Broadband flat supercontinuum generated by chalcogenide double-clad step-index fiber with special dispersion

Abstract

To achave a broader supercontinuum in the mid-infrared band, a chalcogenide double-clad step-index fiber is proposed. Comprising As2Se3, AsSe2, and As2S5 glass, this fiber effectively confines light within the core, minimizing fiber dispersion fluctuations. By iteratively adjusting the dispersion curve of the fiber, enhancement of the supercontinuum spectrum generation is possible. Spectral broadening primarily results from four-wave mixing and self-phase modulation. Raman scattering within the pulse generates unstable higher-order solitons, which, upon breakup, contribute to spectrum broadening. This study explores the effects of pulse laser parameters and fiber length on supercontinuum generation, obtains regular cognition and offers theoretical analyses of the results. Through optimization of parameters, a mid-infrared supercontinuum with an 11 μm width is achieved. These findings underscore the potential of chalcogenide double-clad step-index fiber for generating a mid-infrared supercontinuum light source. The designed fiber structure should be helpful in supercontinuum sources, bio-molecule sensing, and spectroscopy.