Planar surface plasmonic structures for terahertz circuits and sensors

This paper presents planar metal patterned structures that support surface plasmon polaritons (SPPs) like propagation mode. Four unit cells, each having a solid ground plane, were designed that support SPPs. To optimize return loss, these structures were first simulated as infinitely periodic in two dimensions. These were then further optimized by designing waveguide structures. Using multi-band unit cell designs, THz circuits (transmission line and power splitter) were fabricated and tested. A new approach to probe these planar plasmonic devices is presented using wide band THz dielectric probes. Measured results of THz circuits match closely with simulation results. It is also shown through simulations that these structures can be used in the design of THz chemical and biological sensors.