@article{180601,
  keywords = {Magnetic fields, Diode lasers, Absorption spectroscopy, Faraday effect, Spectroscopy, diode lasers, Spectroscopy, molecular, Modulation spectroscopy, Tunable diode lasers},
  author = {Jakob Hayden and Jonas Westberg and Charles Link Patrick and Bernhard Lendl and Gerard Wysocki},
  title = {Frequency-locked cavity ring-down Faraday rotation spectroscopy},
  abstract = { Cavity ring-down Faraday rotation spectroscopy (CRD-FRS) is a technique for trace gas measurements of paramagnetic species that retrieves the molecular concentration from the polarization rotation measured as the difference between simultaneously recorded ring-down times of two orthogonal polarization states. The differential measurement is inherently insensitive to nonabsorber related losses, which makes off-resonance measurements redundant. We exploit this unique property by actively line-locking to a molecular transition for calibration-free trace gas concentration retrieval. In addition, we enhance the effective duty-cycle of the system by implementing a Pound{\textendash}Drever{\textendash}Hall laser lock to the cavity resonance, which allows for ring-down rates of up to 9~kHz. The system performance is demonstrated by measurements of trace oxygen with a minimum detection limit at the ppmv/√Hz-level. },
  year = {2018},
  journal = {Optics Letters},
  volume = {43},
  number = {20},
  pages = {5046-5049},
  month = {10/2018},
  publisher = {OSA},
  url = {http://ol.osa.org/abstract.cfm?URI=ol-43-20-5046},
  language = {eng},
}