Discussion Forum

Hello everybody!

I am interested to obtain dispersion curves (\omega vs \beta) of a loss-less film of silver with thickness of 50 nm which is bounded with air. The dispersion curves are illustrated in Fig. 2.6, page 32 of this book: "S. A. Maier, Plasmonics: Fundamentals and Applications (Springer, Berlin, 2007)" .

According to this figure, I expect to obtain two branches of SPP dispersion. To this aim, I prepared my model with following method:

-- First, I chose "wave optics module with ewfd physics and empty study", and I defined all geometrical and material parameters in the "parameter" section. I also defined the frequency-dependent epsilon of silver in that part. And, electric field componets were chosen as in-plane.

-- Second, I defined the geometry and materials of my design.

-- Third, "numeric port boundry conditions" were applied at the left and right sides of the structure.

-- Finally, "boundary mode analysis" together with "frequency domain" were chosen in the study part. Notice that, using "auxiliary sweep" I defined a range of frequency to be able to change "f0", and by changing "f0" I am able to change frequency dependent permitivity of silver (eps_core).

After running the simulation, I plotted eps_silver (eps_core) and Hy mode profiles for different frequencies. I understood that eps_core was correctly changed by frequency, and mode profiles correctly showed the localized SPPs propagating inside the waveguide for different frequencies.

However, I could not obtain dispersion curves. It is simply different from the book result.

If anyone has worked on creating a dispersion plot on COMSOL before, I would really appreciate your help.