A shaper for providing long laser target waveforms

We discuss the features of a shaping device consisting of a spectral amplitude modulator followed by a pair of diffraction gratings arranged as a linear dispersive stretcher. The proposed system is aimed at transforming input short pulses into long target pulses. The basic of the shaper is the construction of an amplitude profile in the frequency domain and the reproduction of the profile in the time domain. The foreseen characteristics of mechanical simplicity, stability to parameters perturbations and the capability of providing long rectangular pulses with fast rise-time make the device interesting for laser systems devoted to irradiation of radiofrequency electron gun photocathodes.