Anti-reflection film and super lens

Abstract

The utility model provides an anti-reflection film and a super lens, and the anti-reflection film comprises anti-reflection structures which are arranged in an array, and the anti-reflection structures are sub-wavelength structures; the filling structure is arranged between the anti-reflection structures; the antireflection film is used for the super lens, and the super lens comprises a substrate and micro-nano structures which are arranged on the substrate in an array mode. The antireflection film is arranged on a target interface; the media on the two sides of the target interface at least comprise the micro-nano structure or the substrate. According to the antireflection film provided by the invention, the light transmittance of the super lens is more ideal.

Description

Technical Field

[0001] The present application relates to the field of super lenses, and in particular to an anti-reflection film and a super lens. Background Art

[0002] When light travels from one medium to another, it will pass through the interface between the media; however, in addition to passing through the interface, light will usually be reflected at the interface. Therefore, if the difference caused by the absorption of light in the medium is not taken into account, the greater the reflectivity of light at the interface, the smaller the transmittance.

[0003] In many applications in the field of metalens, the light transmittance of the metalens is often required to be as large as possible. Therefore, in the related art, an anti-reflection film is provided in the metalens to reduce the light reflectivity and thus improve the light transmittance. However, the anti-reflection film provided by the related art is often difficult to fully improve the light transmittance of the metalens, which results in the light transmittance of the metalens being less than ideal. Utility Model Content

[0004] One purpose of the present application is to provide an anti-reflection film and a super lens. The anti-reflection film provided in the present application can make the light transmittance of the super lens more ideal.

[0005] According to one aspect of an embodiment of the present application, an antireflection film is disclosed, the antireflection film comprising: antireflection structures arranged in an array, the antireflection structures being sub-wavelength structures; a filling structure disposed between the antireflection structures;

[0006] Among them, the anti-reflection film is used for a superlens, and the superlens includes a substrate and an array-arranged micro-nano structure arranged on the substrate; the anti-reflection film is arranged at a target interface; and the media on both sides of the target interface at least contain the micro-nano structure or the substrate.

[0007] In an exemplary embodiment of the present application, the heights of all the anti-reflection structures in the same layer are kept consistent.

[0008] In an exemplary embodiment of the present application, the media on both sides of the target interface are respectively a first side medium and a second side medium; the target interface includes at least two sub-regions, and the anti-reflection structures in the same sub-region have the same size; the square value of the equivalent refractive index of the anti-reflection film in each sub-region matches the product of the equivalent refractive index of the first side medium corresponding to the same sub-region and the equivalent refractive index of the second side medium corresponding to the same sub-region.

[0009] In an exemplary embodiment of the present application, when at least three anti-reflection structures are included in the same sub-region, the anti-reflection structures in the same sub-region are periodically arranged in an array.

[0010] In an exemplary embodiment of the present application, among the media on both sides of the target interface, at least one side of the media includes the micro-nano structure.

[0011] In an exemplary embodiment of the present application, each sub-region of the target interface includes an anti-reflection structure group, and the anti-reflection structure group includes at least one anti-reflection structure; the anti-reflection structure group in each sub-region is matched one-to-one with the micro-nano structure corresponding to the same sub-region.

[0012] In an exemplary embodiment of the present application, in a sub-region corresponding to at least two of the micro-nano structures, the distance between the anti-reflection structure groups is consistent with the distance between the matching micro-nano structures.

[0013] In an exemplary embodiment of the present application, the size fluctuation amplitude of the micro-nanostructure corresponding to the same sub-region is smaller than a preset size threshold.

[0014] In an exemplary embodiment of the present application, a vertical projection of the micro-nano structure corresponding to the same sub-region on the corresponding sub-region completely covers the anti-reflection structure in the corresponding sub-region.

[0015] In an exemplary embodiment of the present application, a vertical projection of the micro-nano structure corresponding to the same sub-region on the corresponding sub-region is located outside the anti-reflection structure in the corresponding sub-region.

[0016] In an exemplary embodiment of the present application, a vertical projection of the micro-nano structure corresponding to the same sub-region on the corresponding sub-region and the anti-reflection structure in the corresponding sub-region partially overlap with each other.

[0017] In an exemplary embodiment of the present application, of the media on both sides of the target interface, the medium on one side is the substrate, and the medium on the other side is air.

[0018] According to one aspect of an embodiment of the present application, a metalens is disclosed, wherein the metalens is provided with an anti-reflection film provided by any one of the above embodiments.

[0019] The anti-reflection film provided in the embodiment of the present application has an equivalent refractive index that can be adjusted in a way that is no longer limited to the type of material; the equivalent refractive index of the anti-reflection film can also be adjusted by adjusting the position distribution and size of the anti-reflection structure, so that the equivalent refractive index of the anti-reflection film can be adjusted more finely. Therefore, the actual equivalent refractive index of the anti-reflection film provided in the present application can more easily and accurately match the target equivalent refractive index that needs to be met, thereby making the light transmittance of the metalens more ideal.

[0020] Other features and advantages of the present application will become apparent from the following detailed description, or may be learned in part by the practice of the present application.

[0021] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and other objects, features and advantages of the present application will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings.

[0023] Figure 1 The figure shows the relative position of the target interface and the media on both sides thereof when no anti-reflection film is provided.

[0024] Figure 2 A schematic diagram showing the relative positions of the target interface and the media on both sides thereof when the anti-reflection film provided by the present application is provided in one embodiment of the present application.

[0025] Figure 3 A schematic structural diagram of a super lens is shown.

[0026] Figure 4 A schematic diagram of the structure when an anti-reflection film is provided on a superlens in one embodiment of the present application is shown.

[0027] Figure 5 A schematic diagram of the structure when an anti-reflection film is provided on a superlens in one embodiment of the present application is shown.

[0028] Figure 6 A schematic diagram of the structure when an anti-reflection film is provided on a superlens in one embodiment of the present application is shown.

[0029] Figure 7 A top view of a sub-region in a target interface in an embodiment of the present application is shown.

[0030] Figure 8 A top view of a sub-region in a target interface in an embodiment of the present application is shown.

