Noise-like pulses under different intra-cavity nonlinearity

We report on the influence of the average nonlinear coefficient on noise-like pulse (NLP) in a figure-of-eight erbium-doped fiber laser. Since the nonlinear switching point of nonlinear amplifying loop mirror (NALM) shifts with distinct laser configurations, through changing the length of highly nonlinear fiber (HNLF) in NALM, properties of output pulse have been compared and analyzed. The spectral evolutions occur and the peak power of NLP presents a decline when the HNLF is lengthened in NALM. Also, the tuning range of the duration of NLP shows a difference based on the average nonlinear coefficient selected.