Abstract
We theoretically proposed an ultra-broadband infrared light absorber and demonstrated that a high absorption could be obtained in the range of ultra-broadband infrared light using the iron thin layers. The simulation results showed that the proposed absorber could achieve a close-to-unity absorption rate across a wide infrared spectral range, and that the average absorption rate would reach 90.6% over the range of 1.4-11.4μm. The high absorption rate resulted from the excitation of strong localized surface plasmon resonance in the iron layers and the superposition of different resonance frequencies. Numerical analysis results demonstrated that our proposed absorber had a broader efficient absorption range than most previously reported broadband infrared light absorbers.
Highlights
Metamaterials (MMs) are artificial materials with a subwavelength structure that can be fabricated to exhibit special physical properties not found in traditional materials, such as electromagnetic cloaking [1], a negative refractive index [2], perfect absorption [3], refractive index sensor [4]–[8], and so on
Similar to MMs working in the microwave, infrared, and visible bands, broadband and ultra-broadband absorbers working in the range of infrared light have various potential applications, including in thermal radiators [23], thermophotovoltaics (TPV) [10], [24], [25], stealth devices [26], and infrared imaging [27]
We show that this high broadband absorption ratio is due to a strongly localized surface plasmon resonance (LSPR) and to the superposition of multiresonant frequencies, which are caused by iron layers of different widths
Summary
Metamaterials (MMs) are artificial materials with a subwavelength structure that can be fabricated to exhibit special physical properties not found in traditional materials, such as electromagnetic cloaking [1], a negative refractive index [2], perfect absorption [3], refractive index sensor [4]–[8], and so on. Designing broadband and ultra-broadband infrared absorbers is challenging, in part because the plasmonic characteristics of metal-based configurations deteriorate rapidly at long wavelengths [28]. The average absorption ratio in this range was up to 90.2%, which to the best of our knowledge is larger than the ratios of most investigated infrared light absorbers We show that this high broadband absorption ratio is due to a strongly localized surface plasmon resonance (LSPR) and to the superposition of multiresonant frequencies, which are caused by iron layers of different widths. In comparison with existing absorbers, this one has the merits of a simpler structure and a wider working wavelength, giving it great potential for application in thermal radiators, TPV, stealth devices, infrared imaging, and related technologies
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