Polyacrylonitrile enabled soliton mode-locked fiber laser

Exploring novel saturable absorber (SA) materials with superior performance to enable mode-locking operation remains a forefront in ultrafast laser research. In this study, we unveil the potential of polyacrylonitrile (PAN) based SA for ultrafast fiber laser applications. By probing the nonlinear absorption characteristics of PAN SA within the telecommunication band using the balanced twin-detector method, we reveal its substantial modulation depth of 10.7 %. Incorporating PAN SA into the Erbium-doped fiber laser (EDFL) cavity facilitated stable mode-locking operation. The resultant EDFL system produces a conventional soliton pulse train centered at 1568.4 nm wavelength, with mode-locking sustained over a pump power range from 87.2 to 254.1 mW. Moreover, the laser exhibits a pulse duration of 3.64 ps and achieves a maximum pulse energy of 2.04 nJ. These results highlight the efficacy of PAN-based SA, demonstrating properties comparable to established 2D SAs. The implications of this research are pivotal in advancing the application of novel organic polymers in ultrafast lasers.