A Novel Broadband Sub-Terahertz T-Junction Frequency Doubler Utilizing Spoof Surface Plasmon Polaritons

In this article, a novel wideband sub-terahertz (sub-THz) frequency doubler utilizing high-isolated waveguide T-junction dividers is proposed. It applies two terahertz monolithic integrated circuit (TMIC) doublers based on GaAs Schottky barrier diode (SBD) in two T-junction dividers. To achieve high isolation between two output ports of the divider, a nickel-based spoof surface plasmon polaritons (SSPPs) is employed as a matching load, for its natural stopband characteristic with perfect absorptivity in terahertz (THz) frequencies. Experimental results demonstrate that the doubler features a broad bandwidth from 170 to 220 GHz, an excellent output power of 41 mW, and a maximum conversion efficiency of 10.3%. Furthermore, the device exhibits high isolation between two output ports, underscoring the potential value of SSPPs in THz devices.