论文标题
有效的扰动框架，用于几乎周期性表面辐射模式的耦合
Efficient perturbative framework for coupling of radiative and guided modes in nearly periodic surfaces
论文作者
论文摘要
我们提出了一个半分析框架，用于计算缓慢变化（几乎均匀或几乎周期性）表面的辐射和引导波的耦合，这与大区域元面积中非局部效应的剥削尤其重要。我们的框架弥合了缓慢变化的表面理论的差距：除了蛮力数值模拟外，当前的近似方法还可以对引导或辐射波进行建模，但不能轻易地模拟其耦合。我们通过结合两种方法来解决这个问题：局部周期性近似，该方法通过组成一组周期性散射问题和空间耦合波理论来近似辐射散射，从而允许使用特征力膨胀来对引导波进行扰动建模。我们为几乎均匀和几乎周期性的表面得出了框架，并根据蛮力有限差分时间域模拟验证每种情况，随着表面变化较慢，它们的一致性增加了一致性。
We present a semi-analytical framework for computing the coupling of radiative and guided waves in slowly varying (nearly uniform or nearly periodic) surfaces, which is especially relevant to the exploitation of nonlocal effects in large-area metasurfaces. Our framework bridges a gap in the theory of slowly varying surfaces: aside from brute-force numerical simulations, current approximate methods can model either guided or radiative waves, but cannot easily model their coupling. We solve this problem by combining two methods: the locally periodic approximation, which approximates radiative scattering by composing a set of periodic scattering problems, and spatial coupled-wave theory, which allows the perturbative modeling of guided waves using an eigenmode expansion. We derive our framework for both nearly uniform and nearly periodic surfaces, and we validate each case against brute-force finite-difference time-domain simulations, which show increasing agreement as the surface varies more slowly.
