Development of a fiber used for fabricating application oriented near-field optical probes

We propose and develop a new fiber for application oriented probes for near-field optical microscopy. Based on a geometric model of selective etching, we design the fiber having the germanosilicate-doped silica core, an inner pure silica cladding, and an outer fluorine doped silica cladding. The fiber is fabricated by vapor-phase axial deposition. By selective etching of the fiber in buffered hydrogen fluoride solutions, we fabricated three probes having high-resolution capability and/or high-transmission efficiency for applications to high-resolution imaging and local spectroscopy. The apex diameters of the probes were less than 10 nm.