Prospects of high energy ultrashort pulse generation with frequency shifted feedback fiber oscillators

The pulse energies available directly from passively mode-locked Ytterbium-doped fiber oscillators have been significantly increased during the past few years. Cavity designs with large net group velocity dispersion (GVD) have been favoured to avoid the formation of solitons which may limit the pulse energy. Recently, pulse energies above 20 nJ have been reached with all-normal dispersion (ANDi) fiber lasers. The mode-locking in these lasers is based on the spectral filtering of a highly chirped pulse in the cavity and dechirped pulse durations in the order of 100 fs have been reported [1].