A multi-band terahertz metamaterial absorber based on a Pi and U-shaped structure

The design of a multi-band metamaterial absorber consisting of a Pi-shaped structure enclosed by a U-shaped ring on top of a polyimide dielectric spacer has been presented in this paper. From the simulation results, it is found that the structure offers three prominent absorption bands at 1.45 THz, 1.80 THz and 2.70 THz with peak absorptions of 97.78%, 97.92% and 96.81%, respectively. The absorption mechanism is studied and it is found that three of the absorption bands are caused due to the Pi-shaped and the U-shaped structure, while the 1.80THz and 2.70 THz enhanced absorption bands appear as a consequence of coupling between the two structures. Parametric analysis has been carried out to justify the choice of the design parameters and the structure is also analyzed for its polarization sensitivity and angle sensitivity. The proposed structure can find practical application in terahertz imaging and terahertz spectroscopy.