Laser and infrared compatible stealth film structure using FP interference effect

Abstract

The present invention discloses a laser and infrared compatible stealth film structure using F-P interference effect, belonging to the technical field of multi-band compatible stealth materials. Its basic structure is [AB] i T j [AB] i [M1DM2], where i , j is the number of arrangement periods of the dielectric film layer, i The value is 1 or 2; j The value is 0 or 1; the materials of the dielectric layer A, dielectric layer B, dielectric layer T, and dielectric layer D are independently selected from ZnS, ZnO, ZnSe, Al2O3, SiO2, and TiO2; the M1DM2 is a metal-dielectric-metal film structure, and the materials of the metal layer M1 and the metal layer M2 are independently selected from Ag, Au, and Al. The film structure of the present invention has the characteristics of narrow-band low reflection in 1.06μm and 10.6μm multi-laser frequency domains, and the wide-band high reflection characteristics of 1-2.5μm, 3-5μm, and 8-14μm multi-band infrared windows, and has strong multi-spectrum compatible stealth capabilities, and has very important military application value.

Description

Technical Field

[0001] The invention relates to a laser and infrared compatible stealth film system structure utilizing FP interference effect, belonging to the technical field of multi-band compatible stealth materials. Background Art

[0002] The detection and guidance technology on the modern battlefield has become increasingly diversified. Multi-band advanced military reconnaissance equipment such as radar, laser, infrared and visible light are all used in combination. In particular, infrared passive detection and laser active detection have generally formed a multi-mode composite guidance method, which is widely used in precision-guided asymmetric lethal strike weapons such as missiles. Therefore, the development of multi-spectrum compatible stealth protection systems such as visible light, infrared, laser and radar waves has become an important topic in the field of stealth today, in order to avoid high-precision locking and destruction strikes of multi-source detection, and enhance the battlefield survivability and penetration capability of military equipment.

[0003] The laser detection and guidance bands are mainly 1.06 µm corresponding to YAG lasers and 10.6 µm corresponding to carbon dioxide lasers. Traditional laser stealth means usually use coatings of strong absorption materials such as rare earth, semiconductors, plasma, and conductive polymers in the hope that the reflectivity of the laser band can be reduced to the lowest level. The working bands of infrared detectors mainly use three infrared atmospheric window bands: near-band 1-2.5μm, medium-band 3-5μm, and long-band 8-14μm. Traditional infrared stealth means mainly rely on low-emissivity coating technologies such as metal fillers, semiconductor fillers, dielectric / metal multilayer composite films, and diamond-like carbon films in the hope of having high reflectivity for thermal infrared light waves to reduce infrared heat absorption and achieve infrared low-emissivity effects. However, the laser wavelengths are in the near-infrared and far-infrared infrared window bands respectively. If you want to achieve compatible stealth for both passive infrared detection and active laser detection, you must simultaneously increase the infrared reflectivity of the material and reduce the reflectivity at the laser wavelength. These two stealth principles are contradictory in a sense and are difficult to be achieved by traditional stealth materials. In particular, achieving compatible stealth of multi-frequency domain laser and multi-band infrared will involve limitations such as cross-frequency domain, wide frequency domain, and contradictions in stealth principles, which has become the main "bottleneck" problem that multi-spectrum compatible stealth technology needs to overcome. As laser and infrared play an increasingly important role in detection and guidance, achieving compatible stealth material technology for laser frequency domains such as 1.06 µm and 10.6 µm and near, medium and long-range multi-band infrared has become an important topic in the military field. Summary of the invention

[0004] In view of the above-mentioned prior art, the present invention provides a laser and infrared compatible stealth film structure using the FP interference effect (Fabry-Perot). The present invention uses the combination of FP cavity interference and special photonic crystals to design a multi-layer structure thin film material with a specific configuration, and synergistically exerts the comprehensive effects of FP cavity destructive interference, photon bandgap, and photon localization to achieve laser and infrared compatible multi-spectrum stealth function, providing important technical support for improving the battlefield survivability of military equipment.

