Study of improved second harmonic generation in double microring resonators

In this study, second harmonic generation (SHG) is studied in AlGaAs microring resonators. Efficiency of frequency conversion is investigated in single and double microring structures. The effects of input power and loss of the ring waveguide are considered. In a double microring structure, we have to take into account the effect of the generated second harmonic field, which is coupled into the next microring. It is shown that the total efficiency decreases exponentially with the loss and a low loss double microring structure provides 100% conversion efficiency with lower input power compared to a single microring structure. For this purpose, coupled nonlinear Schrodinger equations (C-NLSE) are simplified to a time invariant integrative form. This method is compared to the exact solution of C-NLSE utilizing finite difference time domain (FDTD) method.