Double-clad large mode area Er-doped fiber for high-energy and high-peak power amplifiers

In this paper we present a novel design of an Er-doped double-clad fiber for short-pulse amplifiers. It was shown that the P2O5-Al2O3-SiO2 core glass matrix leads to significant increase of the efficiency of cladding pumped amplifiers based on heavily Er-doped fibers. By using such a fiber we have demonstrated, to the best of our knowledge, the first nanosecond mJ-energy level Er-doped fiber amplifier with diffraction limited beam quality. Additionally, we report on the direct amplification of 100 fs pulses with the same fiber achieving of peak powers in excess of 100 kW