Genetic Algorithm Synthesis of Low-Loss Multi-layer Negative Index Metamaterial Stacks for the Mid-Infrared

In order to realize practical applications for negative index metamaterials at optical wavelengths, it is necessary to develop design and fabrication techniques for bulk materials. This paper presents one such design methodology employing stacked Frequency Selective Surfaces optimized using a Genetic Algorithm for low loss and a negative refractive index. A design example is presented, showing that the loss can be minimized by optimizing a 5-layer stack. Further analysis reveals that the metamaterial properties of the stack are approaching those of a bulk medium.