title: Comb-locked cavity ring-down spectrometer.
abstract: Extreme frequency accuracy and high sensitivity are obtained with a novel comb-locked cavity-ring-down spectrometer operating in the near-infrared from 1.5 to 1.63 μm. A key feature of our approach is the tight frequency locking of the probe laser to the comb, ensuring very high reproducibility and accuracy to the frequency axis upon scanning the comb repetition rate, as well as an efficient light injection into a length-swept high-finesse passive cavity containing the gas sample. Spectroscopic tests on the (30012) ← (00001) P14e line of CO2 at ∼1.57 μm demonstrate an accuracy of ∼17 kHz on the line center frequency in a Doppler broadening regime over the time scale of about 5 min, corresponding to four consecutive spectral scans of the absorption line. Over a single scan, which consists of 1500 spectral points over 75 s, the limit of detection is as low as 5.7 × 10(-11) cm(-1).
authors.affiliation: Dipartimento di Fisica - Politecnico di Milano and IFN-CNR, Piazza Leonardo da Vinci 32, 20133 Milano, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Gatti
authors.affiliation: Dipartimento di Fisica - Politecnico di Milano and IFN-CNR, Piazza Leonardo da Vinci 32, 20133 Milano, Italy.
authors.forename: Tommaso
authors.initials: T
authors.lastname: Sala
authors.affiliation: Dipartimento di Fisica - Politecnico di Milano and IFN-CNR, Piazza Leonardo da Vinci 32, 20133 Milano, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Gotti
authors.affiliation: IFN-CNR-UOS Padova, Via Trasea 7, 35131 Padova, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Cocola
authors.affiliation: IFN-CNR-UOS Padova, Via Trasea 7, 35131 Padova, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Poletto
authors.affiliation: Dipartimento di Fisica e Astronomia, Università di Bologna, Via Berti-Pichat 6/2, 40127 Bologna, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Prevedelli
authors.affiliation: Dipartimento di Fisica - Politecnico di Milano and IFN-CNR, Piazza Leonardo da Vinci 32, 20133 Milano, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Laporta
authors.affiliation: Dipartimento di Fisica - Politecnico di Milano and IFN-CNR, Piazza Leonardo da Vinci 32, 20133 Milano, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Marangoni