Tunable upconversion emission in NaLuF4-glass-ceramic fibers doped with Er3+ and Yb3+

Abstract

[EN] Novel glass-ceramic optical fibers containing NaLuF nanocrystals doped with 0.5ErF and 2YbF (mol%) have been prepared by the rod-in-tube method and controlled crystallization. NaLuF nanocrystals with a size around 20 nm are obtained after heat treatment at 600 °C. Intense upconverted green and red emissions due to (H, S) → I and F → I transitions, respectively, together with a blue emission due to H → I transition have been observed under excitation at 980 nm. The intensity of the green and red upconversion bands shows a nearly linear dependence on the excitation power which can be explained by saturation effects in the intermediate energy states and proves that a sensitized energy transfer upconversion process is responsible for the population of the emitting levels of Er ions. The upconversion emission color changes from yellow to green by increasing the excitation power density which allows to manipulate the color output of the Er emission in the glass-ceramic fibers. The tunable emission color is easily detected with the naked eye. This interesting characteristic makes these glass-ceramic fibers promising materials for photonic applications.