As a side note you will also want to ensure that you are running a high enough resolution spatially. While the default in the software and for most people is 10 points per smallest wavelength in the material, this is only for characterizing the source. If your features such as the waveguides of your resonator are less than your wavelength (a typical condition in integrated devices where refractive indices are high) you need to ensure you are running a sufficiently high resolution to characterize the spatial layout. While 10 points per smallest feature is a good rule of thumb you should keep an eye on this and run convergence testing. One way of checking is to use the refractive index viewers in Designer as these are based off the grid and not the drawn specifications.