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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