An infrared broadband absorber

Abstract

The present invention provides an infrared broadband absorber. The present invention introduces an asymmetric Bragg structure layer and a metal material film with a high absorption rate to form an efficient absorption structure. The phase change material and the dielectric material form an asymmetric Bragg structure, which further improves the absorption rate of the device. In combination with the MgF2 low refractive index layer, by optimizing the materials and thickness of each layer, effective suppression of reflection and enhanced absorption of light of different wavelengths are achieved. Compared with the existing technology, the infrared broadband absorber of the present invention has a simple structure and can achieve an absorption effect of more than 90% within an ultra-wide range. 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.

Description

Technical Field

[0001] The present 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, demand for infrared absorption materials is increasing across multiple fields, particularly in infrared stealth, thermal management, photothermal conversion, infrared sensors, and energy absorption. Traditional absorption materials primarily utilize metal-dielectric structures to absorb light in specific wavelength bands. However, most existing technologies face the following challenges: Narrow absorption bandwidth and inability to cover a wide wavelength band: Many existing infrared absorption materials only achieve efficient absorption within a narrow wavelength band, failing to cover a wider infrared wavelength range, limiting their applicability in practical applications. Low absorption efficiency: Most traditional absorption materials achieve high absorption within a specific wavelength band, but their overall absorption efficiency is generally low. In particular, in broadband applications (such as 1.7μm to 12μm), absorption efficiencies often struggle to reach above 90%. High reflectivity makes it difficult to achieve low reflectivity: Low reflectivity materials are crucial in practical applications, particularly in stealth technology. However, many existing materials face limitations in balancing absorption efficiency and reflectivity, failing to effectively suppress reflections and resulting in some light energy loss. Narrow absorption band: Most broadband absorption is concentrated in the visible to 2500nm range, and the absorption range cannot be further expanded. Alternatively, gratings, metasurfaces, and other special materials are used to create ultra-broadband absorption structures to address these issues. However, these methods often fail to maintain electromagnetic impedance matching across the entire operating frequency band, and they are complex in structure and processing, and cannot achieve ultra-broadband and high absorption.

[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, in order to solve or at least partially solve the defects of the prior art.

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

[0006] substrate;

[0007] A first metal layer is 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 that are alternately stacked; the dielectric layer is made of 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 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 dielectric layer is made of 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 stacked in sequence;

[0037] The anti-reflection layer is made of MgF2 and has a thickness of 450 to 1000 nm.

[0038] The fourth dielectric layer is made of TiO2 and has a thickness of 200nm to 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 to 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 integrates the asymmetric Bragg structure layer with a highly absorptive metal film to form a highly efficient absorption structure. The phase change material and dielectric material form an asymmetric Bragg structure, further enhancing the device's absorptivity. Combined with the MgF2 low-refractive-index layer, by optimizing the materials and thicknesses of each layer, effective reflection suppression and enhanced absorption of light of different wavelengths are achieved. This structure can be fabricated using conventional thin-film fabrication processes such as magnetron sputtering, offering advantages such as high ultra-broadband absorption efficiency, simple fabrication, and large-scale fabrication. Compared to existing technologies, the infrared broadband absorber of the present invention boasts a simple structure and achieves absorption efficiency exceeding 90% across an ultra-wide range, with an absorption relative bandwidth exceeding 152.8%. This not only provides a significant opportunity for ultra-broadband spectrum detection, but also offers a viable technical approach for ultra-broadband countermeasures and stealth. It is expected to achieve countermeasures and stealth against active and passive hybrid sensing equipment, expanding the material's potential for applications in infrared absorption, infrared stealth, photothermal conversion, and sensing. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] 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 description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0050] Figure 1 Schematic diagram of the structure 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 the absorption spectrum of the mid-infrared broadband absorber in the amorphous state in Comparative Example 4;

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

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

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

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

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

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

[0062] Figure 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] Figure 14 This is an absorption spectrum of the infrared broadband absorber in the amorphous state in Example 1;

[0064] Figure 16 This is a schematic structural diagram of the infrared broadband absorber in Comparative Example 11;

[0065] Figure 15 Graphs showing the absorption spectra of the infrared broadband absorber in the amorphous and crystalline states in Example 1;

