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

Fluorescence lifetime of Er3þ 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 Er3þ 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 8C. After the annealing treatment, time-resolved fluorescence emission of Er3þ (1.55 mm; 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 8C for 5 min and 550 8C for 5 min successively, although its transparency was lost. This increase implies that the Er3þ 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. # 2003 Elsevier B.V. All rights reserved