[0031] Fig. 9 A schematic diagram of the structure of a metalens to be provided with an anti-reflection film in one embodiment of the present application is shown.

[0032] Fig.10 A top view of a sub-region in a target interface in an embodiment of the present application is shown.

[0033] Fig.11 A top view of a sub-region in a target interface in an embodiment of the present application is shown.

[0034] Fig.12 A top view of a sub-region in a target interface in an embodiment of the present application is shown.

[0035] Reference numerals:

[0036] P-target interface; M1-first side medium of target interface; M2-second side medium of target interface; 1-anti-reflection film; 10-anti-reflection structure group; 11-anti-reflection structure; 12-filling structure between anti-reflection structures; 20-substrate of superlens; 21-micro-nano structure of superlens; 22-spacer structure between micro-nano structures. DETAILED DESCRIPTION

[0037] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these example embodiments are provided so that the description of the present application will be more comprehensive and complete and the concepts of the example embodiments will be fully conveyed to those skilled in the art. The accompanying drawings are only schematic illustrations of the present application and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted.

[0038] In addition, the described features, structures or characteristics may be combined in one or more example embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the example embodiments of the present application. However, those skilled in the art will appreciate that the technical solution of the present application may be practiced while omitting one or more of the specific details, or other methods, components, steps, etc. may be adopted. In other cases, known structures, methods, implementations or operations are not shown or described in detail to avoid obscuring the present application and making the various aspects of the present application obscure.

[0039] The setting of the anti-reflection film is to reduce the reflectivity of light at the interface by applying the interference principle, thereby increasing the transmittance of light at the interface; the anti-reflection film can be set as a single layer or a multi-layer. It should be noted that for a specific target interface, in order for the anti-reflection film to increase the light transmittance of the target interface as much as possible, the anti-reflection film as a whole needs to meet a specific target equivalent refractive index; it should also be noted that each layer of the anti-reflection film set in the relevant technology is a thin film structure made of a single material without an internal heterogeneous structure. Therefore, the relevant technology can only change the equivalent refractive index of the anti-reflection film by changing the material of the single-layer anti-reflection film, or changing the material combination of the multi-layer anti-reflection film.

[0040] It is understandable that the types of materials that can be used as anti-reflection films are very limited, so the related art can only adjust the equivalent refractive index of the anti-reflection film in a very limited number of options; that is, the anti-reflection film provided by the related art is limited by the type of materials, making it difficult to freely configure its equivalent refractive index. Therefore, the actual equivalent refractive index of the anti-reflection film provided by the related art is often difficult to accurately match the target equivalent refractive index that needs to be met, resulting in the target interface The light transmittance is not ideal. It is understandable that when the target interface is an interface in the metalens, the light transmittance of the target interface is not ideal, it is difficult to fully improve the light transmittance of the metalens, which results in the light transmittance of the metalens being not ideal.

[0041] In order to overcome the above-mentioned defects of the related art, the present application provides an anti-reflection film. Since the regulation method of the equivalent refractive index of the anti-reflection film provided by the present application is no longer limited to the material type, the equivalent refractive index of the anti-reflection film provided by the present application can be configured more freely, so the actual equivalent refractive index of the anti-reflection film provided by the present application can more easily and accurately match the target equivalent refractive index that needs to be met, thereby making the light transmittance of the metalens more ideal.

[0042] Figure 1 The figure shows the relative position of the target interface and the media on both sides thereof when no anti-reflection film is provided. Figure 2 A schematic diagram showing the relative positions of the target interface and the media on both sides thereof when the anti-reflection film provided by the present application is provided in one embodiment of the present application.

[0043] See also Figure 1 In one embodiment, when the anti-reflection film is not provided, the first side medium M1 and the second side medium M2 are in contact with each other, thus forming a target interface P at the junction. In order to improve the light transmittance of the target interface P, see Figure 2 , an anti-reflection film 1 provided in the present application is disposed at the target interface P; after the anti-reflection film 1 is disposed, the anti-reflection film 1 can be regarded as a part of the target interface P.

[0044] For details, see Figure 2 The antireflection film 1 provided in the present application includes antireflection structures 11 arranged in an array. Each antireflection structure 11 is a sub-wavelength structure; that is, the size of each antireflection structure 11 is less than or equal to the central wavelength of the working band, or slightly larger than the central wavelength. In addition, the antireflection film 1 provided in the present application is further provided with a filling structure 12 between adjacent antireflection structures 11; the material of the filling structure 12 can be air, or other materials that are transparent in the working band.

[0045] It should be noted that the material of the anti-reflection structure 11 is different from the material of the filling structure 12. It can be seen that the anti-reflection film 1 provided in the present application is a thin film structure composed of at least two types of materials and having an internal heterogeneous structure. Therefore, it can be understood that when the proportion of the area covered by the anti-reflection structure 11 in the anti-reflection film 1 changes, the equivalent refractive index of the anti-reflection film 1 will change accordingly; and the proportion of the area covered by the anti-reflection structure 11 in the anti-reflection film 1 can be regulated by the position distribution and size of the anti-reflection structure 11. Therefore, in the embodiment of the present application, the way to regulate the equivalent refractive index of the anti-reflection film 1 is no longer limited to the type of material; the equivalent refractive index of the anti-reflection film 1 can also be adjusted by adjusting the position distribution and size of the anti-reflection structure 11.

[0046] Obviously, the position distribution and size adjustment have a high degree of freedom, so the equivalent refractive index of the anti-reflection film 1 provided in the present application can be adjusted more finely, which helps to accurately match the target equivalent refractive index to be met, and further helps to make the light transmittance of the target interface as close to the ideal state as possible.

[0047] It should be noted that the anti-reflection film 1 provided in the present application is used for a metalens, that is, the target interface to be provided with the anti-reflection film 1 is a certain interface in the metalens. Since the anti-reflection film 1 provided in the present application helps the light transmittance of the target interface to be as close to the ideal state as possible, the anti-reflection film 1 can further make the light transmittance of the metalens more ideal.

