## 3 MMA Design Analysis  
The design evaluations of the proposed absorber have been discussed to understand the absorption performance of the different design stages. Figure 3 illustrates the absorption characteristics of the four different steps of the designed hexagonal ring resonator. Firstly, one single hexagonal ring was used and achieved low absorption at visible and far-infrared wavelengths. After that, another hexagonal ring was used inside the first ring to achieve  
Figure 1: MMA unit cell design (**a**) 3 \(\times\) 3 array, (**b**) perspective view, (**c**) front view. Figure 2: The proposed MMA’s absorption, reflectance and transmittance curves. a better absorption, which shows 99% absorptivity at visible optical wavelength. This excellent high absorption has been achieved due to the coupling capacitance between this hexagonal ring and the addition inductivity by the second ring. Later, three hexagonal rings were used to increase the absorption, which resulted in the additional coupling capacitance and inductance to increase the absorption. Therefore, the smaller rings are responsible for the absorption at the lower wavelength region, and larger hexagonal rings gradually provide higher absorption at the higher wavelength region. The design concept reflects the proportional relationship between the operational wavelength and resonator size. The analysis of the MMA design parameters has been presented to understand the absorption sensitivity of parametric variation. Figure 4 presents the absorption analysis for different design parameters. The total dimension of the unit cell or periodicity of the structure is investigated by changing \"P\" from 60 to 78 nm with a 6 nm interval shown in Figure 4a. The value \"P\" suppressing shows better absorption for visible optical-region wavelength than the infrared-region wavelength. For the increment of periodicity, the absorption value increases in the near-infrared region and decreases in the far-infrared region. This occurs due to the coupling of two adjacent unit cell structures. Moreover, the absorption level and absorption bandwidth of the MMA is significantly influenced by its thickness. The top, middle- and bottom-layer thickness investigations are presented in Figure 4b-d, individually. Figure 4b illustrates the absorption for different resonator heights at the top surface, whereas the height increases by 1 nm from 1 to 5 nm. It shows good average absorption, but the visible region did not achieve a good absorption level compared to the infrared region for the increment of \"tw\". This occurs due to the increment of thickness \"tw\", which increases the overall size of resonators. The high absorption shifts towards a higher wavelength with the increment of resonator size. The lower value of the \"tw\" shows almost 100% absorption for the visible region. However, the absorption level reduces by less than 90% for the infrared regions due to the proportional relationship of resonator size and operating wavelength Figure 4c investigates the absorption by varying the substrate thickness \"ts\". With the increment of ts from 11 nm to 16 nm, the overall absorption value decreases; however, the absorption percentage increases in the infrared region. On the other hand, with the suppression of the thickness (11 to 6 nm), absorption is high for the visible range. This phenomenon is also related to the size and wavelength relation; if the size of the unit cell decreases, high absorption shifts towards a lower wavelength. On the other hand, high absorption shifts towards a higher wavelength with an increment of unit cell size. The EM wave transmission through the MMA unit cell is  
Figure 3: Absorption for four different stages at normal incidence. blocked by Nickel material. The EM wave blocking capacity can be assumed by skin depth \(\delta=\sqrt{\rho/\pi\mathrm{f}\mu}=\sqrt{\rho\lambda/\pi\mathrm{\mu}}\), where the wavelength is proportional to skin depth. Hence, to block the larger wavelength a higher skin depth is necessary [35].