Terahertz surface plasmon polaritons travelling on laser-induced porous graphene

Abstract

Surface plasmon polaritons (SPPs) have shown huge application potentials in photonic on-chip devices, sensing, imaging, and metamaterials. However, in the terahertz (THz) regime, metals used in the visible and near infrared frequencies cannot support SPPs due to their near-zero skin depth. At present, feasible methods mainly include exploiting spoof SPPs through complex structural design on metals or using semiconductors. In this work, we experimentally demonstrate that porous graphene induced by laser beams with low fabrication cost can support SPPs in the THz regime with good performance. Using a classical structure of the semicircular slit, a super-resolution focus with a size of ∼0.43λ is characterized by a THz-SPPs imaging system. Furthermore, by changing the fabrication parameters of the laser, the propagation loss of SPPs is found to be effectively controlled. This method for controllably excited THz-SPPs on laser-induced porous graphene is of great significance for the design and wide-range applications of more compact THz on-chip devices.