Investigation of electromagnetic properties of terahertz meta-surfaces tunable using multidirectional magnetic field

• Applicant: Professor Dr. Ulrich Mescheder
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering ; Synthesis and Properties of Functional Materials ; Communication Technology and Networks, High-Frequency Technology and Photonic Systems, Signal Processing and Machine Learning for Information Technology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 525135725

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.

• DFG Programme: Research Grants
• International Connection: Poland
• Major Instrumentation: projektbezogenes Upgrade eines vorhandenen optischen 3D Profilmessgeräts
• Instrumentation Group: 5090 Spezialmikroskope
• Cooperation Partner: Professor Dr.-Ing. Przemyslaw Grzegorz Lopato