A multi-band laser-guided stealth-long-wave infrared stealth structure

Abstract

This invention belongs to the field of multispectral camouflage technology, specifically relating to a multi-band laser-guided stealth-long-wave infrared stealth structure. It includes several periodically distributed absorbing units, each comprising, from top to bottom, a cross-shaped symmetrical structure, a phase change material cube, a dielectric cube, a metal cube, a phase change material thin film, and a metal thin film, stacked sequentially. The cross-shaped symmetrical structure includes a large cross structure whose center is directly opposite the center of the square thin film, and four identical small cross structures arranged symmetrically in the four quadrants with the center of the large cross structure as the origin. The large and small cross structures have equal thickness and are all centrally symmetrical figures with equal length and width in both the longitudinal and transverse directions. This invention combines localized plasmon resonance and Mie resonance to counter laser guidance, achieving laser stealth-long-wave infrared stealth compatibility.

Description

Technical Field

[0001] This invention relates to the field of multispectral camouflage technology, specifically to a multi-band laser-guided stealth-long-wave infrared stealth structure. Background Technology

[0002] With the continuous improvement of the accuracy and stability of contemporary infrared active and passive guidance technologies, the probability of guided weapons hitting targets has greatly increased, making targets vulnerable to destruction once exposed. Furthermore, infrared guidance technology is evolving towards multi-mode cooperative guidance, resulting in guidance methods that are omnidirectional, multi-angle, and highly tolerant. As the antithesis of infrared guidance, multispectral stealth in the infrared band is becoming increasingly important and challenging in countering the ever-evolving infrared multi-mode cooperative guidance methods.

[0003] Stealth is a method of controlling the emitted or reflected wavelengths to disappear from the detector's field of view. Stealth across different spectra can be achieved through spectral matching, absorption peak modulation, and reflection suppression. However, compatible solutions for laser stealth and long-wave infrared stealth remain rare because the design of such materials is extremely challenging.

[0004] For stealth in the long-wave infrared band, the target object needs low absorptivity (low emissivity) in the detection band (8-14 μm). According to the Stefan-Boltzmann law, the intensity of the infrared signal emitted by an object is proportional to the fourth power of its surface emissivity (ε) and its absolute temperature (T). Compared to precisely controlling temperature, changing surface emissivity is a more efficient and convenient strategy for regulating thermal radiation. For objects near room temperature (300 K), most of their radiant energy is concentrated in the 8-14 μm band, which is an atmospheric window band and can be transmitted over long distances in the atmosphere without loss. Therefore, a low emissivity in this band is required; however, this will make heat dissipation difficult, reducing the thermal stability of the structure. Compared to simple static camouflage stealth, dynamic camouflage is more adaptable to changing battlefield environments. By dynamically adjusting the radiation spectrum, it can achieve a radiative cooling effect.

[0005] In contrast to stealth targeting passive guidance, laser stealth operates on the opposite principle. Due to the fundamental principles of laser guidance and other testing methods, laser stealth typically employs absorption methods. However, with the advent of multi-band laser guidance systems, single-band laser stealth is no longer sufficient. The design of multi-band laser stealth devices often achieves efficient absorption across multiple bands by exciting various resonant modes. Furthermore, simultaneously achieving multi-band laser stealth and long-wave infrared stealth requires resolving the contradiction between the low emissivity required for long-wave infrared stealth (8-14μm) and the high absorptivity required for laser stealth at 10.6μm. While some stealth solutions have been proposed for both active and passive infrared detection, there are few reports on methods for achieving stealth against both active and passive infrared detection simultaneously, particularly dynamic tunability for both. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a multi-band laser-guided stealth-long-wave infrared stealth structure that can be used to counter laser guidance and implement long-wave infrared stealth.

