Triple-band electromagnetically induced transparency effects enabled by two sets of arc-ring-type resonators at terahertz frequency

A new type of terahertz metamaterial resonance device with triple-band electromagnetically induced transparent (EIT) is introduced in this paper. Its unit cell consists of two sets of arc-ring-type resonators placed on a dielectric sheet, which can generate three EIT transparency peaks at terahertz region. The generation of these transparent peaks is mainly attributed to the coupling effect between the resonant modes of the arc-ring-type resonators. Influence of the arc length and radius of the arc-ring-type resonators and the width of the air layer between the inner arc-ring-type resonators and outer arc-ring-type resonators on the transmission spectrum is studied. Furthermore, active tunability of the transparent peaks is achieved by incorporating photosensitive silicon with tunable conductivity in the metamaterial structure. The results show that depending on the change of conductivity as well as the position of photosensitive silicon, the EIT effect can be shown as an adjustable switch from triple-band to dual-band or from triple-band to single-band. In addition, the refractive index sensing performance of the metamaterial device is discussed. The metamaterial device has the excellent characteristics of simple structure design and active modulation, which are important and useful for the development of photoelectric switches, sensors and filter devices.