Effect of F/O ratio on up-conversion and down-conversion luminescence properties of Er3+/Yb3+ co-doped SiO2–Al2O3–AlF3-Gd2O3–Na2O glass

Abstract

Er3+/Yb3+ co-doped SiO2–Al2O3–AlF3-Gd2O3–Na2O glass with different F/O ratios were prepared. The effect of F/O ratio on the structure and optical properties of the glasses was investigated. The amorphous nature of the glasses was determined by XRD, and the glass transition temperature (Tg) and the crystallization peak temperature (Tc) were obtained from the DSC curves. The change in the structure of the glass network was analyzed by infrared spectroscopy. The density and absorption spectra of the bulk glass was also investigated. The excitation spectrum, emission spectrum and 4S3/2 level fluorescence lifetime of Er3+ ions in the glasses were tested by a Xenon lamp with adjustable wavelength. The up-conversion luminescence spectrum of Er3+ ions was measured under excitation of a 980 nm laser. The results show that the green (2H11/2, 4S3/2) and red (4F9/2) up-conversion luminescence intensity is the highest when the F/O ratio is 0.214. According to the variation law of up-conversion luminescence intensity and pump power, it is confirmed that the up-conversion green (2H11/2 → 4I15/2, 4S3/2 → 4I15/2) and red (4F9/2 → 4I15/2) light of Er3+ ions are the three-photon absorption process based on excited state absorption (ESA) and energy transfer up-conversion (ETU) mechanism. Finally, energy transfer transitions between Er3+ and Yb3+ are also analyzed. The CIE chromaticity coordinates were calculated from the emission spectrum obtained at two different excitation wavelengths of 378 nm and 980 nm.