Design and Characterization of 3D Printed Polymer Terahertz Multi-Mode Interference Couplers

In this paper, we present the design of one-dimensional symmetric and paired 1×2 multi-mode interference (MMI) couplers at 140 GHz applying a modal propagation analysis together with electromagnetic simulation. The designed couplers are fabricated by 3D printing and are characterized by terahertz frequency-domain spectroscopy. The measured amplitude imbalances between the outputs of the couplers are as good as 0.32 dB.