Generation of submilli-joule picosecond square shaped pulses for low emittance electron generation in photocathode RF-GUN

Arbitrary shaping of a sub-milli joule femtosecond pulses has been demonstrated by manipulation of optical frequency phase components on the Fourier plane. The shaped pulses were pulse trains and picosecond square pulses for low emittance electron generation in a RF photocathode. Since the pulse shaping apparatus was placed between an oscillator and a pulse stretcher in order to avoid damage to the liquid crystal spatial light modulator, phase-only modulation was used for shaping to avoid damage to optical elements in a regenerative amplifier. The phase modulation was designed by simulated annealing optimization method.