[0007] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0008] This invention provides a multi-band laser-guided stealth-long-wave infrared stealth structure, comprising a plurality of periodically distributed absorbing units. Each absorbing unit includes, from top to bottom, a cross-symmetric structure, a phase change material cube, a dielectric cube, a metal cube, a phase change material thin film, and a metal thin film stacked sequentially. The phase change material thin film and the metal thin film are two square thin films with equal and completely overlapping sides. The phase change material thin film and the metal thin film of the plurality of absorbing units correspond to form a continuous and uninterrupted phase change material thin film layer and metal thin film layer. The cross-symmetric structure includes a large cross structure whose center is directly opposite the center of the square thin films, and four cross-shaped structures with the center of the large cross structure as the origin. The large cross structure is a centrally symmetrical arrangement of identical small cross structures in the four quadrants. The large cross structure has the same thickness as the small cross structures and is a centrally symmetrical figure with equal length and width in both the longitudinal and transverse directions. The phase change material block, dielectric block, and metal block are three square blocks with their geometric centers overlapping. The geometric center of each square block is directly opposite the center of the large cross structure. The stacked structure formed by the cross-symmetric structure, phase change material block, dielectric block, and metal block is distributed at equal intervals on the phase change material thin film to form a periodic array. The thickness of the cross-symmetric structure, phase change material block, dielectric block, metal block, and phase change material thin film is all less than the laser wavelength.

[0009] In one embodiment, a through hole is formed in the center of the large cross structure to form an air column.

[0010] In one embodiment, the large cross structure is composed of four identical cuboids joined together, and the end faces of the four cuboids enclose an air column at the joint.

[0011] In one embodiment, the square film has a side length of 1300–1500 nm, the cuboid has a length of 210–225 nm along the longitudinal and transverse directions of the large cross structure, the cuboid has a width of 100–120 nm along the longitudinal and transverse directions of the large cross structure, the distance between the centers of two adjacent small cross structures on the absorbing unit is 610–630 nm, the small cross structure has a length of 290–310 nm along its own longitudinal and transverse directions, and the small cross structure has a width of 100–120 nm along its own longitudinal and transverse directions. The width is 100-120 nm, the thickness of the cross-symmetric structure is 250-270 nm, the phase change material block, the dielectric block, and the metal block completely overlap and have a side length of 990-1010 nm, the thickness of the phase change material block is 60-70 nm, the thickness of the dielectric block is 250-270 nm, the thickness of the metal block is 170-190 nm, the thickness of the phase change material film is 110-120 nm, and the thickness of the metal film is ≥100 nm.

[0012] In one embodiment, the square film has a side length of 1400 nm, the cuboid has a length of 225 nm along the longitudinal and transverse directions of the large cross structure, and a width of 110 nm along the longitudinal and transverse directions of the large cross structure. The distance between the centers of two adjacent small cross structures on the absorbing unit is 620 nm, the length of each small cross structure along its own longitudinal and transverse directions is 300 nm, the width of each small cross structure along its own longitudinal and transverse directions is 110 nm, the thickness of the cross-symmetric structure is 260 nm, the phase change material block, the dielectric block, and the metal block completely overlap and have a side length of 1000 nm, the thickness of the phase change material block is 66 nm, the thickness of the dielectric block is 263 nm, the thickness of the metal block is 181 nm, the thickness of the phase change material film is 115 nm, and the thickness of the metal film is 100 nm.

[0013] In one embodiment, the phase change material block, the dielectric block, and the metal block are three square blocks with equal side lengths that completely overlap.

[0014] In one embodiment, the thickness of the metal film is not less than 0.1 μm.

[0015] In one embodiment, the materials of the large cross structure, the small cross structure, and the phase change material block are all Ge2Sb2Te5.

[0016] In one embodiment, the material of the dielectric block is germanium or silicon, and the material of the metal block is platinum or gold.

[0017] In one embodiment, the phase change material film is made of Ge2Sb2Te5, and the metal film is made of platinum or gold. The amorphous Ge2Sb2Te5 film layer has a high refractive index, and the metal film, as the lower metal substrate reflective layer, uses platinum or gold to enhance the absorption of guided lasers.