[0048] Figure 3 A schematic diagram of the structure of a metalens is shown. Figure 3 The super lens includes a substrate 20 and an array of micro-nano structures 21 arranged on the substrate 20. The micro-nano structures 21 are sub-wavelength structures; a spacing structure 22 is also provided between the micro-nano structures 21; the material of the spacing structure 22 can be air or other materials that are transparent in the working band. The micro-nano structures 21 and the spacing structures 22 on the same layer together constitute a layer of structural surface 2.

[0049] In the embodiment of the present application, the media on both sides of the target interface P include at least a micro-nano structure 21 or a substrate 20 - that is, the target interface P can be an interface formed by the structural surface 2 connecting with the air, or an interface formed by the two layers of structural surfaces 2 connecting with each other, or an interface formed by the structural surface 2 connecting with the substrate 20, or an interface formed by the substrate 20 connecting with the air.

[0050] For details, see Figure 3 . Figure 3 In the metalens shown, only one structure surface 2 is provided on one side surface of the substrate 20. Thus, Figure 3There are three interfaces in the metalens shown as target interfaces P: interface P1 formed by the structural surface 2 and air; interface P2 formed by the structural surface 2 and substrate 20; and interface P3 formed by the substrate 20 and air.

[0051] When the interface P1 is the target interface P, the anti-reflection film 1 is disposed between the structure surface 2 and the air, thereby increasing the transmittance of light when propagating between the structure surface 2 and the air. When the interface P2 is the target interface P, the anti-reflection film 1 is disposed between the structure surface 2 and the substrate 20, thereby increasing the transmittance of light when propagating between the structure surface 2 and the substrate 20. When the interface P3 is the target interface P, the anti-reflection film 1 is disposed between the substrate 20 and the air, thereby increasing the transmittance of light when propagating between the substrate 20 and the air.

[0052] It should be noted that although Figure 3 In the metalens shown, only one layer of micro-nano structure 21 is provided on one side surface of the substrate 20, but this does not mean that the anti-reflection film 1 provided in the present application is only provided for Figure 3 The metalens shown.

[0053] In one embodiment, the antireflection film 1 provided in the present application is used for a superlens, and at least one layer of micro-nano structure 21 is provided on both sides of the surface of the substrate 20. That is, both sides of the substrate 20 of the superlens are provided with structure surfaces 2.

[0054] In one embodiment, the antireflection film 1 provided in the present application is used for a superlens, and at least two layers of micro-nano structures 21 are provided on at least one side surface of its substrate 20. That is, a structural surface 2 is provided on a certain side surface of the substrate 20, and the side surface is provided with at least two layers of structural surfaces 2.

[0055] In one embodiment, the micro-nano structure 21 in the metalens to be provided with the anti-reflection film 1 is a positive micro-nano structure. After the positive micro-nano structure is obtained by semiconductor technology, if the spacing structure 22 between the positive micro-nano structures is not filled with a specific material other than air, the material between the positive micro-nano structures is air.

[0056] In one embodiment, the micro-nano structure 21 in the metalens to be provided with the anti-reflection film 1 is a negative micro-nano structure. After the negative micro-nano structure is just processed by the semiconductor process, if the negative micro-nano structure is not filled with a specific material other than air, the material of the negative micro-nano structure is air, and the spacing structure 22 between the negative micro-nano structures is a material other than air.

[0057] It should be noted that when a semiconductor process is used to process a superlens, multiple superlenses are usually processed on a whole wafer. If the anti-reflection film provided by the relevant technology is used to coat the entire wafer, all superlenses will be coated with a uniform thickness of anti-reflection film made of a single material without internal heterogeneous structure, and this coating result obviously cannot make each superlens obtain an ideal light transmittance. Therefore, if the anti-reflection film provided by the relevant technology is used, the wafer can only be cut first, each superlens is separated, and then each superlens is coated separately. Since the anti-reflection film 1 provided in the present application can improve the light transmittance of the superlens by adjusting the size of the anti-reflection structure 11, even if all superlenses on the entire wafer are coated with the anti-reflection film 1 provided in the present application of uniform thickness, each superlens can also obtain a relatively ideal light transmittance. In this way, when the anti-reflection film 1 provided in the present application is used for a superlens, the wafer cutting process and the separate coating process are avoided, thereby simplifying the processing flow of the superlens and reducing the processing cost of the superlens.

[0058] It should also be noted that the anti-reflection film 1 provided in the present application can also be processed by semiconductor technology, thereby accurately preparing each anti-reflection structure 11 in the anti-reflection film 1, and is also suitable for synchronous processing with the super lens.

[0059] In one embodiment, the heights of all anti-reflection structures 11 in the same layer are kept consistent, so as to reduce the difficulty of processing the anti-reflection structures 11 in the entire target interface P.

[0060] In one embodiment, the medium on one side of the target interface P is the substrate 20 and the medium on the other side is air. That is, in this embodiment, the anti-reflection film 1 is used to increase the transmittance of light when it propagates between the substrate 20 and the air.

[0061] It should be noted that the distribution of the media on both sides of the target interface P may have different performances at different positions of the target interface P. Therefore, at different positions of the target interface P, the requirements for the equivalent refractive index of the anti-reflection film 1 will be different. Therefore, if the different positions of the target interface P are not roughly distinguished, and the target interface P is directly taken as a whole, and then the target equivalent refractive index of the anti-reflection film 1 corresponding to the entire target interface P is determined, and then the size of the anti-reflection structure 11 is controlled so that the anti-reflection film 1 meets the target equivalent refractive index corresponding to the entire target interface P, then the specialized requirements for the equivalent refractive index of the anti-reflection film 1 at many positions in the target interface P are actually difficult to be fully met, which will lead to the actual light transmittance at some positions of the target interface P being less than ideal.

[0062] Therefore, in one embodiment, the anti-reflection film 1 is adaptively arranged to adapt to different sub-regions of the target interface P, so as to fully meet the specialized requirements of the equivalent refractive index of the anti-reflection film 1 at different positions in the target interface P, thereby ensuring that the light transmittance at each position of the target interface P is actually ideal.

