A problem of refractive index

[Alvin]

Hi,
I design two waveguides and the refractive index in the layout shows as the attachments.Then I run the 3D simulation, but the refractive index displayed in the Results Analyzer is different.I don’t know why and how can I fix it.
Thanks for any help!

[Alvin]

the outline of the waveguide

[Alvin]

the bpm file

[Steve Dods]

The picture shown in 3.png is Y Cut of a 3D simulation. The picture in 2.png is the refractive index of a 2D simulation. In OptiBPM, the settings for 2D and 3D are independent. It is possible to set one of them the right way and the other the wrong way.

[Alvin]

Thanks for your reply.But even if I run the 2D simulation ,the refractive index displayed in the Results Analyzer is different from which in the main layout.You can have a try with the attachment.It’s very weird.

[Steve Dods]

In the Simulation Parameters dialog box, in the Global Data tab, there is a field called “Number of displays”. The default is 100. It is the number of times OptiBPM samples the problem in propagation to determine what to draw. You are displaying a grating which has lots of ups and downs. With only 100 samples, some of the ups and downs are missed. Increase the Number of displays to 500. Your grating will appear as it really is now.

[Alvin]

You are great! Thanks a million!
There is no problem about the 2D simulation.But I still confuse about the 3D simulation.

1.I’m not sure the “X-Z slice” graph displays the refractive index distribution in X-Z planar at which y position.(picture 0)

2.Does it display at y=0? If it does,then how can I view the distributions in the x-z planar when y=-1,1,or some other values?

3.I find I can set the Additional Output Data and specify some y cut positions.But I feel it is too troublesome since I just want to view the distribution instead of outputting it.Is there an easier way to achieve that?

4.Could you please tell me the difference of refractive index between in XZ slice and in Y cut graphs(picture 0 and picture 01,02)?The picture 01 and 02 display what I think is right while the picture 0 I think is strange.

I hope my poor English doesn’t bother you. Thanks again for your attention.

[Steve Dods]

In the Simulation Parameters dialog box, in the 3D Isotropic tab, there is a panel called View Cut. It asks for a mesh point, one in X and the other on the Y axis. It will show the X and Y coordinate of the selected mesh point. The Y mesh point selects which Y cut is used to make the XZ display.

[Alvin]

I’m truly grateful for your help.

[Author]

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