Frequency conversion of a chirped Ti:sapphire laser pulse to 11.4 m wavelength with SrMoO₄ Raman shifter and LiGaS₂ DFG crystal

The simple mid-IR laser source based on femtosecond Ti:Sapphire laser and successive frequency conversion of its stretched up to 50 ps pulses in SrMoO4 Raman-active crystal and LiGaS2 second order nonlinear crystal is demonstrated. Energy of the mid-IR pulse at 11.4 mu m wavelength was up to 250 nJ that was four times higher than the previous results for the similar setup. The influence of pump pulse intensity on spectral and energetic parameters of laser pulses after SrMoO4 and LiGaS2 crystals were studied in details.