Generation of 25-fs High Energy Pulses by SPM-Induced Spectral Broadening in a Photonic Crystal Fiber Laser System

We demonstrate 25-fs laser pulse generation from a photonic crystal fiber (PCF) laser system, which consists of a high energy all normal dispersion mode-locked oscillator based on an ytterbium-doped large mode area PCF and a passive PCF-based grating-pair compressor. The oscillator directly delivers 314-nJ highly-chirped pulses with a duration of 1.32 ps at a repetition rate of 15.58 MHz, which can be dechirped to 75 fs, corresponding to a peak power of 3 MW. The output laser pulses from the oscillator are directly injected to a piece of passive PCF for spectral broadening and dechirped by a transmission grating pair compressor, which results in a short pulse duration of 25 fs with 1-W average power.