Efficient self-similar evolution and intensity noise suppression in high-gain femtosecond fiber amplifiers using pump-wavelength optimization

Abstract

We demonstrate efficient self-similar pulse evolution and noise suppression in a free-running nonlinear femtosecond fiber amplifier based on the pump-wavelength optimization. Experiments and simulations show the broader and flatter absorption cross-sections around 915 nm can reduce the influences of the gain shaping and fluctuations of pump laser diodes (LDs). 50-fs transform-limited pulses are generated with the amplifier rms RIN of 0.035% (1 kHz to 10 MHz). ∼75% reduction in the pulse deviation from the ideal parabolic pulse and ∼27% reduction in the relative intensity noise (RIN) have been observed, even under a more than 2 times higher pump-LD RIN. This scheme gives an easy way for high-power pulse generation with ultra-short pedestal-free duration and low noise, thus demonstrate the potential for high-optical-coherence and high-signal-to-noise-detection related applications.