Efficient extraction of high pulse energy from partly quenched highly Er 3+ -doped fiber amplifiers

We demonstrate efficient pulse-energy extraction from partly-quenched highly erbium-doped aluminosilicate fiber amplifiers. Although the average-power efficiency degrades, the highest achievable pulse energy is largely unaffected, and our results point to an increasingly promising outcome for short pulses. In one case, using 0.2-μs, 23-μJ pulses to seed a short (2.6 m) partly-quenched Er-doped-fiber with intrinsic saturation energy estimated to 85 μJ, we reached an output pulse energy of 0.8 mJ. Unlike unquenched fibers, the efficiency improves at low repetition rates, due to higher pulse energy. Thus, according to our results, it is possible to amplify pulses to high energy in short highly-Er-doped fibers designed to reduce nonlinear distortions, at the expense of the average-power efficiency.