[0005] The present invention is achieved through the following technical solutions:

[0006] A laser and infrared compatible stealth film structure using FP interference effect, the basic structure of which is [AB]iTj[AB]i[M1DM2], wherein i and j are the arrangement period numbers of the dielectric film layer, i is 1 or 2; j is 0 or 1;

[0007] The materials of the dielectric layer A, dielectric layer B and dielectric layer T are independently selected from ZnS, ZnO, ZnSe, Al2O3, SiO2 and TiO2;

[0008] The M1DM2 is a metal-dielectric-metal film structure, the materials of the metal layer M1 and the metal layer M2 are independently selected from Ag, Au, and Al; the material of the dielectric layer D is selected from ZnS, ZnO, ZnSe, Al2O3, SiO2, and TiO2;

[0009] The refractive indices of dielectric layer A, dielectric layer B, dielectric layer T, and dielectric layer D at 10.6 µm are nA, nB, nT, and nD, respectively. The thicknesses of dielectric layer A, dielectric layer B, dielectric layer T, and dielectric layer D are dA, dB, dT, and dD, respectively. Because the optical wavelength that interferes or resonates in the microstructure is usually an integer multiple of the equivalent optical thickness of the micro-nanostructure, they have the following relationship: nA×dA≈nB×dB≈nT×dT≈nD×dD≈(2650±Δ) / k nm, where k is 1 or 2, Δ is the error correction compensation, and 0≤Δ≤150; the thicknesses of metal layer M1 and metal layer M2 are both 5 to 25 nm.

[0010] The application of the laser and infrared compatible stealth film structure using the FP interference effect as or in the preparation of infrared and laser compatible stealth materials. In specific applications, the dielectric layer and metal layer can be coated layer by layer on the substrate surface using advanced micro-nano manufacturing technologies such as atomic layer deposition, magnetron sputtering, and evaporation plating, so as to prepare the film structure with high precision. The substrate is selected from indium tin oxide (ITO), antimony tin oxide (ATO), quartz, PET, etc.

[0011] The laser and infrared compatible stealth film system structure utilizing the FP interference effect of the present invention is composed of a photonic crystal [AB]iTj[AB]i and an asymmetric FP cavity M1DM2, wherein M1-D-M2 is a metal-dielectric-metal film system structure, wherein the metal layer M1 and the metal layer M2 are made of commonly used metal reflective films such as Ag, Au, and Al, which have a double-sided strong reflective mirror effect; the materials of the dielectric layer A, the dielectric layer B, the dielectric layer T, and the dielectric layer D are selected from optical film materials such as ZnS, ZnO, ZnSe, Al2O3, SiO2, and TiO2. The present invention utilizes the asymmetric FP destructive interference effect of M1DM2 and the comprehensive effects of the photonic bandgap and photon localization of the photonic crystal [AB]iTj[AB]i to design a composite thin film material with a specific film structure, achieving narrow-band low-reflection characteristics in the 1.06μm and 10.6μm laser frequency domains, and wide-band high-reflection characteristics in three infrared window bands of near-infrared 1-2.5μm, mid-infrared 3-5μm and far-infrared 8-14μm, thereby achieving a multi-band compatible stealth effect of laser and infrared.

[0012] The laser and infrared compatible stealth film structure using the FP interference effect of the present invention has a microstructure that is a new type of film structure with a simple arrangement rule, and has the characteristics of narrow-band low reflection in 1.06μm and 10.6μm multi-laser frequency domains, and the characteristics of wide-band high reflection in 1-2.5μm, 3-5μm and 8-14μm multi-band infrared windows, and has a strong multi-spectrum compatible stealth capability. The present invention uses the synergistic effect of FP interference and photon localization to accurately realize "spectral hole digging" at the laser frequency domain in the reflection spectrum of the infrared wide-range high-reflection "photon bandgap" feature, and cleverly resolves the conflict and contradiction between the stealth principle of low reflection "trapped light" required by laser stealth and the high reflection and low radiation required by infrared stealth, which is conducive to the equipment target avoiding the attack of laser and infrared dual-mode guided weapons in the battlefield, and has very important military application value.

[0013] Various terms and phrases used herein have the general meanings that are well known to those skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 : Schematic diagram of the membrane system structure of Example 1.

[0015] Figure 2 : Schematic diagram of the infrared reflection spectrum of Example 1.

[0016] Figure 3 : Schematic diagram of the membrane system structure of Example 2.

[0017] Figure 4 : Schematic diagram of the infrared reflection spectrum of Example 2.

[0018] Figure 5: Schematic diagram of the membrane system structure of Example 3.

[0019] Figure 6 : Schematic diagram of infrared reflection spectrum of Example 3. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with the embodiments. However, the scope of the present invention is not limited to the following embodiments. It will be appreciated by those skilled in the art that various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention.

