Infrared broadband absorber

Abstract

The invention provides an infrared broadband absorber. According to the invention, an efficient absorption structure is formed by introducing the non-antisymmetric Bragg structure layer and the metal material film with relatively high absorption rate. The phase change material and the dielectric material form an antisymmetric Bragg structure, the absorptivity of the device is further improved, and the MgF2 low-refractive-index layer is combined, and the materials and the thickness of each layer are optimized, so that effective reflection suppression and absorption enhancement of light with different wavelengths are realized. Compared with the prior art, the infrared broadband absorber is simple in structure, the absorption effect of 90% or above can be achieved within the ultra-wide range, the relative absorption bandwidth exceeds 152.8%, a great opportunity is provided for ultra-wide spectrum detection, a feasible technical approach is provided for ultra-wide spectrum confrontation and invisibility, and the infrared broadband absorber has the advantages of being high in practicability and wide in application range. And confrontation and stealth on active and passive composite sensing detection equipment are expected to be realized, and the application potential of the material in the fields of infrared absorption, infrared stealth, photothermal conversion, sensing and the like is expanded.

Description

Technical Field

[0001] The invention relates to the technical field of phase change materials, and in particular to an infrared broadband absorber. Background Art

[0002] With the rapid development of optical materials and nanomaterials technology, the application demand of infrared absorption materials in many fields, especially in infrared stealth, thermal management, photothermal conversion, infrared sensors and energy absorption, is increasing. Traditional absorption materials mainly absorb light in a specific band through metal-dielectric structures, but most existing technologies face the following problems: Narrow absorption bandwidth and inability to cover a wide band: Many existing infrared absorption materials can only achieve efficient absorption in a narrow band and are difficult to cover a wider infrared band, which limits their applicability in practical applications. Low absorption efficiency: Most traditional absorption materials can achieve high absorption in a specific band, but the overall absorption efficiency is generally not high, especially in applications with wide frequency bands (such as 1.7μm to 12μm), the absorption efficiency is often difficult to reach more than 90%. High reflectivity and difficulty in achieving low reflectivity: In practical applications, especially in stealth technology, low reflectivity materials are crucial. However, many existing materials have limitations in the balance between absorption efficiency and reflectivity, and cannot effectively suppress reflection, resulting in partial light energy loss. Narrow absorption band: Most broadband absorption is mainly concentrated in the range from visible light to 2500nm, and the absorption range cannot be further expanded. Or use gratings, metasurfaces and other special materials to achieve ultra-wideband absorption structures to solve these problems. These methods often cannot maintain electromagnetic impedance matching in the entire working frequency band, and the structure and processing technology are complex, and it is impossible to achieve ultra-wideband range and high absorption effects.

[0003] Based on the defects of current infrared absorption materials, it is necessary to improve them. Summary of the invention

[0004] In view of this, the present invention proposes an infrared broadband absorber and a preparation method thereof, and a method for detecting cortisol concentration, so as to solve or at least partially solve the defects existing in the prior art.

[0005] In a first aspect, the present invention provides an infrared broadband absorber, comprising:

[0006] substrate;

[0007] A first metal layer, located on the surface of the substrate;

[0008] a second metal layer, located on the first metal layer away from the substrate surface;

[0009] A first dielectric layer, located on the second metal layer away from the substrate surface;

[0010] A third metal layer, located on the first dielectric layer away from the substrate surface;

[0011] an asymmetric Bragg structure layer, located on the third metal layer away from the substrate surface, the asymmetric Bragg structure layer comprising a phase change layer and a dielectric layer which are staggered and stacked with each other; the material of the dielectric layer is a phase change material or a dielectric material;

[0012] An anti-reflection layer, located on the substrate surface of the asymmetric Bragg structure layer;

[0013] Wherein, the imaginary refractive index of the phase change layer in the infrared band is less than 1; the refractive index of the phase change layer is greater than 1;

[0014] The imaginary refractive index of the dielectric layer in the infrared band is less than 1;

[0015] The refractive index of the dielectric layer is greater than 2;

[0016] The thickness of the phase change layer and the dielectric layer are both less than 1 μm.

[0017] Preferably, the thickness d of the phase change layer is i =N×(λ / 4n i )+Δd1, where N is an integer, 0﹤Δd1≤λ / 4n i , λ represents wavelength, λ≥350nm, n i represents the refractive index of the phase change layer;

[0018] The thickness d of the dielectric layer j =N×(λ / 4n j )+Δd2, where N is the sum of the number of phase change layers and dielectric layers in the asymmetric Bragg structure layer, 0﹤Δd2≤λ / 4n j , λ represents wavelength, λ≥350nm, n j Represents the refractive index of the dielectric layer.

[0019] Preferably, the average reflectivity R of the asymmetric Bragg structure layer is HR,max Less than 30%.

[0020] Preferably, the imaginary refractive index of the anti-reflection layer in the infrared band is less than 1, and the refractive index of the anti-reflection layer is less than the refractive indexes of the phase change layer and the dielectric layer.

[0021] Preferably, the sum of the number of phase change layers and dielectric layers in the asymmetric Bragg structure layer is ≥4.

[0022] Preferably, the phase change material used in the phase change layer includes at least one of GeTe, SbTe, SnSb, AgInSbTe, InSbTe, GeSb, Se2Sb3, Sb2S3 and GST;

[0023] And / or, the material of the anti-reflection layer includes at least one of fluoride, oxide, nitride, sapphire, zinc selenide, zinc sulfide, titanium oxide, hafnium oxide, and polytetrafluoroethylene.

[0024] Preferably, the material of the first dielectric layer is a dielectric material;

[0025] The material of the dielectric layer is a dielectric material, and the dielectric material includes at least one of tantalum pentoxide, lithium niobate, silicon, silicon nitride, silicon dioxide, calcium fluoride, polytetrafluoroethylene, aluminum oxide, quartz, silicon, titanium dioxide, tantalum pentoxide, zinc sulfide, aluminum nitride and magnesium aluminum spinel;

[0026] The imaginary refractive index of the first dielectric layer in the infrared band is less than 1; the refractive index of the first dielectric layer is greater than 2.

[0027] Preferably, the material of the dielectric layer is a phase change material, and the phase change material includes at least one of GeTe, SbTe, SnSb, AgInSbTe, InSbTe, GeSb, Se2Sb3, Sb2S3 and GST.

[0028] Preferably, the materials used for the first metal layer, the second metal layer and the third metal layer include at least one of gold, aluminum, copper, silver, titanium, molybdenum, nickel, chromium, iron and germanium;

[0029] The imaginary refractive index of the first metal layer and the third metal layer in the infrared band is greater than 2;

[0030] The refractive index of the first metal layer, the second metal layer and the third metal layer is greater than 2;

[0031] The thickness of the first metal layer is greater than 100 nm and less than 1 μm;

[0032] The thickness of the second metal layer is greater than 50 nm and less than 1 μm;

[0033] The thickness of the third metal layer is less than 200 nm and greater than 10 nm;

[0034] The thickness of the anti-reflection layer is less than 1 μm;

[0035] The thickness of the phase change layer is less than 500 nm.

