This work is about numerical optimizers applied to nanophotonic devices. Nanophotonic devices are key elements in telecommunication systems. They allow the transport of massive amounts of data and help in that way to ensure the function of all the various networks. In this work the design of two elements, a plasmonic slot waveguide and a grating coupler are optimized. With the focus more on the numerical optimizers, a variety of algorithms are applied and compared for the use of the two nanophotonic structures. In addition, their performance is tested on various benchmark functions. Based on these results several ideas to improve an evolutionary strategy are implemented and evaluated. The book is therefore organized in three main parts, where the first part covers the work on the plasmonic slot waveguide, the second part the evaluation of the benchmark functions and the last part is about the optimization of the grating coupler. The main goal is to evaluate different numerical optimizers. Therefore some statistical results are presented, but as important as the numbers is the great amount of different images providing a good feeling for the work principles and performance of the optimizers.