GENERATION OF SUBPICOSECOND INFRARED PULSES TUNABLE BETWEEN 5.2 MU-M AND 18 MU-M AT A REPETITION RATE OF 76 MHZ

Infrared (IR) pulses are generated via difference frequency mixing of the signal and idler output of an optical parametric oscillator (OPO), pumped by a Ti:sapphire laser at a repetition rate of 76 MHz. AgGaS2 (2 mm thick) and GaSe (1 mm thick) crystals are applied as nonlinear m edia. GaSe has a larger tuning range and is more efficient in the whol e spectral range than AgGaS2. The average IR power reaches up to 2.0 m W at 8.5 mu m when the GaSe crystal is used, and up to 1.3 mW at the s ame wavelength when AgGaS2 is applied for the frequency conversion.