ABSTRACT A one-dimensional periodic microstructure was presented for an ultrabroadband near-perfect absorber for thermal radiation. The microstructure comprised a curved periodic stack of tungsten (15 nm) and polymethylpentene (TPX) (35 nm) with 20 layers deposited on a half-cylindrical cavity fabricated on a tungsten substrate. Visible to midinfrared regions (200 nm to 10.9 μm) allow an average measured light absorptivity of approximately 90% for transverse magnetic polarized waves at normal incidence; this property is insensitive to polar angle even when the incident angle is 80°. These superior performances were primarily attributed to intrinsic bandgap absorption in tungsten, excitation of SPPs at the air/W interface, and the resonance of the slow-light effect and its higher-order modes. Furthermore, the spectrum range of near-perfect absorption could be tuned by adjusting the center half-cylindrical shell radius, total pair number and dielectric permittivity. Moreover, the imperfection tolerance of the proposed system was studied by varying the filling ratio of metal in a periodic shell. This work may provide new guidelines for designing metamaterials absorbers that can obtain highly enhanced absorption over an ultrabroadband and in a wide range of angle of incidence.

中文翻译：

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基于弯曲周期 W/TPX 堆栈的超宽带近乎完美的各向异性超材料吸收器

摘要 提出了一种超宽带近乎完美的热辐射吸收体的一维周期性微观结构。微结构包括钨 (15 nm) 和聚甲基戊烯 (TPX) (35 nm) 的弯曲周期性堆叠，在钨基板上制造的半圆柱腔上沉积 20 层。可见到中红外区域（200 nm 至 10.9 μm）允许测量的平均光吸收率对于垂直入射的横向磁极化波约为 90%；即使入射角为 80°，该属性对极角也不敏感。这些优异的性能主要归因于钨的固有带隙吸收、空气/W 界面处 SPP 的激发以及慢光效应及其高阶模式的共振。此外，近乎完美的吸收光谱范围可以通过调整中心半圆柱壳半径、总对数和介电常数来调整。此外，通过改变周期壳中金属的填充率来研究所提出系统的缺陷容限。这项工作可能为设计超材料吸收体提供新的指导方针，这些吸收体可以在超宽带和宽入射角范围内获得高度增强的吸收。