All-fiber all-normal-dispersion femtosecond laser with nonlinear multimodal interference based saturable absorber

摘要

In this letter, we demonstrate the first all-fiber all-normal dispersionytterbium-doped oscillator with nonlinear multimodal interference basedsaturable absorber capable to generate ultrashort dissipative soliton pulses.Additional to functioning as a saturable absorber, the use of multimode fibersegments between single mode fibers also ensures the bandpass filtering viamultimode interference reimaging necessary to obtain dissipative solitonmode-locking. The oscillator generates dissipative soliton pulses at 1030 nmwith 5.8 mW average power, 5 ps duration and 44.25 MHz repetition rate. Pulsesare dechirped to 276 fs via an external grating compressor. All-fiber cavitydesign ensures high stability and $\sim$70 dB sideband suppression is measuredin RF spectrum. Numerical simulations are performed to investigate cavitydynamics and obtained results well-matched with experimental observations. Theproposed cavity presents an alternative approach to achieve all-fiberdissipative soliton mode-locking with a simple and low-cost design.