Passive mode-locked Tm–Ho Co-doped fiber lasers with polymer-coated CdTe saturable absorber on arc-shaped fiber

This work demonstrates mode-locked pulses obtained using a polymer-coated cadmium telluride (CdTe) saturable absorber (SA). The arc-shaped fiber was fabricated using a two-step wheel-polishing process, and CdTe SA was drop-casted onto it. Then, it was overcoated with an ultraviolet (UV) cured polymer. This method enhances the fiber’s durability and protects the CdTe SA from air, dust and moisture. The fabricated SA has a saturation intensity of 11.2[Formula: see text]MW/cm 2 and a modulation depth of 19.8%. A stable mode-locked optical spectrum with a center wavelength of 1909.6[Formula: see text]nm, 3[Formula: see text]dB bandwidth of 2.9[Formula: see text]nm, and pulse width of 1.32[Formula: see text]ps was obtained at a threshold pump power of 398[Formula: see text]mW. The mode-locked laser has a relatively high signal-noise ratio (SNR) of 64.9[Formula: see text]dB. Hence, this simple polymer-coating technique enables the application of other volatile compounds as SA for future investigation.