Q-switched Yb-doped microstructure fiber laser using GaAs as saturable absorber

A passive Q-switched Yb-doped microstructure fiber (MF) laser is demonstrated using a GaAs wafer as the saturable absorber. A high Ytterbium-doped fiber with a core diameter of 21 µm and a numerical aperture of 0.04 was used as the active fiber. The large-diameter core allows for greater energy storage than conventional single-mode core designs and the small NA of the core ensures the good beam quality of the laser. A pulse duration as short as 80 ns was obtained with the maximum repetition rate of 830 Hz. The maximum average output power is 5.8 W at 1080 nm wavelength.