Metasurface mid-infrared band-stop filter, preparation method and infrared detector

Abstract

The present invention provides a metasurface mid-infrared band-stop filter, a preparation method and an infrared detector. Along the thickness direction of the filter, the metasurface mid-infrared band-stop filter includes: a substrate, a first anti-reflection layer and a metasurface layer in sequence. The metasurface layer includes: at least one filter unit, each filter unit includes a plurality of filter pixels, each filter pixel includes a plurality of cross structures arranged in an array, and the periods of any two filter pixels in each filter unit are different, and the cross structure is made of metal. The metasurface mid-infrared band-stop filter disclosed in the present invention has a filtering center wavelength range of 3~5μm. The filter can achieve band-stop filtering of light in the mid-infrared spectrum; the transmittance can also be improved by setting a first anti-reflection layer between the substrate and the metasurface layer; at the same time, the metasurface mid-infrared band-stop filter also has the advantages of narrow bandwidth and small overall volume.

Description

Technical Field

[0001] The embodiments of the present disclosure belong to the field of infrared detector technology, and specifically relate to a metasurface mid-infrared band-stop filter, a preparation method, and an infrared detector. Background Art

[0002] Infrared detection technology has a wide range of uses in military reconnaissance, aerospace, medical diagnosis, spectroscopy and other fields, and mid-infrared optical infrared detection devices are an important type of device in infrared detection technology.

[0003] The existing infrared detector filters achieve selective transmission of light by coating multiple layers of film on a semiconductor substrate, which requires a long optical path length, which results in a large device size and poor design flexibility, and is not conducive to the miniaturization and integration of detection devices. In addition, the existing infrared detector filters also have defects such as large device size, small number of filter bands, wide filter bandwidth, and low transmittance. Summary of the invention

[0004] The embodiments of the present disclosure aim to solve at least one of the technical problems existing in the prior art, and provide a metasurface mid-infrared band-stop filter, a preparation method and an infrared detector.

[0005] A first aspect of the present disclosure provides a metasurface mid-infrared band-stop filter, which includes, along the thickness direction of the metasurface mid-infrared band-stop filter, a substrate, a first anti-reflection layer and a metasurface layer in sequence, and the metasurface layer includes: at least one filtering unit, each of the filtering units includes a plurality of filtering pixels, each of the filtering pixels includes a plurality of cross structures arranged in an array, the periods of any two of the filtering pixels in each of the filtering units are different, and the cross structure is made of metal.

[0006] In some embodiments of the present disclosure, each of the filtering units includes n*n filtering pixels, where n≥2.

[0007] In some embodiments of the present disclosure, a spacer is provided on a surface of the first anti-reflection layer facing away from the substrate, and the spacer separates two adjacent filtering pixels.

[0008] In some embodiments of the present disclosure, the isolation member and the cross structure are both made of metal aluminum, and the distance between the isolation member and the nearest cross structure is greater than 100 nm.

[0009] In some embodiments of the present disclosure, the width of the isolation member ranges from 1.50 μm to 3.00 μm.

[0010] In some embodiments of the present disclosure, the long side of the cross structure ranges from 0.80 μm to 1.50 μm, the short side of the cross structure ranges from 70 nm to 120 nm, and the thickness of the cross structure ranges from 40 nm to 100 nm.

[0011] In some embodiments of the present disclosure, the period of the cross structure ranges from 1.60 μm to 3.00 μm.

[0012] In some embodiments of the present disclosure, a second anti-reflection layer is provided on the side of the substrate facing away from the super-surface layer.

[0013] A second aspect of the present disclosure provides a method for preparing a metasurface mid-infrared band-stop filter, which is used to prepare the metasurface mid-infrared band-stop filter according to any of the above embodiments, and the preparation method comprises: Depositing an anti-reflection material on the surface of the substrate to form a first anti-reflection layer; sputtering metal on the surface of the first anti-reflection layer to form a metal layer; The surface of the metal layer is etched by an etching method to obtain a super surface layer with a cross structure arranged in an array.

