动态可重构金属-半导体八木宇田纳米天线
Dynamically reconfigurable metal-semiconductor Yagi-Uda nanoantenna
摘要：
我们提出了一种新型的可调谐八木宇田纳米天线组成的金属介电（银锗）核壳纳米粒子。我们表明，由于在每个纳米粒子中的两种类型的共振的组合，这种混合八木宇田纳米天线可以在两个不同的制度。除了传统的非共振操作制度在低频下，其特征在于在向前方向上的高度定向发射，有另一个在较高的频率所造成的混合磁电响应的核-壳纳米粒子。该制度是基于范霍夫奇点的激发，并且在该制度中的发射伴随着在相同的窄频率范围内的方向性和Purcell因子的高值。我们的分析揭示了灵活的动态调谐的混合纳米天线的发射模式的可能性，通过电子-空穴等离子体激发100飞秒泵浦脉冲与相对较低的峰值强度$\sim$ 200 MW/cm $^2$。
英文摘要：
We propose a novel type of tunable Yagi-Uda nanoantenna composed of metal-dielectric (Ag-Ge) core-shell nanoparticles. We show that, due to the combination of two types of resonances in each nanoparticle, such hybrid Yagi-Uda nanoantenna can operate in two different regimes. Besides the conventional nonresonant operation regime at low frequencies, characterized by highly directive emission in the forward direction, there is another one at higher frequencies caused by hybrid magneto-electric response of the core-shell nanoparticles. This regime is based on the excitation of the van Hove singularity, and emission in this regime is accompanied by high values of directivity and Purcell factor within the same narrow frequency range. Our analysis reveals the possibility of flexible dynamical tuning of the hybrid nanoantenna emission pattern via electron-hole plasma excitation by 100 femtosecond pump pulse with relatively low peak intensities $\sim$200 MW/cm$^2$.
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