design and realization of a perfect metamaterial absorber in terahertz band

A metamaterial-based absorber with metal–dielectric–metal (mdm) structure design strategy is proposed and verified in terahertz the band. an absorption peak (amplitude is 92%) is obtained at the resonance frequency point 4.2 thz. simulation results show that this absorption peak originates from the resonance of localized surface plasmon modes. the measured fwhm of this absorption peak is 0.07 thz, and the quality factor q is 60. in the first sets of experiments, the lattice constant p is reduced from 8 to 6 μm, which leads to this absorption amplitude enhance from 92 to 97.4%, and the resonance frequency point move from 4.2 to 4.08 thz. similarly, when the diameter d is increased in the second sets of experiments, the absorption amplitude is also enhanced. in the third set of experiments, samples are covered with different liquid layers (acetonitrile, acetone, methanol, or benzene layers). four measured maximum absorption values are achieved: 97%, 98%, 99%, and 99.4%, respectively. the resonance frequency point is also moved to lower frequency point. the feasibility of this absorber for liquid refractive index sensing is proven. in the fourth groups of experiments, samples are covered with an ethanol layer or a chloroform layer; the absorption peaks are both reduced and moved to higher frequency points with the measured temperature increasing. the feasibility of this absorber for temperature sensing is also verified.