[0014] A third aspect of the present disclosure proposes an infrared detector, which includes the metasurface mid-infrared band-stop filter according to any of the above embodiments.

[0015] The metasurface mid-infrared band-stop filter, preparation method and infrared detector of the disclosed embodiment include a substrate, a first anti-reflection layer and a metasurface layer, wherein the first anti-reflection layer is arranged on the surface of the substrate, and the metasurface layer is arranged on the surface of the first anti-reflection layer away from the substrate. The metasurface layer includes: at least one filter unit, each filter unit includes a plurality of filter pixels, the structure of each filter pixel is arranged periodically, and the periods of any two filter pixels in each filter unit are different, that is, the periods of the plurality of filter pixels in each filter unit are different, that is, the filter bands of the plurality of filter pixels in each filter unit are different, so that each filter unit can attenuate light of multiple different mid-infrared bands. Each filter pixel includes a plurality of metal structures arranged in an array, and when the mid-infrared light is incident on the surface of the metal structure, the local surface plasma resonance is excited at the junction of the metal structure and the medium, and the absorption of the central wavelength of the metal structure in the range of 3~5μm is enhanced, thereby realizing the band-stop filtering function of the mid-infrared spectrum. The metal structure is specifically a cross structure, and the cross structure is a centrally symmetrical structure, which can make the cross structure have the characteristics of being insensitive to X and Y polarizations, so as to filter incident light of different polarization directions, and improve the application range of the metasurface mid-infrared band-stop filter. The metasurface mid-infrared band-stop filter of the disclosed embodiment has a filtering center wavelength range of 3~5μm. The metasurface mid-infrared band-stop filter can achieve band-stop filtering of light in the mid-infrared spectrum. At the same time, the metasurface mid-infrared band-stop filter also has the advantages of narrow bandwidth and small overall volume; by adjusting the parameters of the cross metal structure, it is also possible to filter light of different center wavelengths in the mid-infrared spectrum; and by setting a first anti-reflection layer between the substrate and the metasurface layer, the transmittance can also be improved. In addition, the metasurface mid-infrared band-stop filter is small in size, which can realize the miniaturization and integration of infrared detectors. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the overall structure of the metasurface mid-infrared band-stop filter of an embodiment of the present disclosure; Figure 2 for Figure 1 A top view of the metasurface mid-infrared band-stop filter shown; Figure 3 for Figure 2 The overall structural diagram of the filter unit shown; Figure 4 for Figure 2 A partial structural schematic diagram of the filtering unit shown; Figure 5 for Figure 3 Schematic diagram of the arrangement of the cross structure shown; Figure 6 for Figure 3 A schematic diagram of the structure of the cross structure shown; Figure 7is a transmission spectrum diagram of the metasurface mid-infrared band-stop filter of an embodiment of the present disclosure; Figure 8 Schematic diagram of a substrate before step S100 of the method for preparing a metasurface mid-infrared band-stop filter according to an embodiment of the present disclosure; Fig. 9 Schematic diagram of step S100 of the method for preparing a metasurface mid-infrared band-stop filter according to an embodiment of the present disclosure; Fig.10 Schematic diagram of step S200 of the method for preparing a metasurface mid-infrared band-stop filter according to an embodiment of the present disclosure; Fig.11 Schematic diagram of step S300 of the method for preparing a metasurface mid-infrared band-stop filter according to an embodiment of the present disclosure.

[0017] The reference numerals in the accompanying drawings represent the following: 100. Metasurface mid-infrared band-stop filter; 10. Substrate; 20. a first anti-reflection layer; 30. Super surface layer; 31. Filter unit; 311. Filter pixel; 3111. Cross structure; 3112. Isolator; 40. A second anti-reflection layer; 50. Metal layer; P, period; L, long side; S, short side; H, thickness of the cross structure. DETAILED DESCRIPTION

[0018] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0019] It should be understood that the terms used herein are only for the purpose of describing specific example embodiments and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" as used herein may also be meant to include plural forms. The terms "include", "comprise", "contain", and "have" are inclusive, and therefore specify the existence of stated features, steps, operations, elements and / or parts, but do not exclude the existence or addition of one or more other features, steps, operations, elements, parts, and / or combinations thereof. The method steps, processes, and operations described herein are not interpreted as necessarily requiring them to be performed in the specific order described or illustrated, unless the execution order is clearly indicated. It should also be understood that additional or alternative steps may be used.

