An infrared and laser compatible stealth structure and design method

Abstract

An infrared- and laser-compatible stealth structure and design method are disclosed, belonging to the field of infrared artificial electromagnetic metamaterials. The structure, from bottom to top, comprises a bottom metal film, an intermediate dielectric pattern, and a top metal pattern. The patterns include both small and large-sized patterns, with the small-sized patterns arranged in a square pattern around the large-sized patterns. The design method involves selecting the shapes and sizes of the large and small patterns, exciting magnetic resonances at 1.064 μm and 6.5 μm respectively, and combining them according to the aforementioned arrangement. This invention, an infrared- and laser-compatible stealth structure and design method, achieves a compatible and modulated effect of narrowband high absorption in the 1.06 μm laser band, broadband high absorption in the 6.5 μm infrared wave, and low emissivity in the atmospheric window. It overcomes the limitations of conventional infrared stealth coatings, which have a single stealth band and are not conducive to heat dissipation, and integrates laser stealth, infrared stealth, and radiative cooling functions.

Description

Technical Field

[0001] This invention belongs to the field of infrared artificial electromagnetic metamaterials, specifically relating to an infrared and laser compatible stealth structure and its design method. Background Technology

[0002] In future low-power or even zero-power electronic countermeasures modes, optoelectronic detection, with its all-weather capability and strong anti-jamming ability, is gradually becoming one of the main threats to targets such as aircraft, vehicles, and ships. With the improvement of sensor components and computer hardware and software, the spectrum range of optoelectronic detection has gradually broadened, evolving from early infrared detection to laser detection and infrared detection, significantly enhancing its capabilities. A certain aircraft has successfully applied an Infrared Search and Track (IRST) system combined with a laser system, possessing functions such as infrared search and tracking, laser designation, ranging, and laser angle tracking. This not only enables long-range target tracking, identification, detection, and early warning, but also provides precise guidance information for missiles, with an effective range of tens or even hundreds of kilometers.

[0003] The current mature optical stealth method is infrared low-emissivity coating, which has been widely applied. However, this coating only possesses the characteristic of low emissivity across the entire infrared band, making it difficult to meet the requirements of laser stealth. Furthermore, low emissivity is not conducive to surface heat dissipation, posing challenges to further improving infrared stealth capabilities. Therefore, how to achieve high-performance stealth across infrared, laser, and other optical bands simultaneously on the surface is one of the key issues currently facing optical stealth design. Summary of the Invention

[0004] To address threats from various optical detection methods, including infrared and laser, this invention provides an infrared- and laser-compatible stealth structure and design method. By designing and combining different patterns on a surface, and utilizing the magnetic resonance generated by patterns of different sizes at different infrared wavelengths, infrared and laser-compatible stealth can be achieved simultaneously.

[0005] An infrared and laser compatible stealth structure comprises, from bottom to top, a bottom metal film 1, an intermediate dielectric pattern 2, and a top metal pattern 3;

[0006] The infrared and laser compatible stealth structure is described above, in which the intermediate medium pattern 2 and the top metal pattern 3 are overlapped on the bottom metal film 1; the intermediate medium pattern 2 and the top metal pattern 3 have two types: large-size patterns and small-size patterns; the large-size pattern is cross-shaped, and the small-size patterns are distributed in a square arrangement around the cross-shaped structure; a cross-shaped large-size pattern and the small-size patterns distributed around the cross-shaped structure constitute a structural cycle.

[0007] The infrared and laser compatible stealth structure described above has a small-sized pattern in the shape of a disc, square, or cross.

[0008] The infrared and laser compatible stealth structure is made of aluminum, silver, gold or tungsten as the bottom metal film 1 and the top metal pattern 3. The thickness of the bottom metal film 1 or the top metal pattern 3 is greater than the skin depth of infrared electromagnetic waves in metal.

