0.5 μJ pulses from a giant-chirp ytterbium fiber oscillator

We present a mode-locked all-normal dispersion ytterbium fiber oscillator with output pulse energies beyond 0.5 mu J. The oscillator is mode-locked using nonlinear polarization rotation, and stable single-pulse operation is achieved by spectral filtering inside the resonator. The oscillator generates strongly chirped output pulses at a repetition rate of 4.3 MHz which can be compressed down to 760 fs. (C) 2011 Optical Society of America