Laser-induced periodic structures on polymers for the formation of gold or silver nanowires showing pronounced plasmon resonances

Ripples, also denoted as laser-induced periodic surface structures (LIPSS), are frequently observed coherent structures in laser surface processing. For polyethylene terephthalate (PET), LIPSS can be induced by irradiation with linearly polarized ns-pulsed UV laser light at fluences well below the ablation threshold. The lateral period of the observed LIPSS is close to the wavelength λ divided by the effective index of refraction n_eff (~ 1.3). Gold or silver nanowires can be formed on top of the polymer structures by means of evaporation under an inclined angle. These separated nanowires exhibit localized surface plasmon resonances (SPR) in the VIS to NIR spectral region, overlapping with the so-called biological window. This together with the alignment of human cells on such LIPSS structures renders our nanowires as very promising candidates for biosensing applications.