High-Power Thulium-Doped All-Fiber Superfluorescent Sources

Power scaling of broadband and narrowband thulium-doped all-fiber superfluorescent sources based on master-oscillator power-amplifier configuration is reported. For scaling the output-power of broadband superfluorescent fiber source, a stable low-power broadband superfluorescent fiber seed source and a two-stage cladding-pumped thulium-doped fiber amplifiers were adopted. The thulium-doped fiber power amplifier yielded 122 W of broadband superfluorescence output, and the wavelength range spanned from 1935-2075 nm with a full width at half maximum (FWHM) of 25 nm. To the best of our knowledge, this is the first demonstration of superfluorescence power exceeding 100 W from thulium-doped fiber amplifiers at 2 μm. In addition, we also investigate the power scaling of narrowband thulium-doped superfluorescent fiber source based on a tunable narrowband superfluorescent fiber seed source by selecting a small region out of a broadband superfluorescence spectrum using a narrowband fiber Bragg grating. The two-stage cladding-pumped thulium-doped all-fiber amplifiers were used directly to boost average power to 120 W, the center wavelength and the FWHM were 1963.5 and 1.2 nm, respectively. The presented high power broadband and narrowband superfluorescent fiber source could be of great interest and open up the prospect of many new applications such as laser materials processing and metrology.