[0020] Although the terms first, second, third, etc. can be used in the text to describe multiple elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms can only be used to distinguish an element, component, region, layer or section from another region, layer or section. Unless the context clearly indicates, terms such as "first", "second" and other numerical terms do not imply order or sequence when used in the text. Therefore, the first element, component, region, layer or section discussed below can be referred to as the second element, component, region, layer or section without departing from the teaching of the example embodiments.

[0021] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature as shown in the figure, such as "inside", "outside", "inner side", "outer side", "below", "below", "above", "above", etc. Such spatial relative terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the figure. For example, if the device in the figure is turned over, the element described as "below other elements or features" or "below other elements or features" will be subsequently oriented to "above other elements or features" or "above other elements or features". Therefore, the example term "below..." may include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or in other directions) and the spatial relative descriptors used in the text are interpreted accordingly.

[0022] like Figures 1 to 6 As shown, the first aspect of the present disclosure provides a metasurface mid-infrared band-stop filter. Along the thickness direction of the metasurface mid-infrared band-stop filter, the metasurface mid-infrared band-stop filter 100 includes in sequence: a substrate 10, a first anti-reflection layer 20 and a metasurface layer 30. The metasurface layer 30 includes: at least one filtering unit 31, each filtering unit 31 includes a plurality of filtering pixels 311, each filtering pixel 311 includes a plurality of cross structures 3111 arranged in an array, and the period P of any two filtering pixels 311 in each filtering unit 31 is different, and the cross structure 3111 is made of metal.

[0023] The metasurface mid-infrared band-stop filter 100 of the disclosed embodiment includes a substrate 10, a first anti-reflection layer 20 and a metasurface layer 30, wherein the first anti-reflection layer 20 is disposed on the surface of the substrate 10, and the metasurface layer 30 is disposed on the surface of the first anti-reflection layer 20 away from the substrate 10. The metasurface layer 30 includes: at least one filtering unit 31, each filtering unit 31 includes a plurality of filtering pixels 311, and the structure of each filtering pixel 311 is arranged in a periodic P manner, and the period P of any two filtering pixels 311 in each filtering unit 31 is different, that is, the period P of the plurality of filtering pixels 311 in each filtering unit 31 is different, that is, the filtering spectral bands of the plurality of filtering pixels 311 in each filtering unit 31 are different, so that each filtering unit 31 can attenuate light of a plurality of different mid-infrared spectral bands. Each filter pixel 311 includes a plurality of metal structures arranged in an array. When mid-infrared light is incident on the surface of the metal structure, the local surface plasma resonance is excited at the interface between the metal structure and the medium, enhancing the absorption of the central wavelength of the metal structure in the range of 3 to 5 μm, thereby realizing the band-stop filtering function of the mid-infrared spectrum. The metal structure is specifically a cross structure 3111, which is a centrally symmetrical structure, so that the cross structure 3111 has the characteristic of being insensitive to X and Y polarizations, so as to filter incident light of different polarization directions, thereby improving the application range of the metasurface mid-infrared band-stop filter.

[0024] The metasurface mid-infrared band-stop filter 100 of the embodiment of the present disclosure has a filtering central wavelength range of 3~5μm. The metasurface mid-infrared band-stop filter 100 can be used to achieve band-stop filtering of light in the mid-infrared spectrum. At the same time, the metasurface mid-infrared band-stop filter 100 also has the advantages of narrow bandwidth and small overall volume. By adjusting the parameters of the cross metal structure, it is also possible to filter light with different central wavelengths in the mid-infrared spectrum. By setting a first transmittance-enhancing layer 20 between the substrate 10 and the metasurface layer 30, the transmittance can also be improved.

