光偶极天线的远场方向性研究

摘要

By simulating the field distributions of two optical dipole antenna models with the finite-difference time-domain (FDTD) method, the variation regularity of their far-field radiation with their length increasing and the factors which can influence their far-field directivity are studied. The results show that the variation regularity of optical dipole antenna is analogous to that of classic symmetrical dipole antenna. But in the far-field directivity plot of optical dipole antenna, sidelobes occur much more quickly, owing to the existence of high-order localized surface plasmon modes. These results hold a significant promise of improving the performance of optical antennas.%用时域有限差分方法模拟了两种光偶极天线模型的场分布,研究了光偶极天线的远场辐射特性随其长度增加而变化的规律以及影响其远场方向性的因素,发现光偶极天线的远场方向性随其长度增加而变化的规律类似于经典对称振子天线的相应规律.但高阶局域表面等离激元模式的存在使得光偶极天线的远场辐射图更快地出现了旁瓣.这些发现对于提高光天线的性能具有重要意义.