Design and Simulation of a Terahertz High-order Mode Power Coupler for Sheet Beam Traveling Wave Amplifiers

The design and simulation of a terahertz high-order mode power coupler for sheet beam traveling wave amplifiers are presented in this paper. The proposed power coupler has functions of both the mode conversion and the beam wave convergence/separation. To improve the performance of this structure, some auxiliary structures are introduced, including a rectangular septum, a matching step and a pair of symmetric Bragg reflectors. The proposed power coupler has numerous competitive advantages, such as broad bandwidth, high transmission coefficient and high conversion efficiency, high port isolation, low port reflection, and high mode purity.