We experimentally determine tensile force-elongation diagrams of tapered optical fibers with a nanofiber waist. The tapered optical fibers are produced from standard silica optical fibers using a heat and pull process. Both, the force-elongation data
and scanning electron microscope images of the rupture points indicate a brittle material. Despite the small waist radii of only a few hundred nanometers, our experimental data can be fully explained by a nonlinear stress-strain model that relies on material properties of macroscopic silica optical fibers. This is an important asset when it comes to designing miniaturized optical elements as one can rely on the well-founded material characteristics of standard optical fibers. Based on this understanding, we demonstrate a simple and non-destructive technique that allows us to determine the waist radius of the tapered optical fiber. We find excellent agreement with independent scanning electron microscope measurements of the waist radius.