[0025] It should be noted that the period P in this embodiment refers to the center distance between two adjacent cross structures 3111 in each filtering pixel 311. Figure 5 As shown, the distance between the cross centers of two adjacent cross structures 3111. The cross structure 3111 includes two rectangular structures of the same size arranged symmetrically. The long side L of the cross structure 3111 refers to the length of any rectangular structure, and the short side S of the cross structure 3111 refers to the width of any rectangular structure. Figure 6 shown.

[0026] Specifically, the metasurface layer 30 may include a filter unit 31, and a filter unit 31 includes a plurality of filter units 31 with different periods P, which can filter light of different central wavelengths in the mid-infrared spectrum. The metasurface layer 30 also includes a plurality of two or more filter units 31, and the two or more filter units 31 are regularly arranged together to increase the number of filter units 31 per unit area, so as to improve the filtering effect of the metasurface mid-infrared band-stop filter 100.

[0027] In some embodiments of the present disclosure, Figure 2 , Figure 3 As shown, each filter unit 31 includes n*n filter pixels 311, where n≥2. The n*n filter pixels 311 are arranged in an array, specifically, the n*n filter pixels 311 form an array arrangement of a square with n rows and n columns. In this embodiment, each filter unit 31 includes 3*3 filter pixels 311, and 9 filter pixels 311 form an array arrangement of a square with 3 rows and 3 columns. The size of the filter unit 31 arranged in a square is 75μm×75μm, and the size of each filter pixel 311 is 25μm×25μm. The filtering wavelengths of any two of the nine filtering pixels 311 are different. The filtering wavelengths of the nine filtering pixels 311 are 3.1 μm, 3.3 μm, 3.5 μm, 3.7 μm, 3.9 μm, 4.1 μm, 4.3 μm, 4.5 μm, and 4.7 μm, respectively. The transmission spectra of the nine filtering pixels 311 are as follows: Figure 7 shown.

[0028] In this embodiment, n can also be 2, 4, 5, 6, 7, 8, 9, 10, or n is other values ​​greater than 2. Correspondingly, the number of filtering wavelengths of each filtering pixel 311 is n*n, and the filtering wavelengths of any two filtering pixels 311 among the n*n filtering pixels 311 are different.

[0029] On the basis that n is equal to 3, the metasurface mid-infrared band-stop filter 100 of this embodiment includes 640*512 filter pixels 311, among which some filter units 31 located at the edge of the metasurface layer 30 are incomplete filter units 31, that is, some filter pixels 311 in the complete filter unit 31 serve as the edge of the metasurface layer 30, and the remaining filter pixels 311 in the complete filter unit 31 are removed.

[0030] In some embodiments of the present disclosure, Figure 4As shown, the surface of the first anti-reflection layer 20 facing away from the substrate 10 is provided with an isolating member 3112, and the isolating member 3112 isolates two adjacent filter pixels 311. Since the periods P of the two adjacent filter pixels 311 are different, that is, the structures of the two filter pixels 311 are different and the filtering wavelengths are different, the two adjacent filter pixels 311 are isolated by the isolating member 3112 to reduce the mutual interference between the two adjacent filter pixels 311, thereby improving the accuracy of the filter pixels 311 filtering the corresponding wavelengths, and at the same time, ensuring that the central wavelength of the metasurface mid-infrared band-stop filter 100 is in the range of 3μm~5μm, ensuring that the bandwidth is within the expected range, thereby improving the accuracy of the metasurface mid-infrared band-stop filter 100. Specifically, the two adjacent filter pixels 311 can come from the same filter unit 31, and the two adjacent filter pixels 311 can also come from different filter units 31.

