FIMMWAVE

The Effective Index Mode Solver

This well-known approximate method is both a fast and reliable way of finding estimates for modes where the waveguide refractive index cross-section can be well approximated by the expression ne=f(x)g(y); many semiconductor structures fit into this category. The EIM reduces the ne(x,y) profile to a 1d "effective index" profile ne(x). We then use our home grown high performance 1D+z solver (also used in the FMM Solver) which makes it extremely robust. In particular it can deal with structures with completely decoupled cores.

In the case of 1D+z structures (i.e. that have no x-dependence or y-dependence), the Effective Index Solver will use analytic results which will make calculations in FIMMPROP extremely fast and accurate.

A 1D+Z TE mode calculated with the Effective Index Solver, displayed in the MOLAB interface.

Features:

Very fast! Ideal for a quick validation of your structure
Analytical calculation of 1D+z structures
Use of analytical overlaps in FIMMPROP
Mode analysis tools - compute confinement factor, group index, dispersion etc, see utilities.

The Effective Index Solver supports perfect electric wall and perfect magnetic wall boundary conditions, Impedance boundary conditions (anywhere between the perfect electric wall and the perfect magnetic wall), periodic boundary conditions and Perfectly Matching Layers (PMLs). 

Structures for which the Effective Index Solver is recommended:

Weakly guided structures
1D+z calculations

See also the Mode Solver Features Table for comparison with other solvers.