Generation of 107 W, 1.07 mJ femtosecond pulses from chirped- and divided-pulse Sagnac Yb-fiber amplifiers by suppression of static mode degradation

We investigate the effect of static mode degradation (SMD) on the power scaling of mJ-level Sagnac Yb-fiber amplifiers. We find that SMD can be effectively suppressed by inserting a polarization-filtering device between two rod-type fibers. Consequently, the resulting amplifier system exhibits improved combining efficiency and average power, and it can deliver 240 fs pulses with 1.07 mJ energy and 107 W average power. This mJ femtosecond source of hundred-watt average power is of particular importance for high-field science applications.