Fig. 1. Results of numerical simulations without the intracavity bandpass filter. (a) Temporal and (b) spectral evolution of the pulse. (c) Temporal shape (blue curve) and phase (red curve) at the 600th round trip. (d) Spectral shape (blue curve) and phase (red curve) at the 600th round trip.

Fig. 2. Results of numerical simulations with the intracavity bandpass filter. (a) Characteristics of the output pulses versus the bandwidth of the incorporated bandpass filter. (b) Evolution of the output pulses and (c) steady output spectrum and phase of the simulated oscillator with a 2-nm bandpass filter.

Fig. 3. (a) Schematic of the experimental oscillator. (b) Pulse train at a repetition rate of 1.84 MHz. (c) Radio-frequency spectra of the obtained pulses. LD: laser diode; WDM: wavelength division multiplexer; BP: bandpass filter; OFM: optical fiber mirror.

Fig. 4. Comparison of the spectra with (blue curves) and without (red curves) the bandpass filter when the oscillator operates in the (a) multiple-pulse and (b) single-pulse operation regimes. For a better comparison, the blue curves are red-shifted by 6.4 nm.

Fig. 5. (a) Schematic configuration of the pre-amplifier. ISO: isolator; PBS: polarized beam splitter; ESF: Er-doped single-mode fiber; FRM: Faraday rotation mirror. (b) Spectral profiles when the intracavity bandpass filter in the laser oscillator is activated (blue curve) or removed (red curve). (c) Autocorrelation trace measured by the PulseCheck.

Fig. 6. (a) Slope efficiency of the double-cladding amplifier. Inset: autocorrelation trace of the amplified pulses. (b) Average power stability.

Fig. 7. Output power of the laser system in an incubator as the temperature changes.