Hello everyone, I hope that I am not asking too much here. I am a PhD
student who wants to use Meep for some Transmission/Reflection calculations
of a complicated periodic gold structure. I have two questions here.
I am very grateful for all the effort that Steven and the Meep community
have put into the mailing list, and I have spent a large amount of time
looking through the mail archive for an answer to my question. I would
really be grateful if Steven could post to this mailing list a definitive
answer for people in my predicament.
I have (multiple) sets of parameters for modeling gold using the simple
Drude formulation:
epsilon = epsilon_infinity - (w_p^2) / (w^2 - i*w*Gamma)
But Meep uses the following function for one pole:
epsilon = "epsilon" + ("omega"^2 * "sigma") / ("omega"^2 - w^2 - (i * w *
"gamma") )
which is defined in the .ctl file via:
(define gold
(make dielectric
(epsilon __________ )
(E-polarizations
(make polarizability (omega _________) (gamma _________) (sigma
__________))
)
)
)
I have the plasma frequency w_p and the loss term Gamma that are fit to
specific sets of data. I do not know how to obtain the parameters "omega"
and "sigma" but I presume that "epsilon" is the same between the models, and
is not effected by any units in Meep since it is just the frequency
independent dielectric constant. I have read multiple times that I need to
fit my data to a series of Lorentz poles. Is there a way to get Meep to
understand my parameters without working out the fit from scratch? The
cited references in papers were all books that I do not have. I am willing
to learn but the approach to this problem is not immediately obvious and
from the posts I have read a lot of other people have the same problem.
My other question is about frequency. Say that I start with the drude
parameters below:
Meep length scale a = 1nm
epsilon_infinity = 9.07
w_p = 2pi * 2.16 * 10^15 Hz
Gamma = 2pi * 1.84 * 10^13 Hz
Now I convert to Meep units (in the way I believe is correct):
Meep_w_p = (2pi * 2.16 * 10^15 Hz) * [(2pi) * (3*10^8 m/s) / (10^-9 m)]/[1
Hz]
Meep_Gamma = (2pi * 1.84 * 10^13 Hz) * [(2pi) * (3*10^8 m/s) / (10^-9 m)]/[I
Hz]
Do I now fit these parameters to the Lorentz pole sum just as if they were
w_p and Gamma, and pick "sigma" "omega" and "gamma" to fit the form of the
Lorentz pole sum afterwards?
Thanks again for any help.
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