中红外-甚长波多模式谐振三波段超材料吸波体(特邀)

Multimode resonance triple-band metamaterial absorber from mid-infrared to very long wavelengths(invited)

超材料吸波体可以将入射电磁波集中在亚波长尺度内并进行高效吸收,因此在光电探测、热发射器、能量收集等领域具有广泛的应用前景。迄今报道的多波段超材料吸波体主要为某一波长范围内多个相近波长的完美吸收,想要实现大光谱范围内的多波长吸收则需要多个结构的联合工作。基于钛十字形谐振器-氮化硅介质层-钛反射层三层结构,设计并数值模拟了一种工作波长范围跨越中波红外、长波红外以及甚长波红外的三波段超材料吸波体。利用超材料吸波体激发的传播型表面等离激元谐振、局域型表面等离激元谐振以及氮化硅本征吸收模式,实现了4.8μm、9.1μm和18μm三个波长处97.3%、94.4%和93.6%的高吸收率。超材料吸波体的工作波长可以通过改变其几何参数进行调节,且具有偏振和入射角不敏感性。该工作中所用材料均为现有工艺中的常用材料,在气体检测、红外成像等领域具有应用前景。

Metamaterial absorbers can confine and completely absorb incident electromagnetic waves to the subwavelength scale and have promising applications in detection,thermal emitters,energy harvesting,cooling,etc.The multiband metamaterial absorbers reported thus far are mainly the perfect absorption of multiple similar wavelengths in a specific wavelength range.Achieving multiwavelength absorption over a wide spectral range requires the combined work of multiple structures.Based on the three-layer structure of the titanium cross resonator-silicon nitride dielectric layer-titanium reflective layer,a triple-band metamaterial absorber with operating wavelengths spanning midwave infrared,longwave infrared,and very longwave infrared was designed and numerically simulated.Using the propagating surface plasmon resonance,the localized surface plasmon resonance,and the silicon nitride intrinsic absorption mode excited by the metamaterial absorber,high absorption reached 97.3%,94.4%,and 93.6% at wavelengths of 4.8 μm,9.1 μm and 18 μm respectively.Meanwhile,the wavelengths of the three absorption peaks can be flexibly manipulated by changing the geometric parameters of the metamaterial absorber,and the absorber exhibits insensitivity to polarization and incident angle.The materials used in this work are commonly used in existing processes and have application prospects in gas detection and infrared imaging.