Simulations on Generating Long Flat-Top Laser Pulses for Fast Ignition of Laser Fusion

A modified input–output algorithm is first applied to generate long flat-top pulses using a phase-only pulse shaper for fast ignition of laser fusion. More accurate long (10–20 ps) flat-top pulses can be obtained within several hundred iterations that take much shorter simulation time compared with "trial-and-error" algorithms. Also the flat-top pulses generated by the input–output algorithm are free from noise in the wings of the main pulse, thus higher pulse contrast with reduced pedestal can be obtained, which is very important for the fast ignition of laser fusion. Simulations also show that flatness on the flat-top of the pulse is fairly insensitive to perturbations of input signals.