Learning Forum

[minusunny]

Hi, I am trying to simulate a phase shifter in varFDTD. The injection axis is 'X' and in the result, more power is in Ey than Ex.  if I am trying to extract the phase, should I look into the phase of Ex or Ey?

[Guilin Sun]

As you know, the phase is associated with a field component. So you can use the domiant field component. However, a better way might be to use S parameters. Eg in your case, you can use S21 to evaluate the phase. Onething you may need to consider is: where exactly do you want to quantify the phase? relative to source or any special location? the monitor gives the phase at the monitor plane, whether it is for field components or S parameters. You may need to remove the propagation phase from source to device front surface and the device back surface to the monitor, which has analytical solutions.  

[minusunny]

I am doing a phase shifter based on the grating. I should get phase shift at the output.  It is a passive component.I used frequency and power monitor , linear Y for the data extraction. The screenshot of my simulation arrangement and the code i used to extract data is given below. I am getting 90 degree phase shift on Ex, but the phase of Ey is varying verymuch with respect to simulation window and the phase is way off. Ey phase is very sensitive to simulation window, i tried a sweep and was not able to figure out a stable value for simulation window as it is varying so much.

[Guilin Sun]

Are you doing 2D simulation? otherwisde you should use a 2D monitor not a 1D line monitor.

Which field component, Ex or Ey (transversal component) is the dominant?

Have you considered my suggestion to use S parameter?  Since this is waveguide and the mode does not have a flat wavefront, you cannot use the phase at one point or a line or a plane to quantify the phase.

Only S parameter can have one unique value of phase, after propagation phase compensation.

I hope this helps.

[minusunny]

Ey component is dominant. So i have to use EME to extract s-parameters? Also, can i use frequency and power monitor to extract phase?

[Guilin Sun]

Port in FDTD can give you S parameters.

https://optics.ansys.com/hc/en-us/articles/360034382554-Ports-FDTD-Simulation-Object

https://optics.ansys.com/hc/en-us/articles/360042800213-Ring-resonator-getting-started-Final-parameter-extraction