Numerical and experimental study of the dynamics of cross polarization coupling in a single whispering-gallery microresonator

The cross polarization coupling (CPC) between orthogonally polarized modes in a single whispering-gallery microresonator can lead to electromagnetically induced transparency (EIT) like effects. Depending on the CPC strength, coupled mode induced transparency (CMIT), coupled mode induced attenuation (CMIA), or Autler-Townes splitting (ATS) can be observed. Previously, the values of CPC strength were found by fitting the experimental throughput spectra to a steady-state model. However, our dynamical analysis suggests an independent way of estimating the CPC strength by sinusoidal modulation at the input. From experimentally determined parameters, we first find one estimate of the CPC strength by model fitting as before. From the modulation frequency that gives the minimum throughput amplitude on resonance, we find another estimate of the CPC strength. Our preliminary experimental results show that the two values agree quite well, which means we have an independent way of finding the CPC strength.