An all fiberized, 1.89-μm Q-switched laser employing carbon nanotube evanescent field interaction

An all-fiber-integrated, Q-switched thulium-doped fiber laser based on carbon nanotube (CNT) evanescent field interaction is experimentally demonstrated. It is shown that a saturable absorber based on a CNT-deposited D-shaped fiber can readily be incorporated into a thulium-doped fiber ring cavity for a passive Q-switching operation at a wavelength of ∼ 1.89 μm. Using the laser scheme stable Q-switched pulses with a temporal width of ∼ 7.155 μs could be obtained at a repetition rate of 14.18 kHz. The temporal stability of the output pulses was also investigated.