Learning Forum

[Chris Kopetski]

By the default setting of EME, the searching index was defined as ?use max index?, but in my case, the waveguide is not the highest index material in a simulation region. Usually, I used the following scripts to do that in the FDEnset(?search?, ?near n?);nset(?use max index?, 0);nset(?n?, core_index);nHow do I make that type of change in the EME solver?.Question migrated from the Lumerical Knowledge Exchangen

[Chris Kopetski]

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Use the seteigensolver command: 

Here's a simple example that changes the mode solver settings for cell 1 of the EME solver

select("EME");

set("allow custom eigensolver settings",1);

select("EME::Cells::cell_1");

seteigensolver("number of trial modes",25);

seteigensolver("use max index",0);

seteigensolver("n",2);

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[dravo]

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Related to this:

How can I custom select specific modes for each cell group? Say for example for group span 2 with cell nos 7-12, I want to select modes 4,5 and 7 only. Or alternatively, how to set the search for modes in a range like we can with FDE? That particular property seems to be inactive.

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[Guilin Sun]

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Unfortunately, EME does not allow users to select specific modes. However, you can take some measures to get the modes

1: use symmetry type of BCs to get ride of modes with unwanted polarization, if the modes desired have such symmetry property;

2: search the modes around a specific refractive index

However, both method may not give the modes with specific mode number.

Please note that using symmetry BCs will give you mode list different from without it. A reliable way might be to check the polarization, and the neff.

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