Terahertz dual-band/broadband metamaterial absorber enabled by SiO2: polyimide and PET dielectric substrates with absorption characteristics

A compact dual-band/broadband polarization in-sensitive terahertz (THz) metamaterial absorber (MMA) is discussed in this article. It consists of a simple planar structure as a unit cell and an optically transparent indium tin oxide (ITO) ground plane, which are separated by a 50 µm dielectric substrate. We designed three combinations of MMA, which are ITO–SiO2–ITO, ITO–polyimide–ITO and ITO–polyethylene terephthalate (PET)–ITO for the same planar structure. The proposed structure has dual-band absorbance with peak absorptivity of >98% for all three given combinations. By changing the substrate of the structure, the resonant frequency and bandwidth of the absorber structure is varied and by adjusting the design parameters, broadband absorbance is achieved for the same planar structure. The numerical simulation of the absorber shows that the broadband absorptivity is >98% for all three substrates. Polyimide, PET and SiO2 based absorbers are demonstrated with bandwidth of 0.467, 0.527 and 0.6 THz with covered broadband frequency range of 0.390–0.857, 0.407–0.934 and 0.433–1.03 THz, respectively. ITO–PET–ITO absorber structures also possess optical transparency. These bandwidths are convenient and compatible with electronic and magnetic sources in the terahertz region. This study provides applications in THz detection, sensing, bolometric imaging, and stealth and communication systems. All three absorbers have greater absorbance characteristics for transverse electric and transverse magnetic polarizations. The proposed structure is working well for wide angles of incident and polarization angles wave up to 90°.