Optimization of terahertz broadband metamaterial absorber using a multi-level coordinate search optimization technique

In this paper, a multilevel coordinate search (MCS) optimization technique with a kriging model is employed to optimize an ultrathin broadband terahertz metamaterial absorber (MMA). The reported design consists of a discontinuous circular gold resonator over a lossy polyimide dielectric substrate layer. The introduced optimization technique is linked with the finite element method to analyze and simulate the investigated MMA. The proposed design could achieve a high absorptivity (more than 90%) in the frequency range from 0.97 to 3.76 THz with a wide bandwidth of 2.79 THz and a high relative absorption bandwidth (RAB) of 117.97%. In addition, the reported MMA is polarization insensitive for both transverse electric (TE) and transverse magnetic (TM) polarized waves. Further, the absorptivity of the suggested design is greater than 80% over large incident angle range (up to \({40}^{^\circ })\) ${40}^{{}^{\circ }})$ for the TE and TM polarizations. Therefore, the suggested optimization technique could be used efficiently for the design and optimization of the terahertz MMAs.