Sierpinski Metamaterial for Near-perfect Terahertz Tunable Broadband Absorber Using Vanadium Dioxide

Metamaterials (MTM’s) are well known for their fascinating control over electromagnetic waves. The inclusion of vanadium dioxide (VO
2
) a tunable phase-changing material, in the MTM’s design opens up an additional degree of freedom at terahertz (THz) waveband. In this work, Sierpinski Triangle fractal structure is patterned on the silicon substrate. The frequency dependence of the relative permittivity of VO
2
is modeled using the Drude model.Due to the inclusion of mutli-sized triangles, the proposed pattern exhibits broadband frequency response in the absorption spectrum for TE polarization. The proposed absorber shows near 100% absorbance from 4.2 THz to 5.8 THz and the absorptance bandwidth is 99.37% for VO
2
conductivity of 2000 S/m, whereas for 500 S/m, the MTM absorber shows 80%–90% of absorptance from ∼ 4 THz to 6 THz due to the mixed (metallic and insulator) phase of VO
2
. It is highlighted that the impedance matching condition is implemented to check the reliability of the obtained absorption. We anticipate that the incorporation of the fractal structure in VO
2
-based metamaterial fulfils the realization of broadband THz devices for communication, imaging and sensing applications.