Terahertz ultra-broadband and multi-frequency narrowband perfect absorber based on compound metamaterial

A perfect absorber in the terahertz band with ultra-broadband and triple narrowband is achieved, using Vanadium Dioxide (VO 2 ) and patterned graphene hybrid metamaterials, which can be converted by adjusting the temperature. When only VO 2 is present in the structure, the absorption spectrum shows broadband absorption in metallic phases of VO 2 . Adding graphene to metallic VO 2 , the absorption bandwidth over 95% is expanded to 5.5[Formula: see text]THz, which is 1.9 times broader compared to the absence of graphene, and the absorption bandwidth over 99% increases to 1.72[Formula: see text]THz. Adding graphene to insulating VO 2 , three narrowband absorptions appear with absorption rates approaching 100%. Polarization characteristics show that ultra-broadband is insensitive to polarization angle, while multi-frequency narrowband exhibits sensitivity. Therefore, the proposed tunable multifunctional absorber can greatly optimize the absorption capacity of ultra-broadband and multi-frequency narrow bands, demonstrating great potential in future practical applications.