230-kW peak power femtosecond pulses from a high power tunable source based on amplification in Tm-doped fiber

We report for the first time an all-fiber laser system that generates tunable Watt-level femtosecond pulses at around 2 mu m without an external pulse compressor. The system is based on amplification of a Raman shifted Er-doped fiber laser in a Tm-doped 25-mu m-core fiber. We obtain 108-fs pulses at 1980 nm with an average power of 3.1 W and a pulse energy of 31 nJ. The peak power at the output of the amplifier is estimated as similar to 230 kW, which to the best of our knowledge is the highest peak power obtained from a femtosecond or a few-picosecond amplifier based on any doped fiber. The amplified output is frequency-doubled to produce 78-fs pulses at 990 nm with an average power of 1.5 W and a pulse energy of 15 nJ. We demonstrate broad wavelength tunability around 2 mu m as well as around 1 mu m. (c) 2005 Optical Society of America.