Mechanically tunable metamaterials terahertz dual-band bandstop filter**Project supported by the National Natural Science Foundation of China (Grant Nos. 61265005 and 11574059), the Natural Science Foundation of Guangxi, China (Grant Nos. 2015GXNSFDA19039 and 2014GXNSFAA118376), the Foundation from Guangxi Key Laboratory of Automatic Detection Technology and Instrument, China (Grant Nos. YQ14114 and YQ15106) and the Innovation Project of Guangxi Graduate Education, China

Abstract

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.