SHAPING OF FEMTOSECOND PULSES USING PHASE-ONLY FILTERS DESIGNED BY SIMULATED ANNEALING

We describe generation of shaped femtosecond waveforms by using freque ncy-domain phase-only filters designed by numerical optimization techn iques. The task of filter design for pulse shaping in the time domain is directly analogous to the design of phase-only filters for beam sha ring and array generation in the spatial domain. We experimentally tes ted phase filters that were designed to produce ultrafast square and t riangle pulses and femtosecond pulse sequences. Our results demonstrat e the ability to generate high-quality terahertz-repetition-rate seque nces of femtosecond pulses by means of low-loss phase-only filtering. On the other hand experiments that tested generation of individual sha ped pulses, such as square pulses, were less successful than previous experiments that used simultaneous phase and amplitude filtering. Our results indicate the importance of building increased robust new again st variations in the input pulse shape into the only filter design.