Directional couplers and ring resonators are ubiquitous in modern PIC design. Simulating them, however, tends to be a relatively time-consuming process, especially if you want to evaluate 3D vectorial effects such as polarization conversion. The 3D Ring Resonator module allows for a quick and simple calculation of the coupling between waveguides. The module uses a variant of Coupled Mode Theory that takes into account the varying distance and tilt between waveguides.