Route to the minimum pulse duration in normal-dispersion fiber lasers

The factors that control the pulse duration in all-normal-dispersion lasers are identified. To minimize the pulse duration the cavity dispersion should be as small as possible. For fixed dispersion increasing pulse energy leads to shorter pulses with more structured spectra. Experiments performed with ordinary single-mode fiber at 1 μm wavelength agree reasonably with numerical simulations and produce clean ~80 fs pulses. The simulations indicate that 30 fs pulses can be reached at higher energies.