Learning Forum

[Color]

Hello,

I have a periodic structure that takes a long tome in FDTD to simulate. I want to try to simulate this using RCWA. I tried to look at a couple of documentations but they do not apply to my case. I am not that much interested in the total transmission or reflection that the RCWA gives me. I am interested in using power monitors and checking the power that goes through monitors at different planes. These monitors could be normal to the direction of propagation or parallel to it. For example, if I have a z propagating wave, I would have monitors with z-normal or x-normal or y-normal properties. It seems that doing such a thing is not that easily achievable with the basic documentations that I see on the website. Can you please help me figure this out?

 

Thanks a lot

[Guilin Sun]

Maybe I can give you some background information then you decide what to do next.

RCWA is simulating periodic structures. This means the side transmission is not a result that people need, since at the periodi boundary, the net power flow is zero. Otherwise it will not be periodic.

Maybe you can take a step back, and think over what can be assessed for such periodic structure.

 

 

[Color]

Thank you for the comment. I did not mention that the power monitors are at the periodic boundaries (though if the unit cell is asymmetric, there will be power flow at the boundary). The monitors are acually within my structure at different points. The question is how can I get transmitted power in different parts of a simulation when I use the RCWA, not just reflection and transmission? The field and power monitors seem to not work in RCWA the way they work in FDTD. Sorry if it was not clear!

[Color]

Hello? Any progress here? Can we have transmission monitors in RCWA, or have field monitors? I see this mentioned on the website, but such a thing does not exist in lumerical 2023 R1.2!!

https://optics.ansys.com/hc/en-us/articles/16277147107731

[Guilin Sun]

It works in R1.3:

 

[Color]

Thank you. I do have that monitor that you have put in the simulation in the R1.2 version as well but once I run the simulation, it does not have any results. Does yours have results in it?

[Color]

Yes!! I installed the R1.3 and it has the field monitor built in. Awesome! It does not show the transmission, however. It only has the electric and magnetic fields. How can we get the transmission from this? Should we do the poynting vector calculation? And how would the effect of source power come into play here because physically, there is no source and in Lumerical, transmission monitors normalize the transmission to injected power by source. Any tips are appreciated.

 

 

 

[Guilin Sun]

It is field monitor;

you should be able to get transmission and reflection from RCWA object as usual.

[Color]

Sorry. I think I did not phrase that correctly. I am trying to find transmission in the middle of the structure and that is why I want to use the monitors. The RCWA object will only give the total reflection and transmission not the reflection and transmission in a specific part of the object.

[Guilin Sun]

Inside the device it is cavity. So we cannot measure its transmission. Yes, RCWA only gives the final, measuable transmission. If you really want such quantity, please file a feature request by referring to this post: 

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