Learning Forum

[tavak]

I implemented a time-dependent material in my FDTD setup. The material is similar to the one used in this example, i.e., stepindex material. I was trying to plot the displacement field or polarization density (D = eps0*epsr*E = eps0*E+P) at a specific point in the time-dependent material as a function of time. Nonetheless, I could not find any monitor or group analysis that shows the time dependency of epsr or D. If I can extract either the permittivity profile or the displacement field vs time (even at a single point), I can ensure that my time-dependent material follows the profile that I intended. Briefly, I am looking for a way by which I can plot the permittivity vs time like the following (from this example):

Thanks

[Guilin Sun]

Right now the plugin material cannot be monitored by regular index monitor (it is CW, frequency domain monitor), nor by time (it only monitors the fields vs time). You may modify the plugin code to output the fields, and less possibly pemittivity (maybe the perturbation is ok).  However the plugin material is an advanced feature that we can only provide very basic support.

[tavak]

Thanks for the description. There is a predefined group analysis entitled "Displacement Field," which provides D as a function of frequency. Is there any option to monitor D as a function of time rather than frequency? Thanks again.

[Guilin Sun]

I am not sure if you have watched this video: https://www2.lumerical.com/videos/Lumerical_Material_Plugin_Practical_Demo_p1.mp4

Do you mean the Chi3 material? Usually we can outout E fields, since all related examples use E update equations. Internally D is  obtained through convolution. I am not sure if it can be output. But you can try if you know the variable names and add it to the "storage" parameters. You may refer to Chi3 and laser material  fourleveltwoelectron.