Modes of 2d semiconductor


I am using mode solver to calculate modes and dispersion relation.
when i created the file, i only got modes when i use metal boundary condition. But in case using PML and periodic boundary conditions then there is no physical mode? Why is that? and How to solve this issue? dispersion.lms (1.2 MB)

Hello @s.a.a.elrafey,

I had a chance to look at your file and I it is not clear what you are hoping to achieve. Could you please share more information on this topic? The FDE solver is looking for guided modes at it seems that you are using a 2D rectangle based on sampled data. This would have been calculated based on transmission through a thin film? What sort of guiding behavior are you expecting? Do you have any sense of what the effective index might be? Is the orientation correct? What substrate are you using?

The modes that the FDE solver is finding are non-physical in the metal case although they are valid solutions to the eigensolver. The simulation is not seeing the 2D structure, you can check this by disabling the WS2 rectangle and running the solver again for either case.


Thanks for your replay

Yes it’s a thin 2d film and its date was calculated depending on the transmission measurements. I think according to the calculated equation we can get TE and TM mode. However I don’t know if the orientation is correct or not. The
substrate that we will use PDMS and the surrounding air but it this file I tried only symmetric system (air).


We aim to get the same output as this file (FDTD solver) but we need to use (Mode Solver )


WS2.fsp (393 KB)

Hey @s.a.a.elrafey,

What were the meaningful results from the FDTD simulation that you obtained? The ordientation of the FDE region in mode should be the same as the injection axis in FDTD so Y normal.

Let me know if you have any further questions.


I changed the orientation of the FDE region in the mode to be normal but the output is very strange even using the correct orientation WS2_mode.lms (5.3 MB)