Q-Switched Bismuth-Doped Fiber Laser at 1330 nm

We report on, to the best of our knowledge, the first Q-switched bismuth-doped fiber laser operating at ~1.3 μm. An acousto-optic modulator (AOM)-based active Q-switching was realized in a ring cavity with a bismuth-doped phosphosilicate fiber as an active medium. Stable pulsing in the range from 1310 to 1350 nm was achieved using various fiber Bragg gratings. The dependence of the laser operation on the unsaturable loss of the active fiber was studied. Optimization of the scheme and selection of an appropriate bismuth-doped fiber provided maximum pulse energy of ~11.5 μJ at the output of the laser. Using the data obtained, the evaluation of the extractable energy and the concentration of the bismuth active centers in the fiber samples under investigation was performed.