2 µm mode-locked fiber laser with a carbon nanotube absorber

We demonstrate a 2 μm passive mode-locked fiber laser. A single-wall carbon nanotube (SWCNT) is used as saturable absorber. Thulium-doped fiber (TDF) is used as the gain medium. The output wavelength is grating stabilized to 1998.85 nm by a high reflective (HR) fiber Bragg grating (FBG) together with a two by two coupler. A 8.22 MHz fundamental mode-locked pulsed laser with output signal power of 4.68 dBm is produced.