[0036] Preferably, the asymmetric Bragg structure layer includes a first phase change layer, a second dielectric layer, a second phase change layer, a third dielectric layer, a third phase change layer, and a fourth dielectric layer which are stacked in sequence;

[0037] Wherein, the material of the anti-reflection layer is MgF2, and the thickness is 450-1000nm;

[0038] The material of the fourth dielectric layer is TiO2, and the thickness is 200nm-500nm;

[0039] The material of the third phase change layer is Ag5In4Sb 76 Te 17 , thickness is 10nm~200nm;

[0040] The material of the third dielectric layer is TiO2, and the thickness is 10nm to 400nm;

[0041] The material of the second phase change layer is Ag5In4Sb 76 Te 17 , thickness is 10nm~400nm;

[0042] The material of the second dielectric layer is TiO2, and the thickness is 20nm~400nm;

[0043] The material of the first phase change layer is Ag5In4Sb 76 Te 17 , thickness is 20nm-400nm;

[0044] The material of the third metal layer is Cr, and the thickness is 20nm to 300nm;

[0045] The material of the first dielectric layer is TiO2, and the thickness is 20nm to 400nm;

[0046] The material of the second metal layer is Ge, and the thickness is 50nm-200nm; the material of the first metal layer is Cr, and the thickness is greater than 300nm.

[0047] The infrared broadband absorber of the present invention has the following beneficial effects compared with the prior art:

[0048] 1. The infrared broadband absorber of the present invention comprises a substrate, a first metal layer, a second metal layer, a first dielectric layer, a third metal layer, an asymmetric Bragg structure layer, and an anti-reflection layer; the present invention introduces a non-antisymmetric Bragg structure layer and a metal material film with a high absorptivity to form an efficient absorption structure. The phase change material and the dielectric material form an antisymmetric Bragg structure, which further improves the absorptivity of the device, and is combined with the MgF2 low refractive index layer, and by optimizing the materials and thickness of each layer, the reflection of light of different wavelengths can be effectively suppressed and the absorption can be enhanced. The structure can be made by conventional thin film preparation processes such as magnetron sputtering, and has the advantages of high ultra-wideband absorption efficiency, simple preparation, and large-area preparation. Compared with the prior art, the infrared broadband absorber of the present invention has a simple structure and can achieve an absorption effect of more than 90% in an ultra-wide range, and the relative absorption bandwidth exceeds 152.8%. It not only provides a major opportunity for ultra-wide spectrum detection, but also provides a feasible technical approach for ultra-wide spectrum confrontation and stealth. It is expected to achieve confrontation and stealth against active and passive composite sensing detection equipment, and expand the application potential of materials in the fields of infrared absorption, infrared stealth, photothermal conversion and sensing. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0050] Figure 1 It is a structural schematic diagram of the infrared broadband absorber of the present invention;

[0051] Figure 2 is an absorption spectrum diagram of the infrared broadband absorber in Example 1 when it is in an amorphous state;

[0052] Figure 3 This is the absorption spectrum of the infrared broadband absorber in comparative example 1 when it is in an amorphous state;

[0053] Figure 4 This is the absorption spectrum of the infrared broadband absorber in the amorphous state in Comparative Example 2;

[0054] Figure 5 This is the absorption spectrum of the infrared broadband absorber in the amorphous state in Comparative Example 3;

[0055] Figure 6 This is an absorption spectrum of the infrared broadband absorber in the amorphous state in Comparative Example 4;

[0056] Figure 7This is an absorption spectrum of the infrared broadband absorber in the amorphous state in Comparative Example 5;

[0057] Figure 8 This is an absorption spectrum of the infrared broadband absorber in the amorphous state in Comparative Example 6;

[0058] Fig. 9 This is an absorption spectrum of the infrared broadband absorber in the amorphous state in Comparative Example 7;

[0059] Fig.10 This is an absorption spectrum of the infrared broadband absorber in the amorphous state in Comparative Example 8;

[0060] Fig.11 This is an absorption spectrum of the infrared broadband absorber in the amorphous state in Comparative Example 9;

[0061] Fig.12 This is an absorption spectrum of the infrared broadband absorber in the amorphous state in Comparative Example 10;

[0062] Fig.13 Reflection and absorption spectra of an asymmetric Bragg structure layer in an amorphous state prepared directly on a substrate according to the method of Example 1;

[0063] Fig.14 is an absorption spectrum diagram of the infrared broadband absorber in the amorphous state in Example 1;

[0064] Fig.16 This is a schematic diagram of the structure of the infrared broadband absorber in Comparative Example 11;

[0065] Fig.15 The absorption spectra of the infrared broadband absorber in the amorphous state and the crystalline state in Example 1;

[0066] Fig.17 The spectrum of the infrared broadband absorber in comparative example 11 and example 1 is compared within a wavelength of 20000 nm;

[0067] Fig.18 The spectrum of the infrared broadband absorber in the comparative example 11 and the embodiment 1 is compared within the wavelength range of 1700nm to 12000nm;

[0068] Fig.19 The spectrum of the infrared broadband absorber in comparative example 11 and example 1 is compared within the wavelength range of 380nm to 1700nm;

[0069] Fig. 20 is a reflectivity curve of the asymmetric Bragg structure layer in Example 1; DETAILED DESCRIPTION

[0070] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0071] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments. In addition, in the description of the present application, the term "including" means "including but not limited to". Various embodiments of the present invention may be in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a rigid limitation on the scope of the present invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the numbered ranges, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated in this article, it is meant to include any cited numbers (fractions or integers) within the indicated range.

[0072] The embodiment of the present application provides an infrared broadband absorber, comprising:

[0073] substrate;

[0074] A first metal layer, located on the surface of the substrate;

[0075] A second metal layer is located on the first metal layer away from the substrate surface;

[0076] A first dielectric layer is located on the second metal layer away from the substrate surface;

[0077] A third metal layer is located on the first dielectric layer away from the substrate surface;

[0078] an asymmetric Bragg structure layer, located on the third metal layer away from the substrate surface, the asymmetric Bragg structure layer comprising a phase change layer and a dielectric layer which are staggered and stacked with each other; the material of the dielectric layer is a phase change material or a dielectric material;

[0079] An anti-reflection layer is located on the surface of the asymmetric Bragg structure layer substrate;

[0080] Wherein, the imaginary refractive index of the phase change layer in the infrared band is less than 1; the refractive index of the phase change layer is greater than 1;

[0081] The imaginary refractive index of the dielectric layer in the infrared band is less than 1;

[0082] The refractive index of the dielectric layer is greater than 2;

[0083] The thickness of the phase change layer and the dielectric layer are both less than 1 μm.

[0084] The infrared broadband absorber of the present invention, such as Figure 1 As shown, it includes a substrate 112, a first metal layer 111, a second metal layer 110, a first dielectric layer 109, a third metal layer 108, an asymmetric Bragg structure layer, and an anti-reflection layer 101 which are stacked in sequence; the asymmetric Bragg structure layer includes a phase change layer and a dielectric layer which are stacked alternately, that is, the asymmetric Bragg structure layer includes a phase change layer / dielectric layer / phase change layer / dielectric layer, Figure 1 The asymmetric Bragg structure layer includes a first phase change layer 107, a second dielectric layer 106, a second phase change layer 105, a third dielectric layer 104, a third phase change layer 103, and a fourth dielectric layer 102 which are stacked in sequence; that is, the phase change layer and the dielectric layer in the asymmetric Bragg structure layer are interlaced three times, and the sum of the number of phase change layers and dielectric layers is 6; the first phase change layer 107 is bonded to the third metal layer 108; the fourth dielectric layer 102 is bonded to the anti-reflection layer 101; the phase change layers (such as the first phase change layer, the second phase change layer, and the third phase change layer mentioned above) are respectively bonded to the thermal field, the electric field, or the laser pulse. Under stimulation, a transition between a crystalline state and an amorphous state occurs, resulting in a phase change, and light is regulated by changes in the refractive index and the extinction coefficient before and after the phase change; the first metal layer, the second metal layer, and the third metal layer generate sufficient heat under electrical stimulation, so that the reflectivity and extinction coefficient of the phase change material of the phase change layer change when they transform between the amorphous state and the crystalline state, thereby achieving light regulation; specifically, phase change materials (such as AIST) have adjustable optical properties in different phases, and the propagation and absorption characteristics of light can be adjusted by regulating the phase change, thereby achieving efficient broadband absorption in a wide band.

