title: Coherent multiheterodyne spectroscopy using stabilized optical frequency combs.
abstract: The broadband, coherent nature of narrow-linewidth fiber frequency combs is exploited to measure the full complex spectrum of a molecular gas through multiheterodyne spectroscopy. We measure the absorption and phase shift experienced by each of 155 000 individual frequency-comb lines, spaced by 100 MHz and spanning from 1495 to 1620 nm, after passing through hydrogen cyanide gas. The measured phase spectrum agrees with the Kramers-Kronig transformation of the absorption spectrum. This technique can provide a full complex spectrum rapidly, over wide bandwidths, and with hertz-level accuracy.
authors.affiliation: National Institute for Standards and Technology, Boulder, CO 80305, USA.
authors.forename: Ian
authors.initials: I
authors.lastname: Coddington
authors.forename: William C
authors.initials: WC
authors.lastname: Swann
authors.forename: Nathan R
authors.initials: NR
authors.lastname: Newbury