Experimental investigation of high-energy wave-breaking-free-pulse generation in bidirectional-pumping all-fiber laser

We report a passively mode-locked all-fiber laser with bidirectional pumping, emitting high-energy wavebreaking- free pulses. Experimental investigations show that forward and backward pump powers mainly contribute on the chirp and the nonlinear phase shift of pulses, respectively. Nonlinear chirp pulses with 50 nJ pulse energy, 340 ps duration at a 8:2MHz repetition rate are directly emitted from the all-fiber laser pumped by two 550mW, 977nm laser diodes. The pulses cannot be compressed to near the transform limit, showing that the chirp of pulses is nonlinear.