Electromagnetic coupling and waveguiding in Metamaterials studied by Terahertz Near-Field Microscopy

该项目旨在详细了解光子超材料中亚单位（“元原子”）之间的耦合及其潜在机制。为此，我们将研究太赫兹（THz）频率下的超材料结构，通过太赫兹时域光谱学和我们最近开发的太赫兹近场显微镜技术的强大组合，使电场和磁场矢量在亚波长空间和亚皮秒时间分辨率的结构附近实现前所未有的可视化。太赫兹频率的实验非常适合研究超材料中的电磁耦合，因为它们结合了简单的结构制造，由于结构尺寸适中，以及强大的实验工具的可用性。我们的近场成像技术能够可视化负责微观结构之间相互作用的电场和磁场近场。基于测量时相关场，这种方法将进一步允许我们在亚皮秒时间尺度上沿着耦合超材料结构（超材料波导）直接跟踪电磁波的形成和传播。最终，关于结构之间耦合的知识可能导致设计新的基于超材料的波导。

The proposed project aims at obtaining a detailed understanding of coupling between the subunits ("meta-atoms") in photonic metamaterials and its underlying mechanisms. For this purpose we will investigate metamaterial structures at terahertz (THz) frequencies by the powerful combination of THz time-domain spectroscopy and our recently developed THz near-field microscopy technique, enabling unprecedented visualization of electric and mag- netic field vectors in close proximity to the structures with sub-wavelength spatial and sub- picosecond temporal resolution. Experiments at THz frequencies are ideally suited for studying electromagnetic coupling in metamaterials since they combine straightforward structure fabrication, due to moderate structure sizes, with the availability of powerful experimental tools. Our near-field imaging technique enables visualizing the electric and magnetic near- fields responsible for the interaction between the microscopic structures. Based on measuring time-dependent fields this approach will further allow us to directly trace the formation and propagation of electromagnetic waves along coupled metamaterial structures (metamaterial waveguides) on sub-picosecond timescales. Ultimately, the gained knowledge on coupling between structures may lead towards the design of novel metamaterial-based waveguides.