Passively mode locked Yb-doped fiber laser with nearly 2 W average output power

A watt-level Yb-doped ps fiber laser in tri-stage master oscillator power amplifier (MOPA) configuration is investigated. The first stage is a semiconduttor saturable absorption mirror (SESAM) passively mode locked fiber laser with a low average output power of 9.2 mW. A fiber Bragg grating (FBG) is utilized as the output laser cavity mirror. The second stage is an Yb-doped single mode fiber amplifier with a moderate average output power of 108 mW. The last stage is a double clad Yb-doped power amplifier which increases the average output power to 1.9 W. The center wavelength of the mode locked pulse is 1064 nm with a pulse width of 36 ps. The pulse repetition rate, the peak power and the energy of a single pulse is 29.6 MHz, 1.8 kW and 61 nJ, respectively. A small dip located at the center laser wavelength is observed on the output spectrum, which is considered to be caused by the high reflectivity and the narrow bandwidth of the FBG.