I want to simulate a fiber modulator in Lumerical Mode solution by Eigensolver but the results depend on simulation region size. What is the simulation region size at metal boundary condition in Lumerical mode solution?
furthermore after eigenmode analysis in mode solution, I can't recognize TE and TM mode in mode list. Is the first TE mode and the second TM?
I would be very grateful if someone answer my two questions.
thank you. yes I search in knowledge base. I found that, despite PML boundary in FDTD, default boundary condition in mode solution is metal. by using PML in mode solution, the modes may not find.
we have a field in Mode list that named "TE polarization fraction (Ex)". did you mean this? If the number be high, than means we have a partially TE mode. so it don't depend on the order of modes in mode list.right?
The index of mode is determined from the value of effective refractive index value of each mode. The polarization fraction suggests how perfect your polarization is in that direction.
Metal boundary condition is sufficient to get proper values if your simulation region is big enough compared to the wavelength and the structure.
thank you.
I’m simulating a modulator that its parameters (like extinction ratio and insertion loss) are calculated for the TE mode. When I run in mode solution I can’t detect TE mode in mode list. Actually I wrote a script for my simulation and I have a loop in it. In every loop cycle, I should select TE mode. I do it by “select mode (1);” command but I’m not sure the first mode in mode list is TE mode.
Dear Arijit Misra ,
could you please tell me what's the relation between mode index and the value of refractive index? do you have any source more explain this? I want to detect fundamental TE mode in Lumerical Mode Solution. thank you so much.
Dear Akram,
According to the solutions, there can be 'n' number of modes. But only those are guided, for which the effective index is higher than some threshold depending on the material and waveguide structure. This is true for both polarizations. Therefore if you have designed a single mode waveguide, it can have only one mode that is guided. And index of that mode will be one. You can check the polarization of that mode from the user interface easily. Or you can see it graphically as well.
Dear Akram,
If you want to choose the TE mode using script, what you were doing is alright. After select mode 1, you just check if the TE polarization is close to 100% or not. If not, select mode 2.
Starting from max index for Eigen Mode Solver to find the modes, the first two modes should be TE or TM mode.
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