I have a structure that works well given the perfectly etched sidewalls. But I’m suspecting that it is prone to loss due to sidewall roughness, since the mode doesn’t always stay within the core in this particular design. So I’m looking for a way to introduce sidewall roughness to see how much of a loss it results in. I could switch to FDTD as well, if there’s a way to do this there.
The solution I can think of is to specify another material within a few nm of the waveguide sidewalls. This material would also have a non-zero imaginary part of its refractive index. But I would be almost getting back what I put in, since I’d be specifying the loss in that material. I’m really looking for a more elegant solution. Any ideas?