Femtosecond pulse shaping with phase-only filters

We describe the generation of shaped femtosecond multiple pulses by using the phase-only filters designed with optimized techniques, which includes Dammann-type filter and another filter of producing specific unequal-spacing and equal-intensity. We consider the influence for the output pulses with the accuracy of the transitional points, the number of pixels of the mask, the periodic repetition number for the Dammann-type gratings, and the change of the Gaussian spectral phase of the modulated phase plate with the wavelength. On the other hand, experiments of ultrafast temporal pattern recognition by the frequency-resolved optical gating (FROG) characterization technique are also given.