Enhanced temporal resolution in femtosecond dynamic-grating experiments

Recording of gratings by interference of two pump pulses and diffraction of a third probe pulse is useful for investigating ultrafast material phenomena. We demonstrate, in theory and experiment, that the temporal resolution in such configurations does not degrade appreciably even for large angular separation between the pump pulses. Transient Kerr gratings are generated inside calcium fluoride (Ca F2) crystals by two interfering femtosecond (pump) pulses at 388 nm and read out by a Bragg-matched probe pulse at 776 nm. The solution to the relevant coupled-mode equations is well corroborated by the experimental results, yielding a value of the Kerr coefficient of ≈4.4× 10-7 cm2 GW for Ca F2. © 2005 American Institute of Physics.