[0085] The infrared broadband absorber of the present invention adopts a multi-layer metal-dielectric structure design. Through the change of the material refractive index and the increase of the number of layers, it can also effectively enhance the absorption and reduce the reflection loss, thereby improving the absorption efficiency. Specifically, the present invention introduces an asymmetric Bragg structure layer, accurately designs the refractive index and thickness of each layer of material, destroys constructive interference, and combines the regulation of phase change materials to achieve efficient absorption in the infrared wide band range, and the absorption rate can reach more than 90%. This structure not only significantly improves the absorption efficiency, but also reduces the reflectivity through reasonable design, and has extremely high application potential. The present invention realizes ultra-wideband dynamically adjustable efficient absorption in the 1.7μm to 12μm band through the multi-layer metal-asymmetric DBR structure design and the introduction of phase change materials. It is angle-insensitive and can further improve the absorption performance by adjusting the number of layers and the state of the phase change material. This technical strategy overcomes the inherent limitations of the existing structure, has a significant technical advancement significance, and opens up new possibilities for the further development of infrared wide-band absorption technology. The present invention not only provides a new idea for the design of infrared absorption structures, but also provides an effective solution to the technical problems of existing materials in broadband absorption, low reflectivity and tunable absorption.

[0086] The present invention adopts a new technical strategy, that is, a design idea of ​​a dynamically adjustable broadband absorber composed of a phase change material and a dielectric material with a high n (i.e., refractive index) value in the infrared region and a K (i.e., imaginary refractive index in the infrared band) value less than 1 (e.g., 0) and an absorptive metal with a high refractive index and extinction coefficient. Multilayer metal-dielectric design: The basic part of the structure includes a first metal layer / a second metal layer / a first dielectric layer / a third metal layer, such as Cr / Ge / TiO2 / Cr, wherein TiO2 and Ge are used as high refractive index materials, and Cr is a metal layer; such a design not only achieves a high initial absorption rate (30%), but also provides a basis for optical resonance and interference effects in the multilayer structure; in particular, the addition of a metal layer (Cr) helps to increase absorption through the interaction of conductivity loss and metal-medium interface reflection; a phase change material (such as AIST) is introduced as an absorption control layer, and AIST (Ag-In-Sb-Te) is a phase change material that can switch between an amorphous state and a crystalline state, and this phase change is accompanied by a change in the dielectric constant. This makes the absorption characteristics of the layer to electromagnetic waves change in different wavelength ranges, and can achieve tunable absorption by adjusting the phase state. In this scheme, as the dielectric layer phase change layer (such as AIST layer) and the dielectric layer (such as TiO2 layer) in the asymmetric Bragg structure layer are alternately increased, the total absorption rate of the asymmetric Bragg structure layer gradually increases, and finally reaches more than 90% in the range of 1.7μm to 12μm.

[0087] In some embodiments, when light (infrared band electromagnetic waves) is incident on the multilayer film of the infrared broadband absorber of the present invention, the refractive index mismatch between each layer will produce partial reflection and transmission. After multiple layers are superimposed, the light reflected back from the interfaces of different layers will interfere with each other. Once the reflection is suppressed, most of the incident light will enter the structure and be absorbed by the loss of the internal material; coupled with the bottom first metal layer (such as Cr) blocking the transmission, resulting in a high absorption rate in the end. By reasonably designing the layer thickness and refractive index, the interface reflections can be offset (destructive interference) in a wide range of bands, thereby greatly suppressing the overall reflection. Ideally, to achieve near-zero reflection and high absorption, it is necessary to gradually transition the equivalent "optical impedance" of the multilayer film to match the air and the substrate to reduce the interface refractive index difference. MgF2 is usually used as an anti-reflection layer to achieve an anti-reflection effect. TiO2, Ge, Cr, AIST and other layers are alternately superimposed, so that the equivalent impedance to light in the infrared range is close to that of air, and the reflection is greatly reduced. Specifically, metal (Cr) loss: The metal Cr layer has high electrical conductivity and ohmic loss. When electromagnetic waves enter the metal layer, part of the energy is converted into heat and absorbed. When multiple layers of metal are superimposed, if the interference conditions are met at the appropriate wavelength and the reflection is suppressed, the metal loss can significantly contribute to high absorption. AIST (Ag5In5Sb 60 Te 30) Absorption of phase change materials: Phase change materials (AIST) usually have a high imaginary refractive index (k value) in the infrared band, so they can provide effective optical loss. In different phases (amorphous / crystalline), the refractive index and extinction coefficient of AIST will change, but overall, AIST usually still maintains a certain absorption capacity in the infrared region. By periodically or quasi-periodically alternating AIST with TiO2, multiple resonant cavities or interference enhancement zones can be formed, further expanding the absorption band, forming the so-called multiple resonances or Fabry–Pérot resonance superposition, thereby covering an ultra-wide spectrum of 1.7μm to 11μm. Periodic / quasi-periodic stacking forms broadband resonance. The repeated alternation of AIST+TiO2 layers, combined with the bottom / middle metal Cr layer and the anti-reflection layer MgF2, constitute multiple optical microcavities. Each microcavity will have a resonant absorption peak for a specific wavelength. By stacking multiple layers and carefully designing the thickness, the various absorption peaks are "stitched" or "partially overlapped" in the spectrum, thus forming continuous broadband absorption. This is the common multilayer interference theory + metamaterial / phase change material absorption layer combination idea - if each layer is slightly different (thickness or refractive index), high absorption can be obtained over a large range. Low reflection + no transmission = high absorption anti-reflection layer (MgF2): MgF2 has a low refractive index (about 1.38) and can be used as an anti-reflection layer in the infrared to visible range. It can reduce the refractive index difference between the incident light and the underlying dielectric layer, thereby further reducing surface reflection. Bottom metal (Cr, 500nm): The 500nm thick Cr bottom layer is almost opaque and will block light from transmitting to the substrate or the back, so that most of the incident light can only be lost inside the structure. When multilayer interference suppresses the reflection to a very small level and the transmission is blocked by the bottom metal, it will result in absorptivity ≈ 1 - reflectivity - transmittance ≈ 1 - a very small number ≈ more than 90%. Additional potential for phase tuning of phase change materials: AIST (Ag5In5Sb 60 Te 30 ) is that the phase change is adjustable (such as thermal or electro-induced phase change). In different phases, the refractive index (n) and extinction coefficient (k) of the material will be different, resulting in reversible changes in the resonance position or absorption bandwidth. This not only enables efficient broadband absorption, but also further brings adjustable absorption / adjustable reflection functions (if the design can change the position or intensity of the absorption peak during the phase change process). By precisely designing the number of layers, the refractive index of the material, and the switching of the phase change material, it can cover a wider band range and enhance the diversity of application scenarios compared to the traditional single absorption structure. Angled filter rod shape: The anti-reflection layer material uses MgF2 with a lower refractive index to further improve the angle insensitivity, and can protect the structure from environmental influences while adjusting the overall optical properties. The construction of an asymmetric DBR structure can be an alternating combination of phase change materials and dielectric materials, or an alternating combination of dielectric materials and phase change materials.

