The signal flow graph method based on Mason’s rule has been used to simulate a serially coupled triple microring resonator (SCTMRR) optical filter. One of the most important parameters of MRRs is the coupling coefficient. Therefore, calculating the optimum value of this parameter is one of the key challenges to design optical filters. The fuzzy logic system has been used to find mentioned coefficients. The fuzzy system inputs are the on–off ratio, shape factor (SF), and propagation loss parameters of the SCTMRR. The obtained results have been verified by comparison with authentic published works. It has been shown that to achieve minimum ripple and maximum SF of filter drop port response, the internal coupling coefficients should be smaller than the external ones. Just on the basis of fuzzy logic results, it has been proved that SF of the SCTMRR filter could not be >0.6
