Design of broadband modulated one-dimensional photonic crystals based on porous silicon using evolutionary search

This work reports a methodology based on evolutionary search, through genetic algorithms, to design and optimize broadband modulated one-dimensional photonic crystals based on porous silicon in the visible spectral region. The photonic crystal structures consist of chirped layers that form a discrete array of sub-mirrors with different resonance wavelengths. Three modulation functions: exponential, sine, and gaussian, were tested and optimized to maximize the reflectance intensity in a target region. The optical response simulation used the transfer matrix method and effective medium approximation for P, S, and non-polarized light to show the complete optical behavior for several incident angles. It was found that PhC designs with more than 90% reflectively with a total depth less than 6.1 μm and individual layers higher than 40 nm. Those value ranges can be helpful to improve the structure’s mechanical stability.