Independent tuning of bright and dark meta-atoms with phase change materials on EIT metasurfaces.,Nanoscale

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Independent tuning of bright and dark meta-atoms with phase change materials on EIT metasurfaces.
Nanoscale ( IF 5.8 ) Pub Date : 2020-05-14 , DOI: 10.1039/d0nr00457j
Ce Li ₁ , Wei Zhu , Zhe Liu , Ruhao Pan , Sha Hu , Shuo Du , Junjie Li , Changzhi Gu

Affiliation

The realization of tunable metasurfaces is of fundamental importance for boosting the electromagnetic field control ability. Especially, it is important to put forward new modulation methods to further understand their underlying modulation mechanism and expand their application range. In this paper, tunable electromagnetically induced transparency (EIT) metasurfaces based on the phase change material Ge2Sb2Te5 (GST) are proposed and experimentally demonstrated. Different from previous modulation methods of directly introducing the GST film below the metasurfaces, here a two-step lithography method is introduced to combine independent GST strips with bright and dark meta-atoms in the EIT structures, respectively, achieving the independent modulation of the EIT-like spectra. In addition, by applying temporal coupled-mode theory (TCMT), the EIT-like spectra with different GST crystallization levels were analysed and the corresponding characteristic parameters were determined simultaneously. These fitting results reveal that GST strips can modulate the resonances of the bright and dark meta-atoms independently by shifting the resonant frequency and increasing the decay rate, which in turn result in the different modulation features of the EIT-like spectra. This method improves the degree of freedom of active modulation and provides a new route for tunable slow light devices.

中文翻译：

使用EIT超表面上的相变材料独立调整亮和暗亚原子。

可调超颖表面的实现对于提高电磁场控制能力至关重要。特别地，提出新的调制方法以进一步了解其潜在的调制机制并扩大其应用范围非常重要。本文提出了一种基于相变材料Ge2Sb2Te5（GST）的可调谐电磁感应透明性（EIT）超表面，并进行了实验证明。与以前的直接在表面以下引入GST膜的调制方法不同，这里引入了两步光刻方法，将独立的GST条带与EIT结构中的亮和暗亚原子分别结合，从而实现EIT的独立调制类光谱。此外，通过应用时间耦合模式理论（TCMT），分析了不同GST结晶度的类EIT光谱，并同时确定了相应的特征参数。这些拟合结果表明，GST谱带可以通过移动共振频率和增加衰减率来独立地调制亮和暗亚原子的共振，进而导致类EIT光谱具有不同的调制特征。这种方法提高了主动调制的自由度，并为可调慢光设备提供了一条新途径。这些拟合结果表明，GST条带可以通过移动共振频率和增加衰减率来独立地调制亮和暗亚原子的共振，进而导致类EIT光谱的调制特性不同。这种方法提高了主动调制的自由度，并为可调慢光设备提供了一条新途径。这些拟合结果表明，GST谱带可以通过移动共振频率和增加衰减率来独立地调制亮和暗亚原子的共振，进而导致类EIT光谱具有不同的调制特征。该方法提高了主动调制的自由度，并为可调慢光设备提供了一条新途径。

更新日期：2020-04-03

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