[0031] Furthermore, in order to ensure that the isolation member 3112 does not affect the filtering accuracy of the filtering pixel 311, the isolation member 3112 does not contact the cross structure 3111 of the filtering pixel 311. Specifically, the distance between the isolation member 3112 and the closest cross structure 3111 on either side is greater than 100 nm, and within this distance range, the isolation member 3112 will not interfere with the cross structure 3111. And this distance range meets the requirements of the processing technology.

[0032] In some embodiments of the present disclosure, the isolating member 3112 and the cross structure 3111 are made of the same metal material to reduce the influence of the material of the isolating member 3112 on the filtering effect of the cross structure 3111. Further, the materials of the isolating member 3112 and the cross structure 3111 include but are not limited to aluminum, gold, copper, etc. Specifically, in this embodiment, the isolating member 3112 and the cross structure 3111 are both made of aluminum metal to reduce the cost of the metasurface mid-infrared band-stop filter 100.

[0033] In some embodiments of the present disclosure, the thickness of the isolating member 3112 is equal to the thickness of the cross structure 3111. The thickness of the isolating member 3112 is equal to the thickness of the cross structure 3111, and the isolating member 3112 can isolate two adjacent filtering pixels 311 to reduce the mutual interference between the two filtering pixels 311.

[0034] In some embodiments of the present disclosure, the width range of the isolation member 3112 is 1.50 μm to 3.00 μm. The isolation member 3112 can ensure that two adjacent filter pixels do not interfere with each other within this width range. At the same time, within this width range, there is a certain distance between the isolation member 3112 and the cross structure 3111 of the filter pixel 311, that is, the isolation member 3112 does not contact the cross structure 3111 of the filter pixel 311.

[0035] In some embodiments of the present disclosure, the range of the long side L of the cross structure 3111 is 0.80 μm to 1.50 μm, the range of the short side S of the cross structure 3111 is 70 nm to 120 nm, the range of the thickness H of the cross structure 3111 is 40 nm to 100 nm, and the range of the period P of the cross structure 3111 is 1.60 μm to 3.00 μm. Within the range of the long side L, the short side S, the thickness H and the period P of the cross structure 3111, the band-stop absorption of certain wavelengths can be achieved. By adjusting at least one parameter of the long side L, the short side S, the thickness H and the period P of the cross structure 3111, the number, arrangement and other parameters of the cross structure 3111 in the filter pixel 311 can be adjusted, thereby changing the structure of the filter pixel 311, thereby adjusting the parameters such as the number of filter bands and the central wavelength of the super surface mid-infrared band-stop filter 100, and achieving absorption of specific wavelengths. In some embodiments of the present disclosure, a second anti-reflection layer 40 is provided on the side of the substrate 10 facing away from the super surface layer 30, that is, the first anti-reflection layer 20 and the second anti-reflection layer 40 are respectively provided on opposite sides of the substrate 10. The transmittance of the substrate 10 can be improved by the second anti-reflection layer 40. Specifically, the first anti-reflection layer 20 and the second anti-reflection layer 40 can be made of the same material or different materials, as long as the transmittance of the substrate 10 can be improved. In this embodiment, it is preferred that the first anti-reflection layer 20 and the second anti-reflection layer 40 are made of the same material.

[0036] like Figures 8 to 11 As shown, the second aspect of the present disclosure proposes a method for preparing a metasurface mid-infrared band-stop filter, which is used to prepare the metasurface mid-infrared band-stop filter 100 according to any of the above embodiments, and the preparation method comprises: S100: depositing an anti-reflection material on the surface of the substrate 10 to form a first anti-reflection layer 20; S200: sputtering metal on the surface of the first anti-reflection layer 20 to form a metal layer 50; S300: etching the surface of the metal layer 50 by an etching method to obtain a super surface layer 30 with a cross structure arranged in an array.

