Polarization-independent tunable reflector

In this paper, a novel tunable reflector with gain medium was designed, fabricated and measured. By incorporating active elements into two magnetic metamaterial SRRs, gain medium with positive loss, perfect losslessness and even negative loss can be tuned to switch the function of the active reflector among a perfect absorber, a perfect reflector and a gain reflector. The reflectivity of the tunable reflector can be tuned from -20dB to +15dB via three DC control channels. By introducing two more SRRs in one unit cell, polarization-independent function could be realized.