An evolutionary algorithm is applied to the synthesis of an integrated spot-size converter. Evolutionary algorithms turned out to be well suited for the solution of very complex problems having strongly non-linear cost functions defined over the solution space. They mostly work faster than other optimization techniques like random search or the Monte-Carlo method because of their parallel search mechanism, also referred to as implicit parallelism. The intrinsic behaviour of the optimization is demonstrated using an example of a spot-size converter that is implemented as a non-periodic segmented waveguide structure. Only a small number of structures have to be evaluated to achieve a coupling loss below 1.3 dB that is considered to be very good. A supervising method is proposed, introducing an evolution quality figure. This figure is used to visualize and to qualify the evolution of the algorithm. Based on this figure a termination condition is suggested. [References: 24]
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