[0018] The multi-band laser-guided stealth-long-wave infrared stealth structure of this invention is a metasurface structure based on phase change materials, composed of several planar extended absorbing units. Each absorbing unit includes, from top to bottom, a cross-symmetric structure, a phase change material cube, a dielectric cube, a metal cube, a phase change material thin film, and a metal thin film. The cross-symmetric structure is used to enhance the structural Mie resonance, the phase change material cube is used to tune the near-infrared absorption peak and plays an auxiliary role in switching between laser stealth mode and long-wave infrared stealth mode, the dielectric cube is used to excite the Mie resonance, the metal cube is used to excite the local plasmon resonance, and the phase change material thin film is the structural dielectric. The structure consists of a metal layer that plays a major role in switching between laser stealth mode and long-wave infrared stealth mode. The metal thin film serves as the bottom metal reflective layer, enhancing the absorption of incident light through ohmic loss and playing a role in plasmonic resonance excitation. By combining local plasmonic resonance and Mie resonance, a multi-layered stacked micro-nano structure is adopted. In the amorphous state, the structure can simultaneously, efficiently, and with a wide angle absorb 1.064μm, 1.55μm, and 10.6μm wavelength infrared lasers in laser guidance. In the crystalline state, the structure can achieve long-wave infrared (8-14μm) stealth, realizing compatibility between countering laser guidance and implementing long-wave infrared stealth.

[0019] This invention introduces phase change materials into structural design. Through material phase transitions, the designed structure can enter different modes (laser stealth mode, long-wave infrared stealth mode), thereby resolving the contradiction between active and passive stealth in the long-wave infrared band and achieving a dynamic adjustment effect. Furthermore, since it is not necessary to simultaneously consider the high absorption at 10.6 μm and the required low emission at 8-14 μm, the absorption peak at 10.6 μm can be designed as broadband absorption, thus solving the problem of tunable guided lasers.

[0020] Compared with existing technologies, the beneficial effects of this invention are as follows: by combining Mie resonance and local plasmon resonance, and employing a multilayer resonant layer containing micro-nano structures, it achieves simultaneous and efficient absorption of guided lasers with wavelengths of 1.064μm, 1.55μm, and 10.6μm, and the absorption efficiency is insensitive to the incident angle of the laser. Long-wave infrared (8-14μm) stealth can also be achieved through material phase transition. Devices based on this stealth structure have significant advantages such as thinness, light weight, and ease of fabrication on flexible substrates. It overcomes the shortcomings of existing absorbing materials, such as being thick, heavy, having low absorption rate, being sensitive to the incident angle, and having a single stealth band. It has great application value in countering laser guidance and implementing laser stealth-long-wave infrared stealth compatibility.

[0021] Other advantages of the present invention will be described in detail in the following detailed description section with reference to the accompanying drawings. Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0023] In the attached diagram:

[0024] Figure 1 This is a three-dimensional structural diagram of an embodiment of a multi-band laser-guided stealth-long-wave infrared stealth structure according to the present invention;

[0025] Figure 2 for Figure 1 The diagram shows a single absorbing unit in a multi-band laser-guided stealth-long-wave infrared stealth structure.

[0026] Figure 3 for Figure 1 The absorption spectrum of the multi-band laser-guided stealth-long-wave infrared stealth structure in its amorphous state under normal incidence is shown.

[0027] Figure 4 for Figure 1 The diagram shows the emissivity curve of the crystalline state and the absorptivity curve of the atmosphere for the multi-band laser-guided stealth-long-wave infrared stealth structure under normal incidence.

[0028] Figure 5 for Figure 1 The reflectance spectra of the multi-band laser-guided stealth-long-wave infrared stealth structure in the amorphous state under different incident angles, with a wavelength range of 0.8-14 μm;

[0029] Figure 6 for Figure 1The reflectance spectra of the multi-band laser-guided stealth-long-wave infrared stealth structure in the amorphous state under different polarization angles are shown, with a wavelength range of 0.8-14 μm.

