Enhanced terahertz wave generation by an antenna-coupled 4 × 1 UTC-PD array and a T-junction combiner

The terahertz (THz) band holds transformative potential for next-generation communication and sensing systems, yet practical deployment remains hindered by limited output power from available electronic and photonic THz sources. In this work, we demonstrate an on-chip optoelectronic THz wave power enhancement approach by monolithically integrating a microstrip patch antenna and a 4 × 1 T-junction combiner with arrayed InGaAs/InP uni-traveling carrier photodiodes (UTC-PDs) on a silicon carbide (SiC) substrate. Relative to a single UTC-PD device, experimental results show a 10.9 dB increase in detected power at 300 GHz when combining photocurrents from four UTC-PDs biased at -1 V, closely aligning with theoretical predictions of scaling characteristics of current-driven sources. This work also establishes that SiC has the potential to be a robust platform for high-power THz systems.