1：Experimental Design and Method Selection:

The study involved synthesizing high-quality NiPS3 crystals using a modified chemical vapor transport (CVT) method and preparing few-layer NiPS3 nanosheets via a direct liquid-phase exfoliation method. The nonlinear optical properties of NiPS3 nanosheets were characterized to assess their suitability as saturable absorbers (SAs).

2：Sample Selection and Data Sources:

High-quality bulk NiPS3 crystals were synthesized from pure nickel powder, red phosphorus, sulfur, and iodine as a transport agent. Few-layer NiPS3 nanosheets were obtained by sonicating the bulk crystals in N-methyl-2-pyrrolidone (NMP) solvent.

3：List of Experimental Equipment and Materials:

Equipment included a quartz tube for CVT growth, a furnace with dual temperature zones, an atomic force microscope (AFM, Dimension 3100), Raman spectrometer (LABRAMs HR Evolution), X-ray diffraction (XRD) system (Brukers), scanning electron microscopy (SEM, Quanta FEG 250), and transmission electron microscopy (TEM, Tecnais G2 F20). Materials included nickel powder (Ni, 99.99%), red phosphorus (RP, 99.999%), sulfur (S, 99.99%), and iodine (I2).

4：0). Materials included nickel powder (Ni, 99%), red phosphorus (RP, 999%), sulfur (S, 99%), and iodine (I2). Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: The synthesis involved sealing the raw materials in a quartz tube under high vacuum, heating to 700°C, and cooling to room temperature. Few-layer NiPS3 nanosheets were prepared by sonicating bulk crystals in NMP, followed by centrifugation and washing. The SA device was fabricated by dripping NiPS3 nanosheets onto a fiber adapter.

5：Data Analysis Methods:

The nonlinear transmittance of NiPS3 nanosheets was measured under different incident power intensities to determine modulation depth and saturated intensities. The performance of the NiPS3-SA in an Er-doped fiber laser was evaluated for Q-switched and mode-locked operations.