2-COLOR FACILITY BASED ON A BROADLY TUNABLE INFRARED FREE-ELECTRON LASER AND A SUBPICOSECOND-SYNCHRONIZED 10-FS-TI-SAPPHIRE LASER

Subpicosecond synchronization between a mirror-dispersion-controlled 1 0-fs Ti:sapphire laser and the Free-Electron Laser for Infrared Experi ments has been achieved. The measured intensity cross correlation betw een the two lasers is consistent with a jitter of only 400 fs rms. The wide and continuous tunability of the free-electron laser (FEL; 4.2-3 00 mu m) combined with ultrashort pulse duration of six optical cycles and high pulse energy of several tens of microjoules makes a series o f two-color experiments possible in a previously inaccessible waveleng th range. We demonstrate these capabilities by performing a two-color pump-probe experiment to study carrier cooling in GaAs. A FEL tuned fr om 8 to 17 mu m is used as the pump, and a synchronized Ti:sapphire la ser pulse serves as the probe. (C) 1998 Optical Society of America.