Subkilohertz-narrowed, frequency/phase-locked mid-IR quantum cascade lasers for high-precision molecular spectroscopy

The interest in the development of narrow-linewidth mid-IR sources is related to advanced applications such as trace-gas sensing with high-finesse cavities, high-precision spectroscopy and frequency metrology. For all these fields, the mid-IR portion of the electromagnetic spectrum, named also 'molecular fingerprint region', is the best suited for investigating many molecules of atmospheric and astrophysical interest, whose strongest ro-vibrational transitions lie in this spectral region. © 2013 IEEE.