## 2 Design and Simulation Setup
### Numerical Analysis Setup  
A proper and correct simulation setup is required to obtain the necessary absorbance from the dispersing value. CST Microwave Studio 2019 used terahertz mesh in a frequency-domain solver to perform numerical simulations. The proposed MMA's boundary conditions and array structure are depicted in Figure 3a, and Figure 3c reveals the proposed MMA's tetrahedral mesh properties. For transverse electromagnetic (TEM) propagation mode, an installation of a port point is created using both the positive and negative \(z\)-axis. The impedance matching process between the incident wave and the meta surface takes along the positive \(z\)-axis. In addition, the \(x\) and \(y\) axes are constrained, whereas the positive \(z\)-axis is regarded as an open add space for the TEM propagation mode. Moreover, \(y\)-axis and the \(x\)- axis boundaries are specified as perfect magnetic conductors (PMCs) and electric conductors (PECs). The magnetic field is asymmetrical in the PMC and symmetrical in the PEC, but the electric field is asymmetrical in the PEC and symmetrical in the PMC. Since the z-axis is considered to be a free space with a perfectly matched layer (PML) in the opposite direction, scattering is reduced along with the operational wavelength. The configuration has all three axes operating in opposite directions from one another. For  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c} \hline \hline
**Parameters** & **L** & **L\({}_{1}\)** & **L\({}_{2}\)** & **L\({}_{3}\)** & **W** & **W\({}_{1}\)** & **W\({}_{2}\)** & **W\({}_{3}\)** & **W\({}_{4}\)** & **W\({}_{5}\)** & **H\({}_{1}\)** & **H\({}_{2}\)** & **H\({}_{3}\)** & **R\({}_{1}\)**this simulation, we assume that a planar, wide-spectrum wave, and linearly polarized will reach the top of the proposed absorber. The proposed design has been protected when using a perfect electric and magnetic conductor, an electromagnetic response diagram of a crossed rectangle array that is polarization insensitive. As shown in Figure 3b, the optical responses for both the TM and TE propagation modes are identical for these symmetrical 3 \(\times\) 3 array arrangements. The \(x\) and \(y\) axes establish the unit cell's TE and TM mode boundary conditions. When a higher mesh order is applied, it is possible for the simulation's results to be more accurate. All the data has been obtained using frequency domain analysis. In addition, a time-domain analysis may be performed on this specific type of absorber simulation. A tetrahedral mesh was combined with an adaptive mesh generation technique to perform the simulation. The substrate's dielectric properties are estimated to have a free space propagation impedance of approximately 377 \(\Omega\). The quality of this tetrahedral mesh analysis goes somewhere between 0.0300454 and 0.997996 and the lowest and highest corner values are 5.9427 nm and 176.343 nm, respectively. In order to achieve the most accurate results from the simulation, a mesh with a total of 27,821 tetrahedrons and an average quality of 0.757251 was used. Regarding the convergence of the simulation process that CST MWS performed, we did not have any problems.  
Figure 1: The design of the unit cell for visible optical wavelength applications (**a**) front view (**b**) side view (**c**) back view (**d**) perspective view.