Calculation method  

FIMMPROP is based on the EME (EigenMode Expansion) method. Z-variant structures are modelled by joining two or more straight sections together. Once the local modes of the structure are found then propagation along the length of the section is near-instantaneous. Calculations permit both transmission and reflection coefficients of the modes at each joint to be determined for use in the fully bi-directional propagation algorithm. Structures with Z-varying cross-sections such as tapers and Y-junctions are computed using sophisticated extensions to the EME method.  

The algorithm builds a scattering matrix description of the device and all its elements, which means that once the matrices are generated, you can obtain the response to many different input profiles without further computation, e.g. one might want response to both TE and TM excitation. Furthermore, if you alter the structure, the routine needs only recalculate the elements that have changed. This technology allows you to simulate many similar versions of your device almost as quickly as other tools can do just one device and will save you very large amounts of design time.  

Propagation in free space is treated with a special efficient algorithm based on plane wave expansion techniques. An example would be calculating coupling from a laser facet to a fibre.

General
What is FIMMPROP?
Calculation method
Component library
A powerful design interface
Scanning tools...
Graphical tools
Feature/options table

A few examples...
 Design an MMI...
 Optimize a bend..
 Y junctions and tapers...
 Photonic crystals...
Platforms
Customer support