Amrita Pati
Ansys Employee

Yes, that is correct. As Si and SiO2 have different indices, the mesh density will be higher in Si than in SiO2. And there will be grading near the interfaces. Are you re-meshing the simulation domain after you disable the meshoverride region?

Also, I think you should be able to see a higher contrast between the two regions if you increase the mesh accuracy. So, increase the mesh accuracy, remesh, and see if that makes a difference.