Study on the spectral and polarization properties of split circular terahertz resonators

In recent years, terahertz metamaterials have attracted extensive attention because of their high sensitivity to electromagnetic waves in biosensing application. In order to obtain high-quality factor resonance, we designed and fabricated single split-ring structures with the radius of 25.5 μm. In the experiment, we measured the terahertz transmission spectra when the angle between the open gap direction and the incident wave horizontal polarization is set to be 0, 30, 45, 60 and 90 degrees, respectively, and compared the effects of different angles on the transmission characteristics. With the increase of the rotation angle, the frequency of sharpest resonance dip in the terahertz transmission spectra has a remarkable blue-shift. Furthermore, we further simulated the polarization conversion characteristics of the single splitting rings with different rotation angles. It is found that there is no polarization conversion effect when the sample is placed at 0 and 90 degrees. When the sample is rotated by 30 degrees, 45 degrees and 60 degrees, polarization conversion is observed, with the highest conversion efficiency at 45 degrees. Our obtained results indicate that the terahertz metamaterials have great application prospects in biosensors.