Learning Forum

[sara.bassil]

Hello,  I am working with this example in lumerical : https://optics.ansys.com/hc/en-us/articles/19435937674387-Thin-Film-Lithium-Niobate-Electro-Optic-Phase-Modulator  And I modified the structure to put what I wanted. It workes at first but then I run it again and I had this error : "Error: C:/Users/bassil/Desktop/Sara/OH14/Exple/LN_phase_modulator_FEEM.lsf line 40: in expression A(i,...) the index was out of range " line 40 is : neff_TE(1) = neff(mde_num(1)); And when I ask ?mde_num; the answer is 0  Does it mean that the FEEM solver is enable to find an optical mode for the simulation ?  Thank you for your response 

[kghaffari]

Hi Sara,

The command "?mde_num" returning the value 0, indicates that line 39 could not find a mode with a TE polarization fraction above the indicated threshold (0.95 in the example). So to answer your question, I suspect either a TE mode is not found in the reported modes, or no modes are found at all. A good approach to confirm this is by checking the results of FEEM>modeproperties. You should be able to see if any modes are reported and what their TE/TM fractions are.

Best,

Khash