Broadband terahertz equivalent-time sampling system based on a photoconductive antenna

In recent years, remarkable achievements have been witnessed in developing terahertz (THz) communication systems with high data rates. However, the analyzers/receivers of most THz communication systems still heavily rely on electronic circuits with limited bandwidth, obstructing the further exploration of THz resource. In this work, an equivalent-time sampling (ETS) system based on a conventional photoconductive antenna (PCA) is proposed for capturing high-speed THz signals. The PCA is excited by ultrashort optical pulses from a low repetition-rate mode-locked laser (MLL) and hence alternates the sampling of high-speed THz signals into low-frequency domain. The proposed ETS system for THz signals is theoretically analyzed and experimentally demonstrated. In the proof-of-concept experiment, an on-off keying (OOK) signal with a baud rate of 15 Gbaud are successfully sampled and evaluated. The proposed THz ETS system can be easily accessible by low-speed electronics, which is expected to bring new opportunities for high-speed THz time-domain analyzer.