Numerical investigation on influence of the saturable absorber in Tm-doped fiber laser

Abstract

Here we numerically simulate the effect of the saturable absorber (SA) on the output performance of a Tm-doped mode-locked fiber laser in the anomalous dispersion regime. In particular, we analyze the effects of variations in recovery time, modulation depth, nonsaturable loss, and saturable energy on the parameters of the output pulse, such as pulse width and spectral bandwidth. It is demonstrated that the output pulse becomes unstable and broken when the SA recovery time is set below a crucial value. In addition, we demonstrate that the recovery time for stable conventional soliton pulse generation lies within a certain range that is sensitive to the cavity dispersion and modulation depth of the SA. These findings have significant implications for fiber laser design and our understanding of the SA effect at mid-infrared wavelength.