Extreme nonlinearities within a quantum cascade laser
![Quantumcascadelaser](/storages/aglange-physik/_processed_/c/a/csm_QCL_image_9417239fc7.png)
Teaming up with partners from Germany, France, UK and Sweden, we observed high-order terahertz nonlinearities in a free-running quantum cascade laser. Nonlinearities up to eight-wave-mixing as well as the subcycle gain dynamics were revealed by two-dimensional terahertz spectroscopy in a regime of negative absorption. Potential future applications include efficient intracavity frequency conversion under optical gain and mode proliferation to passive mode locking.
The results have been published in Light: Science & Applications.