Fabrication of a pencil-shaped fiber probe with a nanometric protrusion from a metal film for near-field optical microscopy

We propose a method to fabricate a probe with a nanometric protrusion for near-field optical microscopy. The method involves a tapering process based on selective etching of a GeO₂-doped fiber in a buffered hydrogen fluoride solution and a metallizing process by vacuum evaporation and chemical polishing. We fabricated a tapered probe which has a protrusion emerging from a metal film. The protrusion has an apex diameter less than 10nm and a foot diameter less than 20nm. Employing the probe, we succeeded in obtaining a highly resolved image of 20nm gold particles.