An Octaband Polarization Insensitive Terahertz Metamaterial Absorber Using Orthogonal Elliptical Ring Resonators

Terahertz metamaterial absorbers are the latest developments that have tremendous applications in terahertz spectroscopy and terahertz imaging. Especially, the research progressed in the direction of designing multiband absorbers. In this work, a polarization-insensitive metamaterial absorber capable of offering absorption in eight bands is proposed. The unit cell of the absorber consists of two orthogonal elliptical ring resonators (ERRs) that are optimally designed to offer maximum absorption in eight bands. The absorption percentage provided by the structure are 89.46% at 0.63 THz, 99.22% at 1.55 THz, 78.02% at 1.89 THz, 99.27% at 2.33 THz, 99.67% at 2.65 THz, 98.67% at 2.91 THz, 99.64% at 3.22 THz, and 88.02% at 3.42 THz. The absorption characteristics were independent of the polarization angle and thus, the structure is insensitive to variations in polarization angle. This is the first work that reports the design of an octaband terahertz absorber and can find significant use in practical devices.