Watt-level, all-fiber, spectrally flat, and ZBLAN fiber-based MIR supercontinuum extending to 4.6 μm with a record power ratio beyond 3.8 μm

An all-fiber midinfrared supercontinuum with 20-dB spectral coverage from 1.9 to 4.6  μm is demonstrated with a record power ratio beyond 3.8  μm. The supercontinuum is generated in a piece of single-mode ZBLAN (ZrF4-BaF2-LaF3-AlF3-NaF) fiber pumped by a broadband, single-mode thulium-doped fiber amplifier. Under the optimized pulse repetition rate and ZBLAN fiber length, the output spectrum has a good flatness. The power ratio beyond 3.8  μm is measured to be over 30% when the average output power reaches 1.11 W. Based on the all-fiber configuration, we have provided a compact, reliable, and promising supercontinuum source for further spectral extension into the midinfrared region where a high long-wavelength ratio is preferred.