Plasmonic nanoantenna design and fabrication based on evolutionary optimization

Nanoantennas can tailor light-matter interaction for optical communication, sensing,
and spectroscopy. Their design is inspired by radio-frequency rules which partly break down
at optical frequencies. Here we find unexpected nanoantenna designs exhibiting strong light
localization and enhancement by using a general and scalable evolutionary algorithm based
on FDTD simulations that also accounts for geometrical fabrication constraints. The resulting
nanoantennas are “printed” directly by focused-ion beam milling and their fitness ranking is val-
idated experimentally by two-photon photoluminescence. We find the best antennas’ operation
principle deviating from that of classical radio wave-inspired designs. Our work sets the stage
for a widespread application of evolutionary optimization in nano photonics.