Quantitative Molecular Spectroscopy in Cavity

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Quantitative Molecular Spectroscopy in Cavity

Hosted By: Environmental Sensing Technical Group

6 December 2018, 10:00 - 11:00

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In this webinar hosted by the OSA Environmental Sensing Tech Group, Dr. Patrick Dupré from Université du Littoral Côte d'Opale will discuss Cavity Ring-Down Spectroscopy and Cavity-Enhanced Optical Heterodyne Molecular Spectrometry.

Modern sensitive spectroscopy is based on laser sources and cavity, and the limit of detection is strictly due to the value of the signal to noise ratio. The signal is improved by the cavity finesse, since the equivalent absorption length is proportional to the cavity finesse. The minimization of the noise can be obtained by using technique immune to the inherent amplitude fluctuations of the source. However, the photon shot noise is the ultimate quantum noise which cannot be beaten.

In this webinar hosted by the OSA Environmental Sensing Technical Group, Dr. Patrick Dupré from the Université du Littoral Côte d'Opale will be discussing two techniques that are noise immune, Cavity Ring-Down Spectroscopy (CRDS) and Cavity-Enhanced Optical Heterodyne Molecular Spectrometry (NICE-OHMS). The immunity of the CRDS is due to the measurement of a change of the cavity temporal response. The immunity of the NICE-OHMS is due to the heterodyne detection in a frequency range where the source does not exhibit none fluctuation. The outcome of the use of optical cavity is the "trapping" of strong electromagnetic field (EMF) which can easily induce saturated absorption even for relatively weak transitions.

What You Will Learn:

  • Laser noise characteristics
  • How optical cavities can be designed and optimized for laser spectroscopy
  • Advantages of heterodyne detection techniques

Who Should Attend:

  • Developers of trace gas sensors
  • PhD students and professionals doing spectroscopy
  • Designers of optical resonators
 

Presenter

Dr. Patrick Dupré, Université du Littoral Côte d'Opale

Patrick Dupré has a recognized expertise in several fields related to the molecular high resolution and quantitative laser Spectroscopy. This background has been acquired all along Dupré's career in France, the United States of America, the United Kingdom and Germany, in physics and chemistry laboratories. His has diverse scientific interests: going from, the design of spectroscopy experiments, the implementation of the experimental setups, the data acquisition and analysis, to the interpretation and the modeling of the data with effective Hamiltonian. Patrick Dupré is presently involved in setting up the Noise-Immune Cavity-Enhanced Optical Heterodyne Molecular Spectrometry (NICE-OHMS) technique for metrology applications and for the trace detection in the Mid-InfraRed. Spectroscopy with high finesse cavity is an ideal tool for saturated absorption, i.e., under sub-Doppler conditions.