Terahertz power enhancement by combining photocurrent from arrayed UTC-PDs using Wilkinson power combiner

Abstract We designed a novel terahertz wave power combiner which combines HF currents from each photomixer in a micro strip line. The generator is composed of four uni-travelling carrier photodiodes (UTC-PDs) as the photomixers, a 4 × 1 Wilkinson power combiner and a microstrip rectangular patch antenna on a Silicon Carbide (SiC) substrate in which photocurrents of 300 GHz from the UTC-PDs are combined to be fed to the antenna. Experimental results show that the output power is multiplied by 11 dB (approximately 13 times) compared to that of a single UTC-PD. The combined power increases super-linearly with the number of the photomixers, confirms a great advantage of photomixing as a current source.