Short pulses from a gain-switched quantum cascade laser

The picosecond carrier dynamics observed in quantum cascade lasers (QCLs) poses a fundamental obstacle for the formation of intracavity pulses. On the other hand, the ultrafast gain response makes the QCL ideally suited for high frequency modulation of its pump current. In this work, we leverage this property and use short electrical excitations to generate 33 ps optical pulses with up to Watt level peak power. We ensure lasing on a single resonator mode via optical injection seeding. The resulting pulses are characterized in both time and frequency domains using an optical sampling method in combination with a spectrometer. We interpret the obtained results using laser rate equations. The results presented in this work open new pathways for the generation of highly tunable, high power mid-infrared pulses from a monolithic source. (c) 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

By leveraging the picosecond carrier dynamics observed in quantum cascade lasers (QCLs), we have successfully generated 33 ps optical pulses with watt-level peak power using short electrical excitations. Optical injection seeding ensured lasing on a single resonator mode, and the resulting pulses were characterized in both time and frequency domains. These results open new pathways for the generation of highly tunable, high power mid-infrared pulses from a monolithic source.