Plasmonic field guided patterning of ordered colloidal nanostructures

Nano-patterned colloidal plasmonic meta-surfaces are capable of manipulation of light at the subwavelength scale. However, achieving controllable lithography-free nano-patterning for colloidal metasurfaces still remains a major challenge, limiting their full potential in building advanced plasmonic devices. Here, we demonstrate plasmonic field guided patterning (PFGP) of ordered colloidal metallic nano-patterns using orthogonal laser standing evanescent wave (LSEW) fields. We achieved colloidal silver nano-patterns with a large area of 30 mm(2) in <10 min by using orthogonal LSEW fields with a non-focused ultralow fluence irradiation of 0.25 W cm(-2). The underlying mechanism of the formation of the nano-patterns is the light-induced polarization of the nanoparticles (NPs), which leads to a dipole-dipole interaction for stabilizing the nano-pattern formation, as confirmed by polarization-dependent surface-enhanced Raman spectroscopy. This optical field-directed self-assembly of NPs opens an avenue for designing and fabricating reconfigurable colloidal nano-patterned metasurfaces in large areas.