Propagation mechanisms in quadruple-clad fibres: mode coupling, dispersion and pure bend losses

The steep LP01-mode waveguide dispersion in quadrupleclad fibres is due to a coupling process. Unlike W-profilcs, these fibres allow achievement of zero dispersion at two relatively remote wavelengths, with a very small sensitivity to curvature. Because of the coupling process, however, these fibres can also propagate the LP02 mode.