Graphene Supported Ultrathin VO2 Resonators for Multifunctional THz Absorption

The multiple electromagnetic (EM) resonances created using vanadium dioxide (VO2) resonators supported by graphene sheet can provide the metal-free, multifunctional terahertz (THz) absorber. Thermally modulated conductivity of VO2 results in switchable near-perfect absorption over broad frequency band 2 to 14 THz to narrow with full-width, half-maxima of 0.11 THz. The electrically modulated conductivity of graphene can result in the variable electrical length of the generated dipolar field arrangements. Consequently, frequency tunability can be achieved in the broad and narrow absorption spectrum. The graphene-supported VO2 structure provides the ultrathin geometry of thickness ${\approx }\lambda /187$ ( $\lambda $ is the free-space wavelength at the center frequency). The broadband-patterned periodic film can be coated for electronic packaging and THz EM shielding. The narrowband absorber can be utilized as a refractive index sensor with a high value of sensitivity and a quality factor of 1.1 THz/refractive index unit (RIU) and 286, respectively. The proposed sensor can also be utilized for the detection of breast cancer and tumors in the neck and stomach of the human body.