Mode propagation and overlap in Mode
There is a feature in FDE to calculate the mode overlap between nearfields of two waveguide modes.
Is this possible to propagate the near-field some distance x and then take the overlap of this diverged beam with the near field of other waveguide mode using FDE or EME to calculate mode-mismatch.
I am well ware that it's doable via FDTD but it's computational expensive to propagate the mode in FDTD and calculate coupling efficiency. Also in that case I have to take into account the reflections and need to apply anti reflection coatings. FDTD is definitely more accurate but I am not sure what will be the level of accuracy if FDE/EME is used for this purpose.