  An infrared high-brightness light source based on supercontinuum generation
through a SF6 photonic crystal fiber seeded by a Cr^4+:YAG femtosecond
oscillator is developed for high resolution multiplex spectroscopy in the 1.5
$\mu$m region. Moreover, a multiplex high resolution approach based on a
Cr^4+:YAG frequency comb enables to probe large spectral domains, with
simultaneous sensitive measurement of the absorption and the dispersion
associated with all individual spectral features.
