6.8 W all-fiber supercontinuum source at 1.9-2.5 μm

We report a simple method of generating a spectrally flat and high average power spectral density (up to 14 mW/nm) optical supercontinuum in the 1.95-2.5 μm range covering a transparency window of the atmosphere. The supercontinuum was generated from the Tm-doped all-fiber MOPA lasers. The average output power of the picosecond linear-cavity SESAM mode-locked seed lasers operating at 46 and 77 MHz was as low as 6.7 and 2.6 mW, respectively. The corresponding one-stage silica-based fiber amplifier generated a supercontinuum with 5.06 and 6.83 W average power, 550 and 500 nm bandwidths at -10 dB level, and 5 and 8 dB spectral flatness, respectively.