[0021] The instruments, reagents, materials, etc. involved in the following embodiments, unless otherwise specified, are all conventional instruments, reagents, materials, etc. in the prior art and can be obtained through regular commercial channels. The experimental methods, detection methods, etc. involved in the following embodiments, unless otherwise specified, are all conventional experimental methods, detection methods, etc. in the prior art.

[0022] Example 1 Laser and infrared compatible stealth film structure using FP interference effect

[0023] The basic structure is [AB]iTj[AB]i[M1DM2], i=1, and j=1, such as Figure 1 As shown, from top to bottom, there are 8 dielectric film layers, namely, A / B / T / A / B / M1 / D / M2, namely [AB]T[AB][M1DM2]. Among them, the materials of dielectric layer A and dielectric layer T are both zinc selenide (ZnSe), and the refractive index at 10.6 µm is 2.4; the materials of dielectric layer B and dielectric layer D are both titanium dioxide (TiO2), and the refractive index at 10.6 µm is 1.18.

[0024] The thicknesses of dielectric layer A, dielectric layer B, dielectric layer T, and dielectric layer D are dA, dB, dT, and dD, respectively, and have the following relationship: nA×dA≈nB×dB≈nT×dT≈nD×dD≈(2650-Δ) / k nm, where k is 1 or 2, and Δ is the error correction compensation amount. Specifically, for dielectric layer A and dielectric layer T, the value of k is 2, Δ=96, and the thicknesses of dielectric layer A and dielectric layer T are both 532 nm. For dielectric layer B and dielectric layer D, the value of k is 1, Δ=100, and the thicknesses of dielectric layer B and dielectric layer D are both 2161 nm. Metal layer M1 and metal layer M2 are both Ag thin films with thicknesses of 10 nm and 20 nm, respectively.

[0025] The reflectivity characteristics of the above [AB]T[AB][M1DM2] film structure in the infrared band (750-15000 nm) are simulated and analyzed. The results are as follows: Figure 2As shown. As can be seen from the figure, its reflectivity in the 1-2 µm near-infrared window band range forms a "concave" feature, that is, a narrow-band low-reflection feature of "spectral hole digging" is formed with the 1.06 µm frequency domain as the center, and its reflectivity is about 25%, while other near-infrared bands on both sides have a high-reflection "bandbreak" effect. The 3.5-4.5 µm mid-infrared band window has a high-reflection "bandbreak" effect. The reflectivity in the 8-14 µm far-infrared window band range also forms a "concave" feature, forming a narrow-band low-reflection feature of "spectral hole digging" with the 10.6 µm frequency domain as the center, and its reflectivity is about 18%, while other far-infrared bands on both sides have higher reflectivity. It can be seen that the heterogeneous composite film structure [AB]T[AB][M1DM2] of this embodiment benefits from the asymmetric FP destructive interference effect and the photon localization effect, and has a weak reflection "light trapping" feature in the 1.06 µm and 10.6 µm dual laser frequency domains, which is beneficial to reduce the reflection of laser active detection or guidance signals, thereby having a multi-frequency laser compatible stealth effect. At the same time, benefiting from the photon bandgap effect and the strong reflection effect of the metal film, high reflectivity is achieved in the near, medium and far multi-band infrared window interval, that is, low infrared emissivity can be achieved, thereby having a multi-band infrared compatible stealth effect. The structure of this embodiment realizes the multi-band compatible stealth effect of laser and infrared, which is beneficial to equipment targets in complex battlefield background environments to avoid laser and infrared joint detection and guidance, and improve the stealth camouflage capability of equipment.

[0026] Example 2 Laser and infrared compatible stealth film structure using FP interference effect

[0027] The basic structure is [AB]iTj[AB]i[M1DM2], i=1, and j=0, such as Figure 3 As shown, there are 7 dielectric film layers from top to bottom, namely A / B / A / B / M1 / D / M2, namely [AB]2[M1DM2]. Among them, the material of dielectric layer A is zinc sulfide (ZnS), and the refractive index at 10.6µm is 2.19; the materials of dielectric layer B and dielectric layer D are both titanium dioxide (TiO2), and the refractive index at 10.6µm is 1.18.

[0028] The thicknesses of dielectric layer A, dielectric layer B, and dielectric layer D are dA, dB, and dD, respectively, and have the following relationship: nA×dA≈nB×dB≈nD×dD≈(2650-Δ) / k nm, where k is 1 and Δ is 0. Specifically, the thickness of dielectric layer A is 1210 nm. The thicknesses of dielectric layer B and dielectric layer D are both 2246 nm. Metal layer M1 and metal layer M2 are both Au thin films with thicknesses of 5 nm and 15 nm, respectively.

