Cavity-enhanced dual-comb spectroscopy

Birgitta Bernhardt, Akira Ozawa, Patrick Jacquet, Marion Jacquey, Yohei Kobayashi, Thomas Udem, Ronald Holzwarth, Guy Guelachvili, Theodor W. Hänsch, Nathalie Picqué

Research output: Contribution to journalArticlepeer-review


The sensitivity of molecular fingerprinting is dramatically improved when the absorbing sample is placed in a high-finesse optical cavity, because the effective path length is increased. When the equidistant lines from a laser frequency comb are simultaneously injected into the cavity over a large spectral range, multiple trace gases may be identified1 within a few milliseconds. However, efficient analysis of the light transmitted through the cavity remains challenging. Here, a novel approach—cavity-enhanced, frequency-comb, Fourier-transform spectroscopy—fully overcomes this difficulty and enables measurement of ultrasensitive, broad-bandwidth, high-resolution spectra within a few tens of microseconds without any need for detector arrays, potentially from the terahertz to ultraviolet regions. Within a period of just 18 µs, we recorded the spectra of the ammonia 1.0 µm overtone bands comprising 1,500 spectral elements and spanning 20 nm, with a resolution of 4.5 GHz and a noise equivalent absorption at 1 s averaging of 1 × 10−10 cm−1 Hz−1/2, thus opening a route to time-resolved spectroscopy of rapidly evolving single events.
Original languageEnglish
Pages (from-to)55 - 57
Number of pages3
JournalNature Photonics
Publication statusPublished - 29 Nov 2009

Fields of Expertise

  • Advanced Materials Science

Cite this