High performance plasmonic waveguide with compact transition structure

In this work, a compact transition which can efficiently convert guided waves to spoof surface plasmon polaritons (SSPPs) is proposed. By using the S-parameter retrieval technique, the bloch impedance of the SSPP unit cell is extracted and tuned around 50 ohm in a wide frequency band to achieve good impedance matching. Then, the momentum can be matched with fewer gradient matching grooves leading to smaller size. For demonstration, a planar plasmonic waveguide based on the proposed transition structure is designed and simulated. The excellent simulation results validate high-efficiency excitation and propagation of SSPPs in broadband. The proposed plasmonic waveguide can find potential applications in plasmonic devices and integrated circuits in microwave and terahertz frequencies.