A method for generating ultrashort pulses includes directing a master beam having ultrashort pulses and at least one slave beam through an optical gate material. The intensity of the slave beam upstream of the optical gate material is lower than that of the master beam upstream of the optical gate material. The optical gate material and the pulses of the master beam are chosen to induce a Kerr effect when the master beam passes through the optical gate material, the Kerr effect producing a modulation of the phase of the slave beam in association with pulses of the master beam when the slave beam passes through the optical gate material. The modulation of the phase of the slave beam is transformed into a modulation of the amplitude thereof using a complementary optical device to generate a slave beam downstream of the optical gate material having ultrashort pulses.