[0066] Figure 17 Comparison of spectra of the infrared broadband absorber in Comparative Example 11 and Example 1 within a wavelength of 20000 nm;

[0067] Figure 18 Comparison of spectra of the infrared broadband absorber in Comparative Example 11 and Example 1 within a wavelength range of 1700 nm to 12000 nm;

[0068] Figure 19 The spectrum of the infrared broadband absorber in Comparative Example 11 and Example 1 is compared within the wavelength range of 380 nm to 1700 nm;

[0069] Figure 20 is the 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 embodiments described 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 making creative efforts 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 this 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 merely for convenience and brevity and should not be understood as a rigid limitation on the scope of the 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, the range description from 1 to 6 should be considered to have 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, regardless of the range. In addition, whenever a numerical range is indicated herein, 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 is located on the surface of the substrate;

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

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

[0077] a third metal layer, 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 that are alternately stacked; the dielectric layer is made of a phase change material or a dielectric material;

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

[0080] 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 is as follows 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 stacked in sequence; the asymmetric Bragg structure layer includes a phase change layer and a dielectric layer that are alternately stacked, 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 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 the crystalline and amorphous states occurs, resulting in a phase change, and light regulation is achieved through changes in the refractive index and extinction coefficient before and after the phase change. The first, second, and third metal layers generate sufficient heat under electrical stimulation to cause the phase change material of the phase change layer to change its respective reflectivity and extinction coefficient when transforming between the amorphous and crystalline states, 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 within a wide band.

[0085] The infrared broadband absorber of the present invention utilizes a multilayer metal-dielectric structure design. By varying the refractive index of the materials and increasing the number of layers, it can effectively enhance absorption and reduce reflection loss, thereby improving absorption efficiency. Specifically, by introducing asymmetric Bragg structure layers, precisely designing the refractive index and thickness of each layer, and destroying constructive interference, combined with the regulation of phase-change materials, the present invention achieves efficient absorption across a wide infrared band, with an absorptivity exceeding 90%. This structure not only significantly improves absorption efficiency but also reduces reflectivity through rational design, demonstrating its high potential for application. By combining a multilayer metal-asymmetric DBR structure design with the introduction of phase-change materials, the present invention achieves ultra-wideband, dynamically adjustable, efficient absorption in the 1.7μm to 12μm band, with no angle sensitivity. The absorption performance can be further enhanced by adjusting the number of layers and the state of the phase-change materials. This technical strategy overcomes the inherent limitations of existing structures, represents a significant technological advancement, and opens new possibilities for the further development of infrared broadband absorption technology. The present invention not only provides new insights into the design of infrared absorption structures but also offers an effective solution to the technical challenges of existing materials in broadband absorption, low reflectivity, and tunable absorption.

[0086] This invention employs a novel technical strategy: a dynamically adjustable broadband absorber designed using a phase-change material (PMC) with a high n (refractive index) value in the infrared region and a K (imaginary refractive index in the infrared band) value less than 1 (e.g., 0) and a dielectric material, along with an absorptive metal with a high refractive index and extinction coefficient. The multilayer metal-dielectric design comprises a first metal layer, a second metal layer, a first dielectric layer, and a third metal layer, such as Cr / Ge / TiO2 / Cr, with TiO2 and Ge serving as high-refractive-index materials and Cr serving as the metal layer. This design not only achieves a high initial absorption rate (30%) but also provides a foundation for optical resonance and interference effects within the multilayer structure. The addition of the metal layer (Cr) enhances absorption through the interaction of conductivity loss and reflection at the metal-dielectric interface. A phase-change material (e.g., AIST) is introduced as the absorption-modulating layer. AIST (Ag-In-Sb-Te) is a phase-change material capable of switching between amorphous and crystalline states, with this phase transition accompanied by a change in dielectric constant. This allows the layer's absorption characteristics to vary across different wavelengths, enabling tunable absorption by manipulating its phase state. In this scheme, as dielectric phase-change layers (such as AIST layers) and dielectric layers (such as TiO2 layers) are alternately added to the asymmetric Bragg structure, the total absorptivity of the asymmetric Bragg structure gradually increases, ultimately reaching over 90% in the 1.7μm to 12μm range.

