1：Experimental Design and Method Selection

The SA was prepared by dropping a small amount of a mixed solution containing Bi2Te3 and distilled water onto the end surface of a FC/PC fiber ferrule. The nonlinear transmission of the prepared SA was measured using a lab-made, ~1.5 ps fiber laser with a repetition rate of 24 MHz at 1.93 μm.

2：Sample Selection and Data Sources

Commercially available bulk-structured Bi2Te3 powder was used to fabricate the SA. The Bi2Te3 powder was characterized through scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS).

3：List of Experimental Equipment and Materials

Bi2Te3 powder (Sigma Aldrich, Bi2Te3 metal basis),SEM (S-4700, Hitachi, Tokyo, Japan),EDS (7200-H, Horiba, Kyoto, Japan),Index matching gel (G608N, Thorlabs, Newton, NJ, USA),Optical spectrum analyzer (AQ6375, Yokogawa, Tokyo, Japan),Oscilloscope (6050A, Lecroy, Chestnut Ridge, NY, USA),Photodetector (ET-5010F, EOT, Traverse City, MI, USA),Electrical spectrum analyzer (USB-SA124B, Signalhound, Battle Ground, WA, USA),Autocorrelator (FR-103MN, Femtochrome Research, Berkeley, CA, USA)

4：Experimental Procedures and Operational Workflow

The Bi2Te3 powder was mixed with distilled water and dropped onto the facet of the ferrule, left to dry for 24 hours. The SA was inserted within a TDF ring cavity. The laser output was measured by various instruments to analyze the generated dark pulses.

5：Data Analysis Methods

The nonlinear transmission was fitted using a specific curve to determine modulation depth and saturation intensity. The laser output was analyzed for pulse width, repetition rate, and signal-to-noise ratio.