  The rational design of photonic nanostructures consists in anticipating their
optical response from simple models or as variations of reference systems. This
strategy is limited when different objectives are simultaneously targeted.
Inspired from biology, evolutionary approaches drive the morphology of a
nano-object towards an optimum through several cycles of selection, mutation
and cross-over, mimicking the process of natural selection. However, their
extension to scenarii with multiple objectives demands efficient computational
schemes. We present a numerical technique to design photonic nanostructures
with optical properties optimized along several arbitrary objectives. This
combination of evolutionary multi-objective algorithms with frequency-domain
electro-dynamical simulations is used to design silicon nanostructures resonant
at user-defined, polarization-dependent wavelengths. The spectra of pixels
fabricated by electron beam lithography following the optimized design show
excellent agreement with the targeted objectives. The method is self-adaptive
to arbitrary constraints, and therefore particularly interesting for the design
of complex structures within technological limits.
