Optical binding-driven micropatterning and photo-sculpting with silver nanorods

Controlling the nano- and micropatterning of metal structures is an important requirement for various technological applications in photonics and biosensing. We present a method for controllably creating silver micropatterns by laser-induced photo-sculpting. The photo-sculpting is driven by plasmonic interactions between the pulsed laser radiation and the silver nanorods (AgNRs) in aqueous suspension; this process leads to optical binding forces transporting the AgNRs in the surroundings, while the electronic thermalization results in the photo-oxidation, melting, and ripening of the AgNRs into well-defined 3D structures. We called these structures Airy castles due to their structural similarity with a diffraction-limited Airy disk. The photo-sculpted Airy castles contain emissive Ag nanoclusters, allowing for the visualization and examination of the aggregation process using luminescence microscopy. We comprehensively examine the factors that define the photo-sculpting process, namely, the concentration and shape of the AgNRs, as well as the energy, power and repetition rate of the laser. Finally, we investigate the potential applications by measuring the metal-enhanced luminescence of a europium-based luminophore using the Airy castles.