Carbon-based terahertz devices

Carbon nanotubes and graphene are promising for diverse terahertz (THz) device applications. Here, we summarize our recent studies on the THz dynamic conductivities and optoelectronic devices of these materials in the THz region. We show that the THz response of single-wall carbon nanotubes (SWCNTs) is dominated by plasmon oscillations along the nanotubes, which lead to extremely anisotropic THz conductivities. By utilizing the strong THz plasmon resonance as well as its pronounced anisotropy in aligned SWCNT films, we built THz polarizers with perfect performance and polarization-sensitive THz detectors that work at room temperature. In addition, we studied the THz conductivities of graphene samples with and without electrical gating. We demonstrated excitation and active control of surface plasmon polaritons in graphene, as well as a graphene THz modulator with a high modulation depth, a high modulation speed, and a designable resonance frequency.