[0063] In detail, in this embodiment, the target interface P can be divided into at least two sub-regions according to the difference in the specialized requirements for the equivalent refractive index of the anti-reflection film 1 at different positions in the target interface P, so that the specialized requirements for the equivalent refractive index of the anti-reflection film 1 at different positions in each sub-region are relatively close, and there is not too much difference.

[0064] After determining the sub-regions constituting the target interface P, an anti-reflection structure 11 is configured for each sub-region. The anti-reflection structures 11 in the same sub-region have the same size to ensure that the light transmittance at different positions in the same sub-region is affected as consistently as possible by the anti-reflection structure 11.

[0065] For a certain sub-region, determine the equivalent refractive index n of the first side medium M1 corresponding to the sub-region eff1 , and determine the equivalent refractive index n of the second side medium M2 corresponding to the sub-region eff2 According to the optical principle of interference antireflection, the target equivalent refractive index n of the antireflection film 1 in the sub-area is matched c , can be calculated using the following formula: Further transformation of the formula yields: c 2 =n eff1 *n eff2 It can be seen that the target equivalent refractive index n of the AR film 1 target matching in this sub-region c The square value n c 2 , which is equal to the equivalent refractive index n of the first side medium M1 corresponding to the sub-region eff1 The equivalent refractive index n of the second side medium M2 corresponding to the sub-region eff2 The product n eff1 *n eff2 .

[0066] Therefore, after the material of the antireflection structure 11 is determined, for a certain sub-region, the equivalent refractive index of the antireflection film 1 in the sub-region can be adjusted by adjusting the position distribution and size of the antireflection structure 11 in the sub-region. eff1 *n eff2 When , it means that the equivalent refractive index of the antireflection film 1 in the sub-region matches the corresponding target equivalent refractive index n c .

[0067] Therefore, in this embodiment, the equivalent refractive index of the anti-reflection film 1 in each sub-region matches the corresponding target equivalent refractive index; therefore, the specialized requirements for the equivalent refractive index of the anti-reflection film 1 at each position in the target interface P can be fully met, thereby ensuring that the actual light transmittance at each position of the target interface P is relatively ideal.

[0068] It should be noted that, in this embodiment, the principle of adjusting the corresponding equivalent refractive index by adjusting the position distribution and size of the anti-reflection structure 11 in the sub-region is as follows:

[0069] According to Stavenga's equivalent refractive index theory, for a film region including a sub-wavelength structure and a filling structure disposed between the sub-wavelength structures, its equivalent refractive index n eff The filling rate A of various structures inside it satisfies the following relationship: n eff =[A1*(n1) 2 / 3 +A2*(n2) 2 / 3 ] 3 / 2 ; Among them, A1 represents the filling rate of the subwavelength structure in the thin film area, n1 represents the material refractive index of the subwavelength structure, A2 represents the filling rate of the filling structure in the thin film area, n2 represents the material refractive index of the filling structure; the sum of A1 and A2 is 1.

[0070] For the antireflection film 1 in a certain sub-region, its target equivalent refractive index n is known. c , and after determining the material of the antireflection structure 11 and the material of the filling structure 12, the refractive index n of the material of the antireflection structure 11 is 11 and the refractive index n of the material of the filling structure 12 12 Therefore, the filling rate of the antireflection structure 11 in this sub-region is recorded as A 11 The filling rate of the filling structure 12 in this sub-region is A 12 , we can get: n c =[A 11 *(n 11 ) 2 / 3 +A 12 *(n 12 ) 2 / 3 ] 3 / 2 =[A 11 *(n 11 ) 2 / 3 +(1-A 11 )*(n 12 ) 2 / 3 ] 3 / 2 . Further, the formula can be transformed to obtain the following formula:

[0071] By formula It can be seen that in determining the target equivalent refractive index n of the target matching of the antireflection film 1 in a certain sub-region c Then, the material refractive index n of the antireflection structure 11 can be determined in advance. 11 and the refractive index n of the material of the filling structure 12 12 , the target filling rate A of the target matching of the antireflection structure 11 in the sub-region can be determined 11 .

[0072] It should be noted that, in this embodiment, the filling rate of a specific structure in a corresponding region refers to the proportion of the area covered by the specific structure in the corresponding region. For example, if the total area of ​​the vertical projection of the anti-reflection structure 11 on a certain sub-region when observed in a direction perpendicular to the sub-region accounts for 60% of the total area of ​​the sub-region, the filling rate of the anti-reflection structure 11 in the sub-region is 60%.

[0073] Since the target filling rate of the anti-reflection structure 11 describes the proportion of the area covered by the anti-reflection structure 11 in the corresponding sub-region, after determining the target filling rate of the anti-reflection structure 11 in the corresponding sub-region, it is only necessary to set the position distribution and size of the anti-reflection structure 11 in the corresponding sub-region as needed to make the anti-reflection structure 11 in the corresponding sub-region match the corresponding target filling rate.

[0074] It should also be noted that in this embodiment, the square value of the equivalent refractive index of the antireflection film 1 in a certain sub-region matches the equivalent refractive index n of the first side medium M1 corresponding to the sub-region. eff1 The equivalent refractive index n of the second side medium M2 corresponding to the sub-region eff2 The product n eff1 *n eff2 , refers to the square value of the equivalent refractive index of the antireflection film 1 in the sub-region and n eff1 *n eff2 The difference between them is less than the preset difference threshold (for example, the preset difference threshold is 2.5%, then as long as the square value of the equivalent refractive index of the anti-reflection film 1 is equal to n eff1 *n eff2 The difference between them is within ±2.5%, which confirms that the square value of the equivalent refractive index of the AR coating 1 matches n eff1 *n eff2 ). Preferably, the square value of the equivalent refractive index of the antireflection film 1 in each sub-region is equal to the equivalent refractive index n of the first side medium M1 corresponding to the same sub-region. eff1 The equivalent refractive index n of the second side medium M2 corresponding to the same sub-region eff2 The product n eff1 *n eff2 .

