Unveiling spectral purity and tunability of terahertz quantum cascade laser sources based on intra-cavity difference frequency generation
Abstract
Terahertz sources based on intra-cavity difference-frequency generation in mid-infrared quantum cascade lasers (THz DFG-QCLs) have recently emerged as the first monolithic electrically-pumped semiconductor sources capable of operating at room-temperature (RT) across the 1-6 THz range. Despite tremendous progress in power output, that now exceeds 1mW in pulsed and 10 {\mu}W in continuous-wave regime at room-temperature, knowledge of the major figure of merits of these devices for high precision spectroscopy, such as spectral purity and absolute frequency tunability, is still lacking. Here, by exploiting a metrological grade system comprising a terahertz frequency comb synthesizer, we measure, for the first time, the free-running emission linewidth (LW), the tuning characteristics, and the absolute frequency of individual emission lines of these sources with an uncertainty of 4 x 10-10. The unveiled emission LW (400 kHz at 1ms integration time) indicates that DFG-QCLs are well suited to operate as local oscillators and to be used for a variety of metrological, spectroscopic, communication, and imaging applications requiring narrow-linewidth THz sources.
Keywords
Cite
@article{arxiv.1804.11260,
title = {Unveiling spectral purity and tunability of terahertz quantum cascade laser sources based on intra-cavity difference frequency generation},
author = {Luigi Consolino and Seungyong Jung and Annamaria Campa and Michele De Regis and Shovon Pal and Jae Hyun Kim and Kazuue Fujita and Akio Ito and Masahiro Hitaka and Saverio Bartalini and Paolo De Natale and Mikhail A. Belkin and Miriam Serena Vitiello},
journal= {arXiv preprint arXiv:1804.11260},
year = {2018}
}