Stable subpicosecond infrared pulses in the spectral region of 4.5-11.5 ,um are generated by difference-frequency
mixing in AgGaS2. The system uses femtosecond pulses from a Ti:sapphire regenerative amplifier and from a
tunable traveling-wave dye laser. The infrared pulses have a duration of 400 fs, an energy of more than 10 nJ,
and a repetition rate of 1 kHz.