Multi-Step Inverse Design Optimization for Structural Colors Using Dielectric Materials

This paper presents an efficient multistep approach for the inverse design of structural colors based on multilayered pseudo Fabry-Pérot cavities. The methodology focuses on three- and four-layer structures, as additional layers provide only minimal improvement in color space and inevitably increase the fabrication cost. The process consists of three key steps: (1) generating a few thousand data points through forward simulations, (2) training a Decision Tree algorithm to produce an initial design, and (3) refining the design using a random-walk search algorithm to minimize error. This multistep approach significantly reduces computational time while improving design accuracy. In addition, it enables the exploration of the full-color gamut achievable with a given multilayer structure.