Automated Design of Photonic Crystal Demultiplexers

We describe an approach for the automated design of photonic crystals for various applications. Our approach includes gradient-based optimization for arbitrary objective functions, with the electromagnetic fields calculated by an accurate multiple-scattering approach. An example of a two-color silicon photonic crystal demultiplexer designed by our method is presented, with dozens of parameters chosen automatically in reasonable time. The optimized device exhibits strong focusing with low crosstalk for both frequencies.