[0029] The reflectivity characteristics of the above [AB]2[M1DM2] film structure in the infrared band (750-15000 nm) are simulated and analyzed. The results are as follows: Figure 5 As shown. It can be seen from the figure that, firstly, the film structure of this embodiment forms two "light trapping" type narrow band phenomena in the high-reflection "bandbreak" in the 1-2.5 µm near-infrared window band, which are located near the 1.06 µm and 1.7 µm frequency domains, respectively. The 1.06 µm frequency domain is in the commonly used yttrium aluminum garnet laser band, and its reflectivity is only about 15%. Secondly, the film structure of this embodiment has a high-reflection "bandbreak" effect in the 3.5-4.5 µm mid-infrared band window. Finally, the reflectivity in the 8-14 µm far-infrared window band forms a "concave" feature, forming a low-reflection "light trapping" feature centered near the 10.6 µm frequency domain, with a reflectivity of less than 5%, and higher reflectivity in other far-infrared bands on both sides. It can be seen that the heterogeneous composite film structure [AB]2[M1DM2] of this embodiment benefits from the asymmetric FP destructive interference effect and the photon localization effect, and has a weak reflection "light trapping" feature in the 1.06 µm and 10.6 µm dual laser frequency domains, thereby having a multi-frequency laser compatible stealth effect. At the same time, benefiting from the photon bandgap effect and the strong reflection effect of the metal film, high reflectivity is achieved in the near, medium and far multi-band infrared window interval, that is, low infrared emissivity can be achieved, thereby having a multi-band infrared compatible stealth effect. Therefore, the structure of this embodiment is conducive to achieving the multi-band compatible stealth effect of 1.06 µm, 10.6 µm dual-frequency domain laser and near, medium and far infrared, and improving the battlefield survivability and penetration capability of the equipment.

[0030] Example 3 Laser and infrared compatible stealth film structure using FP interference effect

[0031] The basic structure is [AB]iTj[AB]i[M1DM2], i=2, and j=0, such as Figure 5 As shown, from top to bottom, there are 11 dielectric film layers, namely, A / B / A / B / A / B / A / B / M1 / D / M2, that is, [AB]4[M1DM2]. Among them, the material of dielectric layer A is zinc selenide (ZnSe), and the refractive index at 10.6 µm is 2.4; the materials of dielectric layer B and dielectric layer D are both silicon dioxide (SiO2), and the refractive index at 10.6 µm is 2.07.

[0032] The thicknesses of dielectric layer A, dielectric layer B, and dielectric layer D are dA, dB, and dD, respectively, and have the following relationship: nA×dA≈nB×dB≈nD×dD≈(2650-Δ) / k nm, where k is 1 and Δ is 0. Specifically, the thickness of dielectric layer A is 1104 nm. The thicknesses of dielectric layer B and dielectric layer D are both 1280 nm. Metal layer M1 and metal layer M2 are both Ag thin films with thicknesses of 5 nm and 25 nm, respectively.

[0033] The reflectivity characteristics of the above [AB]4[M1DM2] film structure in the infrared band (750-15000 nm) are simulated and analyzed. The results are as follows: Figure 6 As shown. It can be seen from the figure that, firstly, the film structure of this embodiment can achieve a high reflection phenomenon of more than 50% in the 1-2.5 µm near-infrared window band range, which can better achieve the near-infrared stealth effect. Secondly, the film structure of this embodiment can achieve a window reflectivity of more than 80% in the 3-5 µm mid-infrared band, which has a typical high-reflection "bandbreak" phenomenon, and therefore has a very good mid-infrared stealth effect. Finally, in the 8-14 µm far-infrared window band range, a low-reflection "light trap" feature is formed near the 10.6 µm frequency domain, and its reflectivity is less than 5%, while most of the other far-infrared bands on both sides have a reflectivity of 75% to 90%, so it can better achieve the 10.6 µm frequency domain laser and far-infrared compatible stealth effect. It can be seen that the heterogeneous composite film structure [AB]2[M1DM2] of this embodiment benefits from the asymmetric FP destructive interference effect and the photon localization effect, and has a weak reflection "light trapping" feature in the 10.6 µm laser frequency domain; at the same time, it benefits from the photon bandgap effect and the strong reflection of the metal film, and achieves high reflectivity in the near, medium and far multi-band infrared window range, that is, it can achieve infrared low emissivity. Therefore, the structure of this embodiment is conducive to achieving the multi-band compatible stealth effect of 10.6 µm frequency domain laser and near, medium and far infrared.

