Theory of the profile-moments description of single-mode fibres

摘要: Single-mode optical fibres are characterised by the moments Ωm of their refractive-index profiles. An accurate description light propagation along such is obtained when complete profile details replaced reduced data in form Ω0, Ω2 and Ω4. The average or effective waveguide parameter Ṽ, which incorporates emerges naturally universal formulas given terms = Ω2/Ω0 Ω4 Ω4/Ω0. These cover fundamental-mode eigenvalue, group velocity dispersion parameters, field spot size fraction power propagating within core, cutoff for second mode. They simple to apply good accuracy, demonstrated a wide variety examples, indicates that they suitable use fibre design studies. also lead qualitative ofwaveguide behaviour: different have similar properties these considered as functions residual magnitude scaling can be attributed shape enters principally through Ω2.