A Broadband Plasmonic Metasurface Superabsorber at Optical Frequencies: Analytical Design Framework and Demonstration,Advanced Optical Materials

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A Broadband Plasmonic Metasurface Superabsorber at Optical Frequencies: Analytical Design Framework and Demonstration
Advanced Optical Materials ( IF 8.0 ) Pub Date : 2018-06-10 , DOI: 10.1002/adom.201800253
Arvind Nagarajan _{1,

2} , Kumar Vivek _{1,

2} , Manav Shah ₃ , Venu Gopal Achanta ₃ , Giampiero Gerini _{1,

2}

Affiliation

Plasmonic metasurface based superabsorbers exhibit high absorbance. While the absorption peak can be tuned by the geometry/size of the sub‐wavelength resonator, broadband absorption can be obtained by harnessing spectrally shifted resonances of multiple resonators of various size/shapes in a unit cell. Metal dispersion hinders high‐performance broadband absorption at optical frequencies and careful designing is essential to achieve good structures. A novel analytical framework is proposed for designing a broadband superabsorber which is much faster than the time consuming full‐wave simulations that are employed so far. Analytical expressions are derived for the wavelength dependency of the design parameters, which are then used in the optimization of broadband absorption. Numerical simulations report an average polarization‐independent absorption of ≈97% in the 450–950 nm spectral region with a near unity absorption (99.36%) in the 500–850 nm region. Experimentally, an average absorption over 98% is demonstrated in the 450–950 nm spectral region at 20° incident angle. The designed superabsorber is polarization insensitive and has a weak launch angle dependency. The proposed framework simplifies the design process and provides a quicker optimal solution for high‐performance broadband superabsorbers.

中文翻译：

光学频率的宽带等离子超表面超吸收体：分析设计框架和演示

基于等离子体表面的超吸收剂表现出高吸收性。虽然可以通过亚波长谐振器的几何形状/大小来调整吸收峰，但可以通过利用一个晶胞中各种大小/形状的多个谐振器的频谱偏移谐振来获得宽带吸收。金属色散会阻碍高性能宽带在光频率下的吸收，因此精心设计对于获得良好的结构至关重要。提出了一种新颖的分析框架来设计宽带超吸收器，该框架比迄今为止采用的费时的全波仿真要快得多。导出了设计参数的波长依赖性的解析表达式，然后将其用于宽带吸收的优化。数值模拟报告表明，在450–950 nm光谱范围内，偏振无关的平均吸收率约为97％，而在500–850 nm范围内具有接近单位吸收率（99.36％）。实验表明，在20°入射角的450–950 nm光谱区域中，平均吸收率超过98％。设计的超级吸收剂对偏振不敏感，并且对发射角的依赖性很弱。所提出的框架简化了设计过程，并为高性能宽带超吸收器提供了更快的最佳解决方案。

更新日期：2018-06-10

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