GENERATION OF HIGHLY COHERENT TUNABLE MIDINFRARED FEMTOSECOND PULSES BY PARAMETRIC FREQUENCY-MIXING AT 82 MHZ

Near-transform-limited femtosecond infrared pulses are generated in th e 2.8 to 3.6 mu m spectral region by parametric frequency-mixing in KT P of the synchronised outputs of an 82 MHz femtosecond Ti : sapphire l aser and a tunable visible-range femtosecond optical parametric oscill ator pumped by the second-harmonic of the Ti : sapphire laser. Infrare d pulse-widths down to 90 fs are measured and the dependence of pulse duration on frequency and mixing-crystal thickness is accurately descr ibed by a detailed calculation and a simple analytical expression.