Following Up: Power Passing through a Monitor at an Angle

- July 2, 2024 at 6:36 pm
  
  scorsett
  Subscriber
  
  Hello!
  Last November, I made this post: https://innovationspace.ansys.com/forum/forums/topic/power-passing-through-a-monitor-at-an-angle/
  It was unintentionally missed, and I did not receive a response until this February. By then, I had switched to exploring other topics. However, my original question is back.
  The short summary of my question (see the link above for full details) is that Lumerical seems to report power passing through a monitor based on the surface norm of the Poynting vector; this method appears to fail, understandably, for light passing through monitors at an angle.
  The summary of the response I received is that standard DFT monitors are not suitable for analyzing gratings emitting at an angle, and I should instead use grating analysis. Unfortunately, my structures are aperiodic (apodized, chirped, bilayer gratings) and are therefore not suitable for the Lumerical grating-analysis tools.
  Therefore, I have now looped back to the original problem/question: is there truly no way to get power passing through a monitor as defined by, say, the electric field, in Lumerical? It seems unlikely that Lumerical is by default incapable of accurately reporting powers for common emitter structures like aperiodic gratings. Can any suggestions be given for getting past this issue?
  Thank you in advance!
- July 4, 2024 at 6:38 pm
  
  Guilin Sun
  Ansys Employee
  
  As you know, the Poynting vector can be decomosed into longitudinal and transversal parts, and it is the longitudinal one that is used to calculate, measure the power. Please visit this definition:https://optics.ansys.com/hc/en-us/articles/360034405354-transmission-Script-command
  So there is no problem for the monitor to record the power passing through it. You do not need to use grating-like analysis. The original question was for grating device, not aperiodic.
  If your intention is to measure the transmitted power it should work.
  One thing you have to be careful when doing aperiodic simulation: the injecting source must have a fixed power, and should not change when its size is chan ged. For periodic simulation the plane wave is always larger than the simulation region. However for aperiodic, it can be very different. This is another topic if you have questions.
  
  However