[0009] The infrared and laser compatible stealth structure described above uses an intermediate medium pattern 2 made of inorganic infrared transparent materials such as magnesium fluoride, aluminum oxide, hafnium oxide, zinc sulfide, silicon, and germanium.

[0010] The infrared and laser compatible stealth structure has an intermediate medium pattern 2 with the same thickness for both the large and small patterned patterns, and a top metal pattern 3 with the same thickness for both the large and small patterned patterns.

[0011] The second aspect of this invention provides a method for designing infrared and laser-compatible stealth structures, involving the mechanism of magnetic resonance. The specific method is as follows:

[0012] Step S1: Obtain the relationship between the structural period, size, thickness, material refractive index and magnetic resonance wavelength of the intermediate dielectric pattern 2 and the top metal pattern 3.

[0013] Select the type of small-sized pattern, the metal type of the bottom metal film 1 and the top metal pattern 3, substitute the size, thickness and material dielectric constant of the intermediate dielectric pattern 2 and the top metal pattern 3 into the LC equivalent circuit model, calculate the magnetic resonance wavelength under the above parameter changes, and obtain the relationship between the absorption peak and the incident wavelength.

[0014] Step S2: Obtain the relationship between the dimensions of the large-size pattern and the small-size pattern, the material refractive index and thickness parameters of the intermediate medium pattern 2, and the absorption spectrum curve.

[0015] By selecting the size parameters of the small-sized pattern with a magnetic resonance wavelength of 1.064 μm, and the material and thickness parameters of the intermediate medium pattern 2, the absorption spectrum curves under the variation of the above parameters are calculated.

[0016] By selecting the size parameters of the large-size pattern with a magnetic resonance wavelength of 6.5 μm, and the material and thickness parameters of the intermediate medium pattern 2, the absorption spectrum curves under the variation of the above parameters are calculated.

[0017] Step S3: Determine the dimensions of the large-size pattern and the small-size pattern, as well as the material refractive index and thickness parameters of the intermediate medium pattern 2.

[0018] By observing the size of the small and large patterns, the refractive index and thickness parameters of the intermediate medium pattern 2, and the absorption spectrum curves, the same refractive index and thickness parameters of the intermediate medium pattern 2 were selected for the small and large patterns, so that the absorption at 1.064 μm and 6.5 μm reached the strongest.

[0019] Step S4: Using the material refractive index and thickness parameters of the intermediate medium pattern 2 between the small-sized pattern and the large-sized pattern obtained above, according to... Figure 1 Combine them in the form of [the given text].

[0020] The beneficial effects of this invention are as follows: This invention utilizes the properties of metamaterials to excite magnetic resonance. By adjusting the size of the pattern, the refractive index of the material, and the thickness, it achieves infrared absorption effects with a narrow band of 1.064μm and a wide band of 5-8μm. The design structure is simple and easy to manufacture, and the method has strong applicability. Attached Figure Description

[0021] Figure 1 Schematic diagram of the unit structure of the present invention;

[0022] The labels in the diagram are: 1. Bottom metal film, 2. Intermediate dielectric pattern, 3. Top metal pattern;

[0023] Figure 2 The simulation results of the spectral absorption characteristics for Example 1 are shown in the figure. Detailed Implementation

[0024] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention is described.

[0025] Specific example 1:

[0026] An infrared and laser compatible stealth structure, from top to bottom, comprises a bottom metal film 1, an intermediate dielectric pattern 2, and a top metal pattern 3, made of aluminum, silicon, and aluminum, respectively. The bottom metal film 1 has a thickness of 200 nm, and the period between the intermediate dielectric pattern and the top metal pattern is 1800 nm.

[0027] The small-sized pattern is disc-shaped with a diameter of 80nm; the large-sized pattern is cross-shaped with a length of 1560nm and a width of 60nm; the thickness of the intermediate dielectric pattern 2 is 90nm, and the thickness of the top metal layer is 150nm.

