Learning Forum

[Thang Tran]

Hi Lumerical's users,

I'm having trouble with my index preview. Whenever I examine my index preview, the parameter it displays doesn't align with the parameter I've entered. For example, the thickness I want to input is 45 nm (z_min (um) = 0.16; z_max (um) = 0.205). However, in the index preview, my design's 50 nm thickness is shown. If I change the input to z_max = 0.2, the index thickness will become 40 nm. Can anyone help me with this problem? Thank you.

[Amrita Pati]

Hi Thang,

I suppose you are using the FDTD solver. It might be the case that the mesh is to coarse to report the index accurately. If there are not enough mesh points, the actual interfaces (that you see in the index monitor) can move from the interfaces you have set. Can you increase the mesh resolution (either by increasing the mesh accuracy or by including a mesh override region) and let me know if anything changes?

Regards,
Amrita

[Thang Tran]

Hi Amrita,
Thank you for your advice; I have found out the problem. It come from the node I chose for the z-direction. It need to be an integer number. For example, if I choose 1 node = 10 nm,  the thickness must be 10, 20, 30 nm, etc.

Regards,

Thang