Parametric Characterization of Self-Heating in Depletion-Type Si Micro-Ring Modulators

The influence of self-heating on the static transmission characteristics of depletion-type Si micro-ring modulators (MRMs) is investigated. Self-heating, caused by free-carrier absorption of the input light inside the doped ring waveguide, increases the effective refractive index of the ring waveguide and results in the red-shifted resonance wavelength. This phenomenon is modeled based on the coupled-mode equation with a newly-introduced self-heating coefficient R. The accuracy of our model is confirmed by measurement. In addition, dependence of R on device size and doping concentration is experimentally investigated and the resulting dependence is explained.