Polarized spectral analysis of Er 3+ ions in Er 3+:LiGd(MoO 4) 2 crystal

Abstract

The Er 3+:LiGd(MoO 4) 2 crystal with Ø21 × 33 mm 3 was grown by the Czochralski technique, and the absorption spectra, the fluorescence spectra and the fluorescence decay curves were measured at room temperature. Some spectroscopic parameters, such as the parameters of oscillator strengths, the spontaneous transition probabilities, the fluorescence branching ratios, the radiative lifetimes and the emission cross-sections were estimated based on Judd–Ofelt theory and Füchtbauer–Ladenburg method. The infrared emission at 1450–1650 nm, due to 4I 13/2 → 4I 15/2 transition and the visible emission at 520–569 nm corresponding to 2H 11/2, 4S 3/2 → 4I 15/2 transition were observed in Er 3+:LiGd(MoO 4) 2 crystals under 979 nm excitation at room temperature. The emission cross-sections are 4.37 × 10 −20 cm 2 at 553 nm and 0.584 × 10 −20 cm 2 at 1561 nm for π-polarization, and the following measured lifetimes are 4.57 ms and 10.74 μs. The upconversion emissions were attributed to energy transfer between Er 3+ ions and the excited state absorption.