Generation of watt-level supercontinuum covering 2-6.5 µm in an all-fiber structured infrared nonlinear transmission...

We demonstrate a watt-level mid-infrared supercontinuum source, with the spectrum covering the infrared region from 2 to 6.5 µm, in an all-fiber structured laser transmission system. To further improve the SC spectral bandwidth, power and system compactness in the follow-up As₂S₃ fiber, we theoretically and experimentally explored some knotty problems that would potentially result in the As₂S₃ fiber end-facet failure and low SC output power during the high-power butt-coupling process and proposed an optimal coupling distance on the premise of the safety of As₂S₃ fiber end face. In addition, we also built a multi-pulse pumping model for the first time to more precisely estimate the SC spectral evolution in As₂S₃ fiber. This work will give an important reference to someone who is working on the all-fiber structured, high-power mid- and far-infrared supercontinuum source.