We present a femtosecond frequency comb vernier spectrometer in the near infrared with a femtosecond Er doped fiber laser, a scanning high-finesse cavity and an InGaAs camera. By utilizing the properties of a frequency comb and a scanning high-finesse cavity such a spectrometer provides broad spectral bandwidth, high spectral resolution, and high detection sensitivity on a short time scale. We achieved an absorption sensitivity of ∼8 × 10-8cm-1Hz-1/2, corresponding to a detection limit of ∼70 ppbv for acetylene, with a resolution of ∼1.1 GHz in single images taken in 0.5 seconds and covering a frequency range of ∼5 THz. Such measurements have broad applications for sensing greenhouse gases in this fingerprint near infrared region with a simple apparatus.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics