Abstract
We present an efficient designing process of nano-photonic polarization control elements using Genetic Algorithm (GA). Photonic nanostructures, which have a periodic metallic pattern pitching smaller than light wavelength, can produce unique optical functions such as polarization transformation by the near-field light effect. Because of the complex interaction between the light and metal, it is essentially difficult to optimize the nanostructure, thus no systematic design procedure is currently in operational. To tackle this problem, we utilize the finite-difference time-domain (FDTD) method to simulate and evaluate the polarization transformation efficiency and apply GA to optimize it. To drive the GA optimization procedure, a periodic 2D nanostructure is deformed by mutation. Started from a circular shape, the metallic pattern comes into a specific shape, which has two sharp tips and smooth S-shape outline curve. The optimization procedure takes approximately 20 days to reach a local minimum. Experiment results show efficacy of the proposed design procedure based on FDTD and GA.
