An ultrabroadband, omnidirectional, and polarization-insensitive absorber based on cascaded nanorod arrays (CNAs) is numerically demonstrated, and an average absorptivity of 98.2% with a relative absorption bandwidth (RAB) of 149.8% can be achieved in the 0.38–2.65 μm wavelength range. The proposed CNA-based absorber requires only several pairs of multilayers to achieve excellent absorption performance. More significantly, the physical mechanism for this intriguing ultrabroadband absorption results from the synergistic effect of localized surface plasmon (LSP) and plasmonic resonant cavity (PRC) modes, which is fundamentally different from the tapered metal/dielectric multilayer-based absorbers associated with the slow-light mode. We investigated the absorption properties of the CNA-based metasurface by using the impedance theory, which indicates that the impedance of the structure matches well with the impedance of the free space from the visible to near-infrared wavelength range. In addition, the absorption properties of the CNA-based metasurface are robust to the variation of the structural parameters and the metal/dielectric materials, and ultrabroadband absorption performance can be maintained within 0–60° for both TM and TE modes.

中文翻译：

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用于超宽带、全向和偏振不敏感吸收的级联纳米棒阵列

数值证明了基于级联纳米棒阵列 (CNA) 的超宽带、全向和偏振不敏感吸收器，在 0.38-2.65 μm 波长下的平均吸收率为 98.2%，相对吸收带宽 (RAB) 为 149.8%范围。所提出的基于 CNA 的吸收器只需要几对多层即可实现出色的吸收性能。更重要的是，这种有趣的超宽带吸收的物理机制源于局部表面等离子体 (LSP) 和等离子体共振腔 (PRC) 模式的协同效应，这与基于锥形金属/电介质多层吸收器的慢速吸收器有着根本的不同。 - 光模式。我们使用阻抗理论研究了基于 CNA 的超表面的吸收特性，这表明该结构的阻抗与从可见光到近红外波长范围的自由空间阻抗匹配良好。此外，基于 CNA 的超表面的吸收特性对结构参数和金属/电介质材料的变化具有鲁棒性，并且对于 TM 和 TE 模式，超宽带吸收性能可以保持在 0-60° 范围内。