Dual-broadband terahertz absorber based on phase transition characteristics of VO2

A dual-broadband absorption metamaterial based on a composite structure consisting of metal and vanadium dioxide is designed and analyzed. By controlling the temperature of vanadium dioxide, the absorption band of the device can be manipulated. At T = 300 K, before the VO2 phase transition, the designed structure can achieve broadband absorption. Results indicate that the absorption rate can exceed 90% in the broad spectral range of 1.375-2.087THz. In the case of T = 350 K, VO2 transforms into a metallic state, and the absorption band is transferred to 2.6-7.03 THz. Especially, the structure is insensitive to the polarization angle of the incident wave, which is beneficial for maintaining stable absorption performance when the incident angle is less than 45 degrees. The proposed absorber can be applied to many other fields such as modulation devices, terahertz switching, and power harvesting fields.