Method to produce high-resolution scanning near-field optical microscope probes by beveling optical fibers

Abstract

A new two-step method to fabricate scanning near-field optical microscope (SNOM) probes with an aperture size clearly below 100 nm has been developed. For the first step, a chemical etching process is used in which an optical fiber is dipped with its acrylate jacket into hydrofluoric acid to get a suitable tapered shape of the fiber. The second step consists of beveling the etched fiber using a modified micropipette beveler to obtain a tip diameter in the nanometer range as well as a smooth surface to allow a good aluminum metallization by evaporation. By varying the beveling angle tapered shapes with different cone angles can be obtained. First transmission experiments with our probes show an optical resolution below 80 nm. In comparison to fiber tips obtained by a standard heating and pulling method, the transmission efficiency of these tips is up to three orders of magnitude higher due to the optimized tapered shape.