Broad-spectrum and all-fiber passively Q-switched Tm-doped fiber laser based on SESAM

We demonstrate a compact broad-spectrum and all-fiber passively Q-switched Tm-doped fiber laser based on semiconductor saturable absorber mirror (SESAM). The central wavelength of this laser is at 1952.4 nm with 3-dB bandwidth as large as 10.17 nm. The repetition rate of the Q-switched pulses can increase from 48 kHz to 126 kHz as the pump power changes from 270 to 640 mW. The narrowest pulse width and the maximum average output power of this Q-switched laser are 590 ns and 69.3 mW, respectively. The corresponding pulse energy is calculated to be 550 nJ.