Characteristics of pulse fiber amplifier with China-made LMA fiber and (6+1)×1 multimode combiner

A pulse master-oscillator fiber power amplifier system with china-made large-mode-area fiber and a (6+1)×1 multimode combiner is demonstrated. The system generates up to 4.8 W of amplified radiation (100 kHz) at a wavelength of 1064 nm with a near-diffraction-limited beam quality (M2=1.2), and the overall slope efficiency with respect to the launched pump power is 50%. Some basic characteristics of this system, including the pulse-amplification characteristics, the gain characteristics, as well as the emission spectrum characteristics are investigated in detail.