  We theoretically investigate the interaction between the conductive graphene
layer with the dual-spectral electromagnetically induced transparency (EIT)
metamaterial and achieve independent amplitude modulation of the transmission
peaks in terahertz (THz) regime. The dual-spectral EIT resonance results from
the strong near field coupling effects between the bright cut wire resonator
(CWR) in the middle and two dark double-split ring resonators (DSRRs) on the
two sides. By integrating monolayer graphene under the dark mode resonators,
the two transmission peaks of the EIT resonance can exhibit independent
amplitude modulation via shifting the Fermi level of the corresponding graphene
layer. The physical mechanism of the modulation can be attributed to the
variation of damping factors of the dark mode resonators arising from the
tunable conductivity of graphene. This work shows great prospects in designing
multiple-spectral THz functional devices with highly flexible tunability and
implies promising applications in multi-channel selective switching, modulation
and slow light.