[0034] The above examples are provided to those skilled in the art to fully disclose and describe how to make and use the claimed embodiments, and are not intended to limit the scope of the disclosure herein. Modifications that are obvious to those skilled in the art will fall within the scope of the appended claims.

Claims

1. A laser and infrared compatible stealth film structure using FP interference effect, characterized in that: Its basic structure is [AB] i T j [AB] i [M1DM2], where i and j are the arrangement period numbers of the dielectric film layer, i=1, and j=1; M1DM2 is a metal-dielectric-metal film structure; The refractive indices of dielectric layer A, dielectric layer B, dielectric layer T, and dielectric layer D at 10.6 μm are n A 、n B 、n T 、n D The thicknesses of dielectric layer A, dielectric layer B, dielectric layer T, and dielectric layer D are d respectively. A d B d T d D , with the following relationship: n A× d A ≈n B× d B ≈n T× d T ≈n D× d D ≈(2650±Δ) / k nm, where k is 1 or 2, Δ is the error correction compensation, and 0≤Δ≤150; The materials of dielectric layer A and dielectric layer T are both zinc selenide, and the refractive index at 10.6 μm is 2.4; The materials of dielectric layer B and dielectric layer D are both titanium dioxide, and the refractive index at 10.6 μm is 1.18; The thickness of dielectric layer A and dielectric layer T are both 532 nm; the thickness of dielectric layer B and dielectric layer D are both 2161 nm; The metal layer M1 and the metal layer M2 are both Ag thin films with thicknesses of 10 nm and 20 nm respectively.

2. A laser and infrared compatible stealth film structure using FP interference effect, characterized in that: Its basic structure is [AB] i T j [AB] i [M1DM2], where i and j are the arrangement period numbers of the dielectric film layer, i=1, and j=0; M1DM2 is a metal-dielectric-metal film structure; The refractive indices of dielectric layer A, dielectric layer B, dielectric layer T, and dielectric layer D at 10.6 μm are n A 、n B 、n T 、n D The thicknesses of dielectric layer A, dielectric layer B, dielectric layer T, and dielectric layer D are d respectively. A d B d T d D , with the following relationship: n A× d A ≈n B× d B ≈n T× d T ≈n D× d D ≈(2650±Δ) / k nm, where k is 1 or 2, Δ is the error correction compensation, and 0≤Δ≤150; The material of dielectric layer A is zinc sulfide, and the refractive index at 10.6 μm is 2.19; The materials of dielectric layer B and dielectric layer D are both titanium dioxide, and the refractive index at 10.6 μm is 1.18; The thickness of dielectric layer A is 1210 nm; the thickness of dielectric layer B and dielectric layer D are 2246 nm; The metal layer M1 and the metal layer M2 are both Au thin films with thicknesses of 5 nm and 15 nm respectively.

3. A laser and infrared compatible stealth film structure using FP interference effect, characterized in that: Its basic structure is [AB] i T j [AB] i [M1DM2], where i and j are the arrangement period numbers of the dielectric film layers, i=2, and j=0; M1DM2 is a metal-dielectric-metal film structure; The refractive indices of dielectric layer A, dielectric layer B, dielectric layer T, and dielectric layer D at 10.6 μm are n A 、n B 、n T 、n D The thicknesses of dielectric layer A, dielectric layer B, dielectric layer T, and dielectric layer D are d respectively. A d B d T d D , with the following relationship: n A× d A ≈n B× d B ≈n T× d T ≈n D× d D ≈(2650±Δ) / k nm, where k is 1 or 2, Δ is the error correction compensation, and 0≤Δ≤150; The material of dielectric layer A is zinc selenide, and the refractive index at 10.6 μm is 2.4; The materials of dielectric layer B and dielectric layer D are both silicon dioxide, and the refractive index at 10.6 μm is 2.07; The thickness of dielectric layer A is 1104 nm; the thickness of dielectric layer B and dielectric layer D are both 1280 nm; The metal layer M1 and the metal layer M2 are both Ag thin films with thicknesses of 5 nm and 25 nm respectively.

4. Use of the laser and infrared compatible stealth film structure utilizing FP interference effect as claimed in any one of claims 1 to 3 as or in the preparation of infrared and laser compatible stealth materials.

5. The use according to claim 4, characterized in that: In specific applications, each dielectric layer and metal layer is coated layer by layer on the surface of the substrate by atomic layer deposition, magnetron sputtering and / or evaporation plating.

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