THz Transmission Line and Passive Devices Based on Surface Plasomon Polariton

Abstract

Surface Plasmon Polaritons (SPPs) are electromagnetic waves that travel along a metal-dielectric interface. They are a type of surface wave which have tighter spatial confinement and higher local field density. SPPs have been well-studied in plasmonic and photonics. They have been proven to have many potential applications. However, passive devices based on SPPs that can efficiently transmit signals has not been well-investigated, to the best of my knowledge. In my final year report, I managed to design THz transmission lines and power dividers based on spoof SPPs. First of all, to get familiar with the SPPs and design process, I used HFSS (High Frequency Simulation Software) and designed transmission lines working at microwave frequencies (MF) based on SPPs. To achieve a smooth transition between SPPs and guided wave, I used a smooth matching transition to maximize the efficiency. Both simulation and measurement results indicated that the transmission line had good performance. By applying coupled-mode theory, I designed a 1-2 power divider based on the previous transmission line. The simulation results of S-parameters showed excellent performance in the certain microwave frequency band. Then I switched to CST and continued my design on THz transmission line and power divider. The overall structure of THz devices was similar to MF devices. With different optimization methods, I managed to design and refine the THz transmission line and power divider with good simulation results. All the devices are feasible and have a broad application prospect.