[0028] The simulation results obtained using the finite-difference time-domain method are as follows: Figure 2As shown, the absorptivity at 1.064 μm is 82%, the absorptivity at 6.5 μm is 92%, and the average absorptivity at 3-5 μm and 8-14 μm is less than 10%, i.e., the emissivity is less than 10%.

[0029] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An infrared and laser-compatible stealth structure, characterized in that, From bottom to top, it includes a bottom metal film (1), an intermediate dielectric pattern (2), and a top metal pattern (3); The infrared and laser compatible stealth structure is described in which the intermediate medium pattern (2) and the top metal pattern (3) are overlapped on the bottom metal film (1); the intermediate medium pattern (2) and the top metal pattern (3) are of two types: large-size pattern and small-size pattern; the large-size pattern is cross-shaped, and the small-size pattern is distributed around the cross-shaped structure in a square arrangement; a cross-shaped large-size pattern and the small-size patterns distributed around the cross-shaped structure constitute a structural cycle.

2. The infrared and laser compatible stealth structure according to claim 1, characterized in that, Small-sized patterns are available in disc, square, or cross shapes.

3. The infrared and laser compatible stealth structure according to claim 1, characterized in that, The bottom metal film (1) and the top metal pattern (3) are made of aluminum, silver, gold or tungsten. The thickness of the bottom metal film (1) or the top metal pattern (3) is greater than the skin depth of the infrared electromagnetic wave in the metal.

4. The infrared and laser compatible stealth structure according to claim 1, characterized in that, The intermediate medium pattern (2) is made of magnesium fluoride, aluminum oxide, hafnium oxide, zinc sulfide, silicon, and germanium.

5. The infrared and laser compatible stealth structure according to claim 1, characterized in that, The intermediate medium pattern (2) of the large-size pattern and the small-size pattern have the same thickness, and the top metal pattern (3) of the large-size pattern and the small-size pattern have the same thickness.

6. A design method for an infrared and laser-compatible stealth structure as described in any one of claims 1-5, characterized in that, Here are the steps: Step S1: Obtain the relationship between the structural period, size, thickness, material refractive index and magnetic resonance wavelength of the intermediate dielectric pattern (2) and the top metal pattern (3); Select the type of small-sized pattern, the metal type of the bottom metal film (1) and the top metal pattern (3), substitute the size, thickness and material dielectric constant of the intermediate dielectric pattern (2) and the top metal pattern (3) into the LC equivalent circuit model, calculate the magnetic resonance wavelength under the above parameter changes, and obtain the relationship between the absorption peak and the incident wavelength. Step S2: Obtain the relationship between the dimensions of the large-size pattern and the small-size pattern, the material refractive index and thickness parameters of the intermediate medium pattern (2), and the absorption spectrum curve; The size parameters of the magnetic resonance wavelength of the small-sized pattern at 1.064 μm, the material and thickness parameters of the intermediate medium pattern (2), are selected, and the absorption spectrum curves under the variation of the above parameters are calculated. The size parameters of the magnetic resonance wavelength of the large-size pattern are selected as 6.5 μm, and the material and thickness parameters of the intermediate medium pattern (2) are selected. The absorption spectrum curves under the changes of the above parameters are calculated. Step S3: Determine the dimensions of the large-size pattern and the small-size pattern, as well as the material refractive index and thickness parameters of the intermediate medium pattern (2); Observe the size of the small-sized pattern and the large-sized pattern, the material refractive index and thickness parameters of the intermediate medium pattern (2) and the absorption spectrum curves. Select the same material refractive index and thickness parameters of the intermediate medium pattern (2) of the small-sized pattern and the large-sized pattern so that the absorption at 1.064μm and 6.5μm reaches the strongest. Step S4: Combine the parts using the material refractive index and thickness parameters of the intermediate medium pattern (2) between the small-sized pattern and the large-sized pattern obtained above.

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