[0087] In some embodiments, when light (infrared 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 the multiple layers are stacked, 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, it will eventually show a high absorption rate. By rationally designing the layer thickness and refractive index, the interface reflections can be made to cancel each other out (destructive interference) over a wide range of wavelengths, 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 that of the air and the substrate to reduce the interfacial 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 stacked so that the equivalent impedance to light in the infrared range is close to that of air, and the reflection is greatly reduced. Specifically, let's analyze: 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 stacked, if the interference conditions are met at the appropriate wavelength and reflection is suppressed, the metal loss can significantly contribute to high absorption. AIST (Ag5In5Sb 60 Te 30Absorption of phase-change materials: Phase-change materials (AISTs) typically have a high imaginary refractive index (k value) in the infrared, thus providing effective optical loss. While the refractive index and extinction coefficient of AISTs vary in their different phases (amorphous / crystalline), overall, AISTs generally maintain a certain level of absorption in the infrared. By alternating AISTs with TiO2 in a periodic or quasi-periodic fashion, multiple resonant cavities or interference-enhanced regions can be formed, further broadening the absorption band. This creates so-called multiple resonances or Fabry–Pérot resonances, thus covering an ultra-broad spectrum from 1.7μm to 11μm. Periodic / quasi-periodic stacking creates broadband resonances. The repeated alternation of AIST and TiO2 layers, combined with the bottom / middle metallic Cr layers and the anti-reflection layer MgF2, creates multiple optical microcavities. Each microcavity has a resonant absorption peak at a specific wavelength. By stacking multiple layers with carefully designed thicknesses, the absorption peaks are spectrally "stitched" or "partially overlapped," resulting in continuous broadband absorption. This is the idea behind combining the common multilayer interference theory with metamaterial / phase-change material absorption layers. If each layer has a slight difference (thickness or refractive index), high absorption can be achieved over a wide area. Low reflection + no transmission = high-absorption anti-reflection layer (MgF2): MgF2 has a low refractive index (approximately 1.38) and can be used as an anti-reflection layer from the infrared to the visible range. It reduces the refractive index difference between the incident light and the underlying dielectric layer, further reducing surface reflection. Bottom metal (Cr, 500nm): The 500nm thick Cr bottom layer is nearly opaque, blocking light from reaching the substrate or the back, causing most of the incident light to be lost within the structure. When multilayer interference reduces reflection to a minimum, and transmission is blocked by the bottom metal, the result is absorptivity ≈ 1 - reflectivity - transmittance ≈ 1 - a very small fraction ≈ over 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 about 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 wavelength range and enhance the diversity of application scenarios compared to the traditional single absorption structure. Filter rod shape with angle: 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 material and dielectric material, or an alternating combination of dielectric material and phase change material.

[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 d of the phase change layer is 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 represents,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 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 exhibits absorption characteristics in the long-wavelength range. The thickness of the first metal layer (thickness > 300 nm) must be such that light cannot pass through. 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 exhibits broad absorption characteristics 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 ratio of crystallization and amorphization 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 anti-reflection layer is made of fluorides (MgF2, CaF2), oxides (SiO2, Al2O3), nitrides (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 10 nm.

[0096] In some embodiments, 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, including at least one of GeTe, SbTe, SnSb, AgInSbTe, InSbTe, GeSb, Se2Sb3, Sb2S3 and GST; the percentage of each atom is adjustable.

[0099] In some embodiments, 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-mentioned metals all have strong infrared absorption properties. Their high electrical conductivity makes them exhibit 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 most 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 layer 111 of the broadband absorption cavity structure applies voltage to cause the phase change material to undergo a phase change. The main function of the first metal layer 111 is 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 zero loss, 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 chalcogenides and their alloys, including but not limited to: GST, GSST, IST, GeSbTe, AgInSbTe, InSbTe, AgSbTe, Ag2In4Sb 76 Te 17 (AIST) and other phase change materials with a K value less than 1 and a refractive index greater than 1 in the infrared band. In addition, the atomic percentages in the above chemical formulas can be varied. The phase change material may further contain at least one dopant, such as C or 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 changing the transmittance and reflectivity of the phase change layer; the asymmetric Bragg structure layer and the anti-reflection layer 101 together constitute an anti-reflection layer structure, further improving the absorption of the device, and 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, 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 state; 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 very short falling edge of the pulse causes the phase change material to be rapidly 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 ratio of light absorption by the broadband absorption cavity is controlled by the changes in the transmittance and reflectivity of the third phase change layer 103, the second phase change layer 105, and the first phase change layer 107 when they transform between the amorphous state and the crystalline state. By applying different voltages to the first metal layer 111, the phase change material layer is changed from amorphous state to partially crystallized to completely crystallized. The magnitude of the applied voltage depends on the actual needs, and the absorption ratio of the target light is adjusted according to actual needs. The phase change layer of this 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, as Figure 1As shown, the infrared broadband absorber of the present invention includes: 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 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;

