Local optical imaging of nanoholes using a single fluorescent rare-earth-doped glass particle as a probe

We have developed a local optical imaging technique that uses a fluorescent rare-earth-doped fluoride glass particle as a probe. This particle is glued at the end of an atomic force microscope tip and scanned over the surface of a nanostructured sample illuminated by a laser beam. The intensity of the laser-induced fluorescence of the particle is then recorded as a function of the position on the sample surface. This method has enabled us to image the light scattered by 250-nm large nanoholes made in a thin chromium film. The advantages of this material over other fluorescent probes is that it has a strong fluorescence when excited at 980 nm, it operates at room temperature, and does not present any evidence of photobleaching.