[0075] It should also be noted that when the equivalent refractive index of the anti-reflection film 1 in each sub-region matches the corresponding target equivalent refractive index, each sub-region has the necessary prerequisite to achieve an ideal light transmittance in the dimension of the equivalent refractive index. On this basis, the height of the anti-reflection structure 11 in each sub-region is further optimized to make the light transmittance of each sub-region meet the target requirements. Therefore, when the light transmittance of each sub-region meets the target requirements, the light transmittance of the target interface P naturally also meets the target requirements.

[0076] In one embodiment, the height of the anti-reflection structure 11 in the same sub-region is kept consistent, so as to reduce the difficulty of processing the anti-reflection structure 11 in a single sub-region.

[0077] Considering that the distribution of the media on both sides of different sub-regions may be different, not only the target equivalent refractive index that the anti-reflection film 1 in different sub-regions needs to match may be different, but also the thickness that the anti-reflection film 1 in different sub-regions needs to match to achieve the corresponding optimal light transmittance (it can be understood that the thickness of the anti-reflection film 1 is the height of the anti-reflection structure 11) may also be different. Therefore, the practice of keeping the height of the anti-reflection structure 11 in all sub-regions consistent will make it difficult for the light transmittance of some sub-regions to reach the upper limit that it can reach.

[0078] Therefore, in one embodiment, although the height of the anti-reflection structure 11 in the same sub-region is consistent, there are at least two types of height of the anti-reflection structure in the target interface P. That is, the height of the anti-reflection structure 11 in not all sub-regions is consistent; the height of the anti-reflection structure 11 in at least one sub-region is different from the height of the anti-reflection structure 11 in another sub-region. In this way, the overall performance of the light transmittance of the target interface P is further improved.

[0079] In one embodiment, when the same sub-region includes at least three antireflection structures 11, the antireflection structures 11 in the same sub-region are periodically arranged in an array. That is, when the same sub-region includes three or more antireflection structures 11, the antireflection structures 11 in the same sub-region are made of the same material, have the same size, have the same height, and have the same adjacent intervals in the same direction.

[0080] In this embodiment, the anti-reflection structures 11 in the same sub-region are arranged in an array periodically so that the light transmittance at different positions in the same sub-region is affected as uniformly as possible by the anti-reflection structures 11, thereby ensuring that the specialized requirements for light transmittance at each position in the same sub-region can be met to a certain extent, thereby avoiding the difficulty in satisfying the specialized requirements for light transmittance at individual positions to a basic extent.

[0081] In one embodiment, at least one medium on both sides of the target interface P includes the micro-nano structure 21. That is, in this embodiment, at least one medium on both sides of the target interface P is the structure surface 2; thus, the anti-reflection film 1 is used to increase the transmittance of light when propagating between the structure surface 2 and the adjacent medium of the structure surface 2; the adjacent medium of the structure surface 2 can be air, can be the substrate 20, or can be another layer of the structure surface.

[0082] Specifically, Figure 4 FIG. 1 is a schematic diagram showing a structure in which an antireflection film 1 is provided on a superlens in one embodiment of the present application. Figure 5 FIG. 1 is a schematic diagram showing a structure in which an antireflection film 1 is provided on a superlens in one embodiment of the present application. Figure 6 FIG. 1 is a schematic diagram showing a structure in which an antireflection film 1 is provided on a superlens in one embodiment of the present application.

[0083] See also Figure 4 In one embodiment, of the media on both sides of the target interface P, one medium is the structure surface 2 and the other medium is air. Therefore, in this embodiment, the anti-reflection film 1 is disposed between the structure surface 2 and the air to increase the transmittance of light when propagating between the structure surface 2 and the air.

[0084] See also Figure 5 In one embodiment, of the media on both sides of the target interface P, one medium is the structure surface 2, and the other medium is the substrate 20. Therefore, in this embodiment, the anti-reflection film 1 is disposed between the structure surface 2 and the substrate 20 to improve the transmittance of light when propagating between the structure surface 2 and the substrate 20.

[0085] See also Figure 6 In one embodiment, of the media on both sides of the target interface P, one medium is a structural surface 2, and the other medium is another structural surface 2. Therefore, in this embodiment, the anti-reflection film 1 is disposed between the two structural surfaces 2 to improve the transmittance of light when propagating between the two structural surfaces 2.

[0086] When at least one of the media on both sides of the target interface P includes a micro-nano structure 21, the presence of the micro-nano structure 21 will put forward corresponding specialized requirements for the equivalent refractive index at the corresponding position of the target interface P. Therefore, in order to make the actual light transmittance at each position on the target interface P as ideal as possible, it is necessary to meet the specialized requirements put forward by each micro-nano structure 21.

[0087] To this end, in one embodiment, when at least one of the media on both sides of the target interface P includes a micro-nano structure 21, each sub-region of the target interface P includes an anti-reflection structure group, and the anti-reflection structure group includes at least one anti-reflection structure 11; the anti-reflection structure group in each sub-region is matched one-to-one with the micro-nano structure 21 corresponding to the same sub-region.

[0088] Specifically, in this embodiment, the antireflection structures 11 in the same sub-region are divided into at least one antireflection structure group; depending on application requirements, each antireflection structure group may include only one antireflection structure 11 or may include multiple antireflection structures 11.

[0089] Furthermore, in this embodiment, the anti-reflection structure group in each sub-region is matched one-to-one with the micro-nano structure 21 corresponding to the same sub-region, which means that if there are n micro-nano structures 21 in a certain sub-region, there are also n anti-reflection structure groups in the sub-region, and if the sub-region is divided into n sub-sub-regions with no overlapping parts, each sub-sub-region can have only one micro-nano structure 21 corresponding to it, and each sub-sub-region can have only one anti-reflection structure group. n is a positive integer.

[0090] Figure 7 FIG. 1 shows a top view of a sub-region of a target interface P in an embodiment of the present application. Figure 7 In one embodiment, there are 25 micro-nano structures 21 corresponding to a certain sub-region in the target interface P; there are 25 anti-reflection structures 11 in the sub-region, and each anti-reflection structure 11 itself constitutes an anti-reflection structure group 10. Thus, Figure 7 As shown, the sub-region can be divided into 25 sub-sub-regions; each sub-sub-region corresponds to one and only one micro-nano structure 21, and each sub-sub-region has one and only one anti-reflection structure group 10. Therefore, in this embodiment, the anti-reflection structure group 10 matches the micro-nano structure 21 one by one.

