1：Experimental Design and Method Selection:

The study employs a thulium doped fiber laser (TDFL) with zinc oxide (ZnO) as the saturable absorber (SA) for mode-locking operation in the 2.0-micron region. The ZnO nanorods are prepared using the facile hydrothermal method and embedded in a polyethylene oxide composite film to form the SA.

2：0-micron region. The ZnO nanorods are prepared using the facile hydrothermal method and embedded in a polyethylene oxide composite film to form the SA. Sample Selection and Data Sources:

2. Sample Selection and Data Sources: The ZnO nanorods are fabricated using zinc acetate dihydrate and ammonia solution, with sodium hydroxide and polyethylene oxide as additional reagents. The SA's nonlinear absorption characterization is determined using the twin detector technique.

3：List of Experimental Equipment and Materials:

Equipment includes a Princeton Lightwave 1560 nm laser diode, isolators, wavelength division multiplexers, a TmDF200 TDF, a polarization controller, a Yokogawa AQ6375 Optical Spectrum Analyzer, a Keysight DSOX3102T oscilloscope, and an A.P.E. Pulsecheck150 autocorrelator.

4：Experimental Procedures and Operational Workflow:

The laser setup involves pumping the TDF in both forward and backward directions, with the SA assembly formed by sandwiching the ZnO based SA film between fiber ferrules. The mode-locked output is analyzed for its optical spectrum, pulse train, and stability over time.

5：Data Analysis Methods:

The optical spectrum, pulse width, and stability of the mode-locked pulses are analyzed using various instruments, and the peak power is calculated from the pulse energy and width.