Surface-plasmon-mediated programmable optical nanofabrication of an oriented silver nanoplate

We report polarized femtosecond laser-light-mediated growth and programmable assembly of photoreduced silver nanoparticles into triply hierarchical micropatterns. Formation of erected arrays of nanoplates with a thickness as small as λ/27 (λ, the writing laser wavelength) level is demonstrated. The growth mechanism of nanoplates has been clarified: (i) the excited surface plasmons enhance the local electric field and lead to spatially selective growth of silver atoms at the opposite ends of dipoles induced on early created silver seeds; (ii) the optical attractive force overcomes electrostatic repulsion in the enhanced local electric field to assemble the silver nanoparticles directly. The triply hierarchical micropattern shape and location, the nanoplate orientation, and thickness are all attained in controlled fashion.