Exploration of a Kilowatt-Level Terahertz Amplifier Based on Higher-Order Mode Interaction

Theparameters for a kilowatt-level high-power terahertz amplifier were explored based on the higher-order mode and extended-interaction mechanism. It has been demonstrated that the antisymmetric electrical field mode (TM21) has a unique advantage in achieving high power. Physical factors on power extraction were studied. In particular, the heavily reduced Q(0) has a great effect on the coupling characteristic as well as the output power. It is found that the critical coupling state, i.e., Q(e) = Q(0), defines an upper limit of the power that can be extracted from the output circuit. The design of a complete interaction circuit was accomplished. The particle-in-cell (PIC) simulations showed that a saturated power of 1.2 kW can be achieved at 220 GHz with a voltage of 45 kV and a total current of 2 x 0.6 Awhere two beamswere used. The saturated gain is over 30 dB with a 3-dB bandwidth of similar to 400 MHz.