Coherent multiheterodyne spectroscopy using stabilized optical frequency combs.
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.
Coddington
Ian
I
National Institute for Standards and Technology, Boulder, CO 80305, USA.
Swann
William C
WC
Newbury
Nathan R
NR