Giant-chirp oscillators for short-pulse fiber amplifiers

A new regime of pulse parameters in a normal-dispersion fiber laser is identified. Dissipative solitons exist with remarkably large pulse duration and chirp, along with large pulse energy. A low-repetition-rate oscillator that generates pulses with large and linear chirp can replace the standard oscillator, stretcher, pulse-picker, and preamplifier in a chirped-pulse fiber amplifier. The theoretical properties of such a giant-chirp oscillator are presented. A fiber laser designed to operate in the new regime generates $\sim 150\mathrm{ps}$ pulses at a $3\mathrm{MHz}$ repetition rate. Amplification of these pulses to $1\mu \mathrm{J}$ energy with pulse duration as short as $670\mathrm{fs}$ demonstrates the promise of this new approach.