Two-Section Folded-Waveguide Slow-Wave Structure for Terahertz Extended Interaction Oscillator

Extended interaction oscillator (EIO) is a promising terahertz (THz) power source, which has many potential important applications, such as military radar, medical imaging and material science research, and so on. To improve the operation performances of the THz EIO, a novel type of two-section folded waveguide (TSFW) slow wave structure (SWS) is proposed in this paper. The dispersion characteristics for TSFW obtained by an equivalent circuit model are analyzed, and the output characteristics for TSFW EIO are studied and optimized with the help of 3-D particle-in-cell simulation. Comparing with the single section of FW SWS, the remarkable enhancement of output power in the TSFW SWS is observed from 50 up to 130 W. Based on the proposal model, the TSFW is fabricated with a high speed numerical control milling machine and its transmission characteristics are tested. The results of the cold test are in agreement with theoretical predications.