Comb tooth resolved MIR spectroscopy using a VECSEL frequency comb and a virtually-imaged phased array spectrometer

Robert Rockmore, Ricky Gibson, R. Jason Jones, Jerome V. Moloney

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Mid infrared frequency combs allow for high resolution absorption spectroscopy of molecular species, which have strong signatures in this spectral region. Dual comb spectroscopy can provide broadband and high-resolution capability, but requires two fully stabilized frequency combs which adds complexity to the system. Previous work has demonstrated that frequency combs coupled with a high resolution spectrometer, consisting of a virtually imaged phased array (VIPA) along with a grating, can perform time-resolved, broadband and high- resolution absorption spectroscopy with a single frequency comb. The VIPA spectrometer disperses the spectrum in two dimensions and images it onto a focal plane detector array. If the comb teeth can be resolved, the VIPA is easily calibrated and provides comb-tooth resolved resolution and accuracy. However, in previous work, the repetition rate of the laser sources used was too low to be resolved directly, and additional passive "filter cavities" had to be employed to increase the effective repetition rate of the frequency comb. In this work we use a fully stabilized mid infrared frequency comb based on a 1.6 GHz repetition rate modelocked vertical external cavity surface emitting laser (VECSEL) and difference frequency generation to produce an off set free comb in the 3- 4 micron wavelength range. The source is directly coupled to the VIPA spectrometer to provide comb-tooth resolved absorption spectroscopy. We discuss the system's performance in gas absorption spectroscopy and its time resolving capabilities, which are limited only by the speed of the detector system.

Original languageEnglish (US)
Title of host publicationVertical External Cavity Surface Emitting Lasers (VECSELs) X
EditorsJennifer E. Hastie
ISBN (Electronic)9781510632899
StatePublished - 2020
EventVertical External Cavity Surface Emitting Lasers (VECSELs) X 2020 - San Francisco, United States
Duration: Feb 4 2020Feb 5 2020

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceVertical External Cavity Surface Emitting Lasers (VECSELs) X 2020
Country/TerritoryUnited States
CitySan Francisco


  • Difference frequency generation
  • Frequency comb
  • GHz
  • Methane
  • Mid-infrared
  • Spectroscopy
  • VIPA

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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