Fig. 1. Schematic diagram of the experimental laser oscillator: SM-LD, single-mode laser diode; WDM, wavelength division multiplexer; Yb, ytterbium fiber; PC, polarization controller; PBS, polarization beam splitter; SF, spectral filter; MM-LD, multimode laser diode; DC-MPC, double-cladding multimode pump signal combiner; DC-Yb, double-cladding ytterbium fiber; OSC, oscilloscope; OSA, optical spectrum analyzer; AC, autocorrelator.

Fig. 2. PBS output: (a) train of output pulses (the inset shows a zoom of a pulse to verify single-pulse operation), and (b) the pulse spectrum.

Fig. 3. Output of the oscillator coupler after the isolator and before the amplifier stage: (a) AC temporal chirped pulse profile and (b) pulse spectrum.

Fig. 4. Output SPD of the amplifier (2.4 m Yb) at different amplifier pump power levels: (a) SPD including the pump wavelength and (b) pulse SPD showing the spectrum widening with increasing pump power.

Fig. 5. Output power and pulse width at different pump power.

Fig. 6. Output pulse of Yb-doped fiber: (a) temporal profile at different pump power and (b) no pump spectrum.

Fig. 7. Autocorrelation pulse profile (a) at 2.5 W pump power and (b) at 3 W pump power and up, showing shoulder oscillations.

Fig. 8. Compressed pulse width versus anomalous dispersion at different pump powers.

Fig. 9. Shortest compressed pulse width in femtosecond versus pump power in watts at −24,680  fs2 anomalous dispersion.

Fig. 10. Spectra of compressed pulses at different pump levels: (a) the pump spectrum is included and (b) zoomed-in pulse spectra.