Tunable metamaterial absorber based on resonant strontium titanate artificial atoms

Dynamic control of the absorption frequency and intensity of metamaterial absorbers has attracted considerable attention, and many kinds of tunable metamaterial absorbers have been proposed. Unfortunately, due to the integration of separate resonant unit and tunable unit, these designed metamaterial absorbers suffer from complex structure and low sensitivity. We numerically and experimentally demonstrate a tunable metamaterial absorber composed of artificial dielectric atoms as both resonant and tunable unit arrayed periodically in the background matrix on the metallic plate. Polarization insensitive and wide incident angle absorption band with simulated and experimental absorptivity of 99 % and 96 % at 9.65 GHz are achieved at room temperature. The absorption frequency can be gradually modulated by temperature, however, the absorption intensity at working frequency remains near unity. The dielectric atoms based tunable metamaterial absorbers with simple structure have potential applications as temperature sensors and frequency selective thermal emitters.