Radiation enhancement of a terahertz backward wave oscillator with a two-stage rectangular waveguide grating

In this paper, we present a novel structured THz BWO based on a rectangular waveguide grating with improved output characteristics. The circuit enabled, with a simple change, separation of the two sections without increasing the overall size. A conventional one-stage circuit with 45 grooves and a novel two-stage circuit with 15 and 25 grooves were quantitatively compared using the 3D MAGIC PIC code. The oscillation time could be drastically reduced, and the conversion efficiency could be increased by more than two times. Importantly, this structure enabled an output increase without increasing the circuit size. It can be expected to improve the output of a compact high-power THz source.