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

[0107] The fourth dielectric layer 102 is made of TiO2 and has a thickness of 200nm-500nm;

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

[0109] The third dielectric layer 104 is made of TiO2 and has a thickness of 10nm-400nm;

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

[0111] The second dielectric layer 106 is made of TiO2 and has a thickness of 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 second metal layer 110 is made of Ge and has a thickness of 50 nm to 200 nm.

[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 partially crystallized and then completely crystallized; 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 partially crystallized and then completely crystallized.

[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%. Traditional broadband microwave absorber designs usually use gratings, metasurfaces or other special materials to achieve ultra-broadband absorption structures. Taking the field of metasurface broadband absorbers as an example, common strategies include multi-resonant coupling or the introduction of highly absorptive materials to broaden the absorption bandwidth. For example, by using meta-atoms with different geometric shapes (such as fractal metasurfaces) or meta-atoms of different sizes, multiple resonant modes can be achieved. However, although many proposed microwave absorbers exhibit broadband characteristics and absorption rates higher than 90%, they can usually only achieve multiple discrete absorption bands. These methods often cannot maintain electromagnetic impedance matching throughout the entire operating frequency band, and the structure and processing technology are complex, and they cannot achieve ultra-broadband range and high absorption effects. The present invention introduces an asymmetric Bragg structure layer and a metal material film with a higher absorption rate to form an efficient absorption structure. The phase change material and dielectric material form an asymmetric 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 using 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 coated with metal Cr and Ge, avoids metal oxidation. It has the advantages of high ultra-wideband absorption efficiency, simple preparation, and large-area preparation. Compared with the existing technology, 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 the fields of infrared absorption, infrared stealth, photothermal conversion and sensing.

[0119] The infrared broadband absorber of the present application is further described below. This section further illustrates the present invention with reference to specific examples, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means employed in the examples are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment employed 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, and satisfies 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 the following conditions are met (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 191nm, and it meets the following conditions (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, and 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 it meets the following conditions (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, and satisfies the following conditions (d i =N×(λ / 4n i )+Δd1),n i =3.73, λ=1700nm, Δd1=92nm, N=1;

[0129] The third metal layer 108 is made of Cr and has a thickness of 47 nm;

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

[0131] The second metal layer 110 is made of Ge and has a thickness of 20 nm;

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

[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: Figure 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 each layer 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-mentioned 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 as follows: Cr as the target, a temperature of 25°C, an argon flow rate of 60 sccm, a sputtering chamber pressure of 0.6 Pa, and a sputtering power of 25 W.

[0141] The process conditions for depositing the second metal layer are as follows: Ge as the target, the temperature is room temperature 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;

[0142] The process conditions for depositing the first dielectric layer are as follows: TiO2 as the target, the temperature is room temperature 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 50 W;

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

[0144] The process conditions for depositing the first phase change layer are: Ag5In4Sb 76 Te 17 The target material is 25°C, the temperature is room temperature, 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 as follows: TiO2 as the target, the temperature is room temperature 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 50 W;

[0146] The process conditions for depositing the second phase change layer are: Ag5In4Sb 76 Te 17 The target material is 25°C, the temperature is room temperature, 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 as follows: TiO2 as the target, the temperature is room temperature 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 50 W.

