Active modulation and switching of toroidal resonance in micromachined reconfigurable terahertz metamaterials

Abstract In recent years, the toroidal dipole has attracted growing interests due to its unique electromagnetic radiation properties and great potential applications. However, active control of the toroidal resonance at the terahertz frequency has remained largely unexplored due to the scarcity of compact tunable elements so far. Here, dynamic control of the toroidal resonance in a micromachined reconfiguration terahertz metamaterial is proposed and demonstrated numerically. Simulated results show that for TE wave, the intensity and operating mode of the toroidal resonance can be actively controlled through driving micromachined structure. Furthermore, switching between a dual resonance and a single resonance is also realized for TM wave. Therefore, the works open on the opportunities for controlling the electromagnetic responses in free space and designing the terahertz modulators, ultrasensitive sensors and switchable devices.