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-infrared spectral region are generated by optical parametric oscillator (OPO) and optical parametric amplifier (OPA) stages. Synchronous pumping of two OPO's in parallel delivers tunable pulsed in the range 1.2-1.7 μm with a duration of 300 fs. Subsequent frequency conversion in two OPA's consisting, respectively, of two- and four-crystal setups of AgGaS₂ yields pulses in the wavelength interval 2.6-7 μm with a duration of 0.5 ps and single-pulse energy up to 2 μJ. By simple changes of the operating conditions of the two OPO's, independent adjustments of the resulting mid-infrared 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.