Alternative-frequency-selected terahertz bandstop filter

We demonstrate a design of terahertz metamaterial bandstop filter, which is based on arrays of split-ring resonators (SRRs) and pair rods of vanadium dioxide (VO₂). Each unit cell comprises a pair of SRRs with their splits in opposite directions and a pair of VO₂ rods crossing the SRR perpendicular to the split directions. Two stopband electromagnetic resonances can be switched by optical-pumping or temperature variation. These two stopband frequencies can be easily tuned by the geometric dimensions of the unit cell. This work presents a feasibility of tunable and dynamic terahertz filters with VO₂ in metamaterial structure, and shows potential applications in controllable terahertz devices.