Why does the mode loss fluctuate dramatically when reducing the mesh step？
I am trying to obtain the loss level introduced by a gold(Au) strip in a waveguide. The schemetic diagram is shown in the following.
However, when I reduced the mesh step(from 50nm to 1nm) near the gold(Au) region ('mesh Au'), the simualted loss flucturate dramatically, shown in the above figure. Could you please help to find the causes for loss fluctuation and how to modify my setting to obtain a more accurate loss level? My FDE setting is shown in the following. Thank you so much.