RESUMEN
A series of transparent erbium-doped fluorozirconate glasses has been investigated using differential scanning calorimetry, optical absorption, and upconverted fluorescence spectroscopy. The upconverted fluorescence intensity versus excitation power dependence shows that the ratio of the two-photon upconverted emission in the near infrared at 980 nm to the three-photon upconverted emissions in the visible at 530, 550, and 660 nm decreases with increasing excitation power. The integrated upconverted fluorescence intensity to excitation power ratio shows 'saturation' with increasing excitation power, while the point of saturation shifts to lower excitation power with increasing erbium concentration. The experimental lifetime of the upconverted fluorescence decreases with increasing erbium concentration.
RESUMEN
Thermal processing of as-made fluorozirconate glasses, which were additionally doped with rare-earth and chlorine ions, results in the formation of fluorescent nanocrystals therein. For medical applications, the glasses were doped with divalent europium ions as the fluorescent rare-earth ion, while trivalent neodymium was used to develop up-conversion systems. The samples were annealed up to 290 °C to initiate the growth of hexagonal or orthorhombic phase BaCl2 nanocrystals therein. Upon annealing some of the rare-earth ions were incorporated into the BaCl2 nanocrystals leading to enhanced fluorescence properties. The particle diameters were in the range of a few nanometers to several tens of nanometers.
RESUMEN
Upon excitation at 796 nm, Nd(3+)-doped BaCl(2) single crystals show several upconverted fluorescence bands in the visible spectral range, with the most intense bands at 530, 590 and 660 nm, in addition to the typical fluorescence bands in the infrared spectral range. The power dependence of the infrared fluorescence and the two-photon upconversion fluorescence intensities as well as the corresponding radiative lifetimes have been investigated. No 'saturation' of the fluorescence intensities was observed upon increasing the excitation power.