[0091] Figure 8 FIG. 1 shows a top view of a sub-region of a target interface P in an embodiment of the present application. Figure 8 In one embodiment, there are 25 micro-nano structures 21 corresponding to a certain sub-region in the target interface P; there are 50 anti-reflection structures 11 in the sub-region, and these 50 anti-reflection structures 11 are combined in pairs to form 25 anti-reflection structure groups 10. Thus, Figure 8 As shown, the sub-region can be divided into 25 sub-sub-regions; each sub-sub-region corresponds to one and only one micro-nano structure 21, and each sub-sub-region has one and only one anti-reflection structure group 10. Therefore, in this embodiment, the anti-reflection structure group 10 matches the micro-nano structure 21 one by one.

[0092] In one embodiment, in a sub-region corresponding to at least two micro-nano structures 21 , the distance between the anti-reflection structure groups 10 is consistent with the distance between the matching micro-nano structures 21 .

[0093] Specifically, in this embodiment, if the number of micro-nano structures 21 corresponding to a certain sub-region is greater than or equal to 2, any two of the micro-nano structures 21 are recorded as micro-nano structure A and micro-nano structure B, and the anti-reflection structure group matching the micro-nano structure A is recorded as anti-reflection structure group a, and the anti-reflection structure group matching the micro-nano structure B is recorded as anti-reflection structure group b, then the distance between the anti-reflection structure group a and the anti-reflection structure group b is equal to the distance between the micro-nano structure A and the micro-nano structure B.

[0094] If a certain antireflection structure group 10 includes only one antireflection structure 11 , when calculating the distance between the antireflection structure group 10 and other antireflection structure groups 10 , the position of the only antireflection structure 11 included in the antireflection structure group 10 is used as the position of the antireflection structure group 10 .

[0095] If a certain antireflection structure group 10 includes only two antireflection structures 11 , when calculating the distance between the antireflection structure group 10 and other antireflection structure groups 10 , the midpoint of the line connecting the two antireflection structures 11 in the antireflection structure group 10 is used as the position of the antireflection structure group 10 .

[0096] If a certain anti-reflection structure 10 includes more than three anti-reflection structures 11, when calculating the distance between the anti-reflection structure group 10 and other anti-reflection structure groups 10, the geometric center position of the envelope formed by all the anti-reflection structures 11 in the anti-reflection structure group 10 (for example, the center position of the circumscribed circle corresponding to the envelope) can be used as the position of the anti-reflection structure group 10, or the position where the average distance between the anti-reflection structures 11 in the anti-reflection structure group 10 is the smallest can be used as the position of the anti-reflection structure group 10.

[0097] It should be noted that the sizes of the micro-nano structures 21 in the same layer of the structural surface 2 may not be uniform. Fig. 9 FIG. 1 shows a schematic diagram of the structure of a metalens to be provided with an antireflection film 1 in an embodiment of the present application. Fig. 9 In one embodiment, the sizes of the micro-nano structures 21 in the same layer of structural surface 2 are not uniform. However, it should be noted that the non-uniform sizes of the micro-nano structures 21 in the same layer of structural surface 2 do not mean that the micro-nano structures 21 in the same layer of structural surface 2 are completely non-periodic. Fig. 9 As shown, although the sizes of the micro-nano structures 21 in the same layer structure surface 2 are not uniform, in the local area, the micro-nano structures 21 still have the characteristics of periodic arrangement.

[0098] It should also be noted that when at least one of the two media on both sides of the target interface P includes a micro-nano structure 21, the presence of the micro-nano structure 21 will put forward corresponding specialized requirements for the equivalent refractive index at the corresponding position of the target interface P. In addition, the larger the size fluctuation of the micro-nano structure 21 corresponding to the same sub-region, the more prominent the difference in the specialized requirements for the equivalent refractive index at each position on the corresponding sub-region; however, the material, size and height of the anti-reflection structure 11 in the same sub-region are usually uniform, so it is difficult to fully compensate for the difference in specialized requirements by the anti-reflection structure 11 alone. Therefore, the larger the size fluctuation of the micro-nano structure 21 corresponding to the same sub-region, the more prominent the difference in the specialized requirements for the equivalent refractive index at each position on the corresponding sub-region, which will make it more difficult to meet the specialized requirements for the equivalent refractive index at each position on the corresponding sub-region, and thus the actual light transmittance at each position on the corresponding sub-region is less ideal. Among them, the size of the micro-nano structure 21 is usually described by its cross-sectional radius, and can also be described by its cross-sectional perimeter, its cross-sectional diagonal length, etc.

[0099] Therefore, in one embodiment, when at least one of the media on both sides of the target interface P includes the micro-nano structure 21 , the size fluctuation amplitude of the micro-nano structure 21 corresponding to the same sub-region is less than a preset size threshold.

[0100] Specifically, since the larger the size fluctuation amplitude of the micro-nano structure 21 corresponding to the same sub-region, the less ideal the light transmittance actually exhibited at each position on the corresponding sub-region, in this embodiment, the target interface P can be divided into at least two sub-regions based on the position distribution and size of the micro-nano structure 21; the size fluctuation amplitude of the micro-nano structure 21 corresponding to each sub-region obtained by the division is smaller than the preset size threshold, which is beneficial to improve the light transmittance actually exhibited at each position on each sub-region.

[0101] It should be noted that the size threshold of the size fluctuation amplitude of the micro-nano structure 21 corresponding to the same sub-area is mainly related to the target light transmittance of the target interface and the equivalent refractive index difference of the medium on both sides of the target interface. Specifically, the size threshold of the size fluctuation amplitude of the micro-nano structure 21 corresponding to the same sub-area is negatively correlated with the target light transmittance of the target interface, and is also negatively correlated with the equivalent refractive index difference of the medium on both sides of the target interface. That is, the greater the target light transmittance of the target interface, the smaller the size threshold of the size fluctuation amplitude of the micro-nano structure 21 corresponding to the same sub-area; similarly, the greater the equivalent refractive index difference of the medium on both sides of the target interface, the smaller the size threshold of the size fluctuation amplitude of the micro-nano structure 21 corresponding to the same sub-area. Among them, the equivalent refractive index difference is a difference measured in absolute value.

