to form the first grating on the substrate substrate by a nanoimprint process.

7. The method of fabricating a grating structure according to claim 6, wherein, The preparation of the master template comprises: providing an auxiliary substrate; forming a second film layer on the auxiliary substrate, and exposing, etching and developing the second film layer to prepare a master template having the shape of the first grating; forming the master template having a first hollow pattern by nanoimprinting, which is complementary to the shape of the first grating.

8. The method of fabricating a grating structure according to claim 5, wherein, The first grating is formed on the substrate substrate, comprising: forming a third film layer on the substrate substrate, and exposing, etching and developing the third film layer to prepare the first grating.

9. The method of fabricating a grating structure according to claim 5, wherein, The preparation method of the grating structure further comprises: forming a second grating on the substrate substrate; wherein the second grating is located on the side of the first grating close to the substrate substrate, and the second grating comprises a plurality of second substructures arranged at intervals, and the second substructure is arranged one by one corresponding to the first substructure.

10. The method of fabricating a grating structure according to claim 9, wherein, The second grating and the first grating are prepared by one process.

11. The method of fabricating a grating structure according to any one of claims 5-10, wherein, The method for preparing the grating structure further comprises: A first film layer is formed on the side of the first grating away from the substrate, and the refractive index of the material of the first film layer is not less than the refractive index of the material of the first grating.

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