QCL-pumped molecular laser
The THz range of the electromagnetic spectrum - spanning from 100 GHz to a few THz - has so far been underutilized due to the lack of appropriate sources working in this spectral range. Yet, the THz spectral range offers countless possibilities for communication, astronomy or remote sensing. We are developing new compact and widely tunable THz sources using a molecular gas optically pumped by a quantum cascade laser (QCL). Light from the QCL is sent into a laser cavity and absorbed by the molecular gas that can re-emit THz radiation. The recent work featured in Science demonstrated the concept of QCL pumped molecular laser using nitrous oxide - laughing gas - as the gain medium. This concept is however universal as any molecular gas with a permanent dipole moment can be turned into a THz laser, where the emission frequency and the tunability of the laser depend on the chosen gain medium.