Quantum cascade laser: A promising candidate toward an ultra-stable laser in the mid-IR

The frequency noise properties of free-running single-mode mid-IR Quantum Cascade Lasers (QCLs) operated near room-temperature in CW mode and emitting at 4.6 µm are presented. The frequency noise level measured in this paper is globally a factor of 100 lower than recently reported for a similar QCL but operated at cryogenic temperature. The results are very promising for the future realization of a QCL-based ultra-stable laser in the mid-IR.