Butakov N A, Schuller J A
Opt Express. 2015 Nov 16;23(23):29698-707. doi: 10.1364/OE.23.029698.
Hybrid optical antennas, comprising active materials placed in the gaps of plasmonic split-ring-resonators and nano-dimers, have been the subject of numerous recent investigations. Engineered coupling between the two plasmonic resonators is achieved by modulating the active material, enabling control over the near- and far-field electromagnetic properties. Here, using electromagnetics calculations, we study the evolving optical response of a hybrid metal-semiconductor-metal nanorod antenna as the semiconductor free charge carrier density is continuously varied. In particular, we demonstrate qualitatively new behavior arising from epsilon-near-zero properties in intermediately doped semiconductors. In agreement with optical nano-circuit theory, we show that in the epsilon-near-zero regime such a load acts as an ideal optical resistor with an optimized damping response and strongly suppressed electromagnetic scattering. In periodic arrays, or metasurfaces, we then show how to use these effects to construct high-efficiency nanophotonic intensity modulators for dynamically shaping light.
混合光学天线，由放置在等离子体分裂环谐振器和纳米二聚体间隙中的活性材料组成，是近期众多研究的主题。通过调制活性材料实现两个等离子体谐振器之间的工程耦合，从而能够控制近场和远场电磁特性。在此，我们利用电磁学计算，研究了随着半导体自由电荷载流子密度不断变化，混合金属 - 半导体 - 金属纳米棒天线的光学响应演变情况。特别是，我们展示了中间掺杂半导体中接近零介电常数特性所产生的定性新行为。与光学纳米电路理论一致，我们表明在接近零介电常数 regime 中，这样的负载充当具有优化阻尼响应和强烈抑制电磁散射的理想光学电阻器。在周期性阵列或超表面中，我们接着展示了如何利用这些效应构建用于动态塑造光的高效纳米光子强度调制器。
