Small–sized long wavelength infrared absorber with perfect ultra–broadband absorptivity

Herein, a hierarchical metamaterial (HMM) is reported to achieve multispectral camouflage for thermal infrared detectors and radar. The HMM consists of a frequency‐selective emitter (FSE) integrated with a microwave absorber (MA). The FSE layer has an average absorptivity of 0.18, 0.85, and 0.18 in the wavelength of 3–5, 5–8, and 8–14 μm, respectively, in the case of the normal incidence. The absorptivity of MA maintains more than 91% (87%) in the broadband of 8–12 GHz (the entire X‐band) up to incident angles of ±40° for TM (TE) polarization. Overall, the average surface emissivity of HMM is 0.25, 0.86, and 0.26 in the infrared broadband of 3–5, 5–8, and 8–14 μm, respectively. The FSE considers infrared camouflage and infrared radiative cooling. The performance of HMM in microwave range remains unchanged, compared to MA structure without FSE layer. From the point of view of thickness, the HMM structure is only 2.34 mm. These excellent performances indicate that the herein described proposed HMM has promising applications in multispectral camouflage fields.

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“…The following equations determine the PSPR wavelengths. [ 40 ]

k = k_{0} \sin θ \pm i 2 π / L

k_{PSP} = k_{0} \sqrt{false[ε_{m} ε_{d} false/ false(ε_{m} + ε_{d} false) false]}

…”

Section: Design and Resultsmentioning

confidence: 99%

Thin Multispectral Camouflage Absorber Based on Metasurfaces with Wide Infrared Radiative Cooling Window

Qin

Zhang

Liang

et al. 2022

Advanced Photonics Research

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“…To enhance efficiency, design of appropriate multiband IR absorbers is of current interest. A number of approaches have been proposed recently, based on various surface layers including metamaterials, 11‐20 surface‐structured silicon, 21 vertically aligned carbon nanotubes, 22 electrosprayed carbon‐based coatings, 23 and so on.…”

Section: Introductionmentioning

confidence: 99%

“…Alternative approaches make use of pyramidal‐shaped resonant elements 14‐16 . Some recent promising designs 17‐20 are based on one or more thin and highly resistive metal layers of arrays of titanium disks or rings above the dielectric spacer; the relatively high resistance of titanium results in a low‐Q factor of the surface resonances that helps to achieve a broader absorption band, while tuning is possible via modification of the disk geometry. However, the above designs exhibit a significant degree of fabrication complexity.…”

Section: Introductionmentioning

confidence: 99%

Design of an optimized multilayer absorber into the MWIR and LWIR bands

Bolakis

Vazouras

Michalis

et al. 2021

Micro & Optical Tech Letters

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In this article, we propose a new approach for effective detection of infrared (IR) radiation, using an absorber consisting of two successive metal‐dielectric layers. To this end, a low cost, high‐efficiency composite IR absorber structure consisting of a set of two double‐layered element of thin metal layers paired with dielectric materials is presented. The proposed composite absorber can be tuned based on the metal layer sheet resistance and the thickness of various poly‐Si media; by appropriate choice of physical, electrical, and optical parameters, so that maximal absorption over both mid‐wave IR band regions (MWIR) and long wavelength IR band regions (LWIR) (3–12 μm), is achieved. The outcome of study indicates that the presented absorber configuration may be a promising candidate for integration into microbolometric detectors; while offering improved efficiency and functionality, for not critical timing applications, synchronously in both the MWIR and LWIR atmospheric thermal windows.

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“…The average absorption rate in the 1-3 µm band is as high as 80% [16]. Zhou et al have made an ultra-wideband infrared absorber that works at 8-14 µm by integrating titanium nano-ring structures and titanium nano-antennas in a working unit [17]. In addition to integrating metals with different structures on the surface, the stacked metamaterial can also be used to enhance the absorption of dual-band QWIP.…”

Section: Introductionmentioning

confidence: 99%

Stacked Dual-Band Quantum Well Infrared Photodetector Based on Double-Layer Gold Disk Enhanced Local Light Field

Liu

Zuo

et al. 2021

Nanomaterials

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We propose a stacked dual-band quantum well infrared photodetector (QWIP) integrated with a double-layer gold disk. Two 10-period quantum wells (QW) operating at different wavelengths are stacked together, and gold nano-disks are integrated on their respective surfaces. Numerical calculations by finite difference time domain (FDTD) showed that the best enhancement can be achieved at 13.2 and 11.0 µm. By integrating two metal disks, two plasmon microcavity structures can be formed with the substrate to excite localized surface plasmons (LSP) so that the vertically incident infrared light can be converted into electric field components perpendicular to the growth direction of the quantum well (EZ). The EZ electric field component can be enhanced up to 20 times compared to the incident light, and it is four times that of the traditional two-dimensional hole array (2DHA) grating. We calculated the enhancement factor and coupling efficiency of the device in the active region of the quantum well. The enhancement factor of the active region of the quantum well on the top layer remains above 25 at the wavelength of 13.2 μm, and the enhancement factor can reach a maximum of 45. Under this condition, the coupling efficiency of the device reaches 2800%. At the wavelength of 11.0 μm, the enhancement factor of the active region of the quantum well at the bottom is maintained above 6, and the maximum can reach about 16, and the coupling efficiency of the device reaches 800%. We also optimized the structural parameters and explored the influence of structural changes on the coupling efficiency. When the radius (r1, r2) of the two metal disks increases, the maximum coupling efficiency will be red-shifted as the wavelength increases. The double-layer gold disk structure we designed greatly enhances the infrared coupling of the two quantum well layers working at different wavelengths in the dual-band quantum well infrared photodetector. The structure we designed can be used in stacked dual-band quantum well infrared photodetectors, and the active regions of quantum wells working at two wavelengths can enhance the photoelectric coupling, and the enhancement effect is significant. Compared with the traditional optical coupling structure, the structure we proposed is simpler in process and has a more significant enhancement effect, which can meet the requirements of working in complex environments such as firefighting, night vision, and medical treatment.

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Small–sized long wavelength infrared absorber with perfect ultra–broadband absorptivity

Cited by 59 publications

References 36 publications

Thin Multispectral Camouflage Absorber Based on Metasurfaces with Wide Infrared Radiative Cooling Window

Thin Multispectral Camouflage Absorber Based on Metasurfaces with Wide Infrared Radiative Cooling Window

Design of an optimized multilayer absorber into the MWIR and LWIR bands

Stacked Dual-Band Quantum Well Infrared Photodetector Based on Double-Layer Gold Disk Enhanced Local Light Field

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