All-fiber high energy and peak power broadband Yb-doped fiber amplifier

In this fast track communication, we realized a high energy and peak power broadband (Δλ = 10 nm) all-fiber Yb fiber amplifier chain for the generation of pulses at a wavelength near 1.064 μm, which can possibly be applied in high peak power systems such as high power fiber-laser-driven extreme-ultraviolet lithography or fiber-based inertial confinement fusion (ICF). This system is capable of yielding 31 mJ, 12 ns pulses with peak power above a megawatt at a repetition rate of 20 Hz. Also, to make this system more applicable, a large mode combiner is made to realize an all-fiber structure. Since the system is operated at a low repetition rate, in order to suppress the ASE built between pulse intervals, multi-stage pulse pump technology is applied. Amplification characteristics in the condition of different pump widths were measured.