A passively Q-switched thulium-doped fiber laser with single-walled carbon nanotubes

We demonstrate a passively Q-switched thulium-doped fiber laser by using single-walled carbon nanotube (SWCNT) polyvinyl alcohol (PVA) composite film as the saturable absorber (SA). A relatively large mode area on the SA was employed to avoid damage of the SWCNT/PVA film and benefit pulsed laser operation. Stable pulses of 85-164 kHz repetition rate were generated at 1967 nm with a maximum average output power of 103 mW. The single pulse energy was up to similar to 0.63 mu J with similar to 0.87 mu s pulse duration.