We report the generation of ultrabroadband mid-infrared (mid-IR) pulses by noncollinear difference frequency mixing. The signal and the idler output beams of an optical parametric amplifier are combined in a… Click to show full abstract
We report the generation of ultrabroadband mid-infrared (mid-IR) pulses by noncollinear difference frequency mixing. The signal and the idler output beams of an optical parametric amplifier are combined in a silver thiogallate crystal (AgGaS2) to generate mid-infrared radiation. We show that a noncollinear geometry facilitates broadband phase matching. Spectral bandwidths up to 1750 cm-1 were obtained at an external noncollinear angle of 4.2 deg, which is more than three times broader than in a collinear geometry. The broadband spectrum is tunable in the range of 1500-4500 cm-1. Pulse energies up to 1 μJ were achieved. The broadband pulses were used in sum frequency generation in ZnSe and in vibrational absorption spectroscopy experiments of liquid samples.
               
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