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 microm wavelength agree reasonably with numerical simulations and produce clean approximately 80 fs pulses. The simulations indicate that 30 fs pulses can be reached at higher energies.