Enhancing the performance of THz quasi time-domain spectroscopy systems by low duty cycle laser operation

We investigate the performance of terahertz (THz) quasi time-domain systems (QTDS) driven by electrically pulsed multi-mode laser diodes operating at 659 nm. We show that at the same average output power, a reduced duty cycle considerably increases the obtained bandwidth. In the presented experiment, the high frequency performance is improved by 50 dB/THz. We identify the broadening of the optical spectrum caused by pulsing the laser source to be responsible for the increased THz bandwidth. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement