Learning Forum

[minusunny]

Hi,

 I am getting very low transmission value during s parameter extraction whereas i am getting good values of transmission at the ports. Is there any reason for that, how can i resolve it?

 

Thanks,

Minu

[Guilin Sun]

" s parameter extraction", do you mean you used S parameter matrix sweep utility? It also uses ports. Please make sure you use exactly the same simulation settings and better to use the same file. Also please make sure the source is not located inside lossy waveguide since it will lose power during propagation, and also check the simulation time and autoshutoff min to see if they are proper. eg, simulation reaches autoshutoff for termination. You can also use time monitor to check.

Without setting details it is difficult to recommend solutions.

 

[minusunny]

I figured it out , it was because of the PML layers.My parameters were not extracted properly.  I have a doubt regarding the result extraction script. I need to extract data from ONA. Is there any example for lumerical script file for result extraction from interconnect?

[Guilin Sun]

So the question is from FDTD to INTERCONNECT (ONA)? The forum should be one-question one-post.

Here is a simple reply. In INTERCONNECT you can use script to extract simulation results, and the component parameters you set.

result: 

getresult: https://optics.ansys.com/hc/en-us/articles/360034409854-getresult-Script-command

getresultdata: https://optics.ansys.com/hc/en-us/articles/360034407714-getresultdata-Script-command

getnamed: https://optics.ansys.com/hc/en-us/articles/360034408574-getnamed-Script-command

you can use 

?getresult("ONA_1") 

to know all the results from ONA.

Please write a new post if you have other questions.

 

 

 

 

[minusunny]

Sorry about that. Thanks. In the s parameter extraction in FDTD, i got a warning that my device lacks reciprocity . The FDTD simulation runs fine without any divergernce warning and any other error . The simulation is broadband. What will be the reason for that? I excited all ports during simulation. My device is a 4 X 4 mmi with subwavelength gratings.

Minu

[Guilin Sun]

 

It is just a warning, meaning some of the S parameters are not reciprocal, most likely due to numerical errors. You can either modify FDTD settings with finer mesh/long simulation time with smaller auto shutoff min/increase PML thickness or number of layers etc. Or you can also ignore it because such error can be minimized later if you do converging test. Also, make sure the port/monitor collects the mode power correctly, with sufficient size but not pick up some scattering power, if any.