[0088] In some embodiments, in optics, the imaginary refractive index of a material in the infrared band is a part of the complex refractive index, representing the absorption and loss characteristics of the material for infrared light.

[0089] In some embodiments, the asymmetric Bragg structure layer is specifically AIST / TiO2 / AIST / TiO2 / AIST / TiO2, and the asymmetric Bragg structure layer has obvious destructive interference; specifically, when the thickness of the phase change layer d i =N×(λ / 4n i )+Δd1, where N is an integer (e.g., N is 0, 1, 2, 3, etc.), 0﹤Δd1≤λ / 4n i , λ represents wavelength, λ≥350nm, n i represents the refractive index of the phase change layer; the thickness of the dielectric layer d j =N×(λ / 4n j )+Δd2, where N is an integer (e.g., N is 0, 1, 2, 3, etc.), 0﹤Δd2≤λ / 4n j ,λ indicates,λ≥350nm,n j It represents the refractive index of the dielectric layer, which is used to destroy the constructive interference condition, thereby reducing the reflectivity. Properly increasing the number of layers can significantly increase the absorption rate. The optimal total number of layers of the asymmetric Bragg structure layer stack is 2-20 layers.

[0090] In some embodiments, the average reflectivity R of the asymmetric Bragg structure layer is HR,max Less than 30%.

[0091] In some implementations, the sum of the number of phase change layers and dielectric layers in the asymmetric Bragg structure layer is ≥4.

[0092] In some embodiments, the K value (i.e., the imaginary refractive index in the infrared band) of the first metal layer 111 and the third metal layer 108 is greater than 2; the broadband absorption structure formed by the first metal layer 111, the second metal layer 110, the first dielectric layer 109, and the third metal layer 108 should show absorption characteristics in the long-wave band, the thickness of the first metal layer (thickness>300nm) should satisfy the requirement that light cannot penetrate, and the FP cavity (i.e., Fabry-Perot cavity) formed by the first metal layer 111, the second metal layer 110, the first dielectric layer 109, and the third metal layer 108 has a wide absorption characteristic for infrared light. The voltage applied to the first metal layer 111, the second metal layer 110, or the third metal layer 108 is regulated according to the magnitude of the current to control the crystallization and amorphization ratio of the phase change material in the phase change layer to regulate the absorption of the light.

[0093] In some implementations, the imaginary refractive index (K value) of the anti-reflection layer 101 in the infrared band is less than 1, and the refractive index of the anti-reflection layer 101 is less than the refractive indexes of the phase change layer and the dielectric layer.

[0094] In some implementations, the phase change material used in the phase change layer includes at least one of GeTe, SbTe, SnSb, AgInSbTe, InSbTe, GeSb, Se2Sb3, Sb2S3 and GST; wherein the atomic percentage of each is adjustable.

[0095] In some implementations, the material used for the anti-reflection layer is fluoride (MgF2, CaF2), oxide (SiO2, Al2O3), nitride (Si3N4), sapphire (Al2O3 single crystal), zinc selenide (ZnSe), zinc sulfide (ZnS), titanium oxide (TiO2), hafnium oxide (HfO2), polytetrafluoroethylene (PTFE), etc. The thickness of the anti-reflection layer is greater than 10nm.

[0096] In some implementations, the material of the first dielectric layer and the dielectric layer is a dielectric material, and the dielectric material includes tantalum pentoxide (Ta2O5), lithium niobate (LiNbO3), silicon (Si), silicon nitride (Si3N4), and low refractive index materials such as silicon dioxide (SiO2), calcium fluoride (CaF2), polytetrafluoroethylene (PTFE), aluminum oxide (Al2O3), quartz (SiO2), silicon (Si), titanium dioxide (TiO2), tantalum pentoxide (Ta2O5), zinc sulfide (ZnS), aluminum nitride (AlN) and magnesium aluminum spinel (MgAl2O4), etc.

[0097] In some implementations, the imaginary refractive index of the first dielectric layer in the infrared band is less than 1; and the refractive index of the first dielectric layer is greater than 2.

[0098] In some implementations, the material of the dielectric layer may also be a phase change material, and the phase change material includes at least one of GeTe, SbTe, SnSb, AgInSbTe, InSbTe, GeSb, Se2Sb3, Sb2S3 and GST; the percentage of each atom is adjustable.

[0099] In some implementations, the materials used for the first metal layer, the second metal layer, and the third metal layer include at least one of gold (Au), aluminum (Al), copper (Cu), silver (Ag), titanium (Ti), molybdenum (Mo), nickel (Ni), chromium (Cr), iron (Fe), germanium (Ge), etc.; the imaginary refractive index of the first metal layer and the third metal layer in the infrared band is greater than 2; the refractive index of the first metal layer, the second metal layer, and the third metal layer is greater than 2.

[0100] The above metals are all metals with strong infrared absorption performance. Their high electrical conductivity makes them show high absorption efficiency in the infrared band. Metals also play an important role in infrared radiation absorption and thermal management, especially in high-temperature and infrared optical devices. Among them, the thickness of the first metal layer 111 is greater than 100nm and less than 1μm; the thickness of the second metal layer 110 is greater than 50nm and less than 1μm; the thickness of the third metal layer 108 is less than 200nm and greater than 10nm. Since the increase in the thickness of the phase change layer will increase the temperature required for the crystallization of the phase change material, the more suitable thickness is within 1 micron. The phase change material of the phase change layer can be driven by voltage. When driven by voltage, the first metal metal layer 111 of the broadband absorption cavity structure applies voltage to cause the phase change material to undergo phase change. The function of the first metal metal layer 111 is mainly to absorb light.

[0101] In some implementations, the thickness of the anti-reflection layer is less than 1 μm; the thickness of the phase change layer is less than 500 nm; and the thickness of the first metal layer is greater than 100 nm and less than 1 μm.

[0102] In some embodiments, preferably, the phase change material of the phase change layer in the asymmetric Bragg structure layer is Ag5In5Sb 60 Te 30 The material of the dielectric layer is TiO2, of which Ag5In5Sb 60 Te 30 TiO2 is a material with an extinction coefficient K value (i.e., an imaginary refractive index in the infrared band) of 0. The materials used for the first metal layer, the second metal layer, and the third metal layer are Ge and Cr, which are metals with high extinction coefficients. The phase change material in the broadband absorber cavity is a high refractive index with a loss of 0, including but not limited to Ag5In5Sb 60 Te 30 , and materials with such characteristics formed by doping; further, the phase change material of the phase change layer in the asymmetric Bragg structure layer may also include the following sulfur compounds and their alloys, including but not limited to: GST, GSST, IST, GeSbTe, AgInSbTe, InSbTe, AgSbTe, Ag2In4Sb 76 Te 17 (AIST) and other characteristic phase change materials with K value less than 1 and refractive index greater than 1 in the infrared band. In addition, the atomic percentages in the above chemical formulas can be changed. The phase change material can further contain at least one dopant, such as C and N. Preferably, the phase change material is Ag5In5Sb 60 Te 30 , which has large loss in the infrared range, large refractive index, and Ag5In5Sb 60 Te 30 Good thermal stability.

