Numerical investigation on broadband mid-infrared supercontinuum generation in chalcogenide suspended-core fibers

As₂S₃ and As₂Se₃ chalcogenide 3-bridges suspended-core fibers (SCFs) are designed with shifted zero-dispersion wavelengths (ZDWs) at around 1.5 μm, 2 μm, and 2.8 μm, respectively. A generalized nonlinear Schrödinger equation is used to numerically compare supercontinuum (SC) generation in these SCFs pumped at an anomalous dispersion region nearby their ZDWs. Evolutions of the long-wavelength edge (LWE), the power proportion in the long-wavelength region (PPL), and spectral flatness (SF) are calculated and analyzed. Meanwhile, the optimal pump parameters and fiber length are given with LWE, PPL, and SF taken into account. For As₂S₃ SCFs, SC from a 14 mm-long fiber with a ZDW of 2825 nm pumped at 2870 nm can achieve the longest LWE of ～13 μm and PPL up to ～72%. For As₂Se₃ SCFs, the LWE of 15.5 μm and the highest PPL of ～87% can be achieved in a 10 mm-long fiber with ZDW of 1982 nm pumped at 2000 nm. Although the As₂Se₃ SCFs can achieve much longer LWE than the As₂S₃ SCFs, the core diameter of As₂Se₃ SCFs will be much smaller to obtain a similar ZDW, leading to lower damage threshold and output power. Finally, the optimal parameters for generating SC spanning over different mid-IR windows are given.