Multimode Solitons in Hollow-Core Fibres: Dynamics and Features

The nonlinear propagation of light inside hollow-core fibres (HCFs) is one of the most used techniques to generate ultrashort pulses [1,2]. The simplicity and robustness of the HCF setups make them a perfect option, not only to generate ultrashort pulses [3], but also to study the nonlinear phenomenon itself. The standard post-compression scheme consists of propagating a linearly polarized laser pulse through a HCF with hundreds of microns core diameter, coupling the light into its fundamental spatial mode (the HE
₁₁
mode [4]). During this nonlinear propagation the pulse spectrally broadens and, usually, the spectral phase has to be compensated outside the HCF to finally achieve the desired ultrashort pulse.