1：Experimental Design and Method Selection:

The study involved measuring the output power of an Er/Yb fiber laser with twelve different SMF-28 narrowband output couplers to determine the optimal reflectivity. The phase mask technique was used to inscribe the output couplers.

2：Sample Selection and Data Sources:

The active fiber of the home-made fiber laser was a ~4 m Nufern MM-EYDF-10/125 double-clad fiber. The spectrum was monitored with an Anritsu MS9710B optical spectrum analyzer (OSA).

3：List of Experimental Equipment and Materials:

Equipment included a Coherent Legend Elite femtosecond laser, Anritsu MS9710B OSA, Yokogawa AQ6370D OSA, and a Coherent PowerMax PM30 power meter. Materials included Corning SMF-28 fibers and a phase mask designed for first-order inscription.

4：Experimental Procedures and Operational Workflow:

The output couplers were inscribed on stripped Corning SMF-28 fibers using femtosecond pulses. The reflection and transmission of the output couplers were measured, and the output power of the fiber laser was monitored with a constant pump power of ~18.27 W.

5：27 W. Data Analysis Methods:

5. Data Analysis Methods: The output power and OC reflection measurements were fitted with a homogeneously broadened CW laser model with uniform distributed loss.