INTERDEPENDENCE OF WAVEGUIDE AND MATERIAL DISPERSION

Theoretical work on dispersion in single-mode fibers sometimes uses the assumption that waveguide dispersion Dw and material dispersion Dm are separate effects that contribute additively to the total amount of dispersion Dm+w. Using Gloge’s LP-mode approximation we compute the dispersion of the LP01 (HE11) mode by solving the eigenvalue equation taking dispersion of core and cladding materials into account. The dispersion of the LP01 mode is computed by numerical differentiation of the solution of the eigenvalue equation. The difference Dm+w − Dm is compared to waveguide dispersion Dw, which is computed by ignoring the dispersive properties of the core and cladding materials. We find large percentage deviations between Dm+w − Dm and Dw. The assumption of additivity of material and waveguide dispersion is thus not quite correct. However, because of the small contribution of waveguide dispersion to the total dispersion of the LP01 mode, even a large percentage error in the waveguide dispersion has little influence on the over-all dispersion of the LP01 mode. © 1979 Optical Society of America.