TUNABLE MULTIWAVELENGTH SYNCHRONIZED FEMTOSECOND PULSE TRAINS FOR ULTRAFAST SPECTROSCOPY

By using femtosecond optical techniques including self-phase modulatio n, spectral filtering and dispersion compensation, we constructed a tu nable multiwavelength synchronized femtosecond light source from a cw modelocked femtosecond Ti:sapphire laser, and experimentally character ized its performance, Synchronized femtosecond pulses of different cen tral frequencies can be selected independently within a 60-nm FWHM ban d. Pulse duration can also be programmed from 200 fs to 100 fs by cont rolling the bandwidth. Synchronization between pulses of different wav elengths are experimentally shown to be within a few femtoseconds. We demonstrate applications of the light source in ultrafast pump-probe s pectroscopy with a sensitivity as great as 10(-5) in transient transmi ssion measurements.