[0102] Therefore, after determining the target light transmittance of the target interface and the equivalent refractive index difference of the media on both sides, the size threshold of the size fluctuation amplitude of the micro-nano structure 21 corresponding to the same sub-region can be adaptively configured. For example: when the target light transmittance of the target interface P is 94%, the medium on one side is air, the medium on the other side is the structural surface 2, and the material of the micro-nano structure 21 in the structural surface 2 is single crystal silicon, the average radius of the micro-nano structure 21 is 0.7 μm, and the period of the micro-nano structure 21 is 2.8 μm, the size threshold of the size fluctuation amplitude of the micro-nano structure 21 corresponding to the same sub-region can be set to 20 μm; that is, the size fluctuation amplitude of the micro-nano structure 21 corresponding to the same sub-region should be limited to within ±20 μm.

[0103] Fig.10 FIG. 1 shows a top view of a sub-region of a target interface P in an embodiment of the present application. Fig.10 In one embodiment, the anti-reflection film 1 is used for a metalens, and at least one of the media on both sides of the target interface P includes a micro-nano structure 21; the vertical projection of the micro-nano structure 21 corresponding to the same sub-region on the corresponding sub-region fully covers the anti-reflection structure 11 in the corresponding sub-region.

[0104] In this embodiment, when the anti-reflection structure 11 is processed after the structural surface 2, if the micro-nano structure 21 is a positive micro-nano structure, it is obvious that the anti-reflection structure 11 can be set vertically above the micro-nano structure 21; if the micro-nano structure 21 is a negative micro-nano structure, then after the micro-nano structure 21 is processed, the micro-nano structure 21 is first filled with materials other than air, and then the anti-reflection structure 11 is set vertically above the micro-nano structure 21.

[0105] Fig.11 FIG. 1 shows a top view of a sub-region of a target interface P in an embodiment of the present application. Fig.11 In one embodiment, the anti-reflection film 1 is used for a metalens, and at least one of the media on both sides of the target interface P includes a micro-nano structure 21; the vertical projection of the micro-nano structure 21 corresponding to the same sub-region on the corresponding sub-region is located outside the anti-reflection structure 11 in the corresponding sub-region.

[0106] In this embodiment, when the anti-reflection structure 11 is processed after the structural surface 2, if the micro-nano structure 21 is a positive micro-nano structure, the spacing structure 22 between the micro-nano structures 21 is first filled with materials other than air, and then the anti-reflection structure 11 is arranged vertically above the spacing structure 22; if the micro-nano structure 21 is a negative micro-nano structure, then the anti-reflection structure 11 can obviously be arranged vertically above the spacing structure 22.

[0107] Fig.12 FIG. 1 shows a top view of a sub-region of a target interface P in an embodiment of the present application. Fig.12In one embodiment, the anti-reflection film 1 is used for a metalens, and at least one of the media on both sides of the target interface P includes a micro-nano structure 21; the vertical projection of the micro-nano structure 21 corresponding to the same sub-region on the corresponding sub-region partially overlaps with the anti-reflection structure 11 in the corresponding sub-region.

[0108] In this embodiment, when the anti-reflection structure 11 is processed after the structural surface 2, if the micro-nano structure 21 is a positive micro-nano structure, the spacer structure 22 between the micro-nano structures 21 is first filled with a material other than air, and then the anti-reflection structure 11 is arranged vertically above the boundary edge between the micro-nano structure 21 and the spacer structure 22; if the micro-nano structure 21 is a negative micro-nano structure, the micro-nano structure 21 is first filled with a material other than air, and then the anti-reflection structure 11 is arranged vertically above the boundary edge between the micro-nano structure 21 and the spacer structure 22.

[0109] The present application also provides a metalens, in which an anti-reflection film 1 as provided in any of the above embodiments is provided. Referring to the specific implementation of the anti-reflection film 1 provided in the above embodiments, the specific details of the metalens provided with the anti-reflection film 1 are not repeated here.

[0110] Example 1

[0111] In this embodiment, the target interface of the metalens to be provided with an anti-reflection film has air as the medium on one side and a structural surface provided with a micro-nano structure as the medium on the other side. Table 1 shows the parameters of the metalens when no anti-reflection film is provided in this embodiment.

[0112] Table 1. Metalens parameters when no antireflection film is provided in Example 1

[0113]

[0114] Referring to Table 1, in this embodiment, the micro-nano structure in the structural surface to be in contact with the anti-reflection film is a cylindrical positive structure, and different micro-nano structures are periodically arranged in a square; its period is 2.8μm, its minimum radius is 0.45μm, its maximum radius is 0.95μm, its height is 12μm, and its material is single crystal silicon. The material of the substrate of the super lens is single crystal silicon. The material of the spacing structure between the micro-nano structures is air. The central wavelength of the working band of the super lens is 10μm. Before the anti-reflection film is set, the overall light transmittance of the super lens is 81.43%.

[0115] In this embodiment, in the anti-reflection film disposed in the target interface, the anti-reflection structure is a cylindrical positive structure, the material of the anti-reflection structure is single crystal silicon, and the material of the filling structure disposed between the anti-reflection structures is air.

[0116] Specifically, the target light transmittance of the target interface is 94%. Combined with the difference between the equivalent refractive index of the structural surface and the equivalent refractive index of the air, the size threshold of the size fluctuation amplitude of the micro-nano structure corresponding to the same sub-region is set to 20μm; that is, the size fluctuation amplitude of the micro-nano structure corresponding to the same sub-region should be limited to within ±20μm. When designing the anti-reflection film, first divide the target interface in the metalens into five sub-regions according to the size threshold of the size fluctuation amplitude, and then calculate the target equivalent refractive index of the anti-reflection film target matching in each sub-region, and then calculate the target filling rate of the anti-reflection structure target matching in each sub-region based on the target equivalent refractive index, and then determine the position distribution and size of the anti-reflection structure in each sub-region based on the target filling rate, and then construct an optimization model of the anti-reflection structure based on the position distribution and size of the anti-reflection structure in each sub-region, and optimize the height of the anti-reflection structure in each sub-region in combination with the height constraint of the anti-reflection structure.

