Dipole Power/Purcell Factor in a Thin Solid Film



From the lumerical website: “The Purcell factor result is equivalent to dividing the power emitted by a dipole source in the environment by the power emitted by the dipole in a homogeneous environment (bulk material).”
So I ran three very basic simulations with - 1) an electric dipole emitting 1550 nm polarized in either X, Y or Z direction, 2) dipole is inside a 140nm thick film with n = 2.7.
The purcell factor’s value I got is - 0.94 for both X and Y directional dipoles, but 0.024 for Z directional dipole.

My question is, why the purcell factor is so low for Z-directional dipole? Does it imply that the Z-dipole is radiating low power, thus have low number of available local density of optical states? If that’s the case, why is it only happening for Z-dipole?

I have attached my simulation files as well.

Thank you in advance for the help.Dipole power_1550nm xdipole.fsp (279.8 KB)
Dipole power_1550nm ydipole.fsp (279.8 KB)
Dipole power_1550nm zdipole.fsp (279.8 KB)


Hi @ntabassum

I did some convergence testing and the results were converging but I do not have a clear answer for you. Were you expecting something else or do you have any publication that proves these results are right or wrong?