All-fiber 1.9 µm ultrafast amplifier based on normal dispersion thulium-doped fiber and large mode area silica fiber compressor

All-fiber ultrafast amplifier at the wavelength of 1.9 μm based on normal dispersion thulium-doped germanosilicate fiber and large mode area silica fiber compressor is developed. Pulses at the repetition rate of 23.9 MHz with the duration of 63 fs and the pulse energy of 25 nJ are obtained. We assume that the pulse peak power is 250 kW.