Design and verification of a tunable metamaterial and its sensing application

Abstract

In this study, the authors present a single-band tunable metamaterial absorber in the 3.00–6.00 THz region. This absorption peak (90.00% amplitude) is excited by the cavity resonance at the resonance frequency of 4.55 THz. The cavity resonance mode is achieved in the spacer cavity formed by the metal/strontium titanate (STO)/SU-8 photoresist (SU-8)/STO/metal layers. The effect of structural parameters on this absorption peak is measured in two groups of experiments. As the diameter of holes array D increases, the cavity resonance peak is enhanced to 94.00% and shifted to 4.79 THz. However, for the increase in the thickness of the SU-8 layer T3, this peak is increased to 98.00% and moved to 3.88 THz. To verify the dual detection functions, two sets of experiments are carried out. In the third set of experiments, this absorption peak is increased to 99.80% and shifted to 5.60 THz with the increasing environmental temperature. In the fourth set of experiments, samples are covered by three liquids, and both the absorption amplitude and the resonance frequency are reduced. This tunable metamaterial absorber shows possibilities for applications in environmental temperature sensing and liquid sensing.