I need to calculate the ring-ring and bus-ring coupling coefficients of a microring-based Add-Drop filter with two rings using the Lumerical FDTD, but I do not know how. Can anyone help me? Thanks in advance.
You can consider an input source on one side of the structure and place a monitor on the other side. Then you can obtain the desired coefficient by changing the distance between the waveguide and ring or ring and ring.