title: Precision spectroscopy of acetylene transitions using an optical frequency synthesizer.
abstract: An optical frequency synthesizer is used for saturation spectroscopy of acetylene near 1540 nm. In the synthesizer, a user-specified frequency is generated from an atomic time base by phase locking the second harmonic of a cw near-IR external-cavity diode laser (ECDL) to a Ti:sapphire frequency comb. By stepping the repetition rate of the frequency comb, the ECDL frequency is swept over an acetylene transition in a saturated absorption spectroscopy setup. Hence, a spectral lineshape is measured with an absolute frequency scale. Line-center frequencies determined by fitting theoretical line profiles to the measured data are in good agreement with values measured with the ECDL stabilized to acetylene by third-harmonic locking and with the values recommended by the International Committee for Weights and Measures (CIPM).
authors.affiliation: Centre for Metrology and Accreditation (MIKES), P.O. Box 9, FI-02151 Espoo, Finland.
authors.forename: V
authors.initials: V
authors.lastname: Ahtee
authors.forename: M
authors.initials: M
authors.lastname: Merimaa
authors.forename: K
authors.initials: K
authors.lastname: Nyholm