[0037] The preparation method of the metasurface mid-infrared band-stop filter 100 disclosed in the present invention comprises the following steps: first, depositing an anti-reflection material on one surface of a substrate 10 to form a first anti-reflection layer 20 on the surface of the substrate 10; then, sputtering a metal material on the surface of the first anti-reflection layer 20 to form a metasurface layer 30 on the surface of the first anti-reflection layer 20; finally, spin-coating an electron resist on the metal metasurface layer 30, and then performing an imaging process, and etching the imaged metasurface layer 30 with an electron beam, thereby forming a cross-structured metasurface layer 30 on the surface of the first anti-reflection layer 20. The metasurface mid-infrared band-stop filter 100 prepared according to the preparation method disclosed in the present invention has a filtering center wavelength range of 3~5μm. The metasurface mid-infrared band-stop filter 100 can be used to achieve band-stop filtering of light in the mid-infrared spectrum. At the same time, the metasurface mid-infrared band-stop filter 100 also has the advantages of narrow bandwidth and small overall volume; by adjusting the parameters of the cross metal structure, it is also possible to filter light with different center wavelengths in the mid-infrared spectrum; and by setting a first transmittance-enhancing layer 20 between the substrate 10 and the metasurface layer 30, the transmittance can also be improved.

[0038] In step S100, the material of the substrate 10 is aluminum oxide, and the thickness of the aluminum oxide substrate 10 is 500 μm. The refractive index of the aluminum oxide substrate 10 of this thickness in the 3.1 μm~4.7 μm band is about 1.67. Magnesium fluoride is deposited on the surfaces of the opposite sides of the aluminum oxide substrate 10 to form a first anti-reflection layer 20 and a second anti-reflection layer 40 on the opposite sides of the aluminum oxide substrate 10. The first anti-reflection layer 20 and the second anti-reflection layer 40 are both magnesium fluoride films, the thickness of the magnesium fluoride film is 634 nm, and the refractive index of magnesium fluoride is 1.34. Under the above-mentioned size of the magnesium fluoride film, the optical path in the magnesium fluoride film is about one-fourth of the central wavelength of the metasurface mid-infrared band-stop filter 100.

[0039] In other embodiments of the present disclosure, different materials for the substrate 10 may also be selected according to the working environment of the metasurface mid-infrared band-stop filter 100. When the working environment of the metasurface mid-infrared band-stop filter 100 is a normal temperature environment, materials such as calcium fluoride and magnesium fluoride with low refractive index and high transmittance in the mid-infrared band may be selected as the substrate 10 material; when the working environment of the metasurface mid-infrared band-stop filter 100 is a low temperature environment and the metasurface mid-infrared band-stop filter 100 needs to be bonded to other devices, materials such as aluminum oxide and amorphous silicon may be selected as the substrate 10 material to reduce the tearing of the substrate 10 caused by thermal expansion and improve the stability and reliability of the substrate 10.

[0040] In step S200, metal aluminum is sputtered on the surface of the first anti-reflection layer 20 to form a metal layer 50, i.e., an aluminum film, on the surface of the first anti-reflection layer 20. Specifically, the thickness of the aluminum film is 50 nm. An electronic resist is spin-coated on the aluminum film, and then a patterning process is performed on the surface of the aluminum film on which the electronic resist is spin-coated, i.e., a cross structure pattern arranged in an array is formed on the surface of the aluminum film through a mask.

[0041] Specifically, a plurality of cross structures arranged in an array form a filter pixel pattern, a plurality of filter pixel patterns arranged regularly form a filter unit pattern, and a plurality of filter unit patterns arranged regularly form the pattern of the super surface layer 30. Two adjacent filter pixels are divided by a spacer pattern.

[0042] In step S300, according to the pattern on the surface of the aluminum film, an ion beam is used to etch the surface of the aluminum film so that the aluminum film forms a plurality of cross structures arranged in an array, that is, a super surface layer 30 with cross structures arranged in an array is obtained.

[0043] Specifically, the super surface layer 30 includes a plurality of regularly arranged filter units, each filter unit includes a plurality of regularly arranged filter pixels, each filter pixel includes a plurality of cross structures arranged in an array, and an isolation member is provided between two adjacent filter pixels to reduce mutual interference between the two adjacent filter pixels.

