Dear Scott,
I have another question. I have tried to calculate the reflectance and transmittance of a semi-infinite layer (a substrate) of a homogeneous and continuous material with a constant refractive index at an angle of incidence (AOI) of 45 deg, so the results can be easily verified with the Fresnel equations. Consistently I was getting incompatible results when I tilted the incident wave. Actually, everything indicates that when I am using a wave tilted 45deg, the software does not take it into account, and the result I get is like my wave were tilted 0-degrees (normal incidence). For instance, you can check that my incident wave is RH-polarized, but when I check the intensity of the reflected wave with an observation area I get the same values for both polarizations, x and y, which is incorrect for an AOI=45 deg. Similar happens when you tilt the wave 60 degrees or even 80 degrees. Besides, I have ploted the R vs wavelength at AOI=45 deg and I compared it with Fresnel equations, and the reflectivity result is compatible with normal incidence again.
I have attached a copy of the OptiFDTD layout I am using, and a plot summarizing the main results. The materials layer is longer than the wafer size to get rid of the backside reflectance. I use 3D simulation.
Eventually I found a explanation in the manual (OptiFDTD Technical Background and Tutorials, version 8.1 for Windows 32/64 bits). It says in pag. 41 that: “…Currently, plane wave does not support the tilting angle. Currently, the plane wave simulations is only effective for symmetrical structures”
So, my question is, I am doing something wrong, or the OptiFDTD indeed does not support tilted waves? The weird thing is that I have seen posts in this forum and also papers using OptiFDTD to correctly simulate reflectances or transmittances at different angles of incidence….
About the version, I am using the free 32-bits version. By the way, another question is, if the free version does not support tilted waves as indicated in the manual, does the full version support it?
Thanks in advance!
Luis
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