Design of a tunable terahertz narrowband metamaterial absorber based on an electrostatically actuated MEMS cantilever and split ring resonator array

A dynamically tunable terahertz (THz) narrowband metamaterial absorber is presented. The absorber is based on an electrostatically actuated micro-electro-mechanical systems (MEMS) cantilever and split ring resonator (SRR) array. An equivalent LC circuit model for a transverse electric (TE) polarization wave is introduced to analyze the mechanism of frequency tuning. A finite element method is applied to simulate the mechanical characteristics of the cantilever, and a finite integration technique is used to study the frequency tuning properties of the absorber. The results show that, for a TE polarization wave, there is only one absorption peak in the frequency range from 0.6 to 1.6 THz. The absorption peak frequency can be continuously tuned from 1.32 to 1.28 THz, and then abruptly to 1.12 THz. The maximum tunable frequency is 0.20 THz, which is about 15% of the initial resonance frequency. For a transverse magnetic (TM) polarization wave, there are two tunable absorption peaks in this frequency range. Moreover, for a TE wave, some geometric dimensions affecting the initial resonance frequency are investigated.