Study of Optimal All-Pass Microring Resonator Delay Lines With a Genetic Algorithm

We study the properties of finite-length all-pass side-coupled microring delay lines optimized using a genetic algorithm. The average bandwidth-group delay product is found to follow a linear growth with the number of cascaded stages N. Both the magnitude and the slope of the figure of merit vary with the specific optimization criteria but, for all the cases addressed, they are below the unit slope linear dependence with N of a theoretical upper bound.