Computational Investigation of Multiband EMNZ Metamaterial Absorber for Terahertz Applications

This study presents an Epsilon Mu near-zero (EMNZ) nanostructured metamaterial absorber (NMMA) for visible regime applications. The resonator and dielectric layers are made of tungsten (W) and quartz (fused), where the working band is expanded by changing the resonator layer's design. Due to perfect impedance matching with plasmonic resonance characteristics, the proposed NMMA structure is achieved an excellent absorption of 99.99% at 571 THz, 99.50% at 488.26 THz, and 99.32% at 598 THz frequencies. The absorption mechanism is demonstrated by the theory of impedance, electric field, and power loss density distributions, respectively. The geometric parameters are explored and analyzed to show the structure's performance, and a near-field pattern is used to explain the absorption mechanism at the resonance frequency point. The numerical analysis method describes that the proposed structure exhibited more than 80% absorbability between 550 and 900 THz. The Computer Simulation Technology (CST Microwave Studio 2019) software is used to design the proposed structure. Furthermore, CST-HFSS interference is validated by the simulation data with the help of the finite element method (FEM). The proposed NMMA structure is also exhibits glucose concentration sensing capability as applications. So the proposed broadband absorber may have a potential application in THz sensing, imaging (MRI, thermal, color), solar energy harvesting, light modulators, and optoelectronic devices.