Flatly broadened mid-infrared supercontinuum generation in a cascade of thulium-doped silica fiber amplifiers

• An all-fiber, silica-based supercontinuum source was developed.
• Over 2.3 W in the spectral band of ∼(1.7–2.7) μm was recorded.
• 10 dB spectral flatness from 1.95 to 2.52 μm (span of 570 nm) was demonstrated.
• Tm-doped single-mode silica fibers were utilized as nonlinear and amplification media.

Single-mode, flatly broadened supercontinuum (SC) generated in a thulium two-stage fiber amplifier spanning nearly the mid-infrared band is reported. The output average power and 10 dB bandwidth of the obtained SC are over 2.3 W and 570 nm (from 1.95 μm to 2.52 μm), respectively. For wavelengths beyond 2.4 μm the output power was 495 mW constituting almost 21% of the total output power. Applying Tm-doped single-mode silica fibers as nonlinear and amplification media it was possible to extend the long wavelength cut-off to 2.7 μm.