[0103] In some embodiments, the asymmetric Bragg structure layer includes a first phase change layer 107, a second dielectric layer 106, a second phase change layer 105, a third dielectric layer 104, a third phase change layer 103, and a fourth dielectric layer 102 which are stacked in sequence; the third phase change layer 103, the second phase change layer 105, and the first phase change layer 107 can be converted between a crystalline state and an amorphous state under electrical stimulation or laser stimulation, thereby causing the transmittance and reflectivity of the phase change layer to change; the asymmetric Bragg structure layer and the anti-reflection layer 101 together constitute an anti-reflection layer structure to further improve the absorption of the device; the third phase change layer 103, the second phase change layer 105, and the first phase change layer 107 can control the crystallization state of the phase change material by applying a voltage to the first metal layer 111. Specifically, a medium-intensity pulse voltage is applied to the first metal layer 111, and the metal layer generates heat, and the temperature of the phase change material rises to above the crystallization temperature under the action of heat. , a temperature range below the melting temperature, and maintained for a certain period of time, at which time the lattice is orderly arranged to form a crystalline state, realizing the transition from amorphous to crystalline; applying a short and strong voltage to the first metal layer 111, generating high heat in an instant, causing the temperature of the phase change material to rise above the melting temperature, destroying the long-range order of the crystalline state, and the pulse falling edge is very short, resulting in the phase change material being quickly cooled to below the crystallization temperature, so that the phase change material is fixed in the amorphous state, realizing the transition from crystalline to amorphous state, and the transmittance and reflectivity changes of the third phase change layer 103, the second phase change layer 105, and the first phase change layer 107 when they are mutually transformed between the amorphous state and the crystalline state are used to control the proportion of light absorption by the broadband absorption cavity, wherein different voltages are applied to the first metal layer 111 to make the phase change material layer change from amorphous to partially crystallized to completely crystallized, and the magnitude of the applied voltage depends on the needs of the actual situation, and the absorption ratio of the target light is adjusted according to actual needs. The phase change layer of the phase change broadband absorption cavity structure has very different absorption of light in different states. The phase change material is stable in the crystalline and amorphous states, so the voltage or laser can be removed when the phase change material is in a stable state. Therefore, the power consumption of the entire absorption device during the adjustment process is very low and it is dynamically adjustable.

[0104] In some embodiments, the substrate 112 is a flexible substrate or a rigid substrate; specifically, the substrate 112 may be a silicon substrate. The thickness of the substrate 112 is greater than 500 nm.

[0105] In some embodiments, Figure 1As shown, the infrared broadband absorber of the present invention comprises: a substrate, a first metal layer 111, a second metal layer 110, a first dielectric layer 109, a third metal layer 108, an asymmetric Bragg structure layer, and an anti-reflection layer 101 which are stacked in sequence; the asymmetric Bragg structure layer comprises a first phase change layer 107, a second dielectric layer 106, a second phase change layer 105, a third dielectric layer 104, a third phase change layer 103, and a fourth dielectric layer 102 which are stacked in sequence;

[0106] The anti-reflection layer 101 is made of MgF2 and has a thickness of 450 to 1000 nm.

[0107] The material of the fourth dielectric layer 102 is TiO2, and the thickness is 200nm-500nm;

[0108] The material of the third phase change layer 103 is Ag5In4Sb 76 Te 17 , thickness is 10nm-200nm;

[0109] The material of the third dielectric layer 104 is TiO2, and the thickness is 10nm-400nm;

[0110] The material of the second phase change layer 105 is Ag5In4Sb 76 Te 17 , thickness is 10nm-400nm;

[0111] The material of the second dielectric layer 106 is TiO2, and the thickness is 20nm-400nm;

[0112] The material of the first phase change layer 107 is Ag5In4Sb 76 Te 17 , thickness is 20nm-400nm;

[0113] The material of the third metal layer 108 is Cr, and the thickness is 20nm-300nm;

[0114] The material of the first dielectric layer 109 is TiO2, and the thickness is 20nm-400nm;

[0115] The material of the second metal layer 110 is Ge, and the thickness is 50nm-200nm;

[0116] The material of the first metal layer 111 is Cr, and the thickness is greater than 300 nm.

[0117] In some embodiments, applying a 3V voltage to the first metal layer 111 can cause the phase change material layer to change from an amorphous state to a partially crystallized state to a fully crystallized state; or, placing the entire infrared broadband absorber in a thermal environment at 290°C for 15 minutes can cause the phase change material layer to change from an amorphous state to a partially crystallized state to a fully crystallized state.

[0118] The infrared broadband absorber of the present invention can absorb more than 90% of the incident electromagnetic waves in the range of 1.7μm to 13μm (near infrared to mid-infrared band), and the relative bandwidth exceeds 152.8%. The traditional broadband microwave absorber design usually adopts gratings, metasurfaces or other special materials to realize ultra-wideband absorption structure. Taking the field of metasurface broadband absorbers as an example, common strategies include multi-resonance coupling or introducing highly absorptive materials to broaden the absorption bandwidth. For example, by adopting meta-atoms with different geometric shapes (such as fractal meta-surfaces) or meta-atoms of different sizes, multiple resonance modes can be achieved. However, although many proposed microwave absorbers exhibit broadband characteristics and absorptivity higher than 90%, they can usually only achieve multiple discrete absorption bands. These methods often cannot maintain electromagnetic impedance matching throughout the entire working frequency band, and the structure and processing technology are complex, and the ultra-wideband range and high absorption effect cannot be achieved. The present invention introduces a non-opposed symmetric Bragg structure layer and a metal material film with a higher absorptivity to form an efficient absorption structure. The phase change material and dielectric material form an antisymmetric Bragg structure, which further improves the absorption rate of the device. Combined with the MgF2 low refractive index layer, by optimizing the materials and thickness of each layer, it can effectively suppress reflection and enhance absorption of light of different wavelengths. Each layer of material is made by conventional thin film preparation processes such as magnetron sputtering and magnetron sputtering. The vacuum environment needs to meet the requirements of less than 1×10 -4 Pa, especially when the metal is plated with Cr and Ge, metal oxidation is avoided. It has the advantages of high ultra-wideband absorption efficiency, simple preparation, and large-area preparation. Compared with the prior art, the infrared broadband absorber of the present invention has a simple structure and can achieve an absorption effect of more than 90% in an ultra-wide range, and the absorption relative bandwidth exceeds 152.8%. It not only provides a major opportunity for ultra-wide spectrum detection, but also provides a feasible technical approach for ultra-wide spectrum confrontation and stealth. It is expected to achieve confrontation and stealth against active and passive composite sensing detection equipment, and expand the application potential of materials in infrared absorption, infrared stealth, photothermal conversion and sensing.

[0119] The infrared broadband absorber of the present application is further described below. This section further describes the content of the present invention in conjunction with specific examples, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the examples are conventional means known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0120] Example 1

[0121] This embodiment provides an infrared broadband absorber, such as Figure 1As shown, it includes: a substrate 112, a first metal layer 111, a second metal layer 110, a first dielectric layer 109, a third metal layer 108, an asymmetric Bragg structure layer, and an anti-reflection layer 101 which are stacked in sequence; the asymmetric Bragg structure layer includes a first phase change layer 107, a second dielectric layer 106, a second phase change layer 105, a third dielectric layer 104, a third phase change layer 103, and a fourth dielectric layer 102 which are stacked in sequence;

[0122] The anti-reflection layer 101 is made of MgF2 and has a thickness of 546 nm.