[0030] Explanation of reference numerals in the attached figures: 1. Cross-shaped symmetrical structure; 2. Phase change material block; 3. Dielectric block; 4. Metal block; 5. Phase change material thin film; 6. Metal thin film; 100. Absorbing unit; 7. Substrate. Detailed Implementation

[0031] To further explain the technical solution of the present invention, the present invention will be described in detail below with reference to the accompanying drawings, in which the same reference numerals denote the same parts.

[0032] See also Figure 1 , 2 This embodiment provides a multi-band laser-guided stealth-long-wave infrared stealth structure based on micro / nano structures, including a plurality of periodically distributed absorbing units 100. Each absorbing unit 100 comprises, from top to bottom, a cross-symmetric structure 1, a phase change material block 2, a dielectric block 3, a metal block 4, a phase change material thin film 5, and a metal thin film 6, stacked sequentially. The thickness of the cross-symmetric structure 1, the phase change material block 2, the dielectric block 3, the metal block 4, and the phase change material thin film 5 is all less than the laser wavelength.

[0033] The cross-symmetric structure 1 is a hybrid structure consisting of a large cross structure without a center and four identical small cross structures. The large cross structure and the small cross structures have equal thicknesses and are both centrally symmetric figures with equal lengths and widths in both the longitudinal and transverse directions. The large cross structure without a center is composed of four identical cuboids joined together, with the end faces of the four cuboids forming an air column at the joint. The four identical small cross structures are arranged in the four quadrants in a centrally symmetric manner with the center of the large cross structure as the origin. The hybrid structure of the large cross structure without a center and the four identical small cross structures is used to strengthen the Mie resonance of the structure. Both the large cross structure and the small cross structures are made of Ge2Sb2Te5 material.

[0034] Phase change material cube 2, dielectric cube 3, and metal cube 4 are three perfectly overlapping square cubes with equal side lengths but different thicknesses. Their geometric centers are directly opposite the center of the large cross structure. From top to bottom, their materials are Ge2Sb2Te5, germanium, and platinum, respectively. Phase change material cube 2 is used to tune the absorption peak in the near-infrared band and plays an auxiliary role in switching between laser stealth mode and long-wave infrared stealth mode. Dielectric cube 3 is used to excite Mie resonance, and metal cube 4 is used to excite local plasmon resonance.

[0035] The phase change material thin film 5 serves as the structural dielectric layer and plays a major role in switching between laser stealth mode and long-wave infrared stealth mode; its material is Ge2Sb2Te5. The metal thin film 6 serves as the bottom metal reflective layer, enhancing the absorption of incident light through ohmic loss and playing a role in plasmonic resonance excitation; its material is platinum. A series of absorbing units 100, comprising the phase change material thin film 5 and the metal thin film 6, form a continuous and uninterrupted phase change material thin film layer and metal thin film layer. The micro / nano structure formed by the stacked cross-symmetric structure 1, phase change material cubes 2, dielectric cubes 4, and metal cubes 4 extends at equal intervals along the horizontal direction, forming a periodic array.

[0036] The multi-band laser-guided stealth-long-wave infrared stealth structure proposed in this embodiment is a metasurface structure with a six-layer periodic structure based on phase change materials. Specifically, as shown... Figure 2 As shown, the metasurface structure has a period p = 1400 nm (i.e., the side length of the phase change material film 5 and the metal film 6 in one absorbing unit 100 is 1400 nm). The four identical cuboids that make up the centerless large cross structure have a length l1 = 225 nm and a width w1 = 110 nm along the longitudinal and transverse directions of the large cross structure. The small cross structure has a length l2 = 300 nm and a width w2 = 110 nm along its own longitudinal and transverse directions. The center of two adjacent small cross structures is... The distance l3 = 620 nm, the thickness of each structure in the cross-symmetric structure 1 is the same and the thickness d1 = 260 nm, the phase change material block 2, the dielectric block 3, and the metal block 4 are completely overlapping and the side length w3 = 1000 nm, the thickness of the phase change material block 2 is d2 = 66 nm, the thickness of the dielectric block 3 is d3 = 263 nm, the thickness of the metal block 4 is d4 = 181 nm, the thickness of the phase change material film 5 is h1 = 115 nm, and the thickness of the metal film 6 is h2 = 100 nm.

