Generating and Enhancing THz Pulses Via an Antenna-Coupled Uni-Traveling-Carrier Photodiode Array

THz pulses with \,\mathrm{ps}-level duration are generated and enhanced by fabricating arrayed InP/InGaAs uni-traveling-carrier photodiodes (UTC-PDs) with integrated planar bowtie antennas. We experimentally demonstrated THz pulses generation from an UTC-PD with a duration of 10 \,\mathrm{ps} and 25 \,\mathrm{GHz} repetition rate. Compared with those of an individual UTC-PD excited at a photocurrent of 3 \,\mathrm{mA} and DC bias voltage of -1.5 \,\mathrm{V}, the pulsed THz waves generated from three arrayed UTC-PDs exhibited a 7 \,\mathrm{dB} power enhancement gain after optical time alignment through optic-fiber delay lines. Experimental results indicate that this optoelectronic THz pulses generation based on arrayed UTC-PDs can achieve scalable directional gain and low-profile assembly. Enhanced THz pulses generation will be beneficial for the applications of quasi-time-domain THz spectroscope and pulse-based THz communications.