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High power, widely tunable, narrowband superfluorescent source at 2 μm based on a monolithic Tm-doped fiber amplifier.

We present a widely tunable narrowband superfluorescent source near 2 μm employing a monolithic Tm-doped fiber amplifier (TDFA), and the output power exceeds 250 W. A broadband superfluorescent source with a narrowband tunable band pass filter was used as the seed source. The spectra of the seed source can be tuned in a range of ~1930-2030 nm with full width at half maximum (FWHM) of ~1.7 nm. The Tm-doped fiber amplifier scales up the power of the seed source to a level of more than 250 W with a tuning range of ~35 nm (1966-2001 nm) and a FWHM of ~1.5-2.0 nm, and the slope efficiency is about 0.50. The output power is limited by the available pump power, and the tuning range is limited by the amplifier spontaneous emission at other wavelengths. Higher output power can be achieved if launching more pump power into the amplifier, and the tuning range can be further improved by optimizing the parameters of the TDFA. To the best of our knowledge, this is the first demonstration on a widely tunable narrowband superfluorescent source at 2 μm with average output power exceeding 250 W.