Generation of mid-infrared pulses suitable for two-color IR-spectroscopy with 300-fs time resolution, temporal analysis via two-photon absorption in germanium and first application

The generation of two independently tunable light pulses in the mid-infrared spectral region is reported here. Synchronously pumping two optical parametric oscillators in parallel with a flashlamp-pumped, pulsed Nd:YLF laser delivers tunable radiation in the range 1.2-1.7 μm with duration of 300 fs. Subsequent parametric amplification in AgGaS₂ crystals yields intensive light pulses in the wavelength range of 2.7-7 μm with duration of approximately 1 ps and energies up to 10 μJ. Pulse analysis determining also the zero delay time and the temporal resolution of the experimental system is performed via two-photon absorption in germanium, utilizing the direct band gap. The temporal resolution of the two-color IR-system is determined to be approximately 300 fs and first application to time-resolved spectroscopy in the condensed phase is demonstrated