[0123] The fourth dielectric layer 102 is made of TiO2 and has a thickness of 428 nm, satisfying the following conditions (d j =N×(λ / 4n j )+Δd2),n j =2.26, λ=1700nm, Δd2=52nm;

[0124] The material of the third phase change layer 103 is Ag5In4Sb 76 Te 17 , thickness is 30nm, and meets the following conditions (d i =N×(λ / 4n i )+Δd1),n i =3.73, λ=1700nm, Δd1=30, N=0;

[0125] The material of the third dielectric layer 104 is TiO2, the thickness is 191 nm, and the following conditions are met (d j =N×(λ / 4n j )+Δd2),n j =2.26, λ=1700nm, Δd2=3nm, N=1;

[0126] The material of the second phase change layer 105 is Ag5In4Sb 76 Te 17 , with a thickness of 77nm, satisfies the following conditions (d i =N×(λ / 4n i )+Δd1),n i =3.73, λ=1700nm, Δd1=77nm, N=0;

[0127] The material of the second dielectric layer 106 is TiO2, the thickness is 91nm, and the following conditions are met (d j =N×(λ / 4n j )+Δd2),n j =2.26, λ=1700nm, Δd1=91nm, N=0;

[0128] The material of the first phase change layer 107 is Ag5In4Sb 76 Te 17 , with a thickness of 206 nm, satisfies the following conditions (d i =N×(λ / 4n i )+Δd1),n i =3.73, λ=1700nm, Δd1=92nm, N=1;

[0129] The material of the third metal layer 108 is Cr and the thickness is 47nm;

[0130] The material of the first dielectric layer 109 is TiO2 and the thickness is 213nm;

[0131] The material of the second metal layer 110 is Ge, and the thickness is 20 nm;

[0132] The material of the first metal layer 111 is Cr and the thickness is 500nm;

[0133] The substrate 112 is a Si substrate, and the thickness of the substrate 112 is 1.2 μm;

[0134] The reflectivity curve of the asymmetric Bragg structure layer is as follows: Fig. 20 As shown, the average reflectivity R of the asymmetric Bragg structure layer in the wavelength range of 1700nm to 22000nm HR,max It is 14.49912%.

[0135] Specifically, the imaginary refractive index K value and the refractive index n value of the above layers in the infrared band at wavelength λ=1700nm are shown in Table 1 below:

[0136] Table 1 - Imaginary refractive index K value and refractive index n value of each layer in the infrared band at wavelength λ = 1700nm

[0137]

[0138] The method for preparing the above infrared broadband absorber comprises the following steps:

[0139] A first metal layer, a second metal layer, a first dielectric layer, a third metal layer, a first phase change layer, a second dielectric layer, a second phase change layer, a third dielectric layer, a third phase change layer, a fourth dielectric layer, and an anti-reflection layer are sequentially deposited on a substrate by a magnetron sputtering method;

[0140] The process conditions for depositing the first metal layer are: using Cr as the target material, the temperature is room temperature 25°C, the flow rate of argon is 60sccm, the pressure of the sputtering chamber is 0.6Pa, and the sputtering power is 25W;

[0141] The process conditions for depositing the second metal layer are as follows: Ge is used as the target material, the temperature is room temperature 25°C, the flow rate of argon is 60sccm, the pressure of the sputtering chamber is 0.6Pa, and the sputtering power is 25W;

[0142] The process conditions for depositing the first dielectric layer are: using TiO2 as the target material, the temperature is room temperature 25°C, the flow rate of argon is 60sccm, the pressure of the sputtering chamber is 0.6Pa, and the sputtering power is 50W;

[0143] The process conditions for depositing the third metal layer are: Cr as the target, the temperature is room temperature 25°C, the flow rate of argon is 60sccm, the pressure of the sputtering chamber is 0.6Pa, and the sputtering power is 40W;

[0144] The process conditions for depositing the first phase change layer are: Ag5In4Sb 76 Te 17 The target material is 25°C, the flow rate of argon is 60 sccm, the pressure of the sputtering chamber is 0.6 Pa, and the sputtering power is 25 W.

[0145] The process conditions for depositing the second dielectric layer are: TiO2 as the target, the temperature is room temperature 25°C, the flow rate of argon is 60sccm, the pressure of the sputtering chamber is 0.6Pa, and the sputtering power is 50W;

[0146] The process conditions for depositing the second phase change layer are: Ag5In4Sb 76 Te 17 The target material is 25°C, the flow rate of argon is 60 sccm, the pressure of the sputtering chamber is 0.6 Pa, and the sputtering power is 25 W.

[0147] The process conditions for depositing the third dielectric layer are: using TiO2 as the target material, the temperature is room temperature 25°C, the flow rate of argon is 60sccm, the pressure of the sputtering chamber is 0.6Pa, and the sputtering power is 50W;

[0148] The process conditions for depositing the third phase change layer are: Ag5In4Sb 76 Te 17 The target material is 25°C, the flow rate of argon is 60 sccm, the pressure of the sputtering chamber is 0.6 Pa, and the sputtering power is 25 W.

[0149] The process conditions for depositing the fourth dielectric layer are: using TiO2 as the target material, the temperature is room temperature 25°C, the flow rate of argon is 60sccm, the pressure of the sputtering chamber is 0.6Pa, and the sputtering power is 50W;

[0150] The process conditions for depositing the anti-reflection layer are as follows: MgF2 is used as the target material, the temperature is room temperature 25°C, the flow rate of argon is 60sccm, the pressure of the sputtering chamber is 0.6Pa, and the sputtering power is 50W.

[0151] Comparative Example 1

[0152] This comparative example provides an infrared broadband absorber, which is the same as Example 1 except that it does not contain the anti-reflection layer 101 , and the other layers are the same as those in Example 1.

[0153] Comparative Example 2

[0154] This comparative example provides an infrared broadband absorber, which is the same as Example 1, except that it does not contain the anti-reflection layer 101 and the fourth dielectric layer 102, and the remaining layers are the same as those in Example 1.

[0155] Comparative Example 3

[0156] This comparative example provides an infrared broadband absorber, which is the same as Example 1 except that it does not contain the anti-reflection layer 101 , the fourth dielectric layer 102 , and the third phase change layer 103 , and the remaining layers are the same as those in Example 1.

[0157] Comparative Example 4

[0158] This comparative example provides an infrared broadband absorber, which is the same as Example 1, except that it does not contain the anti-reflection layer 101, the fourth dielectric layer 102, the third phase change layer 103, and the third dielectric layer 104, and the remaining layers are the same as those in Example 1.

[0159] Comparative Example 5

[0160] This comparative example provides an infrared broadband absorber, which is the same as Example 1, except that it does not contain the anti-reflection layer 101, the fourth dielectric layer 102, the third phase change layer 103, the third dielectric layer 104, and the second phase change layer 105, and the remaining layers are the same as Example 1.

[0161] Comparative Example 6

[0162] This comparative example provides an infrared broadband absorber, which is the same as Example 1, except that it does not contain the anti-reflection layer 101, the fourth dielectric layer 102, the third phase change layer 103, the third dielectric layer 104, the second phase change layer 105, and the second dielectric layer 106, and the remaining layers are the same as Example 1.

[0163] Comparative Example 7

[0164] This comparative example provides an infrared broadband absorber, which is the same as Example 1, except that it does not contain the anti-reflection layer 101, the fourth dielectric layer 102, the third phase change layer 103, the third dielectric layer 104, the second phase change layer 105, the second dielectric layer 106, and the first phase change layer 107, and the remaining layers are the same as those in Example 1.

