I am performing 2.5D simulation of slot ring resonator and grating ring resonator. I am kind of struck regarding the position of slab mode. In the normal ring resonator example as long as the slab mode position is in silicon layer the response remains same. But for the structure like slot ring or grating ring where should i put the slab mode (slot or slab in the slot ring sturcture or high index or low index region in the grating ring resonator ). OR is there another way to perform the 2.5 FDTD simulaton of those type of structures?
i would really appreciate any help/suggestion.