[0117] In this embodiment, the target height of the anti-reflection structure that makes the light transmittance of each sub-region optimal is optimized, and then the height of the anti-reflection structure in the target interface of the metalens is uniformly configured to the target height. The target height of the anti-reflection structure finally optimized is 2.137μm. After the anti-reflection film corresponding to the anti-reflection structure is set, the overall light transmittance of the metalens is 94.58%, which is 13.15% higher than the light transmittance without the anti-reflection film.

[0118] Example 2

[0119] In this embodiment, the target interface of the metalens to be provided with an anti-reflection film has air as the medium on one side and a structural surface provided with a micro-nano structure as the medium on the other side. Table 2 shows the parameters of the metalens when no anti-reflection film is provided in this embodiment.

[0120] Table 2. Metalens parameters when no antireflection film is provided in Example 2

[0121]

[0122]

[0123] Referring to Table 2, in this embodiment, the micro-nano structure in the structural surface to be in contact with the anti-reflection film is a cylindrical negative structure, and different micro-nano structures are periodically arranged in a hexagon; its period is 0.8 μm, its minimum radius is 0.07 μm, its maximum radius is 0.13 μm, its height is 0.9 μm, and its material is silicon nitride. The material of the substrate of the superlens is single crystal silicon. The material of the spacing structure between the micro-nano structures is air. The working band of the superlens is 1.55 μm. Before the anti-reflection film is set, the overall light transmittance of the superlens is 84.72%.

[0124] In this embodiment, in the anti-reflection film disposed at the target interface, the anti-reflection structure is a square columnar positive structure, the material of the anti-reflection structure is germanium, and the material of the filling structure disposed between the anti-reflection structures is air.

[0125] Specifically, when designing the anti-reflection film, the target interface in the metalens is first divided into sub-regions that match each micro-nano structure one by one, and then the target equivalent refractive index of the anti-reflection film target match in each sub-region is calculated, and then the target filling rate of the anti-reflection structure target match in each sub-region is calculated based on the target equivalent refractive index, and then based on the target filling rate, the position distribution and size of the anti-reflection structure in each sub-region are determined, and then based on the position distribution and size of the anti-reflection structure in each sub-region, an optimization model of the anti-reflection structure is constructed, and combined with the height constraint of the anti-reflection structure, the height of the anti-reflection structure in each sub-region is optimized.

[0126] In this embodiment, the target height of the anti-reflection structure that makes the light transmittance of each sub-region optimal is optimized, and then the height of the anti-reflection structure in the target interface of the metalens is uniformly configured to the target height. In this embodiment, the target height of the anti-reflection structure finally optimized is 1.509 μm, and the metalens with the anti-reflection film corresponding to the anti-reflection structure reconstructed has an overall light transmittance of 98.74%, which is 14.02% higher than the light transmittance without the anti-reflection film.

[0127] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the utility model disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the appended claims.

Claims

1. An antireflection film, characterized in that: The antireflection film comprises: antireflection structures arranged in an array, wherein the antireflection structures are sub-wavelength structures; and a filling structure disposed between the antireflection structures; Among them, the anti-reflection film is used for a superlens, and the superlens includes a substrate and an array-arranged micro-nano structure arranged on the substrate; the anti-reflection film is arranged at a target interface; and the media on both sides of the target interface at least contain the micro-nano structure or the substrate.

2. The antireflection film according to claim 1, characterized in that: The heights of all the antireflection structures in the same layer are kept consistent.

3. The antireflection film according to claim 1, characterized in that: The media on both sides of the target interface are respectively a first side medium and a second side medium; the target interface includes at least two sub-regions, and the anti-reflection structures in the same sub-region have the same size; the square value of the equivalent refractive index of the anti-reflection film in each sub-region matches the product of the equivalent refractive index of the first side medium corresponding to the same sub-region and the equivalent refractive index of the second side medium corresponding to the same sub-region.

4. The antireflection film according to claim 3, characterized in that: When the same sub-region contains at least three anti-reflection structures, the anti-reflection structures in the same sub-region are periodically arranged in an array.

5. The antireflection film according to claim 3, characterized in that: Among the media on both sides of the target interface, at least one side of the media includes the micro-nano structure.

6. The antireflection film according to claim 5, characterized in that: Each sub-region of the target interface includes an anti-reflection structure group, and the anti-reflection structure group includes at least one anti-reflection structure; the anti-reflection structure group in each sub-region is matched one by one with the micro-nano structure corresponding to the same sub-region.

7. The antireflection film according to claim 5, characterized in that: In the sub-region corresponding to at least two of the micro-nano structures, the distance between the anti-reflection structure groups is consistent with the distance between the matching micro-nano structures.

8. The antireflection film according to claim 5, characterized in that: The size fluctuation amplitude of the micro-nanostructure corresponding to the same sub-region is less than a preset size threshold.

9. The antireflection film according to claim 5, characterized in that: The vertical projection of the micro-nano structure corresponding to the same sub-region on the corresponding sub-region completely covers the anti-reflection structure in the corresponding sub-region.

10. The antireflection film according to claim 5, characterized in that: The vertical projection of the micro-nano structure corresponding to the same sub-region on the corresponding sub-region is located outside the anti-reflection structure in the corresponding sub-region.

11. The antireflection film according to claim 5, characterized in that: The vertical projection of the micro-nano structure corresponding to the same sub-region on the corresponding sub-region and the anti-reflection structure in the corresponding sub-region partially overlap with each other.

12. The antireflection film according to claim 1, characterized in that: Of the media on both sides of the target interface, the medium on one side is the substrate, and the medium on the other side is air.

13. A superlens, characterized in that: The metalens is provided with an anti-reflection film as described in any one of claims 1 to 12.

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