Understanding the impact of cladding modes in multi-mode hollow-core anti-resonant fibres

Multi-moded, anti-resonant hollow-core fibre shows great promise for a range of applications from high power laser delivery to novel, non-linear experiments. Anti-resonant fibers typically guide multiple transverse modes due their large core size, albeit with often differential modal loss. Understanding the behaviour higher order in these fibres is crucial importance if we are exploit benefits optical guidance few- and multi-moded applications, or design more robustly single mode fibres. In this work conduct thorough numerical investigations into origins confinement loss tubular its dependence on fibre’s key structural parameters. We show that away resonances glass, leakage can be interpreted as originating resonant out-coupling between interest lossy cladding tubes, highest when phase-matched. Using insight, estimated posteriori knowledge fields core-guided tube propagation constants. Such quantitative estimate satisfactory by considering only three lowest groups tube. This deeper understanding paves way informed approach designing few various applications.