Generation of Stretched and Soliton Pulses From Passively Mode-Locked EDFL Utilizing Nickel-Phosphorus Trisulfide (NiPS₃)-Based Saturable Absorber

In this study, a nickel-phosphorus trisulfide (NiPS3) saturable absorber (SA) with a ~20.9% modulation depth was used for mode-locking in an erbium-doped fiber laser (EDFL) operating in near-zero and anomalous dispersion regimes. The SA was formed by depositing a layer of NiPS3material onto an arc-shaped fiber. The pulses generated were initially observed in the stretched pulse regime. Then, an 84 m long single-mode fiber (SMF) was added to the cavity to operate in the anomalous dispersion regime. The center wavelength of the pulses was observed at 1566.6 nm and 1561.6 nm for the stretched and anomalous dispersion regimes, respectively, with measured 3-dB bandwidths of 3.2 nm and 1.4 nm. The corresponding repetition rates were 6.6 MHz and 1.8 MHz, while the pulse widths with Gaussian and sech2profiles were 1.53 ps and 2.26 ps. Stable mode-locking operation was obtained with a signal-to-noise ratios (SNRs) of ~66 dB and ~49 dB for the pulses at the stretched and soliton regimes. The findings of this work can contribute towards the optimization of mode-locked fiber laser cavity designs for the C-band wavelength region.