Thermally switchable metal-free THz electromagnetic shield using phase change material

Abstract

A thermally switchable ultrathin terahertz (THz) metal-free electromagnetic shield can be developed with the help of phase change material, vanadium oxide (VO2). The thermal alterations in the phase change material can modulate its conductivity hence the switchable absorptivity can be achieved. An ultrathin, (height ≈λ/7, λ is free space wavelength) ultra-broadband, metal-free absorber structure containing a VO2 resonator, dielectric spacer and graphite reflector operating within 3.88−9.82 THz band is designed and numerically studied. Multiple reflections and destructive interference occurring in the dielectric delivers the absorber operation which is validated through the theory of multiple reflections. Absorber provides the stable response over the incident angle of more than 45°. Moreover, the shielding effectiveness of the developed thin periodic film remains more than 30 dB in the operating frequency range.