High-performance direct terahertz modulator based on resonance mode transformation for high-speed wireless communication

The developing terahertz wireless communication demands higher performance modulators. In this Letter, a mechanism of resonance mode transformation for a high-speed terahertz direct amplitude modulator with rather low insertion loss and high modulation depth is presented. By embedding an H-shaped resonance structure, which consists of a fin-line and two flip-flopped GaAs Schottky diodes, into the E-wall of a waveguide, the fed terahertz waves are modulated by the inductive-capacitive (LC) resonance transformation of the structure. Based on this mechanism, a modulator working in the frequency band around 140 GHz is fabricated and packaged. Thanks to the LC resonance transformation, the presented modulator exhibits a low insertion loss of 1.8 dB at 138 GHz, a large modulation depth higher than 99% at 148 GHz, and high modulation speeds up to 30 Gbps at 146 GHz. Accordingly, the presented mechanism paves a promising route to develop high performance terahertz direct modulators, which is of great significance for terahertz high-speed wireless communication.