PARAMETRIC GENERATION OF SYNCHRONIZED, INDEPENDENTLY TUNABLE SUBPICOSECOND PULSES IN THE MIDINFRARED WITH ADJUSTABLE PULSE DURATION

Intense pulses for two-color pump-probe spectroscopy in the mid-infrar ed spectral region are generated by optical parametric oscillator (OPO ) and optical parametric amplifier (OPA) stages. Synchronous pumping o f two OPO's in parallel delivers tunable pulses in the range 1.2-1.7 m u m with a duration of 300 fs. Subsequent frequency conversion in two OPA's consisting, respectively, of two-and four-crystal setups of AgGa S2 yields pulses in the wavelength interval 2.6-7 mu m with a duration of 0.5 ps and single-pulse energy up to 2 mu J. By simple changes of the operating conditions of the two OPO's, independent adjustments of the resulting midinfrared pulse duration are achieved that range from 0.5 to 2.6 ps while the pulse duration-bandwidth product of the pulses varies from 0.6 to 1.2. (C) 1998 Optical Society of America [S0740-32 24(98)03703-5].