THz radiation using compact folded waveguide TWT oscillators

Microfabricated folded waveguide traveling wave tubes are a promising solution to the generation of compact, wideband, high power terahertz radiation. We present feasibility studies of an oscillator concept using an amplifier with recirculated feedback. Simulations of a 560 GHz oscillator and experimental verification of the principle at 50 GHz are presented. Observation and measurements are reported on the generation of stable single frequency oscillation states. On varying the feedback level, the oscillation changes from a single frequency state at threshold to multifrequency spectra in overdriven state. Investigations on dynamics of the regenerative TWT oscillator will be presented. Additionally, preliminary results of experiments to fabricate 100-400 GHz folded waveguide TWT circuits will be reported.