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Emission Comb Spectroscopy: Development of novel frequency comb spectroscopy methods based on stimulated Raman scattering (EmCoS)
Date du début: 1 sept. 2010, Date de fin: 31 août 2012 PROJET  TERMINÉ 

Coherent control of ultrafast lasers results in well-defined frequency combs revolutionizing many aspects in fundamental and applied science. Most recently, frequency comb technology was used to push the performance of Fourier transform spectroscopy to unprecedented levels. Multi-heterodyne spectroscopy is a rapidly growing research field opening new perspectives in terms of sensitivity, spectral resolution and data acquisition time which has been demonstrated in various experiments on absorption spectroscopy. Here, we propose a novel technique for frequency comb based precision spectroscopy based on stimulated Raman scattering. This approach or emission frequency comb spectroscopy in general has not been addressed so far. We describe two schemes for measuring the Raman response of molecular samples and the corresponding proof-of-principle experiments. Based on the pump probe technique, the consequences of the excitation of rotational transitions in molecular hydrogen will be measured by multi-heterodyning with phase-locked frequency combs. The first technique relies on Raman induced Stokes gain and anti-Stokes loss, respectively, experienced by the probe pulse whereas the second is based on the time dependent measurement of the transient index perturbation. As multi-heterodyne spectroscopy is capable to yield the full complex spectrum, both schemes can be studied with a similar setup. Another goal of this proposal is the design of a tailored fibre based dual frequency comb system to be able to fully exploit the potential of this spectroscopic technique. The advances of our scheme will then be utilized for spatially resolved spectroscopy and microscopy which is particularly useful for biological samples. Broadband measurement allows simultaneous analysis of various transitions. The proposed project constitutes a new direction for nonlinear precision spectroscopy with a huge potential for many branches of science and interdisciplinary research.

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