[0044] A third aspect of the present disclosure proposes an infrared detector, which includes the metasurface mid-infrared band-stop filter 100 according to any of the above embodiments.

[0045] The pixels of the infrared detector disclosed in the present invention correspond to the metasurface mid-infrared band-stop filter 100, and the infrared detector can obtain multiple narrow-band mid-infrared spectral information through the metasurface mid-infrared band-stop filter 100. Specifically, when the metasurface mid-infrared band-stop filter 100 is divided into 640*512 filter pixels, the corresponding resolution of the infrared detector is 640*512. The metasurface mid-infrared band-stop filter 100 can be integrated with the existing infrared detector to provide the infrared detector with more spectral bands and narrow bandwidth high-precision information input.

[0046] Since the metasurface mid-infrared band-stop filter 100 is relatively small in size, the integration of the metasurface mid-infrared band-stop filter 100 in the infrared detector will not increase the volume of the infrared detector too much, thus avoiding the excessive volume of the integrated infrared detector, realizing the miniaturization and integration of the infrared detector, saving equipment load, and improving the reliability of the infrared detector. In addition, the integration of the metasurface mid-infrared band-stop filter 100 with the infrared detector can realize accurate and efficient recognition of mid-infrared band light, realize accurate and efficient filtering of mid-infrared band light, and at the same time, significantly improve the number and resolution of filtering spectrum bands.

[0047] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present disclosure, but the present disclosure is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and substance of the present disclosure, and these modifications and improvements are also considered to be within the scope of protection of the present disclosure.

Claims

1. A metasurface mid-infrared band-stop filter, characterized in that: Along the thickness direction of the metasurface mid-infrared band-stop filter, the metasurface mid-infrared band-stop filter includes: a substrate, a first anti-reflection layer and a metasurface layer in sequence, and the metasurface layer includes: at least one filtering unit, each of the filtering units includes a plurality of filtering pixels, each of the filtering pixels includes a plurality of cross structures arranged in an array, the periods of any two of the filtering pixels in each of the filtering units are different, and the cross structure is made of metal.

2. The metasurface mid-infrared band-stop filter according to claim 1, characterized in that: Each of the filtering units includes n*n filtering pixels, where n≥2.

3. The metasurface mid-infrared band-stop filter according to claim 1 or 2, characterized in that: A spacer is provided on a surface of the first anti-reflection layer facing away from the substrate, and the spacer separates two adjacent filtering pixels.

4. The metasurface mid-infrared band-stop filter according to claim 3, characterized in that: The isolation member and the cross structure are both made of metal aluminum, and the distance between the isolation member and the nearest cross structure is greater than 100 nm.

5. The metasurface mid-infrared band-stop filter according to claim 3, characterized in that: The width of the isolation member ranges from 1.50 μm to 3.00 μm.

6. The metasurface mid-infrared band-stop filter according to claim 1, characterized in that: The long side of the cross structure is in the range of 0.80 μm to 1.50 μm, the short side of the cross structure is in the range of 70 nm to 120 nm, and the thickness of the cross structure is in the range of 40 nm to 100 nm.

7. The metasurface mid-infrared band-stop filter according to claim 1, characterized in that: The period of the cross structure ranges from 1.60 μm to 3.00 μm.

8. The metasurface mid-infrared band-stop filter according to claim 1, characterized in that: A second anti-reflection layer is provided on the side of the substrate facing away from the super surface layer.

9. A method for preparing a metasurface mid-infrared band-stop filter, for preparing the metasurface mid-infrared band-stop filter according to any one of claims 1 to 8, characterized in that: The preparation method comprises: Depositing an anti-reflection material on the surface of the substrate to form a first anti-reflection layer; sputtering metal on the surface of the first anti-reflection layer to form a metal layer; The surface of the metal layer is etched by an etching method to obtain a super surface layer with a cross structure arranged in an array.

10. An infrared detector, characterized in that: The infrared detector comprises a metasurface mid-infrared band-stop filter according to any one of claims 1 to 8.

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