Chemically etched sharpened tip of transparent crystallized glass fibers with nonlinear optical Ba₂TiSi₂O₈ nanocrystals

Glass fibers with a diameter of ∼100 μm are drawn by just pulling up melts of 40BaO · 20TiO₂ · 40SiO₂ glass, and transparent crystallized glass fibers consisting of nonlinear optical fresnoite Ba₂TiSi₂O₈ nanocrystals (particle size: ∼100-200 nm) are fabricated by crystallization of glass fibers. Precursor glass fibers and nanocrystallized glass fibers are etched chemically using a meniscus method, in which an etching solution of 0.1 wt%-HF/hexane is used. Glass fibers with sharpened tips (e.g., the taper length is ∼L = 200 μm and the tip angle is ∼θ=23°) are obtained. It is found that etched nanocrystallized glass fibers also have sharpened tips (L = 50 μm, θ=80°). Compared with precursor glass fibers, nanocrystallized glass fibers show a high resistance against chemical etching in a 0.1 wt%HF solution. Although sharpened tips in nanocrystallized glass fibers do not have nanoscaled apertures, the present study suggests that nanocrystallized glass fibers showing second harmonic generations would have a potential for fiber-type light control optical devices.