This video is taken from the FEEM 100 course on Lumerical University.

## Transcript

In this unit we will explore various settings available in the FEEM solver.

Under the General tab of the solver property editor window, the simulation region parameter

selects which of the simulation regions from the objects tree will be used by the solver.

Note that only one simulation region can be assigned to a solver at a time.

Under the Mesh tab, the Global Mesh Constraints define the degree of refinement of the simulation

mesh.

The number of edges per wavelength determines the target for the size of the triangular

elements in the finite element mesh.

Enabling or disabling the option "refine based on material properties" determines if the

refinement is based on the effective wavelength inside the materials or on the wavelength

in vacuum.

Higher values for the number of edges per wavelength mean a more refined mesh and possibly

more accurate results; however, this might be at the expense of increased execution time

and memory.

The polynomial order corresponds to the order of the basis functions used in the finite

element solver.

This setting does not affect the mesh and allows you to resolve nonlinear variations

in the electric field better, even with a coarse mesh.

By adjusting the edges per wavelength and the polynomial order it is possible to find

a good balance between accuracy and computational cost of the simulation.

There are some additional advanced options for meshing.

In most simulations it is not necessary to modify the default values for these settings,

so we won’t discuss them in this course.

Under the Modal Analysis tab you will find the settings for the eigenmode calculation.

You need to specify the frequency or wavelength of the desired modes, as well as the number

of trial modes.

The solver will look for modes with an effective index near a given value.

You can specify this value directly, or let the solver use the maximum refractive index

in the simulation region by enabling the “use max index” option.

Finally, we have the Advanced tab.

Similar to the Advanced options under the Mesh tab, the default settings here are appropriate

in most cases; therefore, we won’t discuss this tab in this course.