Narrow-linewidth Interband-cascade lasers for high-resolution spectroscopy

Interband Cascade Lasers (ICLs) are gaining field in molecular sensing thanks to their compact sizes and low-power consumption. They emit in the 3-6 μm range, and are valid alternative to QCLs especially for on-field measurement. Their suitability for high-resolution spectroscopy and metrology critically depends on their frequency stability and linewidth. Here we investigate this issues, reporting experimental studies of the frequency noise and intrinsic linewidth of an ICL at 4.6 μm. The main differences with respect to other semiconductor lasers are discussed, as well as quantum-limited operation achievable using low-noise current drivers and frequency locking to high-performance optical resonators.