An Ultrathin Wide Angle Polarization Insensitive Mid-Infrared Metamaterial Absorber for THz Detection

An ultra-thin broadband mid-infrared metamaterial absorber using array of split ring resonators and crossed slot structure in its unit cell has been reported. The simulation of the structure exhibits greater than 90% absorptivity over the frequency range 42 THz to 53 THz. The structure behaves as an absorber for both TE and TM polarizations so long as the angle of incidence is within 60^o. The four fold structural symmetry makes the designed structure insensitive to polarization. The proposed ultra-thin (λ/24) metamaterial absorber is expected to find potential application in THz spectroscopy, imaging techniques and sensing.