title: Frequency-comb-based absolute frequency measurements in the mid-infrared with a difference-frequency spectrometer.
abstract: We demonstrate the possibility of extending the well-established metrological performance of optical frequency-comb synthesizers to the mid-IR region by phase locking the pump and signal lasers of a difference-frequency source to two near-IR teeth of an optical comb. An uncertainty of 800 Hz (1.1 x 10(-11)) in the absolute frequencies of CO2 transitions near 4.2 microm has been measured by cavity-enhanced saturated-absorption spectroscopy. Prospects for the creation of a new dense set of high-quality molecular frequency standards in the IR are discussed.
authors.affiliation: Istituto Nazionale di Ottica Applicata, Largo Fermi 6, 50125 Florence, Italy. mazzotti@inoa.it
authors.forename: D
authors.initials: D
authors.lastname: Mazzotti
authors.forename: P
authors.initials: P
authors.lastname: Cancio
authors.forename: G
authors.initials: G
authors.lastname: Giusfredi
authors.forename: P
authors.initials: P
authors.lastname: De Natale
authors.forename: M
authors.initials: M
authors.lastname: Prevedelli