Reply To: Directional Coupler: how to calculate the coupling coefficients?

[Guilin Sun]

The coupling coefficient is simulated, or specified for INTERCONNECR use. 

If it is power coupling coefficient, you can simulate the power transmission with such settings:

Or you may deduct it from this example: https://optics.ansys.com/hc/en-us/articles/360042800293-Ring-resonator-getting-started-Design-and-initial-simulation

This example might be more helpful: https://optics.ansys.com/hc/en-us/articles/360042322794-Ring-Modulator