Numerical analysis of substrate thickness and its etching effect on broadband/narrowband terahertz metamaterial

In this paper, a class of terahertz metamaterial that supports broadband and narrowband transmission characteristics is proposed. We investigate the effect of substrate thickness and its etching on the transmission characteristics numerically using CST Microwave Studio Software. Guided mode resonances are observed in the dielectric substrate in addition to the fundamental resonance from the metamaterial structure. The fundamental resonance has broadband transmission behavior and the guided-mode resonances show narrow band behavior with high transmittance.The variation in substrate thickness reveals that it plays an important role in guided mode resonances. Then, for a constant substrate thickness, the etching study is done and observed that blue shift in resonances. And, also an additional resonance has been observed within the same frequency range. The designed structure shows polarization-insensitive and angle-resolved transmission characteristics. The proposed metamaterial structure with substrate etching could be utilized for liquid sensing applications.