Sina Vaezi Seyed, Nikmehr Saeid, Pourziad Ali
Appl Opt. 2020 Mar 10;59(8):2431-2442. doi: 10.1364/AO.383028.
A systematic method is proposed to synthesize a nano-antenna based on theoretical principles. This nano-antenna, which is composed of a set of small dielectric spheres, is designed to have a desired far-field radiation pattern and polarization. The basis of the proposed method is expanding all electromagnetic waves into the series of vector spherical wave functions. First, the forward problem of calculation of scattering from single and multiple spheres is studied. For cases with more than one sphere, a multiple scattering method is implemented to calculate total scattering. Near-field and far-field waves, absorption, extinction, and differential scattering cross sections are calculated for a single sphere with different sizes and permittivities. Moreover, far-field waves for linear arrays of small spheres are analyzed. All results are validated using an electromagnetic simulation software. Next, the problem of inverse scattering begins by considering a three-dimensional arbitrary pattern and polarization. The aim is to find a set of spheres that generates this pattern. Particle swarm optimization and non-iterative spectral-domain forward scattering methods are combined as a novel method to find the optimal positions of the spheres.
提出了一种基于理论原理合成纳米天线的系统方法。这种由一组小介电球体组成的纳米天线，旨在具有所需的远场辐射方向图和极化特性。所提方法的基础是将所有电磁波展开为矢量球波函数系列。首先，研究了单个和多个球体散射计算的正问题。对于有多个球体的情况，采用多重散射方法计算总散射。计算了不同尺寸和介电常数的单个球体的近场和远场波、吸收、消光和微分散射截面。此外，还分析了小球体线性阵列的远场波。所有结果均使用电磁仿真软件进行了验证。接下来，通过考虑三维任意方向图和极化来开始逆散射问题。目的是找到一组能产生该方向图的球体。将粒子群优化算法和非迭代谱域前向散射方法相结合，作为一种寻找球体最佳位置的新方法。
