5. Conclusion

In 2019, twenty-five years after their first demonstration, quantum cascade lasers are now a technological reality attracting increasing investment. A large number of companies produce these lasers or use them to build optoelectronic systems.

Their performance and robustness make them an essential technology for mid-infrared spectroscopy, the spectral region where the majority of molecular lines are found. These absorption lines are of great interest for applications such as environmental monitoring, analysis of respiration in medicine, and early detection of degradation in stored food products, to name but a few. Thanks to its precision and speed, quantum cascade laser technology is replacing standard spectroscopy techniques based on spectrometers with thermal sources.

Quantum cascade lasers have enabled semiconductor technology to extend...