1：Experimental Design and Method Selection:

The study proposed a passively fast polarization switching erbium-doped fibre laser using QDWS2 as a saturable absorber to generate polarization domain walls. The methodology included characterizing WS2 quantum dots, measuring nonlinear optical responses, and incorporating the QDWS2-SA into a laser cavity.

2：Sample Selection and Data Sources:

WS2 quantum dots were prepared by the intercalation of the lithium method. The samples were characterized using TEM and AFM.

3：List of Experimental Equipment and Materials:

Equipment included a Ti-sapphire laser for Z-scan measurements, a microfibre for the SA device, and various optical components for the laser setup.

4：Experimental Procedures and Operational Workflow:

The QDWS2-SA was fabricated by depositing QDWS2 on a microfibre. The laser's performance was monitored using oscilloscopes, spectrum analyzers, and power meters.

5：Data Analysis Methods:

Nonlinear absorption coefficients and modulation depths were calculated from Z-scan and I-scan measurements. The laser's output was analyzed for temporal and spectral characteristics.