Chirp characterization of ultrashort pulses utilizing molecular vibrations

A method is presented and demonstrated for chirp characterization of ultrashort laser pulses utilizing identical setup and detection systems of common pump-probe experiments. The coherent intramolecular vibrations that can be impulsively excited in a nonresonant manner in many common solvents are used to directly measure the spectral relative delay of femtosecond pulses. For pump-probe experiments on solutions, this method has the capability of isolating the phase of the signal due to the solute from the phase due to the solvent and to uncompensated chirp in the laser pulse. The method is not restricted to pulses with optical bandwidth narrower than an octave. (C) 2004 American Institute of Physics.