Supercontinuum Generation in Methane-Filled Hollow-Core Fibres Through a Combination of Modulation Instability and Stimulated Raman Scattering

Gas-filled hollow-core fibres have proven to be a very effective system for nonlinear optics in many areas such as frequency conversion, supercontinuum generation, and optical pulse compression. Hollow-core anti-resonant fibres in particular offer the benefit of low loss and high transmission bandwidth with strong mode confinement [1], enabling efficient broadband supercontinuum generation. This is typically achieved by using noble gases and pumping in the anomalous dispersion region to access modulation instability [2], or soliton self-compression dynamics [3], [4]. When pumping noble gases in the normal dispersion region, spectral broadening is driven mostly by self-phase modulation, offering limited spectral broadening due to optical wave breaking.