High-energy picosecond pulses from a 2850 nm fiber amplifier

We report the demonstration of a 2850 nm diode-pumped Ho³⁺, Pr³⁺ co-doped fluoride fiber amplifier that delivers pulses with an average power of 2.45 W, 122 μJ energy, and 500 ps duration at a repetition rate of 20 kHz. To the best of our knowledge, the average power and pulse energy are the highest to be obtained from a sub-nanosecond fiber source operating in the 3 μm spectral region. The amplifier is seeded by an optical parametric generation source and is pumped around 915 nm using widely available InGaAs laser diodes.