[0037] Figure 3 The image shows the absorption spectrum under normal incidence in this embodiment. The absorptivity is calculated using the formula A = 1 - RT, where R and T are the reflectivity and transmittance, respectively, and T is a straight line along the horizontal axis, with transmittance being almost zero. It can be seen that the device achieves an absorptivity of 92% at 1.064 μm, 96.3% at 1.55 μm, and 97.2% at 10.6 μm.

[0038] Figure 4 The figures show the emissivity curves of the C-GST state and the absorptivity curves of the atmosphere under normal incidence conditions in this embodiment. It can be seen that the long-wave infrared atmospheric window region (8-14 μm) has low emissivity, enabling passive stealth in this band.

[0039] Figure 5This is a reflectance diagram for this embodiment under different incident angles. Since the transmittance is almost zero, it can be seen from this diagram that even when the incident angle reaches 57°, the absorptivity changes very little at wavelengths of 1.064μm, 1.55μm, and 10.6μm, indicating that the stealth structure has the characteristic of wide-angle absorption.

[0040] Figure 6 This diagram shows the reflectivity of the laser under different polarization states in this embodiment. Since the transmittance is almost zero, it can be seen from the diagram that the absorptivity remains unchanged under different polarization states, and the center wavelength corresponding to the absorption peak does not shift, indicating that the stealth structure has polarization-independent characteristics.

[0041] In this embodiment, the phase change material thin film layer and the metal thin film layer can be sequentially deposited on the substrate 7 using conventional deposition methods such as magnetron sputtering and electron beam evaporation. The micro-nano structure can be obtained by methods such as electron beam exposure, ion beam etching, and laser etching, which are existing technologies and will not be described in detail here.

[0042] The multi-band laser-guided stealth-long-wave infrared stealth structure of this invention combines Mie resonance and local plasmon resonance, employing a multi-layer resonant layer containing micro- and nano-structures to achieve simultaneous, efficient, and wide-angle absorption of 1.064μm, 1.55μm, and 10.6μm wavelength infrared lasers in laser-guided systems. Simultaneously, long-wave infrared (8-14μm) stealth is achieved through material phase transitions. This structure can be used to counter laser guidance, implement laser stealth, and infrared stealth. Devices based on this stealth structure have significant advantages such as thinness, light weight, and ease of fabrication on flexible substrates, overcoming the shortcomings of existing absorbing materials, including thickness, weight, low absorption rate, sensitivity to incident angle, and limited stealth band. It has significant application value in countering laser guidance and implementing laser stealth-long-wave infrared stealth compatibility.

[0043] The above description is merely a specific embodiment of the present invention. It should be noted that any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-band laser-guided stealth-long-wave infrared stealth structure, characterized in that, The device includes several periodically distributed absorbing units (100). Each absorbing unit (100) comprises, from top to bottom, a cross-symmetric structure (1), a phase change material block (2), a dielectric block (3), a metal block (4), a phase change material film (5), and a metal film (6). The phase change material film (5) and the metal film (6) are two square films with equal side lengths and completely overlapping. The phase change material film (5) and the metal film (6) of several absorbing units (100) form a continuous and uninterrupted phase change material film layer and metal film layer. The cross-symmetric structure (1) includes a large cross structure whose center is directly opposite the center of the square film and four cross structures arranged symmetrically with the center of the large cross structure as the origin. In the four quadrants, there are identical small cross structures. The large cross structure and the small cross structure have the same thickness and are both centrally symmetrical figures with equal length and width in the longitudinal and transverse directions. The phase change material block (2), the dielectric block (3), and the metal block (4) are three square blocks with their geometric centers coincident. The geometric center of the square block is directly opposite the center of the large cross structure. The stacked structure formed by the cross-symmetric structure (1), the phase change material block (2), the dielectric block (3), and the metal block (4) is distributed at equal intervals on the phase change material thin film layer to form a periodic array. The thickness of the cross-symmetric structure (1), the phase change material block (2), the dielectric block (3), the metal block (4), and the phase change material thin film (5) is all less than the laser wavelength.

