Combinatorial fluorescence lifetime measuring system for developing Er-doped transparent glass ceramics

Fluorescence lifetime of Er3+ was measured for F-doped tellurite glasses with parallel heat treatment under a temperature gradient atmosphere in order to find the annealing condition to make transparent glass ceramics in which Er3+ ions are located in the precipitated crystals. The preparation and annealing of the samples were performed in a vertical temperature gradient furnace, where molten glass was sucked into a pre-heated Pyrex glass tube. The annealing temperature range is between 350 and 800 deg. C. After the annealing treatment, time-resolved fluorescence emission of Er3+ (1.55 μm; excitation light source is 977 nm) were measured sequentially along the tube. The lifetime of the emission was about 2.6 ms for as-prepared glass. We have found that the lifetime increased to 5.2 ms when the glass was annealed at 470 deg. C for 5 min and 550 deg. C for 5 min successively, although its transparency was lost. This increase implies that the Er3+ ions are embedded in fluorine-rich phase to bring about reduced non-radiative emission. We are now continuing to find the condition to get transparent glass ceramics