[0165] Comparative Example 8

[0166] This comparative example provides an infrared broadband absorber, which is the same as Example 1, except that it does not contain the anti-reflection layer 101, the fourth dielectric layer 102, the third phase change layer 103, the third dielectric layer 104, the second phase change layer 105, the second dielectric layer 106, the first phase change layer 107, and the third metal layer 108 (only includes the substrate and the first metal layer 111, the second metal layer 110, and the first dielectric layer 109), and the remaining layers are the same as those in Example 1.

[0167] Comparative Example 9

[0168] This comparative example provides an infrared broadband absorber, which is the same as Example 1, except that it does not contain the anti-reflection layer 101, the fourth dielectric layer 102, the third phase change layer 103, the third dielectric layer 104, the second phase change layer 105, the second dielectric layer 106, the first phase change layer 107, the third metal layer 108, and the first dielectric layer 109 (only includes the substrate and the first metal layer 111 and the second metal layer 110), and the remaining layers are the same as those in Example 1.

[0169] Comparative Example 10

[0170] This comparative example provides an infrared broadband absorber, which is the same as Example 1, except that it does not contain the anti-reflection layer 101, the fourth dielectric layer 102, the third phase change layer 103, the third dielectric layer 104, the second phase change layer 105, the second dielectric layer 106, the first phase change layer 107, the third metal layer 108, the first dielectric layer 109, and the second metal layer 110 (only includes the substrate and the first metal layer 111), and the remaining layers are the same as those in Example 1.

[0171] Comparative Example 11

[0172] This comparative example provides an infrared broadband absorber, such as Fig.16 As shown, it includes a silicon substrate 1008, a W (tungsten) layer 1007, a Cr (chromium) layer 1006, a Ge (germanium) layer 1005, a first TiO2 layer 1004, a GSST layer 1003, a second TiO2 layer 1002, and a MgF2 layer 1001 which are stacked in sequence;

[0173] The silicon substrate 1008 has a thickness of 1.2 μm;

[0174] The thickness of the W layer 1007 is 200 nm;

[0175] The thickness of the Cr layer 1006 is 200 nm;

[0176] The thickness of Ge layer 1005 is 25nm

[0177] The first TiO2 layer 1004 has a thickness of 36 nm;

[0178] The GSST (i.e., Germanium Antimony Selenium Telluride (Ge-Sb-Se-Te) phase change material) layer 1003 has a thickness of 8 nm;

[0179] The second TiO2 layer 1002 has a thickness of 50 nm;

[0180] The thickness of the MgF2 layer 1001 is 90 nm.

[0181] Performance Testing

[0182] The reflectivity R of the spectrum is measured by a Nicolet iS50R Fourier transform infrared spectrometer (FT-IR). Since the substrate is opaque, A (Absorption (%)) can be obtained according to the formula A=100-RT, T=0.

[0183] Figure 2 This is an absorption spectrum diagram of the infrared broadband absorber in Example 1 when it is in an amorphous state (i.e., the absorber is not subjected to any treatment and is an absorption spectrum diagram of the absorber when it is left at rest); during the test, the incident light is vertically incident on the anti-reflection layer.

[0184] Figure 3 This is an absorption spectrum diagram of the infrared broadband absorber in comparative example 1 when it is in an amorphous state (i.e., the absorber is not subjected to any treatment and is an absorption spectrum diagram of the absorber when it is left at rest); during the test, the incident light is vertically incident on the fourth dielectric layer.

[0185] Figure 4 This is the absorption spectrum of the infrared broadband absorber in the amorphous state in comparative example 2; during the test, the incident light is vertically incident on the third phase change layer.

[0186] Figure 5 This is the absorption spectrum of the infrared broadband absorber in the amorphous state in comparative example 3; during the test, the incident light is vertically incident on the third dielectric layer.

[0187] Figure 6 This is the absorption spectrum of the infrared broadband absorber in the amorphous state of Comparative Example 4; during the test, the incident light is vertically incident on the second phase change layer.

[0188] Figure 7 This is the absorption spectrum of the infrared broadband absorber in the amorphous state in comparative example 5; during the test, the incident light is vertically incident on the second dielectric layer.

[0189] Figure 8 This is the absorption spectrum of the infrared broadband absorber in the amorphous state of Comparative Example 6; during the test, the incident light is vertically incident on the first phase change layer.

[0190] Fig. 9 This is the absorption spectrum of the infrared broadband absorber in the amorphous state in comparative example 7; during the test, the incident light is vertically incident on the third metal layer.

[0191] Fig.10 This is the absorption spectrum of the infrared broadband absorber in the amorphous state of Comparative Example 8; during the test, the incident light is vertically incident on the first dielectric layer.

[0192] Fig.11 This is the absorption spectrum of the infrared broadband absorber in the amorphous state in Comparative Example 9; during the test, the incident light is vertically incident on the second metal layer.

[0193] Fig.12 This is the absorption spectrum of the infrared broadband absorber in the amorphous state in Comparative Example 10; during the test, the incident light is vertically incident on the first metal layer.

[0194] from Figures 2 to 12 As can be seen from the curve, the asymmetric Bragg structure layer: Ag5In5Sb 60 Te 30 (206nm) / TiO2(91nm) / Ag5In5Sb 60 Te 30 (77nm) / TiO2(191nm) / Ag5In5Sb 60 Te 30(30nm) / TiO2(428nm) can significantly improve the absorption rate of the device, and the MgF2 anti-reflection layer can further improve the absorption rate of the device; at the same time, the first metal layer, the second metal layer, the first dielectric layer, and the third metal layer (Cr(500nm) / Ge(20nm) / TiO2(213nm) / Cr(47nm)), this four-layer structure provides basic absorption capacity, the Cr layer may be used to improve the stability and conductivity of the structure, while the Ge and TiO2 layers provide a higher absorption rate. The absorption rate of these four layers reaches 30% in this band, laying the foundation for the high absorption of the subsequent structure. The combination of phase change material (AIST) and TiO2: By increasing the number of layers of phase change material AIST and TiO2, the absorption rate is further improved. This combination not only improves the absorption rate, but also can dynamically adjust the absorption performance through the characteristics of the phase change material. MgF2, as an anti-reflection layer, may be used to protect the structure from environmental influences and adjust the overall optical properties. The combination of high-refractive-index material (AIST, n≈4) and low-refractive-index material (TiO2, n≈2) forms an asymmetric Bragg structure: this high-contrast refractive-index combination can effectively reduce reflectivity, thereby increasing transmittance and absorption.

[0195] Fig.13 In order to prepare an asymmetric Bragg structure layer directly on a substrate according to the method of Example 1, an infrared broadband absorber (i.e., substrate + Ag5In5Sb 60 Te 30 (206nm) / TiO2(91nm) / Ag5In5Sb 60 Te 30 (77nm) / TiO2(191nm) / Ag5In5Sb 60 Te 30 (30nm) / TiO2(428nm), its reflection and absorption spectra in amorphous state are shown in Fig.13 As shown (during the test, the incident light is vertically incident on the fourth dielectric layer. Fig.13 The solid line is the absorption curve, and the dotted line is the reflection curve. Fig.13 It can be seen that the asymmetric Bragg structure layer has the effect of improving transmission and further enhancing the absorption effect.

[0196] Fig.14 The absorption spectrum of the infrared broadband absorber in the amorphous state in Example 1; during the test, the incident light is incident on the anti-reflection layer at different angles; the results are as follows Fig.14 As shown; Fig.14 0° means that the incident light is perpendicular to the anti-reflection layer, that is, the angle between the incident light and the normal of the anti-reflection layer is 0°, 70° means that the angle between the incident light and the normal of the anti-reflection layer is 70°, and 60° means that the angle between the incident light and the normal of the anti-reflection layer is 60°.