2. The multi-band laser-guided stealth-long-wave infrared stealth structure as described in claim 1, characterized in that, The large cross structure has a through hole in the center to form an air column.

3. The multi-band laser-guided stealth-long-wave infrared stealth structure as described in claim 1, characterized in that, The large cross structure is composed of four identical cuboids joined together, and the end faces of the four cuboids enclose an air column at the joint.

4. The multi-band laser-guided stealth-long-wave infrared stealth structure as described in claim 3, characterized in that, The square film has a side length of 1300–1500 nm. The cuboid has a length of 210–225 nm along the longitudinal and transverse directions of the large cross structure, and a width of 100–120 nm along the longitudinal and transverse directions of the large cross structure. The distance between the centers of two adjacent small cross structures on the absorbing unit (100) is 610–630 nm. The small cross structure has a length of 290–310 nm along its own longitudinal and transverse directions, and a width of 100–120 nm along its own longitudinal and transverse directions. The cross is symmetrical. The thickness of structure (1) is 250-270 nm. The phase change material block (2), the dielectric block (3), and the metal block (4) are completely overlapped and have a side length of 990-1010 nm. The thickness of the phase change material block (2) is 60-70 nm. The thickness of the dielectric block (3) is 250-270 nm. The thickness of the metal block (4) is 170-190 nm. The thickness of the phase change material film (5) is 110-120 nm. The thickness of the metal film (6) is ≥100 nm.

5. The multi-band laser-guided stealth-long-wave infrared stealth structure as described in claim 3, characterized in that, The square film has a side length of 1400 nm, the cuboid has a length of 225 nm along the longitudinal and transverse directions of the large cross structure, the cuboid has a width of 110 nm along the longitudinal and transverse directions of the large cross structure, the distance between the centers of two adjacent small cross structures on the absorbing unit (100) is 620 nm, the small cross structure has a length of 300 nm along its own longitudinal and transverse directions, the small cross structure has a width of 110 nm along its own longitudinal and transverse directions, the thickness of the cross-symmetric structure (1) is 260 nm, the phase change material block (2), the dielectric block (3), and the metal block (4) are completely overlapped and have a side length of 1000 nm, the phase change material block (2) has a thickness of 66 nm, the dielectric block (3) has a thickness of 263 nm, the metal block (4) has a thickness of 181 nm, the phase change material film (5) has a thickness of 115 nm, and the metal film (6) has a thickness of 100 nm.

6. The multi-band laser-guided stealth-long-wave infrared stealth structure as described in claim 1, characterized in that, The phase change material block (2), the dielectric block (3), and the metal block (4) are three square blocks with equal side lengths and completely overlapping.

7. The multi-band laser-guided stealth-long-wave infrared stealth structure as described in claim 1, characterized in that, The thickness of the metal thin film (6) is not less than 0.1 μm.

8. The multi-band laser-guided stealth-long-wave infrared stealth structure as described in any one of claims 1-7, characterized in that, The materials of the large cross structure, the small cross structure, and the phase change material block (2) are all Ge2Sb2Te5.

9. The multi-band laser-guided stealth-long-wave infrared stealth structure as described in any one of claims 1-7, characterized in that, The medium block (3) is made of germanium or silicon, and the metal block (4) is made of platinum or gold.

10. The multi-band laser-guided stealth-long-wave infrared stealth structure as described in any one of claims 1-7, characterized in that, The phase change material film (5) is made of Ge2Sb2Te5, and the metal film (6) is made of platinum or gold.

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