To compute the time-dependent absorbed power density is straightforward:
you would need to manually compute the dot product of the complex
conjugate of E and dP/dt by using P=D-E. You can obtain the
time-dependent E and D fields using the `get_array` function:
https://meep.readthedocs.io/en/latest/Python_User_Interface/#array-slices.
Note though that the fields obtained using `get_array` are interpolated
to the center of each Yee grid voxel which means there will be some
discretization error when computing this dot product. (This
discretization can be reduced by increasing the grid resolution.) Also,
you will need to be careful about the finite-difference approximation
you use to compute the derivative dP/dt to ensure that all the
quantities used to evaluate the dot product are at the same time instant.
On 8/29/21 07:23, Liang Chen wrote:
"I realize that MEEP can calculate the absorbed power density
distribution (space-dependent) corresponding to each frequency
component of a pulse. This is explained in the tutorial "absorbed
power density map of a lossy cylinder." However, the problem I have on
hand requires the space-time-dependent absorbed power density since
the instantaneous absorption is expected to change the material
properties, which will then affect the propagation of electromagnetic
fields (i.e., it is nonlinear, and using Fourier transform after the
simulation is not correct for this problem). If I could get the
instantaneous absorption, I can add the feedback mechanism in the MEEP
code."
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