Mechanically tunable metamaterials terahertz dual-band bandstop filter

We experimentally demonstrate a mechanically tunable metamaterials terahertz (THz) dual-band bandstop filter. The unit cell of the filter contains an inner aluminum circle and an outside aluminum Ohm-ring on high resistance silicon substrate. The performance of the filter is simulated by finite-integration-time-domain (FITD) method. The sample is fabricated using a surface micromachining process and experimentally demonstrated using a THz time-domain-spectroscopy (TDS) system. The results show that, when the incident THz wave is polarized in y-axis, the filter has two intensive absorption peaks locating at 0.71 THz and 1.13 THz, respectively. The position of the high-frequency absorption peak and the amplitude of the low-frequency absorption peak can be simultaneously tuned by rotating the sample along its normal axis. The tunability of the high-frequency absorption peak is due to the shift of resonance frequency of two electrical dipoles, and that of the low-frequency absorption peak results from the effect of rotationally induced transparent. This tunable filter is very useful for switch, manipulation, and frequency selective detection of THz beam.