Efficient application of an all-fiber saturable absorber for the generation of heterogeneous and vector dissipative solitons in fiber lasers

Abstract

A fully fiber-based structural saturable absorber (SA) incorporating graded-index multimode fiber, stepped-index multimode fiber, and graded-index multimode fiber (GIMF–SIMF–GIMF) has been fabricated and applied to a fiber laser. The modulation depth and saturation intensity are measured to be 1.32 % and 26.79 MW/cm², respectively. A heterogeneous soliton with an adjustable optical spectrum interval with 4.6 nm and 3 nm is generated in the anomalous dispersion regime. The main pulse widths are approximately 41.80 ps and 35.56 ps. Additionally, a switchable single vector soliton and bound states of vector dissipative solitons are achieved in the normal dispersion regime. The pulse width of the single vector soliton is measured to be 6.16 ps, while the bound state exhibits a pulse width of 6.49 ps with a temporal separation of 15.22 ps. By employing external cavity compression, the minimum pulse widths for the single and bound states of vector dissipative solitons are reduced to 2.18 ps and 1.55 ps, respectively. These experimental results demonstrate that the GIMF–SIMF–GIMF SA exhibits unique nonlinear optical effects and offers promising potential for soliton generation applications.