[0148] The process conditions for depositing the third phase change layer are: Ag5In4Sb 76 Te 17 The target material is 25°C, the temperature is room temperature, 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 as follows: TiO2 as the target, the temperature is room temperature 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 50 W;

[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 remaining 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 . 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. 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. 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. The remaining layers are the same as those in 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. 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 (it only includes the substrate and the first metal layer 111, the second metal layer 110, and the first dielectric layer 109). 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 include 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 (it only includes the substrate and the first metal layer 111 and the second metal layer 110). 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 include 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 (it only includes the substrate and the first metal layer 111). 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 Figure 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 stacked in sequence;

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

[0174] The W layer 1007 has a thickness of 200 nm;

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

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

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

[0178] The GSST (i.e., Germanium Antimony Selenium Tellurium (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 spectra were measured using 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 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 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 mid-infrared broadband absorber in the amorphous state of 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 mid-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 mid-infrared broadband absorber in the amorphous state of 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 mid-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] Figure 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] Figure 10 This is the absorption spectrum of the mid-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] Figure 11 This is the absorption spectrum of the infrared broadband absorber in the amorphous state of Comparative Example 9; during the test, the incident light is vertically incident on the second metal layer.

[0193] Figure 12 This is the absorption spectrum of the infrared broadband absorber in the amorphous state of 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 30The combination of Cr (30nm) / TiO2 (428nm) significantly improves the device's absorptivity, while the addition of a MgF2 anti-reflection layer further enhances it. Furthermore, the four-layer structure (first metal layer, second metal layer, first dielectric layer, and third metal layer (Cr (500nm) / Ge (20nm) / TiO2 (213nm) / Cr (47nm)) provides the foundation for absorption. The Cr layer likely enhances the stability and conductivity of the structure, while the Ge and TiO2 layers provide high absorptivity. The absorptivity of these four layers reaches 30% in this wavelength band, laying the foundation for high absorption in subsequent structures. The combination of a phase-change material (AIST) and TiO2 further enhances absorptivity by increasing the number of AIST and TiO2 layers. This combination not only improves absorptivity but also potentially allows for dynamic adjustment of absorption performance through the properties of the phase-change material. The MgF2 anti-reflection layer likely protects the structure from environmental influences while also adjusting 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] Figure 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 the figure below. Figure 13 As shown (during the test, the incident light is vertically incident on the fourth dielectric layer. Figure 13 The solid line is the absorption curve, and the dotted line is the reflection curve. Figure 13 It can be seen from the figure that the asymmetric Bragg structure layer has the effect of improving transmission and further enhancing the absorption effect.

[0196] Figure 14 The absorption spectrum of the infrared broadband absorber in the amorphous state in Example 1 is shown in FIG. 1 . During the test, the incident light is incident on the anti-reflection layer at different angles. The results are shown in FIG. Figure 14 As shown; Figure 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] Figure 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. Figure 14 It can be seen that it is angle insensitive.

[0198] Figure 15 These are absorption spectra of the infrared broadband absorber in Example 1 in the amorphous and crystalline states (the entire infrared broadband absorber was 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] Figure 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 Figure 15 It can be seen from the figure that the infrared broadband absorber of the present invention has dynamic adjustability.

[0201] Figure 17 The spectrum of the infrared broadband absorber in comparative example 11 and embodiment 1 is compared within a wavelength of 20000 nm. Figure 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] Figure 18 The spectrum of the infrared broadband absorber in Comparative Example 11 and Example 1 is compared within the wavelength range of 1700nm to 12000nm. Figure 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 Figure 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] Figure 19 The spectrum of the infrared broadband absorber in Comparative Example 11 and Example 1 is compared within the wavelength range of 380 nm to 1700 nm; Figure 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 Figure 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 scope of protection of the present invention.

Claims

1. An infrared broadband absorber, characterized in that: include: substrate; A first metal layer is 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; 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; 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; 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; 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.

2. The infrared broadband absorber according to claim 1, wherein The average reflectivity R of the asymmetric Bragg structure layer HR,max Less than 30%.

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

4. The infrared broadband absorber according to claim 1, wherein The material of the first dielectric layer is a dielectric material; The dielectric layer is made of 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.

5. The infrared broadband absorber according to claim 1, wherein 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.

6. The infrared broadband absorber according to claim 1, wherein 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.

7. The infrared broadband absorber according to claim 1, wherein: 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 stacked in sequence; The anti-reflection layer is made of MgF2 and has a thickness of 450 to 1000 nm. The material of the fourth dielectric layer is TiO2 and the thickness is 200nm to 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 to 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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