[0197] Fig.14 The black solid line is the 0° absorption curve, the green solid line is the 70° absorption curve, and the green dotted line is the 60° absorption curve. Fig.14 It can be seen that it is angle insensitive.

[0198] Fig.15 The absorption spectra of the infrared broadband absorber in Example 1 in the amorphous state and the crystalline state (the entire infrared broadband absorber is placed in a thermal environment at 290° C. for 15 minutes to change the phase change layer of the absorber from the amorphous state to the crystalline state).

[0199] Fig.15 The black dotted line in the middle represents the absorption curve of the infrared broadband absorber in a crystalline state, and the black solid line represents the absorption curve of the infrared broadband absorber in an amorphous state; during the test, the incident light is vertically incident on the anti-reflection layer.

[0200] from Fig.15 It can be seen from the figure that the infrared broadband absorber of the present invention has dynamic adjustability.

[0201] Fig.17 The spectrum diagram of the infrared broadband absorber in comparative example 11 and embodiment 1 is compared within a wavelength of 20000 nm. Fig.17 In the figure, a is the infrared broadband absorber in comparative example 11, and b is the infrared broadband absorber in example 1.

[0202] Fig.18 The spectra of the infrared broadband absorber in comparative example 11 and example 1 are compared within the wavelength range of 1700nm to 12000nm. Fig.18 In the figure, a is the infrared broadband absorber in comparative example 11, and b is the infrared broadband absorber in example 1.

[0203] from Fig.18 It can be seen that the absorption spectrum effect of the infrared broadband absorber of the present invention in the range of 1700nm-20000nm is much higher than that of comparative example 11.

[0204] Fig.19 The spectrum of the infrared broadband absorber in comparative example 11 and example 1 is compared within the wavelength range of 380nm to 1700nm; Fig.19 In the figure, a is the infrared broadband absorber in comparative example 11, and b is the infrared broadband absorber in example 1.

[0205] from Fig.19 It can be seen that the absorption spectrum effect of the infrared broadband absorber in Comparative Example 11 in the range of 380nm-1700nm is much higher than that of the present invention.

[0206] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An infrared broadband absorber, characterized in that: include: substrate; A first metal layer, located on the surface of the substrate; a second metal layer, located on the first metal layer away from the substrate surface; A first dielectric layer, located on the second metal layer away from the substrate surface; A third metal layer, located on the first dielectric layer away from the substrate surface; an asymmetric Bragg structure layer, located on the third metal layer away from the substrate surface, the asymmetric Bragg structure layer comprising a phase change layer and a dielectric layer that are alternately stacked; The material of the dielectric layer is a phase change material or a dielectric material; An anti-reflection layer, located on the substrate surface of the asymmetric Bragg structure layer; Wherein, the imaginary refractive index of the phase change layer in the infrared band is less than 1; the refractive index of the phase change layer is greater than 1; The imaginary refractive index of the dielectric layer in the infrared band is less than 1; The refractive index of the dielectric layer is greater than 2; The thickness of the phase change layer and the dielectric layer are both less than 1 μm.

2. The infrared broadband absorber according to claim 1, characterized in that: The thickness d of the phase change layer i =N×(λ / 4n i )+Δd1, where N is an integer, 0﹤Δd1≤λ / 4n i , λ represents wavelength, λ≥350nm, n i represents the refractive index of the phase change layer; The thickness d of the dielectric layer j =N×(λ / 4n j )+Δd2, where N is the sum of the number of phase change layers and dielectric layers in the asymmetric Bragg structure layer, 0﹤Δd2≤λ / 4n j , λ represents wavelength, λ≥350nm, n j Represents the refractive index of the dielectric layer.

3. The infrared broadband absorber according to claim 1, characterized in that: The average reflectivity R of the asymmetric Bragg structure layer HR,max Less than 30%.

4. The infrared broadband absorber according to claim 1, characterized in that: The imaginary refractive index of the anti-reflection layer in the infrared band is less than 1, and the refractive index of the anti-reflection layer is less than the refractive indexes of the phase change layer and the dielectric layer.

5. The infrared broadband absorber according to claim 1, characterized in that: The sum of the number of phase change layers and dielectric layers in the asymmetric Bragg structure layer is ≥4.

6. The infrared broadband absorber according to claim 1, characterized in that: The phase change material used in the phase change layer includes at least one of GeTe, SbTe, SnSb, AgInSbTe, InSbTe, GeSb, Se2Sb3, Sb2S3 and GST; And / or, the material of the anti-reflection layer includes at least one of fluoride, oxide, nitride, sapphire, zinc selenide, zinc sulfide, titanium oxide, hafnium oxide, and polytetrafluoroethylene.

7. The infrared broadband absorber according to claim 1, characterized in that: The material of the first dielectric layer is a dielectric material; The material of the dielectric layer is a dielectric material, and the dielectric material includes at least one of tantalum pentoxide, lithium niobate, silicon, silicon nitride, silicon dioxide, calcium fluoride, polytetrafluoroethylene, aluminum oxide, quartz, silicon, titanium dioxide, tantalum pentoxide, zinc sulfide, aluminum nitride and magnesium aluminum spinel; The imaginary refractive index of the first dielectric layer in the infrared band is less than 1; the refractive index of the first dielectric layer is greater than 2.

8. The infrared broadband absorber according to claim 1, characterized in that: The material of the dielectric layer is a phase change material, and the phase change material includes at least one of GeTe, SbTe, SnSb, AgInSbTe, InSbTe, GeSb, Se2Sb3, Sb2S3 and GST.

9. The infrared broadband absorber according to claim 1, characterized in that: The materials used for the first metal layer, the second metal layer and the third metal layer include at least one of gold, aluminum, copper, silver, titanium, molybdenum, nickel, chromium, iron and germanium; The imaginary refractive index of the first metal layer and the third metal layer in the infrared band is greater than 2; The refractive index of the first metal layer, the second metal layer and the third metal layer is greater than 2; The thickness of the first metal layer is greater than 100 nm and less than 1 μm; The thickness of the second metal layer is greater than 50 nm and less than 1 μm; The thickness of the third metal layer is less than 200 nm and greater than 10 nm; The thickness of the anti-reflection layer is less than 1 μm; The thickness of the phase change layer is less than 500 nm.

10. The infrared broadband absorber according to claim 1, characterized in that: The asymmetric Bragg structure layer includes a first phase change layer, a second dielectric layer, a second phase change layer, a third dielectric layer, a third phase change layer, and a fourth dielectric layer which are stacked in sequence; Wherein, the material of the anti-reflection layer is MgF2, and the thickness is 450-1000nm; The material of the fourth dielectric layer is TiO2, and the thickness is 200nm-500nm; The material of the third phase change layer is Ag5In4Sb 76 Te 17 , thickness is 10nm~200nm; The material of the third dielectric layer is TiO2, and the thickness is 10nm to 400nm; The material of the second phase change layer is Ag5In4Sb 76 Te 17 , thickness is 10nm~400nm; The material of the second dielectric layer is TiO2, and the thickness is 20nm~400nm; The material of the first phase change layer is Ag5In4Sb 76 Te 17 , thickness is 20nm-400nm; The material of the third metal layer is Cr, and the thickness is 20nm to 300nm; The material of the first dielectric layer is TiO2, and the thickness is 20nm to 400nm; The material of the second metal layer is Ge, and the thickness is 50nm to 200nm; The material of the first metal layer is Cr, and the thickness is greater than 300 nm.

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