Learning Forum

[cgutie22]

To whom it may concern,

I have been scripting various FDTD simulations with a plane wave propogating in the -z direction, and have some monitors nearby.  I did not script an explicit value for the electric field. Looking online, it seems that the magnitude of the electric field is 1 V/m by default. However, when pulling E_x and E_y from power monitors, I find that <|E_x|> and <|E_y|> can be greater than 1. For clarity, <|E_x|> refers to the average of the absolute value of E_x through the monitor.

1) Isn't |E|=sqrt((abs|E_x|^2)+(abs|E_y|^2)+(abs|E_z|^2)) ? If so, why does the monitor read a value greater than 1?

2) Why does this happen?

I am willing to dm files upon request.

[Guilin Sun]

I do not see any description about what material/device you are testing. Please visualize the source amplitude. In many cases the local intensity can be larger than the source intensity, due to refraction, diffraction, scattering and interference.  even for one material half in air, the intensity can be larger than the source since 1+r=t from the Fresnel coefficient.

In addition, please check if the boundary condition is correct: for plane wave, periodic boundary condition should be used. 

https://optics.ansys.com/hc/en-us/articles/360034382874-Understanding-field-truncation-issues-with-finite-sized-plane-wave-sources