†4th Physics Institute and Research Center SCoPE, University of Stuttgart, 70550, Stuttgart, Germany.
§Max Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany.
Nano Lett. 2015 Jul 8;15(7):4255-60. doi: 10.1021/nl5042325. Epub 2015 Jun 3.
Active control over the handedness of a chiral metamaterial has the potential to serve as key element for highly integrated polarization engineering approaches, polarization sensitive imaging devices, and stereo display technologies. However, this is hard to achieve as it seemingly involves the reconfiguration of the metamolecule from a left-handed into a right-handed enantiomer and vice versa. This type of mechanical actuation is intricate and usually neither monolithically realizable nor viable for high-speed applications. Here, enabled by the phase change material Ge3Sb2Te6 (GST-326), we demonstrate a tunable and switchable mid-infrared plasmonic chiral metamaterial in a proof-of-concept experiment. A large tunability range of the circular dichroism response from λ = 4.15 to 4.90 μm is achieved, and we experimentally demonstrate that the combination of a passive bias-type chiral layer with the active chiral metamaterial allows for switchable chirality, that is, the reversal of the circular dichroism sign, in a fully planar, layered design without the need for geometrical reconfiguration. Because phase change materials can be electrically and optically switched, our designs may open up a path for highly integrated mid-IR polarization engineering devices that can be modulated on ultrafast time scales.
主动控制手性超材料的手性有望成为高度集成的极化工程方法、偏振敏感成像设备和立体显示技术的关键元件。然而，这很难实现，因为它似乎涉及从左手手性到右手手性的超分子的重新配置，反之亦然。这种机械致动方式复杂，通常既不能整体实现，也不适合高速应用。在这里，我们通过相变材料 Ge3Sb2Te6 (GST-326)，在一个概念验证实验中展示了一种可调谐和可切换的中红外等离子体手性超材料。我们实现了圆二色响应的大范围可调谐性，从 λ = 4.15 到 4.90 μm，并且我们实验证明，被动偏置型手性层与主动手性超材料的组合允许在完全平面、分层设计中实现可切换的手性，即圆二色性符号的反转，而无需进行几何构型的重新配置。由于相变材料可以进行电和光切换，我们的设计可能为高度集成的中红外极化工程器件开辟一条道路，这些器件可以在超快速时间尺度上进行调制。
