Silica grids with micron to sub-micron mesh sizes and wire diameters of 50 nm are fabricated on fused silica substrates. They are formed by single-pulse structured excimer laser irradiation of a UV-absorbing silicon suboxide (SiOx) coating through the transparent substrate. A polydimethylsiloxane (PDMS) superstrate (cover layer) coated on top of the SiOx film prior to laser exposure serves as confinement for controlled laser-induced structure formation. At sufficiently high laser fluence, this process leads to grids consisting of a periodic loop network connected to the substrate at regular positions. By an additional high-temperature annealing, the residual SiOx is oxidized, and a pure SiO2 grid is obtained.
Pacs: 81.07.-b; 81.07.Gf; 81.65.Cf.