Absolute frequency spectroscopy at 4.3 µm by direct referencing of a Quantum-Cascade-Laser to an Er: Fiber laser-based frequency-comb

摘要

The advent of optical frequency combs [1] has given in the past ten years a tremendous impulse to the field of frequency metrology. At present most comb-assisted experiments have been focused between the ultraviolet and the near-infrared (near-IR) spectral region while very few results [2,3,4] have been reported in the middle-infrared (mid-IR) despite its great interest due to the huge number of fundamental vibrational transitions that simple molecules exhibit in this region. Extensive comb-assisted study of such transitions would both enhance the accuracy of the available databases and favor a deeper insight into the comprehension of molecular physics.