Infrared Camouflage Utilizing Ultrathin Flexible Large‐Scale High‐Temperature‐Tolerant Lambertian Surfaces

Huang, Yun; Ma, Binze; Pattanayak, Arnab; Kaur, S.; Qiu, Min; Li, Qiang

doi:10.1002/lpor.202000391

Cited by 34 publications

(15 citation statements)

References 62 publications

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“…[ 8 ] The camouflage platform with metamaterials to manipulate electromagnetic energy efficiently is one of the solutions to satisfy the needs in energy, [ 9,10 ] military, [ 11–15 ] and space applications. [ 16 ] Hence, many researchers have developed several camouflage platforms with metamaterials, [ 17,18 ] such as metal‐dielectric‐metal (MDM) structure, [ 19,20 ] photonic crystal, [ 21 ] multi‐layers, [ 22,23 ] and novel materials [ 24–27 ] to control the electromagnetic energy for breaking the limits of conventional applications. [ 28,29 ]…”

Section: Introductionmentioning

confidence: 99%

Flexible Assembled Metamaterials for Infrared and Microwave Camouflage

Lee

Lim

Chang

et al. 2022

Advanced Optical Materials

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camouflage platform with metamaterials to manipulate electromagnetic energy efficiently is one of the solutions to satisfy the needs in energy, [9,10] military, [11][12][13][14][15] and space applications. [16] Hence, many researchers have developed several camouflage platforms with metamaterials, [17,18] such as metal-dielectric-metal (MDM) structure, [19,20] photonic crystal, [21] multilayers, [22,23] and novel materials [24][25][26][27] to control the electromagnetic energy for breaking the limits of conventional applications. [28,29] There are two camouflage mechanisms: reduction in the reflection or the emission from the target against the detector at the specific wavelength. In reducing the reflected wave from the target such as the microwave, [30,31] metamaterials for microwave camouflage match the impedance with the medium and consume the incident wave through the energy dissipation in the structure, inducing the unity of absorptivity. Otherwise, when the detector measures the emitted wave from the target in the infrared (IR) wave, the emissivity (absorptivity) in the detected band should be zero; it means the unity reflectivity on the surface contrary to the metamaterials for microwave camouflage. These different mechanisms make the multispectral camouflage difficult because camouflage materials should satisfy both the zero and the unity absorptivity in the different spectral regimes in the same structure. Furthermore, blocking the signal from the target can induce energy accumulation based on the energy conservation law, [32] meaning that we also need to consider the energy dissipation through the undetected spectrum to prevent the unwanted energy accumulation in the structure. [33] Therefore, there have been several studies on metamaterials for camouflage with a specific property of the unity absorptivity for microwave [30,31,34] or reflectivity for IR wave. [33,[35][36][37] However, only a few studies of the multispectral metamaterials have been conducted [38,39] since they should solve the issue of size difference depending on the target wavelength. In metamaterials, the operating wavelength is proportional to the unit cell size. This requires that they contain various unitcell sizes in the same structure to cover the multispectral wavelength range such as microwave (O ∼ centimeter) and IR wave (O ≈ micrometer), [40] which makes the fabrication difficult. Light, heat, and waves in electromagnetic energy are the foundation for the advancement of human being. Camouflage materials based on metamaterials are used to excel the performance limits by manipulating the electromagnetic energy. However, multispectral camouflage materials with flexibility are difficult to fabricate because required radiative properties in each spectral regime are different and have largely different scales of the unit cell in a single structure. The authors propose flexible assembled metamaterials (FAM) by assembling the flexible infrared (IR) emitter and flexible microwave absorber. The authors adopt the intermediate layer to a...

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Section: Introductionmentioning

confidence: 99%

Flexible Assembled Metamaterials for Infrared and Microwave Camouflage

Lee

Lim

Chang

et al. 2022

Advanced Optical Materials

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“…[10,11] Hence, controlling thermal emission in a certain direction within the LWIR band attracts more and more attention for applications, including thermal imaging and sensing, [12][13][14] near-field heat transfer, [15] radiative cooling, [16,17] and infrared encryption. [18][19][20][21] On the one hand, directional thermal emission has been realized by various structures, such as gratings based on surface plasmon polaritons, [22][23][24][25] 2D materials, [26] and polar materials based on Berreman modes. [27][28][29] However, these thermal emitters are essentially narrowband.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Whole LWIR Directional Thermal Emission Based on ENZ Thin Films

