By Cnr Ifn
In the late 1990s and early 2000s, optical frequency combs revolutionized frequency and time metrology, providing linkages that allowed accurate measurement of microwave and optical frequencies. It was for their contributions to optical frequency comb development that John Hall and Theodor Hänsch earned their share of the Nobel Prize in Physics in 2005. An optical frequency comb is a laser source generating a series of thousands/millions of evenly spaced narrow spectral lines exhibiting a perfect phase coherence. As the technology around frequency comb generation has matured, numerous other applications have been discovered. This research activity focuses on the application of frequency combs to broadband and precision molecular spectroscopy following two complimentary experimental approaches: i) direct frequency comb spectroscopy, or broadband comb spectroscopy, where the optical frequency comb is used to directly excite or interrogate the spectroscopic sample; ii) comb-assisted precision spectroscopy where the comb is used as a frequency ruler and the spectroscopic interrogation is performed by a CW tunable probe laser. Synthesis of novel frequency combs in the visible and infrared (near and middle) spectral regions for broadband spectroscopy and long-term calibration of high-resolution astronomical spectrographs
