Passively Q-Switched Thulium-Doped Fiber Laser Using Alcohol

A passively Q-switched thulium-doped fiber laser using isopropyl alcohol as a saturable absorber is experimentally demonstrated. The absorber was made of two FC/PC connectors matched into a cannula with the gap between them filled by isopropyl alcohol. The alcohol-based saturable absorber incorporated into a ring cavity thulium-doped fiber laser leads to passive Q-switching laser operation at the wavelength of 1.88 μm. With the maximum pump power of 1.42 W, passive Q-switched pulses with a minimum duration of 1.46 μs, maximum repetition rate of 66.7 kHz and pulse energy of 0.93 μJ were obtained.