Dear Meep Users and Savants: I am trying to implement a real metal material object in meep. I have started with a very simple 2D simulation of a silver film aligned along X and with a thickness along Y. The simulation uses a plane-wave line source located a few length units below the film, and propagating in the +Y direction. In order to implement the metal I followed the discussion in the tutorial and in the materials section of the meep online documentation. Since, for the moment, I only need the metal properties at a fixed wavelength I used the D-conductivity approach rather than the Drude or Lorentz models. I used data from a standard reference (Johnson and Christy) for Ag at 500nm wavelength. The relative permittivity is -9.811 + 0.3126i for Ag at 500nm.
I find that if I use a negative number for the real part of the permittivity, the simulation generates an h5 output file containing nothing by NaNs (not a number) for the various field components of interest (Ex, Ey, Hz). If I just ignore the sign and use the equivalent positive number (9.811), I get fields that look plausible. HOWEVER, the Hz field should be continuous at the air/metal interface with an amplitude nearly twice the plane wave amplitude. What I see is that the supposed Hz field changes sign at the interface. There seems to be something going on that I do not understand. Can anyone comment on the use of signed permittivity in the D-conductivity? Or the apparent problem with Hz? These two problems might be related. Best regards, John WEINER 22 Avenue de la Sibelle 75014 Paris _______________________________________________ meep-discuss mailing list [email protected] http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/meep-discuss
