Dielectric Constant Engineering of Single-Walled Carbon Nanotube Films for Metamaterials and Plasmonic Devices

We demonstrate the fabrication of plasmonic and metamaterials devices, operating in the terahertz frequency range, by using highly conductive, single-walled carbon nanotube (SWNT) network films. We fabricated various patterns on the SWNT films using photolithography or laser machining techniques, whose resonance behaviors are determined by geometric parameters such as the periodicity of the array patterns or the shape of the individual elements. The excellent mechanical properties of SWNT films enabled us to fabricate free-standing and highly flexible devices. More importantly, using postprocessings such as chemical treatments and nanoparticle coatings, we were able to engineer the dielectric constants of the SWNT films, such as enhancing or degrading the conductive properties. As a result of the postprocessings, the resonance peak of the plasmonic devices was suppressed or retrieved, which is not achievable in conventional metal films. In particular, we were able to control the metamaterials resonances, implying the possibility of fabricating tunable optoelectronic devices without changing the device structures.