Near-field thermal emission from metasurfaces constructed of SiC ellipsoidal particles
Near-field thermal emission from metasurfaces constructed of SiC ellipsoidal particles
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DOI：
10.1063/5.0164073
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发表时间：
2023-05
影响因子：
3.2
通讯作者：
Lindsay P. Walter;Joseph C. McKay;B. Raeymaekers;M. Francoeur
中科院分区：
文献类型：
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作者：
Lindsay P. Walter;Joseph C. McKay;B. Raeymaekers;M. Francoeur
我们模型的近场热发射从超颖表面结构为二维阵列的椭圆形SiC颗粒。该建模方法是从波动电动力学和适用于系统的椭球粒子内的偶极限制。在所有模拟中，颗粒的径向长度被限制在10-100 nm的范围内，颗粒间的间距被限制在至少三倍的颗粒特征长度。组成的椭球粒子的取向和尺寸是不同的，以调整局部表面声子共振和控制超颖表面以上的近场能量密度。结果表明，粒子的取向可以用来调节能量密度中共振的相对大小，并且可以改变粒子的尺寸来调节Reststrahlen带内这些共振的频率。由具有随机尺寸的颗粒构造的超颖表面显示出相对宽带的热发射，而不是在由等效尺寸的椭圆形颗粒制成的超颖表面中看到的三个不同的共振。当超颖表面中的粒子间间距超过粒子特征长度的约三倍时，超颖表面上方的谱能量密度由单个粒子自相互作用主导，并且可以近似为单粒子谱的线性组合。然而，当粒子间的间距是在三倍的特征长度的下限，多粒子相互作用的影响增加和超颖表面以上的光谱能量密度偏离单粒子。这项工作为设计具有所需近场热发射光谱的全介电、基于颗粒的超颖表面（如热开关）提供了指导。
We model near-field thermal emission from metasurfaces structured as two-dimensional arrays of ellipsoidal SiC particles. The modeling approach is developed from fluctuational electrodynamics and is applicable to systems of ellipsoidal particles within the dipole limit. In all simulations, the radial lengths of particles are restricted to the range of 10–100 nm, and interparticle spacing is constrained to at least three times the particle characteristic length. The orientation and dimensions of constituent ellipsoidal particles are varied to tune localized surface phonon resonances and control the near-field energy density above metasurfaces. Results show that particle orientation can be used to regulate the relative magnitude of resonances in the energy density, and particle dimensions may be changed to adjust the frequency of these resonances within the Reststrahlen band. Metasurfaces constructed from particles with randomized dimensions display comparatively broadband thermal emission rather than the three distinct resonances seen in metasurfaces made with ellipsoidal particles of equivalent dimensions. When the interparticle spacing in a metasurface exceeds about three times the particle characteristic length, the spectral energy density above the metasurface is dominated by individual particle self-interaction and can be approximated as a linear combination of single-particle spectra. When interparticle spacing is at the lower limit of three times the characteristic length, however, multiparticle interaction effects increase and the spectral energy density above a metasurface deviates from that of single particles. This work provides guidance for designing all-dielectric, particle-based metasurfaces with desired near-field thermal emission spectra, such as thermal switches.