Tunable passively Q-switched thulium-fluoride fiber laser in the S+/S band (1450.0 to 1512.0 nm) region using a single-walled carbon-nanotube-based saturable absorber.

A tunable passively Q-switched for S+/S band thulium-fluoride fiber (TFF) laser using single-walled carbon nanotubes as a saturable absorber is proposed and demonstrated. The tunability of the proposed laser covers a wavelength region of 1450.0-1512.0 nm, with a range of 62.0 nm. Stable Q-switched operation can be obtained at a pump power of 115.7-229.9 mW at 1492.0 nm. The resulting pulses have a measured repetition rate and pulse width of 12.0-36.4 kHz and 6.2-3.6 μs, respectively. The maximum pulse energy that was achieved in this experiment is 122.8 nJ. To the author's knowledge, this is the first reported tunable passively Q-switched TFF laser that covers the S+/S region that has been demonstrated.