Frequency mismatch ν = 2 ν p + ν s + ν i for the hOPO in orange. The solid circles are experimental measurements using a wavemeter (see Methods) to determine the cold-cavity resonance frequencies (uncertainties are within the size of the data points), while the solid curve is from finite-element method (FEM) simulations where the idler, pump, and signal modes are from the TE 0 , TE 0 , and TM 0 mode families, respectively. The frequency mismatch when all modes are chosen from the TE 0 family is shown in the green solid circles and green solid curve for experiment and simulations, respectively. The top images are the simulated transverse electric field profiles for the hOPO modes, where the cross-sectional parameters of ring width (RW), thickness ( H ), and sidewall angle ( ) are indicated. The lower inset magnifies the right zero crossing of the hOPO ν curve, showing an 9 GHz offset when = 76.