Ying

et al. 2022

Laser & Photonics Reviews

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Long‐wave infrared (LWIR) of 8–14 μm is an imperative atmospheric transmission window for applications such as infrared detectors, radiative cooling, and infrared stealth. Attempts to manipulate thermal emission in the LWIR band consist of either directional emission but narrowband or LWIR emission but non‐directional. Directional thermal emission covering the entire LWIR band has remained elusive, so far. Here, a whole LWIR directional thermal emitter is introduced consisting of top epsilon‐near‐zero (ENZ) films (SiO2/SiO/Al2O3), a dielectric gap (Ge), and bottom ENZ films (TiO2/Ta2O5) on a metal. The emitter exhibits high emissivity (>0.9) in p‐polarization at specific directions (72°–82°) covering the entire 8–14 μm atmospheric window. Additionally, infrared encryption information on the emitter can only be observed in p‐polarization in the oblique direction. This approach introduces a new route toward simultaneous control of bandwidth and directionality of thermal emission and has inclusive applications such as infrared camouflage and energy management.

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“…Any object with an absolute temperature above zero radiates infrared (IR) waves, which is usually called "thermal emission." The manipulation of thermal emission contributes to a wide variety of fields, including thermal camouflage, [1][2][3][4][5][6] radiative cooling, [7][8][9] energy-saving windows, [10] thermophotovoltaics, [11][12][13] and IR stealth. [14,15] The broad IR spectrum can be divided into near-IR (0.75-1.5 µm), short-wavelength IR (1.5-3 µm), mid-wavelength IR (3-8 µm), long-wavelength IR (8-15 µm), and far IR (15-1000 µm).…”

Section: Introductionmentioning

confidence: 99%

Laser‐Induced Tuning and Spatial Control of the Emissivity of Phase‐Changing Ge₂Sb₂Te₅ Emitter for Thermal Camouflage

Kim

Lee

2022

Adv Materials Technologies

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The tuning of a material's emissivity in the atmospheric window range of 8–13 µm is crucial for infrared (IR) adaptive applications such as thermal camouflage, IR stealth, and radiative cooling. A resonator structure comprising a phase‐changing Ge2Sb2Te5 (GST) film on a metal mirror is promising as a tunable thermal emitter because its long‐wavelength IR emissivity can be varied by adjusting the degree of crystallization of the GST film through annealing. However, the space‐selective tuning of the emissivity required for practical use remains a significant challenge. Herein, a hybrid method combining laser irradiation and heat treatment is presented for space‐selective and continuous tuning of the emissivity of a GST‐based resonator. The current study shows that a laser‐induced crystalline layer formed in the near‐surface region of a 400 nm thick amorphous GST film can act as heterogeneous nuclei for crystallization when the film is subsequently annealed, thereby increasing the crystallization rate of the GST film. This results in a large difference in emissivity between the irradiated and nonirradiated areas, and the emissivity difference can be tuned by changing the annealing temperature. Thermal camouflage is experimentally demonstrated by making high‐and low‐temperature regions with low and high emissivity, respectively.

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Infrared Camouflage Utilizing Ultrathin Flexible Large‐Scale High‐Temperature‐Tolerant Lambertian Surfaces

Cited by 34 publications

References 62 publications

Flexible Assembled Metamaterials for Infrared and Microwave Camouflage

Flexible Assembled Metamaterials for Infrared and Microwave Camouflage

Whole LWIR Directional Thermal Emission Based on ENZ Thin Films

Laser‐Induced Tuning and Spatial Control of the Emissivity of Phase‐Changing Ge₂Sb₂Te₅ Emitter for Thermal Camouflage

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Infrared Camouflage Utilizing Ultrathin Flexible Large‐Scale High‐Temperature‐Tolerant Lambertian Surfaces

Cited by 34 publications

References 62 publications

Flexible Assembled Metamaterials for Infrared and Microwave Camouflage

Flexible Assembled Metamaterials for Infrared and Microwave Camouflage

Whole LWIR Directional Thermal Emission Based on ENZ Thin Films

Laser‐Induced Tuning and Spatial Control of the Emissivity of Phase‐Changing Ge2Sb2Te5 Emitter for Thermal Camouflage

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About

Laser‐Induced Tuning and Spatial Control of the Emissivity of Phase‐Changing Ge₂Sb₂Te₅ Emitter for Thermal Camouflage