Metal nanofabrication techniques have become increasingly important for photonic applications with rapid
developments in plasmonics, nanophotonics and metamaterials. While two-dimensional (2D) techniques to create high
resolution metal patterns are readily available, it is more difficult to fabricate 3D metal structures that are required for
new applications in these fields. We present a femtosecond laser technique for 3D direct-writing silver nanostructures
embedded inside a polymer. We induce the photoreduction of silver ions through non-linear absorption in a sample
doped with a silver salt. Utilizing nonlinear optical interactions between the chemical precursors and femtosecond
pulses, we limit silver-ion photoreduction processes to a focused volume smaller than that of the diffraction-limit. The
focal volume is scanned rapidly in 3D by means of a computer-controlled translation stage to produce complex patterns.
Our technique creates dielectric-supported silver structures, enabling the nanofabrication of silver patterns with
disconnected features in 3D. We obtain 300 nm resolution.