A Tm–Ho:fiber amplifier based on single-clad geometry is demonstrated for the generation of high-power femtosecond pulses around 1.9 μm. The amplifier is seeded by the low-power Raman soliton generated by an Er:fiber femtosecond laser. Pulse trains at a repetition rate of 250 MHz tunable from 1.84 to 1.92 μm with corresponding powers from 2.6 to 3 W and durations from 80 to 105 fs have been obtained. Beating with a single-frequency Tm laser has shown that the pulse coherence is highly preserved. The overall power fluctuations have been measured to be as low as 0.6%.
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