Unidirectional coupler optimization of surface plasmon polaritons based on co-simulation of genetic algorithm and COMSOL

The unidirectional excitation of surface plasmon polaritons has been an important subject for the development of plasmonic devices and systems. This study presents the use of co-simulation method of genetic algorithm and COMSOL in MATLAB environment to optimize quasi-periodic and aperiodic surface plasmon polaritons slit unidirectional coupler. The extinction ratio of all the surface plasmon polaritons slit unidirectional couplers is greater than 60 dB under arbitrary initial structure parameters with genetic algorithm options of population size of 20 and generations of 20. Therefore, the co-simulation method of genetic algorithm with COMSOL not only greatly speeds up the process to find the optimal parameters, but also does not depend on the initial structure parameters. Moreover, this method can also be applied to optimization of other photonic devices, such as the perfect mirror, the anti-reflective film of photovoltaic cell surface. Even with little knowledge of optimization, photonic devices with good performance can be obtained with this method.