A Compact Design of Multiband Terahertz Metamaterial Absorber with Frequency and Polarization Tunability

A new and simple design of quad-band metamaterial absorber for terahertz frequency has been proposed. The unit cell of the absorber is composed of a top metallic patch having H-shaped slot and a ground metallic plane, both separated by a dielectric layer. The proposed design is capable of providing four distinct absorption peaks over at 0.81, 1.98, 3.25, and 3.50 THz. Our design is a step ahead of the previously proposed terahertz absorbers for its simplistic design approach which removes the fabrication difficulty. Interestingly, rather placing multiple resonators in a single unit cell, we able to accommodate multiple orders of resonances in the proposed design using only a single metallic structure to achieve multiband absorbance. The sensing performance of the absorber in terms of surrounding index is also analyzed. Moreover, we have shown how the proposed structure can be easily converted into a frequency tunable absorber using a simple stub without changing the overall geometry of the absorber. This fast and easy frequency tunability feature is an additional advantage over the simple design of the structure. Also, we lead our work to its upgradation into a polarization tunable absorber where the absorption frequencies are controllable by the polarization of the incident light. The vibrant design of the proposed absorber is expected to find application in detection, imaging, radar cross-section (RCS) reduction, and sensing-related activities.