Simulating an angled waveguide

To simulate a waveguide with an angle, first the waveguide will need to be rotated, like the screenshot below.

The Mode Source also need to be rotated to get the proper cross section to calculate the eigenmode for injection.

In some situation, the option “rotation offset” is also needed. This is to avoid taking other unwanted structures in the eigenmode calculation. In this grating coupler example, the “rotation offset” is on to make sure the si waveguide is out of the way when calculating the fiber modes. When there is a value in the “rotation offset” option, it will general a plane of reference and move to the offsetted location. In the screenshot below, the plane of reference appears out of the simulation region and the original source is still inside the simulation region. The source will be injected at the location where the source is specified at the geometry tab. Side note, the mode expansion monitor will behave in a very similar way.

1 Like

I have a source that is injecting down in the y-axis. I am trying to get my source to rotate in the XY plane. However, when I set theta=20, it rotates in the YZ plane instead. Phi seems to have no effect.

Is there a way to specify which rotation should be applied? I think it should really have 2 rotation variables not one.

1 Like

Hi Lukas,

If you set PHI=90, it should allow you to rotate the source on the XY plane.I have tried it on Windows and Mac and they both seem to work.

I think THETA should be the polar angle, where PHI should be the azimuthal angle (with respect to the injection axis)

If PHI did not work for you, can you let us know the product version and your OS information so we can try to reproduce it?



thank you.