Investigation of electromagnetic properties of terahertzmeta-surfaces tunable using multidirectional magneticfield

该项目的主要科学目标是开发悬臂式，磁场可重构的太赫兹元表面（MS），基于对其电磁特性依赖性的理解，以及MS与太赫兹范围内电磁波（EMW）在MS设计参数上的相互作用。太赫兹频率范围内（0.1-10太赫兹）材料中的EMW的传播和相互作用是当前国际研究的主题。在过去的二十年里，这一领域取得了巨大的进步，包括光导天线（PCAs）的发明，它可以实现脉冲激发和时域光谱（TDS）。其中，所谓的超材料（MM）是太赫兹范围内增长最快的领域之一。MM是由小于波长的周期性或准周期性排列结构组成的人造材料，具有天然材料所没有的特性，如负折射率和负渗透率，称为双负结构（DNG）。这为与EMW的相互作用开辟了新的可能性。元表面（MS）是二维的MM。它们的性质可以通过设计和制造来确定，也可以通过外部刺激（如光、电流或电位、温度）来主动修改。重新配置MS的一种方法是使用磁场驱动的微机电系统（MF-MEMS），其中结构元件在外部磁场的作用下变形。MEMS被用于开关灯、微镜驱动器和传感应用。然而，到目前为止，它们在可调谐THz-MS中的应用非常有限。在该方案中，驱动磁场矢量将由外部励磁系统自由控制。基于mems的太赫兹质谱结构将被开发出来，可以在任何方向上与磁场相互作用。MS的结构元素将由导电和磁性微梁组成，这些微梁具有磁性可变形性。结构元件的变形会影响质谱在太赫兹范围内的电磁特性，特别是透射、反射（共振频率的变化）和极化。结构元件的设计对ms的电磁特性有重大影响。那些设计被寻求在太赫兹范围内产生EM特性（例如，谐振频率）的大变化。此外，还将研究磁性材料可变形微结构的最佳MEMS制造工艺。技术和科学问题：1)在太赫兹范围内实现有效磁重构的最佳表面设计；2)质谱结构的几何和磁性能对其与太赫兹辐射的有效相互作用和动力学行为的影响；3) MS二次重构的MEMS技术探索；4)长期和交变负荷稳定。

The project’s primary scientific goal is to develop cantilevered, magnetic field reconfigurable terahertz meta-surfaces (MS) based on an understanding of the dependence of their electromagnetic properties as well as the interaction of the MS with electromagnetic waves (EMW) in the THz-range on the design parameters of the MS. The propagation and interactions of EMW in materials in the THz frequency range (0.1-10 THz) i is subject of current international research. Tremendous progress has been made in this field over the last two decades, including the invention of photoconductive antennas (PCAs) that enable pulsed excitation and thus Time Domain Spectroscopy (TDS). Among these, so-called metamaterials (MM) are among the fastest growing areas in the THz range. A MM is an artificial material consisting of periodical or quasi-periodical arranged structures with sizes smaller than the wavelength and which can take on properties not found in natural materials, e.g., both negative refractive index and negative permeability, which are called double negative structures (DNG). This opens up new possibilities for interaction with EMW. Meta-surfaces (MS) are two-dimensional MM. Their properties can be either already determined by design and fabrication or actively modifiable (by external stimuli such as light, electric current or potential, temperature). One way to reconfigure MS is to use magnetic field-driven microelectromechanical systems (MF-MEMS), in which structural elements are deformed by an external magnetic field. MEMS are used, e.g. for switching light, as micro mirror actuators, and in sensing applications. However, their application for tunable THz-MS has been very limited so far. In the proposed project, the driving magnetic field vector will be freely controllable by an external excitation system. MEMS-based THz MS structures will be developed which can interact with the magnetic field in any direction. The MS’s structural elements will consist of conducting and magnetic microbeams that are magnetically deformable. The deformation of the structural elements will affect the electromagnetic properties of the MS in the THz range, especially transmission, reflection (changes in resonance frequencies) and polarization. The design of the structural elements has a significant impact on the electromagnetic properties of MS. Those designs are sought that produce a large change in EM properties (e.g., resonant frequency) in the THz range. Also, the optimal MEMS fabrication processes for deformable microstructures made of magnetic materials will be investigated. Technological and scientific issues: 1) Optimal surface designs for effective magnetic reconfigurability in the THz range; 2) Influence of geometrical and magnetic properties of MS structures on their effective interactivity with THz radiation and dynamic behavior; 3) Exploration of MEMS techniques for secondary reconfiguration of the MS; 4) Long-term and alternating load stability.