Nonlinear terahertz transmission change with controllable graphene devices

Abstract

Graphene, an atom thick two dimensional sheet of carbons, has drawn great attention for its outstanding mechanical, thermal, and electronic propreties. As much of its other exotic properties, graphene shows exceptional amount of light-matter interaction that can be controlled efficiently. The control of the light-matter interaction in graphene-based devices was achieved by two major means; dynamic control of optical conductivity with Fermi level shifting and static manipulation of resonance with graphene plasmons or meta-atom hybridisation. Although nonlinear light-matter interaction of graphene under intense optical fields has even been applied for laser mode-locking in the optical frequencies, its experimental demonstration has only been recently achieved in the terahertz frequencies. Here we show the first experimental demonstrations of extrinsic control over the light-matter interaction of graphene under intense terahertz field. The induced transparencies of graphene under intense terahertz field can be controlled by tuning the factors that affect momentum scattering in graphene; changing number of carriers through Fermi level shifting, and altering terahertz field enhancement by resonance manipulation. This scheme of control over light matter interaction with graphene would open the early steps toward utilisation of controllable nonlinear optical behaviour.