Mid-infrared supercontinuum based on heterogeneous fiber cascade and inline amplification

Using step index As2S3 fiber, a wide continuous spectrum covering 1.9 to 3.6 μ m was generated at pump energies as low as 0.8 nJ. Coupling erbium-doped fluorozirconate fiber with sulfur based fiber for amplification at around 2.8 μ m, resulting in a frequency band spectrum covering 1.9 to 4.1 μ m.

The optical power in the 2.7 to 3 μ m band accounts for 73.2% of the total output power, significantly higher than the proportion in the original continuous spectrum (12.6%). This system provides an all fiber solution for spectral shaping of mid infrared supercontinuum spectra.