Supercontinuum generation in the enhanced frequency chirp regime in multipass cells

We identify, via numerical simulations, the regime of enhanced frequency chirp during nonlinear propagation in multipass cell. This regime - used before the dawn of chirped pulse amplification to generate ultrashort pulses - paves the way for the generation of temporally clean few-cycle pulses. Here, we demonstrate numerically that the spectra of pulses from an Yb-based laser system can be broadened into a flat supercontinuum with a smooth spectral phase compatible with a clean few-cycle pulse with temporal secondary structures with peak intensity below 0.5% that of the main peak.