论文标题
全局$ \ Mathbb {t} $电磁散射上的操作员界限：远场横截面上的上限
Global $\mathbb{T}$ operator bounds on electromagnetic scattering: Upper bounds on far-field cross sections
论文作者
论文摘要
我们提出了一种基于散射$ \ mathbb {t} $运算符的方法，以及对净真实和反应能力的保存，以在任何电磁设计目标上提供物理界限，该目标可以用作净辐射发射，散射或吸收过程。发现这种方法将这种方法与任意形状的，紧凑的均质电敏感性$χ$的散射相对可预测地量化和区分所有光学长度尺度上的介电和金属材料的相对性能。 When the size of a device is restricted to be much smaller than the wavelength (a subwavelength cavity, antenna, nanoparticle, etc.), the maximum cross section enhancement that may be achieved via material structuring is found to be much weaker than prior predictions: the response of strong metals ($\mathrm{Re}[χ] < 0$) exhibits a diluted (homogenized) effective medium scaling $\propto |χ| / \ mathrm {im} [χ] $;低于阈值尺寸低于折射索引（与半波长共振条件一致），与介电（$ \ MATHRM {re} [χ] [χ]> 0 $）相同的最大横截面增强表现出与雷利散射相同的材料依赖性。在所有维度中的边界量的极限中，可实现的散射相互作用渐近区域渐近区域，如Ray Optics所预测的那样。对于代表性的金属和介电材料，通过逆设计发现了能够从数量级（通常是两个倍）内从入射平面波中散射功率的几何形状。该方法的基础完全取决于散射理论，因此很可能应用于声学，量子力学和其他波浪物理学。
We present a method based on the scattering $\mathbb{T}$ operator, and conservation of net real and reactive power, to provide physical bounds on any electromagnetic design objective that can be framed as a net radiative emission, scattering or absorption process. Application of this approach to planewave scattering from an arbitrarily shaped, compact body of homogeneous electric susceptibility $χ$ is found to predictively quantify and differentiate the relative performance of dielectric and metallic materials across all optical length scales. When the size of a device is restricted to be much smaller than the wavelength (a subwavelength cavity, antenna, nanoparticle, etc.), the maximum cross section enhancement that may be achieved via material structuring is found to be much weaker than prior predictions: the response of strong metals ($\mathrm{Re}[χ] < 0$) exhibits a diluted (homogenized) effective medium scaling $\propto |χ| / \mathrm{Im}[χ]$; below a threshold size inversely proportional to the index of refraction (consistent with the half-wavelength resonance condition), the maximum cross section enhancement possible with dielectrics ($\mathrm{Re}[χ] > 0$) shows the same material dependence as Rayleigh scattering. In the limit of a bounding volume much larger than the wavelength in all dimensions, achievable scattering interactions asymptote to the geometric area, as predicted by ray optics. For representative metal and dielectric materials, geometries capable of scattering power from an incident plane wave within an order of magnitude (typically a factor of two) of the bound are discovered by inverse design. The basis of the method rests entirely on scattering theory, and can thus likely be applied to acoustics, quantum mechanics, and other wave physics.
