Polarimetric analysis of thermal emission from both reciprocal and nonreciprocal materials using fluctuation electrodynamics
Polarimetric analysis of thermal emission from both reciprocal and nonreciprocal materials using fluctuation electrodynamics
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DOI：
10.1103/physrevb.106.245407
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发表时间：
2022-09
影响因子：
3.7
通讯作者：
Chiyu Yang;W. Cai;Zhuomin M. Zhang
中科院分区：
文献类型：
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作者：
Chiyu Yang;W. Cai;Zhuomin M. Zhang
在许多具有微/纳米结构的超材料中，已经观察到给定极化的相干热发射。对热发射的完整描述需要对所有偏振态的光谱角发射率进行充分的表征。发射率通常是根据基尔霍夫定律，由吸收率和发射率的等价得到的；然而，这种关系对于非互易介质可能无效。在处理磁光材料和磁性Weyl半金属时，需要更多不受光互易约束的一般方法。在此，基于波动电动力学对热辐射进行了极化分析。利用相干矩阵计算了各向异性介质（包括非互易材料）多层体系的Stokes参数。结果表明，在不同的方向和频率下，热发射可以呈圆偏振或线偏振。这一发现与近年来几个小组提出的修改后的基尔霍夫定律的陈述是一致的，因此，证明了直接和间接方法的适当性。该研究将有助于设计用于能量收集和热控制的理想热辐射器。
Coherent thermal emission for a given polarization has been observed in many metamaterials with micro/nanostructures. A complete description of the thermal emission requires the full characterization of the spectral angular emissivity for all polarization states. Emissivity is typically obtained based on the equivalence between the absorptivity and emissivity according to Kirchhoff's law; however, such relation may be invalid for nonreciprocal media. More general approaches without the constrain of optical reciprocity are necessary when dealing with magneto-optical materials and magnetic Weyl semimetals. Here, a polarimetric analysis of thermal emission is carried out based on fluctuational electrodynamics. The Stokes parameters are obtained using coherency matrix for a multilayered system with anisotropic media, including nonreciprocal materials. The results demonstrate that thermal emission may be circularly or linearly polarized in different directions and frequencies. The findings are consistent with the statements of the modified Kirchhoff's law provided by several groups in recent years, and therefore, justify the appropriateness of both the direct and indirect methods. This study will help the design of desired thermal emitters for energy harvesting and thermal control.